Added enios dirthreshold command, patch from http://www.proxmark.org/forum/viewtopic...

[proxmark3-svn] / armsrc / iso14443a.c

diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index e60f3198cb18172747ff5e716a52c53b54cc51ac..9afe0788c666a79ac4ef2f4f9da09a6b70cabed4 100644 (file)
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -1,30 +1,131 @@
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------

-// Routines to support ISO 14443 type A.
-//
+// Merlok - June 2011, 2012

 // Gerhard de Koning Gans - May 2008
 // Gerhard de Koning Gans - May 2008

+// Hagen Fritsch - June 2010
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// Routines to support ISO 14443 type A.

 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------

+

 #include "proxmark3.h"
 #include "apps.h"
 #include "util.h"
 #include "string.h"
 #include "proxmark3.h"
 #include "apps.h"
 #include "util.h"
 #include "string.h"

+#include "cmd.h"

 
 #include "iso14443crc.h"
 
 #include "iso14443crc.h"

+#include "iso14443a.h"
+#include "crapto1.h"
+#include "mifareutil.h"
+
+static uint32_t iso14a_timeout;
+uint8_t *trace = (uint8_t *) BigBuf+TRACE_OFFSET;
+int rsamples = 0;
+int traceLen = 0;
+int tracing = TRUE;
+uint8_t trigger = 0;
+// the block number for the ISO14443-4 PCB
+static uint8_t iso14_pcb_blocknum = 0;
+
+//
+// ISO14443 timing:
+//
+// minimum time between the start bits of consecutive transfers from reader to tag: 7000 carrier (13.56Mhz) cycles
+#define REQUEST_GUARD_TIME (7000/16 + 1)
+// minimum time between last modulation of tag and next start bit from reader to tag: 1172 carrier cycles 
+#define FRAME_DELAY_TIME_PICC_TO_PCD (1172/16 + 1) 
+// bool LastCommandWasRequest = FALSE;

 
 

-static uint8_t *trace = (uint8_t *) BigBuf;
-static int traceLen = 0;
-static int rsamples = 0;
-static int tracing = TRUE;
-
-typedef enum {
-       SEC_D = 1,
-       SEC_E = 2,
-       SEC_F = 3,
-       SEC_X = 4,
-       SEC_Y = 5,
-       SEC_Z = 6
-} SecType;
-
-static const uint8_t OddByteParity[256] = {
+//
+// Total delays including SSC-Transfers between ARM and FPGA. These are in carrier clock cycles (1/13,56MHz)
+//
+// When the PM acts as reader and is receiving tag data, it takes
+// 3 ticks delay in the AD converter
+// 16 ticks until the modulation detector completes and sets curbit
+// 8 ticks until bit_to_arm is assigned from curbit
+// 8*16 ticks for the transfer from FPGA to ARM
+// 4*16 ticks until we measure the time
+// - 8*16 ticks because we measure the time of the previous transfer 
+#define DELAY_AIR2ARM_AS_READER (3 + 16 + 8 + 8*16 + 4*16 - 8*16) 
+
+// When the PM acts as a reader and is sending, it takes
+// 4*16 ticks until we can write data to the sending hold register
+// 8*16 ticks until the SHR is transferred to the Sending Shift Register
+// 8 ticks until the first transfer starts
+// 8 ticks later the FPGA samples the data
+// 1 tick to assign mod_sig_coil
+#define DELAY_ARM2AIR_AS_READER (4*16 + 8*16 + 8 + 8 + 1)
+
+// When the PM acts as tag and is receiving it takes
+// 2 ticks delay in the RF part (for the first falling edge),
+// 3 ticks for the A/D conversion,
+// 8 ticks on average until the start of the SSC transfer,
+// 8 ticks until the SSC samples the first data
+// 7*16 ticks to complete the transfer from FPGA to ARM
+// 8 ticks until the next ssp_clk rising edge
+// 4*16 ticks until we measure the time 
+// - 8*16 ticks because we measure the time of the previous transfer 
+#define DELAY_AIR2ARM_AS_TAG (2 + 3 + 8 + 8 + 7*16 + 8 + 4*16 - 8*16)
+ 
+// The FPGA will report its internal sending delay in
+uint16_t FpgaSendQueueDelay;
+// the 5 first bits are the number of bits buffered in mod_sig_buf
+// the last three bits are the remaining ticks/2 after the mod_sig_buf shift
+#define DELAY_FPGA_QUEUE (FpgaSendQueueDelay<<1)
+
+// When the PM acts as tag and is sending, it takes
+// 4*16 ticks until we can write data to the sending hold register
+// 8*16 ticks until the SHR is transferred to the Sending Shift Register
+// 8 ticks until the first transfer starts
+// 8 ticks later the FPGA samples the data
+// + a varying number of ticks in the FPGA Delay Queue (mod_sig_buf)
+// + 1 tick to assign mod_sig_coil
+#define DELAY_ARM2AIR_AS_TAG (4*16 + 8*16 + 8 + 8 + DELAY_FPGA_QUEUE + 1)
+
+// When the PM acts as sniffer and is receiving tag data, it takes
+// 3 ticks A/D conversion
+// 14 ticks to complete the modulation detection
+// 8 ticks (on average) until the result is stored in to_arm
+// + the delays in transferring data - which is the same for
+// sniffing reader and tag data and therefore not relevant
+#define DELAY_TAG_AIR2ARM_AS_SNIFFER (3 + 14 + 8) 
+ 
+// When the PM acts as sniffer and is receiving reader data, it takes
+// 2 ticks delay in analogue RF receiver (for the falling edge of the 
+// start bit, which marks the start of the communication)
+// 3 ticks A/D conversion
+// 8 ticks on average until the data is stored in to_arm.
+// + the delays in transferring data - which is the same for
+// sniffing reader and tag data and therefore not relevant
+#define DELAY_READER_AIR2ARM_AS_SNIFFER (2 + 3 + 8) 
+
+//variables used for timing purposes:
+//these are in ssp_clk cycles:
+uint32_t NextTransferTime;
+uint32_t LastTimeProxToAirStart;
+uint32_t LastProxToAirDuration;
+
+
+
+// CARD TO READER - manchester
+// Sequence D: 11110000 modulation with subcarrier during first half
+// Sequence E: 00001111 modulation with subcarrier during second half
+// Sequence F: 00000000 no modulation with subcarrier
+// READER TO CARD - miller
+// Sequence X: 00001100 drop after half a period
+// Sequence Y: 00000000 no drop
+// Sequence Z: 11000000 drop at start
+#define        SEC_D 0xf0
+#define        SEC_E 0x0f
+#define        SEC_F 0x00
+#define        SEC_X 0x0c
+#define        SEC_Y 0x00
+#define        SEC_Z 0xc0
+
+const uint8_t OddByteParity[256] = {

   1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
   0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
   0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
   1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
   0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
   0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,


@@ -43,543 +144,347 @@ static const uint8_t OddByteParity[256] = {
   1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
 };
 
   1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
 };
 

-// BIG CHANGE - UNDERSTAND THIS BEFORE WE COMMIT
-#define RECV_CMD_OFFSET   3032
-#define RECV_RES_OFFSET   3096
-#define DMA_BUFFER_OFFSET 3160
-#define DMA_BUFFER_SIZE   4096
-#define TRACE_LENGTH      3000
+
+void iso14a_set_trigger(bool enable) {
+       trigger = enable;
+}
+
+void iso14a_clear_trace() {
+       memset(trace, 0x44, TRACE_SIZE);
+       traceLen = 0;
+}
+
+void iso14a_set_tracing(bool enable) {
+       tracing = enable;
+}
+
+void iso14a_set_timeout(uint32_t timeout) {
+       iso14a_timeout = timeout;
+}

 
 //-----------------------------------------------------------------------------
 // Generate the parity value for a byte sequence
 //
 //-----------------------------------------------------------------------------
 
 //-----------------------------------------------------------------------------
 // Generate the parity value for a byte sequence
 //
 //-----------------------------------------------------------------------------

-uint32_t GetParity(const uint8_t * pbtCmd, int iLen)
+byte_t oddparity (const byte_t bt)

 {
 {

-  int i;
-  uint32_t dwPar = 0;
-
-  // Generate the encrypted data
-  for (i = 0; i < iLen; i++) {
-    // Save the encrypted parity bit
-    dwPar |= ((OddByteParity[pbtCmd[i]]) << i);
-  }
-  return dwPar;
+       return OddByteParity[bt];

 }
 
 }
 

-static void AppendCrc14443a(uint8_t* data, int len)
+uint32_t GetParity(const uint8_t * pbtCmd, int iLen)

 {
 {

-  ComputeCrc14443(CRC_14443_A,data,len,data+len,data+len+1);
-}
+       int i;
+       uint32_t dwPar = 0;

 
 

-int LogTrace(const uint8_t * btBytes, int iLen, int iSamples, uint32_t dwParity, int bReader)
-{
-  // Return when trace is full
-  if (traceLen >= TRACE_LENGTH) return FALSE;
-
-  // Trace the random, i'm curious
-  rsamples += iSamples;
-  trace[traceLen++] = ((rsamples >> 0) & 0xff);
-  trace[traceLen++] = ((rsamples >> 8) & 0xff);
-  trace[traceLen++] = ((rsamples >> 16) & 0xff);
-  trace[traceLen++] = ((rsamples >> 24) & 0xff);
-  if (!bReader) {
-    trace[traceLen - 1] |= 0x80;
-  }
-  trace[traceLen++] = ((dwParity >> 0) & 0xff);
-  trace[traceLen++] = ((dwParity >> 8) & 0xff);
-  trace[traceLen++] = ((dwParity >> 16) & 0xff);
-  trace[traceLen++] = ((dwParity >> 24) & 0xff);
-  trace[traceLen++] = iLen;
-  memcpy(trace + traceLen, btBytes, iLen);
-  traceLen += iLen;
-  return TRUE;
+       // Generate the parity bits
+       for (i = 0; i < iLen; i++) {
+               // and save them to a 32Bit word
+               dwPar |= ((OddByteParity[pbtCmd[i]]) << i);
+       }
+       return dwPar;

 }
 
 }
 

-int LogTraceInfo(byte_t* data, size_t len)
+void AppendCrc14443a(uint8_t* data, int len)

 {
 {

-  return LogTrace(data,len,0,GetParity(data,len),TRUE);
+       ComputeCrc14443(CRC_14443_A,data,len,data+len,data+len+1);

 }
 
 }
 

-//-----------------------------------------------------------------------------
-// The software UART that receives commands from the reader, and its state
-// variables.
-//-----------------------------------------------------------------------------
-static struct {
-    enum {
-        STATE_UNSYNCD,
-        STATE_START_OF_COMMUNICATION,
-               STATE_MILLER_X,
-               STATE_MILLER_Y,
-               STATE_MILLER_Z,
-        STATE_ERROR_WAIT
-    }       state;
-    uint16_t    shiftReg;
-    int     bitCnt;
-    int     byteCnt;
-    int     byteCntMax;
-    int     posCnt;
-    int     syncBit;
-       int     parityBits;
-       int     samples;
-    int     highCnt;
-    int     bitBuffer;
-       enum {
-               DROP_NONE,
-               DROP_FIRST_HALF,
-               DROP_SECOND_HALF
-       }               drop;
-    uint8_t   *output;
-} Uart;
-
-static int MillerDecoding(int bit)
+// The function LogTrace() is also used by the iClass implementation in iClass.c
+bool RAMFUNC LogTrace(const uint8_t * btBytes, uint8_t iLen, uint32_t timestamp, uint32_t dwParity, bool bReader)

 {
 {

-       int error = 0;
-       int bitright;
-
-       if(!Uart.bitBuffer) {
-               Uart.bitBuffer = bit ^ 0xFF0;
+       // Return when trace is full
+       if (traceLen + sizeof(timestamp) + sizeof(dwParity) + iLen >= TRACE_SIZE) {
+               tracing = FALSE;        // don't trace any more

                return FALSE;
        }
                return FALSE;
        }

-       else {
-               Uart.bitBuffer <<= 4;
-               Uart.bitBuffer ^= bit;
+       
+       // Trace the random, i'm curious
+       trace[traceLen++] = ((timestamp >> 0) & 0xff);
+       trace[traceLen++] = ((timestamp >> 8) & 0xff);
+       trace[traceLen++] = ((timestamp >> 16) & 0xff);
+       trace[traceLen++] = ((timestamp >> 24) & 0xff);
+       if (!bReader) {
+               trace[traceLen - 1] |= 0x80;

        }
        }

+       trace[traceLen++] = ((dwParity >> 0) & 0xff);
+       trace[traceLen++] = ((dwParity >> 8) & 0xff);
+       trace[traceLen++] = ((dwParity >> 16) & 0xff);
+       trace[traceLen++] = ((dwParity >> 24) & 0xff);
+       trace[traceLen++] = iLen;
+       if (btBytes != NULL && iLen != 0) {
+               memcpy(trace + traceLen, btBytes, iLen);
+       }
+       traceLen += iLen;
+       return TRUE;
+}

 
 

-       int EOC = FALSE;
-
-       if(Uart.state != STATE_UNSYNCD) {
-               Uart.posCnt++;
-
-               if((Uart.bitBuffer & Uart.syncBit) ^ Uart.syncBit) {
-                       bit = 0x00;
-               }
-               else {
-                       bit = 0x01;
-               }
-               if(((Uart.bitBuffer << 1) & Uart.syncBit) ^ Uart.syncBit) {
-                       bitright = 0x00;
-               }
-               else {
-                       bitright = 0x01;
-               }
-               if(bit != bitright) { bit = bitright; }
-
-               if(Uart.posCnt == 1) {
-                       // measurement first half bitperiod
-                       if(!bit) {
-                               Uart.drop = DROP_FIRST_HALF;
-                       }
-               }
-               else {
-                       // measurement second half bitperiod
-                       if(!bit & (Uart.drop == DROP_NONE)) {
-                               Uart.drop = DROP_SECOND_HALF;
-                       }
-                       else if(!bit) {
-                               // measured a drop in first and second half
-                               // which should not be possible
-                               Uart.state = STATE_ERROR_WAIT;
-                               error = 0x01;
-                       }
-
-                       Uart.posCnt = 0;
-
-                       switch(Uart.state) {
-                               case STATE_START_OF_COMMUNICATION:
-                                       Uart.shiftReg = 0;
-                                       if(Uart.drop == DROP_SECOND_HALF) {
-                                               // error, should not happen in SOC
-                                               Uart.state = STATE_ERROR_WAIT;
-                                               error = 0x02;
-                                       }
-                                       else {
-                                               // correct SOC
-                                               Uart.state = STATE_MILLER_Z;
-                                       }
-                                       break;
+//=============================================================================
+// ISO 14443 Type A - Miller decoder
+//=============================================================================
+// Basics:
+// This decoder is used when the PM3 acts as a tag.
+// The reader will generate "pauses" by temporarily switching of the field. 
+// At the PM3 antenna we will therefore measure a modulated antenna voltage. 
+// The FPGA does a comparison with a threshold and would deliver e.g.:
+// ........  1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1  .......
+// The Miller decoder needs to identify the following sequences:
+// 2 (or 3) ticks pause followed by 6 (or 5) ticks unmodulated:        pause at beginning - Sequence Z ("start of communication" or a "0")
+// 8 ticks without a modulation:                                                                       no pause - Sequence Y (a "0" or "end of communication" or "no information")
+// 4 ticks unmodulated followed by 2 (or 3) ticks pause:                       pause in second half - Sequence X (a "1")
+// Note 1: the bitstream may start at any time. We therefore need to sync.
+// Note 2: the interpretation of Sequence Y and Z depends on the preceding sequence.
+//-----------------------------------------------------------------------------
+static tUart Uart;

 
 

-                               case STATE_MILLER_Z:
-                                       Uart.bitCnt++;
-                                       Uart.shiftReg >>= 1;
-                                       if(Uart.drop == DROP_NONE) {
-                                               // logic '0' followed by sequence Y
-                                               // end of communication
-                                               Uart.state = STATE_UNSYNCD;
-                                               EOC = TRUE;
-                                       }
-                                       // if(Uart.drop == DROP_FIRST_HALF) {
-                                       //      Uart.state = STATE_MILLER_Z; stay the same
-                                       //      we see a logic '0' }
-                                       if(Uart.drop == DROP_SECOND_HALF) {
-                                               // we see a logic '1'
-                                               Uart.shiftReg |= 0x100;
-                                               Uart.state = STATE_MILLER_X;
-                                       }
-                                       break;
+// Lookup-Table to decide if 4 raw bits are a modulation.
+// We accept two or three consecutive "0" in any position with the rest "1"
+const bool Mod_Miller_LUT[] = {
+       TRUE,  TRUE,  FALSE, TRUE,  FALSE, FALSE, FALSE, FALSE,
+       TRUE,  TRUE,  FALSE, FALSE, TRUE,  FALSE, FALSE, FALSE
+};
+#define IsMillerModulationNibble1(b) (Mod_Miller_LUT[(b & 0x00F0) >> 4])
+#define IsMillerModulationNibble2(b) (Mod_Miller_LUT[(b & 0x000F)])

 
 

-                               case STATE_MILLER_X:
-                                       Uart.shiftReg >>= 1;
-                                       if(Uart.drop == DROP_NONE) {
-                                               // sequence Y, we see a '0'
-                                               Uart.state = STATE_MILLER_Y;
-                                               Uart.bitCnt++;
-                                       }
-                                       if(Uart.drop == DROP_FIRST_HALF) {
-                                               // Would be STATE_MILLER_Z
-                                               // but Z does not follow X, so error
-                                               Uart.state = STATE_ERROR_WAIT;
-                                               error = 0x03;
-                                       }
-                                       if(Uart.drop == DROP_SECOND_HALF) {
-                                               // We see a '1' and stay in state X
-                                               Uart.shiftReg |= 0x100;
-                                               Uart.bitCnt++;
-                                       }
-                                       break;
+void UartReset()
+{
+       Uart.state = STATE_UNSYNCD;
+       Uart.bitCount = 0;
+       Uart.len = 0;                                           // number of decoded data bytes
+       Uart.shiftReg = 0;                                      // shiftreg to hold decoded data bits
+       Uart.parityBits = 0;                            // 
+       Uart.twoBits = 0x0000;                          // buffer for 2 Bits
+       Uart.highCnt = 0;
+       Uart.startTime = 0;
+       Uart.endTime = 0;
+}

 
 

-                               case STATE_MILLER_Y:
-                                       Uart.bitCnt++;
-                                       Uart.shiftReg >>= 1;
-                                       if(Uart.drop == DROP_NONE) {
-                                               // logic '0' followed by sequence Y
-                                               // end of communication
-                                               Uart.state = STATE_UNSYNCD;
-                                               EOC = TRUE;
-                                       }
-                                       if(Uart.drop == DROP_FIRST_HALF) {
-                                               // we see a '0'
-                                               Uart.state = STATE_MILLER_Z;
-                                       }
-                                       if(Uart.drop == DROP_SECOND_HALF) {
-                                               // We see a '1' and go to state X
-                                               Uart.shiftReg |= 0x100;
-                                               Uart.state = STATE_MILLER_X;
-                                       }
-                                       break;

 
 

-                               case STATE_ERROR_WAIT:
-                                       // That went wrong. Now wait for at least two bit periods
-                                       // and try to sync again
-                                       if(Uart.drop == DROP_NONE) {
-                                               Uart.highCnt = 6;
-                                               Uart.state = STATE_UNSYNCD;
-                                       }
-                                       break;
+// use parameter non_real_time to provide a timestamp. Set to 0 if the decoder should measure real time
+static RAMFUNC bool MillerDecoding(uint8_t bit, uint32_t non_real_time)
+{

 
 

-                               default:
-                                       Uart.state = STATE_UNSYNCD;
-                                       Uart.highCnt = 0;
-                                       break;
+       Uart.twoBits = (Uart.twoBits << 8) | bit;
+       
+       if (Uart.state == STATE_UNSYNCD) {                                                                                              // not yet synced
+               if (Uart.highCnt < 7) {                                                                                                 // wait for a stable unmodulated signal
+                       if (Uart.twoBits == 0xffff) {
+                               Uart.highCnt++;
+                       } else {
+                               Uart.highCnt = 0;

                        }
                        }

-
-                       Uart.drop = DROP_NONE;
-
-                       // should have received at least one whole byte...
-                       if((Uart.bitCnt == 2) && EOC && (Uart.byteCnt > 0)) {
-                               return TRUE;
+               } else {        
+                       Uart.syncBit = 0xFFFF; // not set
+                       // look for 00xx1111 (the start bit)
+                       if              ((Uart.twoBits & 0x6780) == 0x0780) Uart.syncBit = 7; 
+                       else if ((Uart.twoBits & 0x33C0) == 0x03C0) Uart.syncBit = 6;
+                       else if ((Uart.twoBits & 0x19E0) == 0x01E0) Uart.syncBit = 5;
+                       else if ((Uart.twoBits & 0x0CF0) == 0x00F0) Uart.syncBit = 4;
+                       else if ((Uart.twoBits & 0x0678) == 0x0078) Uart.syncBit = 3;
+                       else if ((Uart.twoBits & 0x033C) == 0x003C) Uart.syncBit = 2;
+                       else if ((Uart.twoBits & 0x019E) == 0x001E) Uart.syncBit = 1;
+                       else if ((Uart.twoBits & 0x00CF) == 0x000F) Uart.syncBit = 0;
+                       if (Uart.syncBit != 0xFFFF) {
+                               Uart.startTime = non_real_time?non_real_time:(GetCountSspClk() & 0xfffffff8);
+                               Uart.startTime -= Uart.syncBit;
+                               Uart.endTime = Uart.startTime;
+                               Uart.state = STATE_START_OF_COMMUNICATION;

                        }
                        }

+               }

 
 

-                       if(Uart.bitCnt == 9) {
-                               Uart.output[Uart.byteCnt] = (Uart.shiftReg & 0xff);
-                               Uart.byteCnt++;
-
-                               Uart.parityBits <<= 1;
-                               Uart.parityBits ^= ((Uart.shiftReg >> 8) & 0x01);
+       } else {

 
 

-                               if(EOC) {
-                                       // when End of Communication received and
-                                       // all data bits processed..
-                                       return TRUE;
+               if (IsMillerModulationNibble1(Uart.twoBits >> Uart.syncBit)) {                  
+                       if (IsMillerModulationNibble2(Uart.twoBits >> Uart.syncBit)) {          // Modulation in both halves - error
+                               UartReset();
+                               Uart.highCnt = 6;
+                       } else {                                                                                                                        // Modulation in first half = Sequence Z = logic "0"
+                               if (Uart.state == STATE_MILLER_X) {                                                             // error - must not follow after X
+                                       UartReset();
+                                       Uart.highCnt = 6;
+                               } else {
+                                       Uart.bitCount++;
+                                       Uart.shiftReg = (Uart.shiftReg >> 1);                                           // add a 0 to the shiftreg
+                                       Uart.state = STATE_MILLER_Z;
+                                       Uart.endTime = Uart.startTime + 8*(9*Uart.len + Uart.bitCount + 1) - 6;
+                                       if(Uart.bitCount >= 9) {                                                                        // if we decoded a full byte (including parity)
+                                               Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
+                                               Uart.parityBits <<= 1;                                                                  // make room for the parity bit
+                                               Uart.parityBits |= ((Uart.shiftReg >> 8) & 0x01);               // store parity bit
+                                               Uart.bitCount = 0;
+                                               Uart.shiftReg = 0;
+                                       }

                                }
                                }

-                               Uart.bitCnt = 0;

                        }
                        }

-
-                       /*if(error) {
-                               Uart.output[Uart.byteCnt] = 0xAA;
-                               Uart.byteCnt++;
-                               Uart.output[Uart.byteCnt] = error & 0xFF;
-                               Uart.byteCnt++;
-                               Uart.output[Uart.byteCnt] = 0xAA;
-                               Uart.byteCnt++;
-                               Uart.output[Uart.byteCnt] = (Uart.bitBuffer >> 8) & 0xFF;
-                               Uart.byteCnt++;
-                               Uart.output[Uart.byteCnt] = Uart.bitBuffer & 0xFF;
-                               Uart.byteCnt++;
-                               Uart.output[Uart.byteCnt] = (Uart.syncBit >> 3) & 0xFF;
-                               Uart.byteCnt++;
-                               Uart.output[Uart.byteCnt] = 0xAA;
-                               Uart.byteCnt++;
-                               return TRUE;
-                       }*/
-               }
-
-       }
-       else {
-               bit = Uart.bitBuffer & 0xf0;
-               bit >>= 4;
-               bit ^= 0x0F;
-               if(bit) {
-                       // should have been high or at least (4 * 128) / fc
-                       // according to ISO this should be at least (9 * 128 + 20) / fc
-                       if(Uart.highCnt == 8) {
-                               // we went low, so this could be start of communication
-                               // it turns out to be safer to choose a less significant
-                               // syncbit... so we check whether the neighbour also represents the drop
-                               Uart.posCnt = 1;   // apparently we are busy with our first half bit period
-                               Uart.syncBit = bit & 8;
-                               Uart.samples = 3;
-                               if(!Uart.syncBit)       { Uart.syncBit = bit & 4; Uart.samples = 2; }
-                               else if(bit & 4)        { Uart.syncBit = bit & 4; Uart.samples = 2; bit <<= 2; }
-                               if(!Uart.syncBit)       { Uart.syncBit = bit & 2; Uart.samples = 1; }
-                               else if(bit & 2)        { Uart.syncBit = bit & 2; Uart.samples = 1; bit <<= 1; }
-                               if(!Uart.syncBit)       { Uart.syncBit = bit & 1; Uart.samples = 0;
-                                       if(Uart.syncBit & (Uart.bitBuffer & 8)) {
-                                               Uart.syncBit = 8;
-
-                                               // the first half bit period is expected in next sample
-                                               Uart.posCnt = 0;
-                                               Uart.samples = 3;
+               } else {
+                       if (IsMillerModulationNibble2(Uart.twoBits >> Uart.syncBit)) {          // Modulation second half = Sequence X = logic "1"
+                               Uart.bitCount++;
+                               Uart.shiftReg = (Uart.shiftReg >> 1) | 0x100;                                   // add a 1 to the shiftreg
+                               Uart.state = STATE_MILLER_X;
+                               Uart.endTime = Uart.startTime + 8*(9*Uart.len + Uart.bitCount + 1) - 2;
+                               if(Uart.bitCount >= 9) {                                                                                // if we decoded a full byte (including parity)
+                                       Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
+                                       Uart.parityBits <<= 1;                                                                          // make room for the new parity bit
+                                       Uart.parityBits |= ((Uart.shiftReg >> 8) & 0x01);                       // store parity bit
+                                       Uart.bitCount = 0;
+                                       Uart.shiftReg = 0;
+                               }
+                       } else {                                                                                                                        // no modulation in both halves - Sequence Y
+                               if (Uart.state == STATE_MILLER_Z || Uart.state == STATE_MILLER_Y) {     // Y after logic "0" - End of Communication
+                                       Uart.state = STATE_UNSYNCD;
+                                       if(Uart.len == 0 && Uart.bitCount > 0) {                                                                                // if we decoded some bits
+                                               Uart.shiftReg >>= (9 - Uart.bitCount);                                  // add them to the output
+                                               Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
+                                               Uart.parityBits <<= 1;                                                                  // no parity bit - add "0"
+                                               Uart.bitCount--;                                                                                // last "0" was part of the EOC sequence
+                                       }
+                                       return TRUE;
+                               }
+                               if (Uart.state == STATE_START_OF_COMMUNICATION) {                               // error - must not follow directly after SOC
+                                       UartReset();
+                                       Uart.highCnt = 6;
+                               } else {                                                                                                                // a logic "0"
+                                       Uart.bitCount++;
+                                       Uart.shiftReg = (Uart.shiftReg >> 1);                                           // add a 0 to the shiftreg
+                                       Uart.state = STATE_MILLER_Y;
+                                       if(Uart.bitCount >= 9) {                                                                        // if we decoded a full byte (including parity)
+                                               Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
+                                               Uart.parityBits <<= 1;                                                                  // make room for the parity bit
+                                               Uart.parityBits |= ((Uart.shiftReg >> 8) & 0x01);               // store parity bit
+                                               Uart.bitCount = 0;
+                                               Uart.shiftReg = 0;

                                        }
                                }
                                        }
                                }

-                               else if(bit & 1)        { Uart.syncBit = bit & 1; Uart.samples = 0; }
-
-                               Uart.syncBit <<= 4;
-                               Uart.state = STATE_START_OF_COMMUNICATION;
-                               Uart.drop = DROP_FIRST_HALF;
-                               Uart.bitCnt = 0;
-                               Uart.byteCnt = 0;
-                               Uart.parityBits = 0;
-                               error = 0;
-                       }
-                       else {
-                               Uart.highCnt = 0;
-                       }
-               }
-               else {
-                       if(Uart.highCnt < 8) {
-                               Uart.highCnt++;

                        }
                }
                        }
                }

-       }
+                       
+       } 

 
 

-    return FALSE;
+    return FALSE;      // not finished yet, need more data

 }
 
 }
 

+
+

 //=============================================================================
 //=============================================================================

-// ISO 14443 Type A - Manchester
+// ISO 14443 Type A - Manchester decoder

 //=============================================================================
 //=============================================================================

+// Basics:
+// This decoder is used when the PM3 acts as a reader.
+// The tag will modulate the reader field by asserting different loads to it. As a consequence, the voltage
+// at the reader antenna will be modulated as well. The FPGA detects the modulation for us and would deliver e.g. the following:
+// ........ 0 0 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .......
+// The Manchester decoder needs to identify the following sequences:
+// 4 ticks modulated followed by 4 ticks unmodulated:  Sequence D = 1 (also used as "start of communication")
+// 4 ticks unmodulated followed by 4 ticks modulated:  Sequence E = 0
+// 8 ticks unmodulated:                                                                        Sequence F = end of communication
+// 8 ticks modulated:                                                                  A collision. Save the collision position and treat as Sequence D
+// Note 1: the bitstream may start at any time. We therefore need to sync.
+// Note 2: parameter offset is used to determine the position of the parity bits (required for the anticollision command only)
+static tDemod Demod;
+
+// Lookup-Table to decide if 4 raw bits are a modulation.
+// We accept three or four "1" in any position
+const bool Mod_Manchester_LUT[] = {
+       FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, TRUE,
+       FALSE, FALSE, FALSE, TRUE,  FALSE, TRUE,  TRUE,  TRUE
+};

 
 

-static struct {
-    enum {
-        DEMOD_UNSYNCD,
-               DEMOD_START_OF_COMMUNICATION,
-               DEMOD_MANCHESTER_D,
-               DEMOD_MANCHESTER_E,
-               DEMOD_MANCHESTER_F,
-        DEMOD_ERROR_WAIT
-    }       state;
-    int     bitCount;
-    int     posCount;
-       int     syncBit;
-       int     parityBits;
-    uint16_t    shiftReg;
-       int     buffer;
-       int     buff;
-       int     samples;
-    int     len;
-       enum {
-               SUB_NONE,
-               SUB_FIRST_HALF,
-               SUB_SECOND_HALF
-       }               sub;
-    uint8_t   *output;
-} Demod;
-
-static int ManchesterDecoding(int v)
-{
-       int bit;
-       int modulation;
-       int error = 0;
-
-       if(!Demod.buff) {
-               Demod.buff = 1;
-               Demod.buffer = v;
-               return FALSE;
-       }
-       else {
-               bit = Demod.buffer;
-               Demod.buffer = v;
-       }
+#define IsManchesterModulationNibble1(b) (Mod_Manchester_LUT[(b & 0x00F0) >> 4])
+#define IsManchesterModulationNibble2(b) (Mod_Manchester_LUT[(b & 0x000F)])

 
 

-       if(Demod.state==DEMOD_UNSYNCD) {
-               Demod.output[Demod.len] = 0xfa;
-               Demod.syncBit = 0;
-               //Demod.samples = 0;
-               Demod.posCount = 1;             // This is the first half bit period, so after syncing handle the second part
-               if(bit & 0x08) { Demod.syncBit = 0x08; }
-               if(!Demod.syncBit)      {
-                       if(bit & 0x04) { Demod.syncBit = 0x04; }
-               }
-               else if(bit & 0x04) { Demod.syncBit = 0x04; bit <<= 4; }
-               if(!Demod.syncBit)      {
-                       if(bit & 0x02) { Demod.syncBit = 0x02; }
-               }
-               else if(bit & 0x02) { Demod.syncBit = 0x02; bit <<= 4; }
-               if(!Demod.syncBit)      {
-                       if(bit & 0x01) { Demod.syncBit = 0x01; }

 
 

-                       if(Demod.syncBit & (Demod.buffer & 0x08)) {
-                               Demod.syncBit = 0x08;
+void DemodReset()
+{
+       Demod.state = DEMOD_UNSYNCD;
+       Demod.len = 0;                                          // number of decoded data bytes
+       Demod.shiftReg = 0;                                     // shiftreg to hold decoded data bits
+       Demod.parityBits = 0;                           // 
+       Demod.collisionPos = 0;                         // Position of collision bit
+       Demod.twoBits = 0xffff;                         // buffer for 2 Bits
+       Demod.highCnt = 0;
+       Demod.startTime = 0;
+       Demod.endTime = 0;
+}

 
 

-                               // The first half bitperiod is expected in next sample
-                               Demod.posCount = 0;
-                               Demod.output[Demod.len] = 0xfb;
-                       }
-               }
-               else if(bit & 0x01) { Demod.syncBit = 0x01; }
-
-               if(Demod.syncBit) {
-                       Demod.len = 0;
-                       Demod.state = DEMOD_START_OF_COMMUNICATION;
-                       Demod.sub = SUB_FIRST_HALF;
-                       Demod.bitCount = 0;
-                       Demod.shiftReg = 0;
-                       Demod.parityBits = 0;
-                       Demod.samples = 0;
-                       if(Demod.posCount) {
-                               switch(Demod.syncBit) {
-                                       case 0x08: Demod.samples = 3; break;
-                                       case 0x04: Demod.samples = 2; break;
-                                       case 0x02: Demod.samples = 1; break;
-                                       case 0x01: Demod.samples = 0; break;
-                               }
-                       }
-                       error = 0;
-               }
-       }
-       else {
-               //modulation = bit & Demod.syncBit;
-               modulation = ((bit << 1) ^ ((Demod.buffer & 0x08) >> 3)) & Demod.syncBit;
+// use parameter non_real_time to provide a timestamp. Set to 0 if the decoder should measure real time
+static RAMFUNC int ManchesterDecoding(uint8_t bit, uint16_t offset, uint32_t non_real_time)
+{

 
 

-               Demod.samples += 4;
+       Demod.twoBits = (Demod.twoBits << 8) | bit;
+       
+       if (Demod.state == DEMOD_UNSYNCD) {

 
 

-               if(Demod.posCount==0) {
-                       Demod.posCount = 1;
-                       if(modulation) {
-                               Demod.sub = SUB_FIRST_HALF;
+               if (Demod.highCnt < 2) {                                                                                        // wait for a stable unmodulated signal
+                       if (Demod.twoBits == 0x0000) {
+                               Demod.highCnt++;
+                       } else {
+                               Demod.highCnt = 0;

                        }
                        }

-                       else {
-                               Demod.sub = SUB_NONE;
+               } else {
+                       Demod.syncBit = 0xFFFF;                 // not set
+                       if              ((Demod.twoBits & 0x7700) == 0x7000) Demod.syncBit = 7; 
+                       else if ((Demod.twoBits & 0x3B80) == 0x3800) Demod.syncBit = 6;
+                       else if ((Demod.twoBits & 0x1DC0) == 0x1C00) Demod.syncBit = 5;
+                       else if ((Demod.twoBits & 0x0EE0) == 0x0E00) Demod.syncBit = 4;
+                       else if ((Demod.twoBits & 0x0770) == 0x0700) Demod.syncBit = 3;
+                       else if ((Demod.twoBits & 0x03B8) == 0x0380) Demod.syncBit = 2;
+                       else if ((Demod.twoBits & 0x01DC) == 0x01C0) Demod.syncBit = 1;
+                       else if ((Demod.twoBits & 0x00EE) == 0x00E0) Demod.syncBit = 0;
+                       if (Demod.syncBit != 0xFFFF) {
+                               Demod.startTime = non_real_time?non_real_time:(GetCountSspClk() & 0xfffffff8);
+                               Demod.startTime -= Demod.syncBit;
+                               Demod.bitCount = offset;                        // number of decoded data bits
+                               Demod.state = DEMOD_MANCHESTER_DATA;

                        }
                }
                        }
                }

-               else {
-                       Demod.posCount = 0;
-                       if(modulation && (Demod.sub == SUB_FIRST_HALF)) {
-                               if(Demod.state!=DEMOD_ERROR_WAIT) {
-                                       Demod.state = DEMOD_ERROR_WAIT;
-                                       Demod.output[Demod.len] = 0xaa;
-                                       error = 0x01;
-                               }
-                       }
-                       else if(modulation) {
-                               Demod.sub = SUB_SECOND_HALF;
-                       }
-
-                       switch(Demod.state) {
-                               case DEMOD_START_OF_COMMUNICATION:
-                                       if(Demod.sub == SUB_FIRST_HALF) {
-                                               Demod.state = DEMOD_MANCHESTER_D;
-                                       }
-                                       else {
-                                               Demod.output[Demod.len] = 0xab;
-                                               Demod.state = DEMOD_ERROR_WAIT;
-                                               error = 0x02;
-                                       }
-                                       break;
-
-                               case DEMOD_MANCHESTER_D:
-                               case DEMOD_MANCHESTER_E:
-                                       if(Demod.sub == SUB_FIRST_HALF) {
-                                               Demod.bitCount++;
-                                               Demod.shiftReg = (Demod.shiftReg >> 1) ^ 0x100;
-                                               Demod.state = DEMOD_MANCHESTER_D;
-                                       }
-                                       else if(Demod.sub == SUB_SECOND_HALF) {
-                                               Demod.bitCount++;
-                                               Demod.shiftReg >>= 1;
-                                               Demod.state = DEMOD_MANCHESTER_E;
-                                       }
-                                       else {
-                                               Demod.state = DEMOD_MANCHESTER_F;
-                                       }
-                                       break;
-
-                               case DEMOD_MANCHESTER_F:
-                                       // Tag response does not need to be a complete byte!
-                                       if(Demod.len > 0 || Demod.bitCount > 0) {
-                                               if(Demod.bitCount > 0) {
-                                                       Demod.shiftReg >>= (9 - Demod.bitCount);
-                                                       Demod.output[Demod.len] = Demod.shiftReg & 0xff;
-                                                       Demod.len++;
-                                                       // No parity bit, so just shift a 0
-                                                       Demod.parityBits <<= 1;
-                                               }
-
-                                               Demod.state = DEMOD_UNSYNCD;
-                                               return TRUE;
-                                       }
-                                       else {
-                                               Demod.output[Demod.len] = 0xad;
-                                               Demod.state = DEMOD_ERROR_WAIT;
-                                               error = 0x03;
-                                       }
-                                       break;
-
-                               case DEMOD_ERROR_WAIT:
-                                       Demod.state = DEMOD_UNSYNCD;
-                                       break;
-
-                               default:
-                                       Demod.output[Demod.len] = 0xdd;
-                                       Demod.state = DEMOD_UNSYNCD;
-                                       break;
-                       }

 
 

-                       if(Demod.bitCount>=9) {
-                               Demod.output[Demod.len] = Demod.shiftReg & 0xff;
-                               Demod.len++;
-
-                               Demod.parityBits <<= 1;
-                               Demod.parityBits ^= ((Demod.shiftReg >> 8) & 0x01);
+       } else {

 
 

+               if (IsManchesterModulationNibble1(Demod.twoBits >> Demod.syncBit)) {            // modulation in first half
+                       if (IsManchesterModulationNibble2(Demod.twoBits >> Demod.syncBit)) {    // ... and in second half = collision
+                               if (!Demod.collisionPos) {
+                                       Demod.collisionPos = (Demod.len << 3) + Demod.bitCount;
+                               }
+                       }                                                                                                                       // modulation in first half only - Sequence D = 1
+                       Demod.bitCount++;
+                       Demod.shiftReg = (Demod.shiftReg >> 1) | 0x100;                         // in both cases, add a 1 to the shiftreg
+                       if(Demod.bitCount == 9) {                                                                       // if we decoded a full byte (including parity)
+                               Demod.output[Demod.len++] = (Demod.shiftReg & 0xff);
+                               Demod.parityBits <<= 1;                                                                 // make room for the parity bit
+                               Demod.parityBits |= ((Demod.shiftReg >> 8) & 0x01);     // store parity bit

                                Demod.bitCount = 0;
                                Demod.shiftReg = 0;
                        }
                                Demod.bitCount = 0;
                                Demod.shiftReg = 0;
                        }

-
-                       /*if(error) {
-                               Demod.output[Demod.len] = 0xBB;
-                               Demod.len++;
-                               Demod.output[Demod.len] = error & 0xFF;
-                               Demod.len++;
-                               Demod.output[Demod.len] = 0xBB;
-                               Demod.len++;
-                               Demod.output[Demod.len] = bit & 0xFF;
-                               Demod.len++;
-                               Demod.output[Demod.len] = Demod.buffer & 0xFF;
-                               Demod.len++;
-                               Demod.output[Demod.len] = Demod.syncBit & 0xFF;
-                               Demod.len++;
-                               Demod.output[Demod.len] = 0xBB;
-                               Demod.len++;
-                               return TRUE;
-                       }*/
-
+                       Demod.endTime = Demod.startTime + 8*(9*Demod.len + Demod.bitCount + 1) - 4;
+               } else {                                                                                                                // no modulation in first half
+                       if (IsManchesterModulationNibble2(Demod.twoBits >> Demod.syncBit)) {    // and modulation in second half = Sequence E = 0
+                               Demod.bitCount++;
+                               Demod.shiftReg = (Demod.shiftReg >> 1);                                 // add a 0 to the shiftreg
+                               if(Demod.bitCount >= 9) {                                                               // if we decoded a full byte (including parity)
+                                       Demod.output[Demod.len++] = (Demod.shiftReg & 0xff);
+                                       Demod.parityBits <<= 1;                                                         // make room for the new parity bit
+                                       Demod.parityBits |= ((Demod.shiftReg >> 8) & 0x01); // store parity bit
+                                       Demod.bitCount = 0;
+                                       Demod.shiftReg = 0;
+                               }
+                               Demod.endTime = Demod.startTime + 8*(9*Demod.len + Demod.bitCount + 1);
+                       } else {                                                                                                        // no modulation in both halves - End of communication
+                               if (Demod.len > 0 || Demod.bitCount > 0) {                              // received something
+                                       if(Demod.bitCount > 0) {                                                        // if we decoded bits
+                                               Demod.shiftReg >>= (9 - Demod.bitCount);                // add the remaining decoded bits to the output
+                                               Demod.output[Demod.len++] = Demod.shiftReg & 0xff;
+                                               // No parity bit, so just shift a 0
+                                               Demod.parityBits <<= 1;
+                                       }
+                                       return TRUE;                                                                            // we are finished with decoding the raw data sequence
+                               } else {                                                                                                // nothing received. Start over
+                                       DemodReset();
+                               }
+                       }

                }
                }

+                       
+       } 

 
 

-       } // end (state != UNSYNCED)
-
-    return FALSE;
+    return FALSE;      // not finished yet, need more data

 }
 
 //=============================================================================
 }
 
 //=============================================================================


@@ -592,221 +497,160 @@ static int ManchesterDecoding(int v)
 // triggering so that we start recording at the point that the tag is moved
 // near the reader.
 //-----------------------------------------------------------------------------
 // triggering so that we start recording at the point that the tag is moved
 // near the reader.
 //-----------------------------------------------------------------------------

-void SnoopIso14443a(void)
-{
-//     #define RECV_CMD_OFFSET         2032    // original (working as of 21/2/09) values
-//     #define RECV_RES_OFFSET         2096    // original (working as of 21/2/09) values
-//     #define DMA_BUFFER_OFFSET       2160    // original (working as of 21/2/09) values
-//     #define DMA_BUFFER_SIZE         4096    // original (working as of 21/2/09) values
-//     #define TRACE_LENGTH            2000    // original (working as of 21/2/09) values
-
-    // We won't start recording the frames that we acquire until we trigger;
-    // a good trigger condition to get started is probably when we see a
-    // response from the tag.
-    int triggered = TRUE; // FALSE to wait first for card
-
-    // The command (reader -> tag) that we're receiving.
+void RAMFUNC SnoopIso14443a(uint8_t param) {
+       // param:
+       // bit 0 - trigger from first card answer
+       // bit 1 - trigger from first reader 7-bit request
+       
+       LEDsoff();
+       // init trace buffer
+       iso14a_clear_trace();
+
+       // We won't start recording the frames that we acquire until we trigger;
+       // a good trigger condition to get started is probably when we see a
+       // response from the tag.
+       // triggered == FALSE -- to wait first for card
+       bool triggered = !(param & 0x03); 
+       
+       // The command (reader -> tag) that we're receiving.

        // The length of a received command will in most cases be no more than 18 bytes.
        // So 32 should be enough!
        // The length of a received command will in most cases be no more than 18 bytes.
        // So 32 should be enough!

-    uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
-    // The response (tag -> reader) that we're receiving.
-    uint8_t *receivedResponse = (((uint8_t *)BigBuf) + RECV_RES_OFFSET);
-
-    // As we receive stuff, we copy it from receivedCmd or receivedResponse
-    // into trace, along with its length and other annotations.
-    //uint8_t *trace = (uint8_t *)BigBuf;
-    //int traceLen = 0;
-
-    // The DMA buffer, used to stream samples from the FPGA
-    int8_t *dmaBuf = ((int8_t *)BigBuf) + DMA_BUFFER_OFFSET;
-    int lastRxCounter;
-    int8_t *upTo;
-    int smpl;
-    int maxBehindBy = 0;
-
-    // Count of samples received so far, so that we can include timing
-    // information in the trace buffer.
-    int samples = 0;
-       int rsamples = 0;
-
-    memset(trace, 0x44, RECV_CMD_OFFSET);
-
-    // Set up the demodulator for tag -> reader responses.
-    Demod.output = receivedResponse;
-    Demod.len = 0;
-    Demod.state = DEMOD_UNSYNCD;
-
-    // And the reader -> tag commands
-    memset(&Uart, 0, sizeof(Uart));
-    Uart.output = receivedCmd;
-    Uart.byteCntMax = 32; // was 100 (greg)////////////////////////////////////////////////////////////////////////
-    Uart.state = STATE_UNSYNCD;
-
-    // And put the FPGA in the appropriate mode
-    // Signal field is off with the appropriate LED
-    LED_D_OFF();
-    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_SNIFFER);
-    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-
-       // Setup for the DMA.
-    FpgaSetupSsc();
-    upTo = dmaBuf;
-    lastRxCounter = DMA_BUFFER_SIZE;
-    FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
-
-    LED_A_ON();
+       uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
+       // The response (tag -> reader) that we're receiving.
+       uint8_t *receivedResponse = (((uint8_t *)BigBuf) + RECV_RES_OFFSET);
+
+       // As we receive stuff, we copy it from receivedCmd or receivedResponse
+       // into trace, along with its length and other annotations.
+       //uint8_t *trace = (uint8_t *)BigBuf;
+       
+       // The DMA buffer, used to stream samples from the FPGA
+       uint8_t *dmaBuf = ((uint8_t *)BigBuf) + DMA_BUFFER_OFFSET;
+       uint8_t *data = dmaBuf;
+       uint8_t previous_data = 0;
+       int maxDataLen = 0;
+       int dataLen = 0;
+       bool TagIsActive = FALSE;
+       bool ReaderIsActive = FALSE;
+       
+       iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
+
+       // Set up the demodulator for tag -> reader responses.
+       Demod.output = receivedResponse;
+
+       // Set up the demodulator for the reader -> tag commands
+       Uart.output = receivedCmd;
+
+       // Setup and start DMA.
+       FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
+       
+       // And now we loop, receiving samples.
+       for(uint32_t rsamples = 0; TRUE; ) {
+
+               if(BUTTON_PRESS()) {
+                       DbpString("cancelled by button");
+                       break;
+               }

 
 

-    // And now we loop, receiving samples.
-    for(;;) {
+               LED_A_ON();

                WDT_HIT();
                WDT_HIT();

-        int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
-                                (DMA_BUFFER_SIZE-1);
-        if(behindBy > maxBehindBy) {
-            maxBehindBy = behindBy;
-            if(behindBy > 400) {
-                DbpString("blew circular buffer!");
-                goto done;
-            }
-        }
-        if(behindBy < 1) continue;
-
-        smpl = upTo[0];
-        upTo++;
-        lastRxCounter -= 1;
-        if(upTo - dmaBuf > DMA_BUFFER_SIZE) {
-            upTo -= DMA_BUFFER_SIZE;
-            lastRxCounter += DMA_BUFFER_SIZE;
-            AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
-            AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
-        }

 
 

-        samples += 4;
-#define HANDLE_BIT_IF_BODY \
-            LED_C_ON(); \
-                       if(triggered) { \
-                               trace[traceLen++] = ((rsamples >>  0) & 0xff); \
-                trace[traceLen++] = ((rsamples >>  8) & 0xff); \
-                trace[traceLen++] = ((rsamples >> 16) & 0xff); \
-                trace[traceLen++] = ((rsamples >> 24) & 0xff); \
-                               trace[traceLen++] = ((Uart.parityBits >>  0) & 0xff); \
-                               trace[traceLen++] = ((Uart.parityBits >>  8) & 0xff); \
-                               trace[traceLen++] = ((Uart.parityBits >> 16) & 0xff); \
-                               trace[traceLen++] = ((Uart.parityBits >> 24) & 0xff); \
-                trace[traceLen++] = Uart.byteCnt; \
-                memcpy(trace+traceLen, receivedCmd, Uart.byteCnt); \
-                traceLen += Uart.byteCnt; \
-                if(traceLen > TRACE_LENGTH) break; \
-            } \
-            /* And ready to receive another command. */ \
-            Uart.state = STATE_UNSYNCD; \
-            /* And also reset the demod code, which might have been */ \
-            /* false-triggered by the commands from the reader. */ \
-            Demod.state = DEMOD_UNSYNCD; \
-                       LED_B_OFF(); \
-
-               if(MillerDecoding((smpl & 0xF0) >> 4)) {
-            rsamples = samples - Uart.samples;
-                       HANDLE_BIT_IF_BODY
-        }
-               if(ManchesterDecoding(smpl & 0x0F)) {
-                       rsamples = samples - Demod.samples;
-                       LED_B_ON();
-
-                       // timestamp, as a count of samples
-                       trace[traceLen++] = ((rsamples >>  0) & 0xff);
-                       trace[traceLen++] = ((rsamples >>  8) & 0xff);
-                       trace[traceLen++] = ((rsamples >> 16) & 0xff);
-                       trace[traceLen++] = 0x80 | ((rsamples >> 24) & 0xff);
-                       trace[traceLen++] = ((Demod.parityBits >>  0) & 0xff);
-                       trace[traceLen++] = ((Demod.parityBits >>  8) & 0xff);
-                       trace[traceLen++] = ((Demod.parityBits >> 16) & 0xff);
-                       trace[traceLen++] = ((Demod.parityBits >> 24) & 0xff);
-                       // length
-                       trace[traceLen++] = Demod.len;
-                       memcpy(trace+traceLen, receivedResponse, Demod.len);
-                       traceLen += Demod.len;
-                       if(traceLen > TRACE_LENGTH) break;
-
-               triggered = TRUE;
-
-            // And ready to receive another response.
-            memset(&Demod, 0, sizeof(Demod));
-            Demod.output = receivedResponse;
-            Demod.state = DEMOD_UNSYNCD;
-                       LED_C_OFF();
+               int register readBufDataP = data - dmaBuf;
+               int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
+               if (readBufDataP <= dmaBufDataP){
+                       dataLen = dmaBufDataP - readBufDataP;
+               } else {
+                       dataLen = DMA_BUFFER_SIZE - readBufDataP + dmaBufDataP;

                }
                }

+               // test for length of buffer
+               if(dataLen > maxDataLen) {
+                       maxDataLen = dataLen;
+                       if(dataLen > 400) {
+                               Dbprintf("blew circular buffer! dataLen=%d", dataLen);
+                               break;
+                       }
+               }
+               if(dataLen < 1) continue;

 
 

-        if(BUTTON_PRESS()) {
-            DbpString("cancelled_a");
-            goto done;
-        }
-    }
+               // primary buffer was stopped( <-- we lost data!
+               if (!AT91C_BASE_PDC_SSC->PDC_RCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
+                       Dbprintf("RxEmpty ERROR!!! data length:%d", dataLen); // temporary
+               }
+               // secondary buffer sets as primary, secondary buffer was stopped
+               if (!AT91C_BASE_PDC_SSC->PDC_RNCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+               }

 
 

-    DbpString("COMMAND FINISHED");
+               LED_A_OFF();
+               
+               if (rsamples & 0x01) {                          // Need two samples to feed Miller and Manchester-Decoder

 
 

-    Dbprintf("%x %x %x", maxBehindBy, Uart.state, Uart.byteCnt);
-    Dbprintf("%x %x %x", Uart.byteCntMax, traceLen, (int)Uart.output[0]);
+                       if(!TagIsActive) {              // no need to try decoding reader data if the tag is sending
+                               uint8_t readerdata = (previous_data & 0xF0) | (*data >> 4);
+                               if (MillerDecoding(readerdata, (rsamples-1)*4)) {
+                                       LED_C_ON();

 
 

-done:
-    AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-    Dbprintf("%x %x %x", maxBehindBy, Uart.state, Uart.byteCnt);
-    Dbprintf("%x %x %x", Uart.byteCntMax, traceLen, (int)Uart.output[0]);
-    LED_A_OFF();
-    LED_B_OFF();
-       LED_C_OFF();
-       LED_D_OFF();
-}
+                                       // check - if there is a short 7bit request from reader
+                                       if ((!triggered) && (param & 0x02) && (Uart.len == 1) && (Uart.bitCount == 7)) triggered = TRUE;

 
 

-// Prepare communication bits to send to FPGA
-void Sequence(SecType seq)
-{
-       ToSendMax++;
-       switch(seq) {
-       // CARD TO READER
-       case SEC_D:
-               // Sequence D: 11110000
-               // modulation with subcarrier during first half
-        ToSend[ToSendMax] = 0xf0;
-               break;
-       case SEC_E:
-               // Sequence E: 00001111
-               // modulation with subcarrier during second half
-        ToSend[ToSendMax] = 0x0f;
-               break;
-       case SEC_F:
-               // Sequence F: 00000000
-               // no modulation with subcarrier
-        ToSend[ToSendMax] = 0x00;
-               break;
-       // READER TO CARD
-       case SEC_X:
-               // Sequence X: 00001100
-               // drop after half a period
-        ToSend[ToSendMax] = 0x0c;
-               break;
-       case SEC_Y:
-       default:
-               // Sequence Y: 00000000
-               // no drop
-        ToSend[ToSendMax] = 0x00;
-               break;
-       case SEC_Z:
-               // Sequence Z: 11000000
-               // drop at start
-        ToSend[ToSendMax] = 0xc0;
-               break;
-       }
+                                       if(triggered) {
+                                               if (!LogTrace(receivedCmd, Uart.len, Uart.startTime*16 - DELAY_READER_AIR2ARM_AS_SNIFFER, Uart.parityBits, TRUE)) break;
+                                               if (!LogTrace(NULL, 0, Uart.endTime*16 - DELAY_READER_AIR2ARM_AS_SNIFFER, 0, TRUE)) break;
+                                       }
+                                       /* And ready to receive another command. */
+                                       UartReset();
+                                       /* And also reset the demod code, which might have been */
+                                       /* false-triggered by the commands from the reader. */
+                                       DemodReset();
+                                       LED_B_OFF();
+                               }
+                               ReaderIsActive = (Uart.state != STATE_UNSYNCD);
+                       }
+
+                       if(!ReaderIsActive) {           // no need to try decoding tag data if the reader is sending - and we cannot afford the time
+                               uint8_t tagdata = (previous_data << 4) | (*data & 0x0F);
+                               if(ManchesterDecoding(tagdata, 0, (rsamples-1)*4)) {
+                                       LED_B_ON();
+
+                                       if (!LogTrace(receivedResponse, Demod.len, Demod.startTime*16 - DELAY_TAG_AIR2ARM_AS_SNIFFER, Demod.parityBits, FALSE)) break;
+                                       if (!LogTrace(NULL, 0, Demod.endTime*16 - DELAY_TAG_AIR2ARM_AS_SNIFFER, 0, FALSE)) break;
+
+                                       if ((!triggered) && (param & 0x01)) triggered = TRUE;
+
+                                       // And ready to receive another response.
+                                       DemodReset();
+                                       LED_C_OFF();
+                               } 
+                               TagIsActive = (Demod.state != DEMOD_UNSYNCD);
+                       }
+               }
+
+               previous_data = *data;
+               rsamples++;
+               data++;
+               if(data == dmaBuf + DMA_BUFFER_SIZE) {
+                       data = dmaBuf;
+               }
+       } // main cycle
+
+       DbpString("COMMAND FINISHED");
+
+       FpgaDisableSscDma();
+       Dbprintf("maxDataLen=%d, Uart.state=%x, Uart.len=%d", maxDataLen, Uart.state, Uart.len);
+       Dbprintf("traceLen=%d, Uart.output[0]=%08x", traceLen, (uint32_t)Uart.output[0]);
+       LEDsoff();

 }
 
 //-----------------------------------------------------------------------------
 // Prepare tag messages
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------
 // Prepare tag messages
 //-----------------------------------------------------------------------------

-static void CodeIso14443aAsTag(const uint8_t *cmd, int len)
+static void CodeIso14443aAsTagPar(const uint8_t *cmd, int len, uint32_t dwParity)

 {
 {

-    int i;
-       int oddparity;
+       int i;

 
 

-    ToSendReset();
+       ToSendReset();

 
        // Correction bit, might be removed when not needed
        ToSendStuffBit(0);
 
        // Correction bit, might be removed when not needed
        ToSendStuffBit(0);


@@ -817,59 +661,52 @@ static void CodeIso14443aAsTag(const uint8_t *cmd, int len)
        ToSendStuffBit(0);
        ToSendStuffBit(0);
        ToSendStuffBit(0);
        ToSendStuffBit(0);
        ToSendStuffBit(0);
        ToSendStuffBit(0);

-
+       

        // Send startbit
        // Send startbit

-       Sequence(SEC_D);
+       ToSend[++ToSendMax] = SEC_D;
+       LastProxToAirDuration = 8 * ToSendMax - 4;

 
 

-    for(i = 0; i < len; i++) {
-        int j;
-        uint8_t b = cmd[i];
+       for(i = 0; i < len; i++) {
+               int j;
+               uint8_t b = cmd[i];

 
                // Data bits
 
                // Data bits

-        oddparity = 0x01;

                for(j = 0; j < 8; j++) {
                for(j = 0; j < 8; j++) {

-            oddparity ^= (b & 1);

                        if(b & 1) {
                        if(b & 1) {

-                               Sequence(SEC_D);
+                               ToSend[++ToSendMax] = SEC_D;

                        } else {
                        } else {

-                               Sequence(SEC_E);
-            }
-            b >>= 1;
-        }
+                               ToSend[++ToSendMax] = SEC_E;
+                       }
+                       b >>= 1;
+               }

 
 

-        // Parity bit
-        if(oddparity) {
-                       Sequence(SEC_D);
+               // Get the parity bit
+               if ((dwParity >> i) & 0x01) {
+                       ToSend[++ToSendMax] = SEC_D;
+                       LastProxToAirDuration = 8 * ToSendMax - 4;

                } else {
                } else {

-                       Sequence(SEC_E);
+                       ToSend[++ToSendMax] = SEC_E;
+                       LastProxToAirDuration = 8 * ToSendMax;

                }
                }

-    }
-
-    // Send stopbit
-       Sequence(SEC_F);
-
-       // Flush the buffer in FPGA!!
-       for(i = 0; i < 5; i++) {
-               Sequence(SEC_F);

        }
 
        }
 

-    // Convert from last byte pos to length
-    ToSendMax++;
+       // Send stopbit
+       ToSend[++ToSendMax] = SEC_F;

 
 

-    // Add a few more for slop
-    ToSend[ToSendMax++] = 0x00;
-       ToSend[ToSendMax++] = 0x00;
-    //ToSendMax += 2;
+       // Convert from last byte pos to length
+       ToSendMax++;

 }
 
 }
 

-//-----------------------------------------------------------------------------
-// This is to send a NACK kind of answer, its only 3 bits, I know it should be 4
-//-----------------------------------------------------------------------------
-static void CodeStrangeAnswer()
+static void CodeIso14443aAsTag(const uint8_t *cmd, int len){
+       CodeIso14443aAsTagPar(cmd, len, GetParity(cmd, len));
+}
+
+
+static void Code4bitAnswerAsTag(uint8_t cmd)

 {
        int i;
 
 {
        int i;
 

-    ToSendReset();
+       ToSendReset();

 
        // Correction bit, might be removed when not needed
        ToSendStuffBit(0);
 
        // Correction bit, might be removed when not needed
        ToSendStuffBit(0);


@@ -882,32 +719,25 @@ static void CodeStrangeAnswer()
        ToSendStuffBit(0);
 
        // Send startbit
        ToSendStuffBit(0);
 
        // Send startbit

-       Sequence(SEC_D);
-
-       // 0
-       Sequence(SEC_E);
-
-       // 0
-       Sequence(SEC_E);
-
-       // 1
-       Sequence(SEC_D);
-
-    // Send stopbit
-       Sequence(SEC_F);
+       ToSend[++ToSendMax] = SEC_D;

 
 

-       // Flush the buffer in FPGA!!
-       for(i = 0; i < 5; i++) {
-               Sequence(SEC_F);
+       uint8_t b = cmd;
+       for(i = 0; i < 4; i++) {
+               if(b & 1) {
+                       ToSend[++ToSendMax] = SEC_D;
+                       LastProxToAirDuration = 8 * ToSendMax - 4;
+               } else {
+                       ToSend[++ToSendMax] = SEC_E;
+                       LastProxToAirDuration = 8 * ToSendMax;
+               }
+               b >>= 1;

        }
 
        }
 

-    // Convert from last byte pos to length
-    ToSendMax++;
+       // Send stopbit
+       ToSend[++ToSendMax] = SEC_F;

 
 

-    // Add a few more for slop
-    ToSend[ToSendMax++] = 0x00;
-       ToSend[ToSendMax++] = 0x00;
-    //ToSendMax += 2;
+       // Convert from last byte pos to length
+       ToSendMax++;

 }
 
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------


@@ -924,126 +754,220 @@ static int GetIso14443aCommandFromReader(uint8_t *received, int *len, int maxLen
     FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);
 
     // Now run a `software UART' on the stream of incoming samples.
     FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);
 
     // Now run a `software UART' on the stream of incoming samples.

+       UartReset();

     Uart.output = received;
     Uart.output = received;

-    Uart.byteCntMax = maxLen;
-    Uart.state = STATE_UNSYNCD;
+
+       // clear RXRDY:
+    uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;

 
     for(;;) {
         WDT_HIT();
 
         if(BUTTON_PRESS()) return FALSE;
 
     for(;;) {
         WDT_HIT();
 
         if(BUTTON_PRESS()) return FALSE;

-
-        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-            AT91C_BASE_SSC->SSC_THR = 0x00;
-        }
+               

         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {

-            uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                       if(MillerDecoding((b & 0xf0) >> 4)) {
-                               *len = Uart.byteCnt;
-                               return TRUE;
-                       }
-                       if(MillerDecoding(b & 0x0f)) {
-                               *len = Uart.byteCnt;
+            b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       if(MillerDecoding(b, 0)) {
+                               *len = Uart.len;

                                return TRUE;
                        }
                                return TRUE;
                        }

-        }
+               }

     }
 }
 
     }
 }
 

-//-----------------------------------------------------------------------------
-// Main loop of simulated tag: receive commands from reader, decide what
-// response to send, and send it.
-//-----------------------------------------------------------------------------
-void SimulateIso14443aTag(int tagType, int TagUid)
-{
-       // This function contains the tag emulation
-
-       // Prepare protocol messages
-    // static const uint8_t cmd1[] = { 0x26 };
-//     static const uint8_t response1[] = { 0x02, 0x00 }; // Says: I am Mifare 4k - original line - greg
-//
-       static const uint8_t response1[] = { 0x44, 0x03 }; // Says: I am a DESFire Tag, ph33r me
-//     static const uint8_t response1[] = { 0x44, 0x00 }; // Says: I am a ULTRALITE Tag, 0wn me
-
-       // UID response
-    // static const uint8_t cmd2[] = { 0x93, 0x20 };
-    //static const uint8_t response2[] = { 0x9a, 0xe5, 0xe4, 0x43, 0xd8 }; // original value - greg
-
-
-
-// my desfire
-    static const uint8_t response2[] = { 0x88, 0x04, 0x21, 0x3f, 0x4d }; // known uid - note cascade (0x88), 2nd byte (0x04) = NXP/Phillips
-
-
-// When reader selects us during cascade1 it will send cmd3
-//uint8_t response3[] = { 0x04, 0x00, 0x00 }; // SAK Select (cascade1) successful response (ULTRALITE)
-uint8_t response3[] = { 0x24, 0x00, 0x00 }; // SAK Select (cascade1) successful response (DESFire)
-ComputeCrc14443(CRC_14443_A, response3, 1, &response3[1], &response3[2]);
-
-// send cascade2 2nd half of UID
-static const uint8_t response2a[] = { 0x51, 0x48, 0x1d, 0x80, 0x84 }; //  uid - cascade2 - 2nd half (4 bytes) of UID+ BCCheck
-// NOTE : THE CRC on the above may be wrong as I have obfuscated the actual UID
-
-
-// When reader selects us during cascade2 it will send cmd3a
-//uint8_t response3a[] = { 0x00, 0x00, 0x00 }; // SAK Select (cascade2) successful response (ULTRALITE)
-uint8_t response3a[] = { 0x20, 0x00, 0x00 }; // SAK Select (cascade2) successful response (DESFire)
-ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
-
-    static const uint8_t response5[] = { 0x00, 0x00, 0x00, 0x00 }; // Very random tag nonce
-
-    uint8_t *resp;
-    int respLen;
+static int EmSendCmd14443aRaw(uint8_t *resp, int respLen, bool correctionNeeded);
+int EmSend4bitEx(uint8_t resp, bool correctionNeeded);
+int EmSend4bit(uint8_t resp);
+int EmSendCmdExPar(uint8_t *resp, int respLen, bool correctionNeeded, uint32_t par);
+int EmSendCmdExPar(uint8_t *resp, int respLen, bool correctionNeeded, uint32_t par);
+int EmSendCmdEx(uint8_t *resp, int respLen, bool correctionNeeded);
+int EmSendCmd(uint8_t *resp, int respLen);
+int EmSendCmdPar(uint8_t *resp, int respLen, uint32_t par);
+bool EmLogTrace(uint8_t *reader_data, uint16_t reader_len, uint32_t reader_StartTime, uint32_t reader_EndTime, uint32_t reader_Parity,
+                                uint8_t *tag_data, uint16_t tag_len, uint32_t tag_StartTime, uint32_t tag_EndTime, uint32_t tag_Parity);
+
+static uint8_t* free_buffer_pointer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);
+
+typedef struct {
+  uint8_t* response;
+  size_t   response_n;
+  uint8_t* modulation;
+  size_t   modulation_n;
+  uint32_t ProxToAirDuration;
+} tag_response_info_t;
+
+void reset_free_buffer() {
+  free_buffer_pointer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);
+}

 
 

-    // Longest possible response will be 16 bytes + 2 CRC = 18 bytes
-       // This will need
+bool prepare_tag_modulation(tag_response_info_t* response_info, size_t max_buffer_size) {
+       // Example response, answer to MIFARE Classic read block will be 16 bytes + 2 CRC = 18 bytes
+       // This will need the following byte array for a modulation sequence

        //    144        data bits (18 * 8)
        //     18        parity bits
        //      2        Start and stop
        //      1        Correction bit (Answer in 1172 or 1236 periods, see FPGA)
        //      1        just for the case
        // ----------- +
        //    144        data bits (18 * 8)
        //     18        parity bits
        //      2        Start and stop
        //      1        Correction bit (Answer in 1172 or 1236 periods, see FPGA)
        //      1        just for the case
        // ----------- +

-       //    166
-       //
-       // 166 bytes, since every bit that needs to be send costs us a byte
+       //    166 bytes, since every bit that needs to be send costs us a byte

        //
        //

+  
+  // Prepare the tag modulation bits from the message
+  CodeIso14443aAsTag(response_info->response,response_info->response_n);
+  
+  // Make sure we do not exceed the free buffer space
+  if (ToSendMax > max_buffer_size) {
+    Dbprintf("Out of memory, when modulating bits for tag answer:");
+    Dbhexdump(response_info->response_n,response_info->response,false);
+    return false;
+  }
+  
+  // Copy the byte array, used for this modulation to the buffer position
+  memcpy(response_info->modulation,ToSend,ToSendMax);
+  
+  // Store the number of bytes that were used for encoding/modulation and the time needed to transfer them
+  response_info->modulation_n = ToSendMax;
+  response_info->ProxToAirDuration = LastProxToAirDuration;
+  
+  return true;
+}

 
 

+bool prepare_allocated_tag_modulation(tag_response_info_t* response_info) {
+  // Retrieve and store the current buffer index
+  response_info->modulation = free_buffer_pointer;
+  
+  // Determine the maximum size we can use from our buffer
+  size_t max_buffer_size = (((uint8_t *)BigBuf)+FREE_BUFFER_OFFSET+FREE_BUFFER_SIZE)-free_buffer_pointer;
+  
+  // Forward the prepare tag modulation function to the inner function
+  if (prepare_tag_modulation(response_info,max_buffer_size)) {
+    // Update the free buffer offset
+    free_buffer_pointer += ToSendMax;
+    return true;
+  } else {
+    return false;
+  }
+}

 
 

-    // Respond with card type
-    uint8_t *resp1 = (((uint8_t *)BigBuf) + 800);
-    int resp1Len;
-
-    // Anticollision cascade1 - respond with uid
-    uint8_t *resp2 = (((uint8_t *)BigBuf) + 970);
-    int resp2Len;
-
-    // Anticollision cascade2 - respond with 2nd half of uid if asked
-    // we're only going to be asked if we set the 1st byte of the UID (during cascade1) to 0x88
-    uint8_t *resp2a = (((uint8_t *)BigBuf) + 1140);
-    int resp2aLen;
-
-    // Acknowledge select - cascade 1
-    uint8_t *resp3 = (((uint8_t *)BigBuf) + 1310);
-    int resp3Len;
-
-    // Acknowledge select - cascade 2
-    uint8_t *resp3a = (((uint8_t *)BigBuf) + 1480);
-    int resp3aLen;
-
-    // Response to a read request - not implemented atm
-    uint8_t *resp4 = (((uint8_t *)BigBuf) + 1550);
-    int resp4Len;
-
-    // Authenticate response - nonce
-    uint8_t *resp5 = (((uint8_t *)BigBuf) + 1720);
-    int resp5Len;
+//-----------------------------------------------------------------------------
+// Main loop of simulated tag: receive commands from reader, decide what
+// response to send, and send it.
+//-----------------------------------------------------------------------------
+void SimulateIso14443aTag(int tagType, int uid_1st, int uid_2nd, byte_t* data)
+{
+       // Enable and clear the trace
+       iso14a_clear_trace();
+       iso14a_set_tracing(TRUE);
+
+       uint8_t sak;
+
+       // The first response contains the ATQA (note: bytes are transmitted in reverse order).
+       uint8_t response1[2];
+       
+       switch (tagType) {
+               case 1: { // MIFARE Classic
+                       // Says: I am Mifare 1k - original line
+                       response1[0] = 0x04;
+                       response1[1] = 0x00;
+                       sak = 0x08;
+               } break;
+               case 2: { // MIFARE Ultralight
+                       // Says: I am a stupid memory tag, no crypto
+                       response1[0] = 0x04;
+                       response1[1] = 0x00;
+                       sak = 0x00;
+               } break;
+               case 3: { // MIFARE DESFire
+                       // Says: I am a DESFire tag, ph33r me
+                       response1[0] = 0x04;
+                       response1[1] = 0x03;
+                       sak = 0x20;
+               } break;
+               case 4: { // ISO/IEC 14443-4
+                       // Says: I am a javacard (JCOP)
+                       response1[0] = 0x04;
+                       response1[1] = 0x00;
+                       sak = 0x28;
+               } break;
+               default: {
+                       Dbprintf("Error: unkown tagtype (%d)",tagType);
+                       return;
+               } break;
+       }
+       
+       // The second response contains the (mandatory) first 24 bits of the UID
+       uint8_t response2[5];
+
+       // Check if the uid uses the (optional) part
+       uint8_t response2a[5];
+       if (uid_2nd) {
+               response2[0] = 0x88;
+               num_to_bytes(uid_1st,3,response2+1);
+               num_to_bytes(uid_2nd,4,response2a);
+               response2a[4] = response2a[0] ^ response2a[1] ^ response2a[2] ^ response2a[3];
+
+               // Configure the ATQA and SAK accordingly
+               response1[0] |= 0x40;
+               sak |= 0x04;
+       } else {
+               num_to_bytes(uid_1st,4,response2);
+               // Configure the ATQA and SAK accordingly
+               response1[0] &= 0xBF;
+               sak &= 0xFB;
+       }

 
 

-    uint8_t *receivedCmd = (uint8_t *)BigBuf;
-    int len;
+       // Calculate the BitCountCheck (BCC) for the first 4 bytes of the UID.
+       response2[4] = response2[0] ^ response2[1] ^ response2[2] ^ response2[3];
+
+       // Prepare the mandatory SAK (for 4 and 7 byte UID)
+       uint8_t response3[3];
+       response3[0] = sak;
+       ComputeCrc14443(CRC_14443_A, response3, 1, &response3[1], &response3[2]);
+
+       // Prepare the optional second SAK (for 7 byte UID), drop the cascade bit
+       uint8_t response3a[3];
+       response3a[0] = sak & 0xFB;
+       ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
+
+       uint8_t response5[] = { 0x00, 0x00, 0x00, 0x00 }; // Very random tag nonce
+       uint8_t response6[] = { 0x04, 0x58, 0x00, 0x02, 0x00, 0x00 }; // dummy ATS (pseudo-ATR), answer to RATS
+       ComputeCrc14443(CRC_14443_A, response6, 4, &response6[4], &response6[5]);
+
+       #define TAG_RESPONSE_COUNT 7
+       tag_response_info_t responses[TAG_RESPONSE_COUNT] = {
+               { .response = response1,  .response_n = sizeof(response1)  },  // Answer to request - respond with card type
+               { .response = response2,  .response_n = sizeof(response2)  },  // Anticollision cascade1 - respond with uid
+               { .response = response2a, .response_n = sizeof(response2a) },  // Anticollision cascade2 - respond with 2nd half of uid if asked
+               { .response = response3,  .response_n = sizeof(response3)  },  // Acknowledge select - cascade 1
+               { .response = response3a, .response_n = sizeof(response3a) },  // Acknowledge select - cascade 2
+               { .response = response5,  .response_n = sizeof(response5)  },  // Authentication answer (random nonce)
+               { .response = response6,  .response_n = sizeof(response6)  },  // dummy ATS (pseudo-ATR), answer to RATS
+       };
+
+       // Allocate 512 bytes for the dynamic modulation, created when the reader queries for it
+       // Such a response is less time critical, so we can prepare them on the fly
+       #define DYNAMIC_RESPONSE_BUFFER_SIZE 64
+       #define DYNAMIC_MODULATION_BUFFER_SIZE 512
+       uint8_t dynamic_response_buffer[DYNAMIC_RESPONSE_BUFFER_SIZE];
+       uint8_t dynamic_modulation_buffer[DYNAMIC_MODULATION_BUFFER_SIZE];
+       tag_response_info_t dynamic_response_info = {
+               .response = dynamic_response_buffer,
+               .response_n = 0,
+               .modulation = dynamic_modulation_buffer,
+               .modulation_n = 0
+       };
+  
+       // Reset the offset pointer of the free buffer
+       reset_free_buffer();
+  
+       // Prepare the responses of the anticollision phase
+       // there will be not enough time to do this at the moment the reader sends it REQA
+       for (size_t i=0; i<TAG_RESPONSE_COUNT; i++) {
+               prepare_allocated_tag_modulation(&responses[i]);
+       }

 
 

-    int i;
-       int u;
-       uint8_t b;
+       uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
+       int len = 0;

 
        // To control where we are in the protocol
        int order = 0;
 
        // To control where we are in the protocol
        int order = 0;


@@ -1052,130 +976,137 @@ ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
        // Just to allow some checks
        int happened = 0;
        int happened2 = 0;
        // Just to allow some checks
        int happened = 0;
        int happened2 = 0;

+       int cmdsRecvd = 0;

 
 

-    int cmdsRecvd = 0;
-
-       int fdt_indicator;
-
-    memset(receivedCmd, 0x44, 400);
-
-       // Prepare the responses of the anticollision phase
-       // there will be not enough time to do this at the moment the reader sends it REQA
-
-       // Answer to request
-       CodeIso14443aAsTag(response1, sizeof(response1));
-    memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
-
-       // Send our UID (cascade 1)
-       CodeIso14443aAsTag(response2, sizeof(response2));
-    memcpy(resp2, ToSend, ToSendMax); resp2Len = ToSendMax;
-
-       // Answer to select (cascade1)
-       CodeIso14443aAsTag(response3, sizeof(response3));
-    memcpy(resp3, ToSend, ToSendMax); resp3Len = ToSendMax;
+       // We need to listen to the high-frequency, peak-detected path.
+       iso14443a_setup(FPGA_HF_ISO14443A_TAGSIM_LISTEN);

 
 

-       // Send the cascade 2 2nd part of the uid
-       CodeIso14443aAsTag(response2a, sizeof(response2a));
-    memcpy(resp2a, ToSend, ToSendMax); resp2aLen = ToSendMax;
+       cmdsRecvd = 0;
+       tag_response_info_t* p_response;

 
 

-       // Answer to select (cascade 2)
-       CodeIso14443aAsTag(response3a, sizeof(response3a));
-    memcpy(resp3a, ToSend, ToSendMax); resp3aLen = ToSendMax;
-
-       // Strange answer is an example of rare message size (3 bits)
-       CodeStrangeAnswer();
-       memcpy(resp4, ToSend, ToSendMax); resp4Len = ToSendMax;
-
-       // Authentication answer (random nonce)
-       CodeIso14443aAsTag(response5, sizeof(response5));
-    memcpy(resp5, ToSend, ToSendMax); resp5Len = ToSendMax;
-
-    // We need to listen to the high-frequency, peak-detected path.
-    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-    FpgaSetupSsc();
-
-    cmdsRecvd = 0;
-
-    LED_A_ON();
+       LED_A_ON();

        for(;;) {
        for(;;) {

+               // Clean receive command buffer
+               
+               if(!GetIso14443aCommandFromReader(receivedCmd, &len, RECV_CMD_SIZE)) {
+                       DbpString("Button press");
+                       break;
+               }

 
 

-               if(!GetIso14443aCommandFromReader(receivedCmd, &len, 100)) {
-            DbpString("button press");
-            break;
-        }
-       // doob - added loads of debug strings so we can see what the reader is saying to us during the sim as hi14alist is not populated
-        // Okay, look at the command now.
-        lastorder = order;
-               i = 1; // first byte transmitted
-        if(receivedCmd[0] == 0x26) {
-                       // Received a REQUEST
-                       resp = resp1; respLen = resp1Len; order = 1;
-                       //DbpString("Hello request from reader:");
-               } else if(receivedCmd[0] == 0x52) {
-                       // Received a WAKEUP
-                       resp = resp1; respLen = resp1Len; order = 6;
-//                     //DbpString("Wakeup request from reader:");
-
-               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] == 0x93) {   // greg - cascade 1 anti-collision
-                       // Received request for UID (cascade 1)
-                       resp = resp2; respLen = resp2Len; order = 2;
-//                     DbpString("UID (cascade 1) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] ==0x95) {    // greg - cascade 2 anti-collision
-                       // Received request for UID (cascade 2)
-                       resp = resp2a; respLen = resp2aLen; order = 20;
-//                     DbpString("UID (cascade 2) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] ==0x93) {    // greg - cascade 1 select
-                       // Received a SELECT
-                       resp = resp3; respLen = resp3Len; order = 3;
-//                     DbpString("Select (cascade 1) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] ==0x95) {    // greg - cascade 2 select
-                       // Received a SELECT
-                       resp = resp3a; respLen = resp3aLen; order = 30;
-//                     DbpString("Select (cascade 2) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[0] == 0x30) {
-                       // Received a READ
-                       resp = resp4; respLen = resp4Len; order = 4; // Do nothing
-                       Dbprintf("Read request from reader: %x %x %x",
-                               receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[0] == 0x50) {
-                       // Received a HALT
-                       resp = resp1; respLen = 0; order = 5; // Do nothing
-                       DbpString("Reader requested we HALT!:");
-
-               } else if(receivedCmd[0] == 0x60) {
-                       // Received an authentication request
-                       resp = resp5; respLen = resp5Len; order = 7;
-                       Dbprintf("Authenticate request from reader: %x %x %x",
-                               receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-               } else if(receivedCmd[0] == 0xE0) {
-                       // Received a RATS request
-                       resp = resp1; respLen = 0;order = 70;
-                       Dbprintf("RATS request from reader: %x %x %x",
-                               receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-        } else {
-            // Never seen this command before
-               Dbprintf("Unknown command received from reader: %x %x %x %x %x %x %x %x %x",
-                       receivedCmd[0], receivedCmd[1], receivedCmd[2],
-                       receivedCmd[3], receivedCmd[3], receivedCmd[4],
-                       receivedCmd[5], receivedCmd[6], receivedCmd[7]);
-                       // Do not respond
-                       resp = resp1; respLen = 0; order = 0;
-        }
+               p_response = NULL;
+               
+               // doob - added loads of debug strings so we can see what the reader is saying to us during the sim as hi14alist is not populated
+               // Okay, look at the command now.
+               lastorder = order;
+               if(receivedCmd[0] == 0x26) { // Received a REQUEST
+                       p_response = &responses[0]; order = 1;
+               } else if(receivedCmd[0] == 0x52) { // Received a WAKEUP
+                       p_response = &responses[0]; order = 6;
+               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] == 0x93) {   // Received request for UID (cascade 1)
+                       p_response = &responses[1]; order = 2;
+               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] == 0x95) { // Received request for UID (cascade 2)
+                       p_response = &responses[2]; order = 20;
+               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] == 0x93) {   // Received a SELECT (cascade 1)
+                       p_response = &responses[3]; order = 3;
+               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] == 0x95) {   // Received a SELECT (cascade 2)
+                       p_response = &responses[4]; order = 30;
+               } else if(receivedCmd[0] == 0x30) {     // Received a (plain) READ
+                       EmSendCmdEx(data+(4*receivedCmd[0]),16,false);
+                       // Dbprintf("Read request from reader: %x %x",receivedCmd[0],receivedCmd[1]);
+                       // We already responded, do not send anything with the EmSendCmd14443aRaw() that is called below
+                       p_response = NULL;
+               } else if(receivedCmd[0] == 0x50) {     // Received a HALT
+//                     DbpString("Reader requested we HALT!:");
+                       if (tracing) {
+                               LogTrace(receivedCmd, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                       }
+                       p_response = NULL;
+               } else if(receivedCmd[0] == 0x60 || receivedCmd[0] == 0x61) {   // Received an authentication request
+                       p_response = &responses[5]; order = 7;
+               } else if(receivedCmd[0] == 0xE0) {     // Received a RATS request
+                       if (tagType == 1 || tagType == 2) {     // RATS not supported
+                               EmSend4bit(CARD_NACK_NA);
+                               p_response = NULL;
+                       } else {
+                               p_response = &responses[6]; order = 70;
+                       }
+               } else if (order == 7 && len == 8) { // Received authentication request
+                       if (tracing) {
+                               LogTrace(receivedCmd, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                       }
+                       uint32_t nr = bytes_to_num(receivedCmd,4);
+                       uint32_t ar = bytes_to_num(receivedCmd+4,4);
+                       Dbprintf("Auth attempt {nr}{ar}: %08x %08x",nr,ar);
+               } else {
+                       // Check for ISO 14443A-4 compliant commands, look at left nibble
+                       switch (receivedCmd[0]) {
+
+                               case 0x0B:
+                               case 0x0A: { // IBlock (command)
+                                 dynamic_response_info.response[0] = receivedCmd[0];
+                                 dynamic_response_info.response[1] = 0x00;
+                                 dynamic_response_info.response[2] = 0x90;
+                                 dynamic_response_info.response[3] = 0x00;
+                                 dynamic_response_info.response_n = 4;
+                               } break;
+
+                               case 0x1A:
+                               case 0x1B: { // Chaining command
+                                 dynamic_response_info.response[0] = 0xaa | ((receivedCmd[0]) & 1);
+                                 dynamic_response_info.response_n = 2;
+                               } break;
+
+                               case 0xaa:
+                               case 0xbb: {
+                                 dynamic_response_info.response[0] = receivedCmd[0] ^ 0x11;
+                                 dynamic_response_info.response_n = 2;
+                               } break;
+                                 
+                               case 0xBA: { //
+                                 memcpy(dynamic_response_info.response,"\xAB\x00",2);
+                                 dynamic_response_info.response_n = 2;
+                               } break;
+
+                               case 0xCA:
+                               case 0xC2: { // Readers sends deselect command
+                                 memcpy(dynamic_response_info.response,"\xCA\x00",2);
+                                 dynamic_response_info.response_n = 2;
+                               } break;
+
+                               default: {
+                                       // Never seen this command before
+                                       if (tracing) {
+                                               LogTrace(receivedCmd, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       }
+                                       Dbprintf("Received unknown command (len=%d):",len);
+                                       Dbhexdump(len,receivedCmd,false);
+                                       // Do not respond
+                                       dynamic_response_info.response_n = 0;
+                               } break;
+                       }
+      
+                       if (dynamic_response_info.response_n > 0) {
+                               // Copy the CID from the reader query
+                               dynamic_response_info.response[1] = receivedCmd[1];
+
+                               // Add CRC bytes, always used in ISO 14443A-4 compliant cards
+                               AppendCrc14443a(dynamic_response_info.response,dynamic_response_info.response_n);
+                               dynamic_response_info.response_n += 2;
+        
+                               if (prepare_tag_modulation(&dynamic_response_info,DYNAMIC_MODULATION_BUFFER_SIZE) == false) {
+                                       Dbprintf("Error preparing tag response");
+                                       if (tracing) {
+                                               LogTrace(receivedCmd, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       }
+                                       break;
+                               }
+                               p_response = &dynamic_response_info;
+                       }
+               }

 
                // Count number of wakeups received after a halt
                if(order == 6 && lastorder == 5) { happened++; }
 
                // Count number of wakeups received after a halt
                if(order == 6 && lastorder == 5) { happened++; }


@@ -1183,673 +1114,1650 @@ ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
                // Count number of other messages after a halt
                if(order != 6 && lastorder == 5) { happened2++; }
 
                // Count number of other messages after a halt
                if(order != 6 && lastorder == 5) { happened2++; }
 

-               // Look at last parity bit to determine timing of answer
-               if((Uart.parityBits & 0x01) || receivedCmd[0] == 0x52) {
-                       // 1236, so correction bit needed
-                       i = 0;
-               }
-
-        memset(receivedCmd, 0x44, 32);
-

                if(cmdsRecvd > 999) {
                        DbpString("1000 commands later...");
                if(cmdsRecvd > 999) {
                        DbpString("1000 commands later...");

-            break;
-        }
-               else {
-                       cmdsRecvd++;
+                       break;

                }
                }

-
-        if(respLen <= 0) continue;
-
-        // Modulate Manchester
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_MOD);
-        AT91C_BASE_SSC->SSC_THR = 0x00;
-        FpgaSetupSsc();
-
-               // ### Transmit the response ###
-               u = 0;
-               b = 0x00;
-               fdt_indicator = FALSE;
-        for(;;) {
-            if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                               volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                (void)b;
-            }
-            if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                               if(i > respLen) {
-                                       b = 0x00;
-                                       u++;
-                               } else {
-                                       b = resp[i];
-                                       i++;
-                               }
-                               AT91C_BASE_SSC->SSC_THR = b;
-
-                if(u > 4) {
-                    break;
-                }
-            }
-                       if(BUTTON_PRESS()) {
-                           break;
-                       }
-        }
-
-    }
+               cmdsRecvd++;
+
+               if (p_response != NULL) {
+                       EmSendCmd14443aRaw(p_response->modulation, p_response->modulation_n, receivedCmd[0] == 0x52);
+                       // do the tracing for the previous reader request and this tag answer:
+                       EmLogTrace(Uart.output, 
+                                               Uart.len, 
+                                               Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, 
+                                               Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 
+                                               Uart.parityBits,
+                                               p_response->response, 
+                                               p_response->response_n,
+                                               LastTimeProxToAirStart*16 + DELAY_ARM2AIR_AS_TAG,
+                                               (LastTimeProxToAirStart + p_response->ProxToAirDuration)*16 + DELAY_ARM2AIR_AS_TAG, 
+                                               SwapBits(GetParity(p_response->response, p_response->response_n), p_response->response_n));
+               }
+               
+               if (!tracing) {
+                       Dbprintf("Trace Full. Simulation stopped.");
+                       break;
+               }
+       }

 
        Dbprintf("%x %x %x", happened, happened2, cmdsRecvd);
        LED_A_OFF();
 }
 
 
        Dbprintf("%x %x %x", happened, happened2, cmdsRecvd);
        LED_A_OFF();
 }
 

-//-----------------------------------------------------------------------------
-// Transmit the command (to the tag) that was placed in ToSend[].
-//-----------------------------------------------------------------------------
-static void TransmitFor14443a(const uint8_t *cmd, int len, int *samples, int *wait)
+
+// prepare a delayed transfer. This simply shifts ToSend[] by a number
+// of bits specified in the delay parameter.
+void PrepareDelayedTransfer(uint16_t delay)

 {
 {

-  int c;
+       uint8_t bitmask = 0;
+       uint8_t bits_to_shift = 0;
+       uint8_t bits_shifted = 0;
+       
+       delay &= 0x07;
+       if (delay) {
+               for (uint16_t i = 0; i < delay; i++) {
+                       bitmask |= (0x01 << i);
+               }
+               ToSend[ToSendMax++] = 0x00;
+               for (uint16_t i = 0; i < ToSendMax; i++) {
+                       bits_to_shift = ToSend[i] & bitmask;
+                       ToSend[i] = ToSend[i] >> delay;
+                       ToSend[i] = ToSend[i] | (bits_shifted << (8 - delay));
+                       bits_shifted = bits_to_shift;
+               }
+       }
+}

 
 

-  FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);

 
 

-       if (wait)
-    if(*wait < 10)
-      *wait = 10;
+//-------------------------------------------------------------------------------------
+// Transmit the command (to the tag) that was placed in ToSend[].
+// Parameter timing:
+// if NULL: transfer at next possible time, taking into account
+//                     request guard time and frame delay time
+// if == 0:    transfer immediately and return time of transfer
+// if != 0: delay transfer until time specified
+//-------------------------------------------------------------------------------------
+static void TransmitFor14443a(const uint8_t *cmd, int len, uint32_t *timing)
+{
+       
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);

 
 

-  for(c = 0; c < *wait;) {
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-      AT91C_BASE_SSC->SSC_THR = 0x00;          // For exact timing!
-      c++;
-    }
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-      volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-      (void)r;
-    }
-    WDT_HIT();
-  }
+       uint32_t ThisTransferTime = 0;

 
 

-  c = 0;
-  for(;;) {
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-      AT91C_BASE_SSC->SSC_THR = cmd[c];
-      c++;
-      if(c >= len) {
-        break;
-      }
-    }
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-      volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-      (void)r;
-    }
-    WDT_HIT();
-  }
-       if (samples) *samples = (c + *wait) << 3;
+       if (timing) {
+               if(*timing == 0) {                                                                              // Measure time
+                       *timing = (GetCountSspClk() + 8) & 0xfffffff8;
+               } else {
+                       PrepareDelayedTransfer(*timing & 0x00000007);           // Delay transfer (fine tuning - up to 7 MF clock ticks)
+               }
+               if(MF_DBGLEVEL >= 4 && GetCountSspClk() >= (*timing & 0xfffffff8)) Dbprintf("TransmitFor14443a: Missed timing");
+               while(GetCountSspClk() < (*timing & 0xfffffff8));               // Delay transfer (multiple of 8 MF clock ticks)
+               LastTimeProxToAirStart = *timing;
+       } else {
+               ThisTransferTime = ((MAX(NextTransferTime, GetCountSspClk()) & 0xfffffff8) + 8);
+               while(GetCountSspClk() < ThisTransferTime);
+               LastTimeProxToAirStart = ThisTransferTime;
+       }
+       
+       // clear TXRDY
+       AT91C_BASE_SSC->SSC_THR = SEC_Y;
+
+       // for(uint16_t c = 0; c < 10;) {       // standard delay for each transfer (allow tag to be ready after last transmission)
+               // if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       // AT91C_BASE_SSC->SSC_THR = SEC_Y;     
+                       // c++;
+               // }
+       // }
+
+       uint16_t c = 0;
+       for(;;) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = cmd[c];
+                       c++;
+                       if(c >= len) {
+                               break;
+                       }
+               }
+       }
+       
+       NextTransferTime = MAX(NextTransferTime, LastTimeProxToAirStart + REQUEST_GUARD_TIME);
+       

 }
 
 }
 

+

 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------

-// To generate an arbitrary stream from reader
-//
+// Prepare reader command (in bits, support short frames) to send to FPGA

 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------

-void ArbitraryFromReader(const uint8_t *cmd, int parity, int len)
+void CodeIso14443aBitsAsReaderPar(const uint8_t * cmd, int bits, uint32_t dwParity)

 {
 {

-       int i;
-       int j;
+       int i, j;

        int last;
        int last;

-    uint8_t b;
+       uint8_t b;

 
        ToSendReset();
 
        // Start of Communication (Seq. Z)
 
        ToSendReset();
 
        // Start of Communication (Seq. Z)

-       Sequence(SEC_Z);
+       ToSend[++ToSendMax] = SEC_Z;
+       LastProxToAirDuration = 8 * (ToSendMax+1) - 6;

        last = 0;
 
        last = 0;
 

-       for(i = 0; i < len; i++) {
-        // Data bits
-        b = cmd[i];
-               for(j = 0; j < 8; j++) {
-                       if(b & 1) {
+       size_t bytecount = nbytes(bits);
+       // Generate send structure for the data bits
+       for (i = 0; i < bytecount; i++) {
+               // Get the current byte to send
+               b = cmd[i];
+               size_t bitsleft = MIN((bits-(i*8)),8);
+
+               for (j = 0; j < bitsleft; j++) {
+                       if (b & 1) {

                                // Sequence X
                                // Sequence X

-                               Sequence(SEC_X);
+                               ToSend[++ToSendMax] = SEC_X;
+                               LastProxToAirDuration = 8 * (ToSendMax+1) - 2;

                                last = 1;
                        } else {
                                last = 1;
                        } else {

-                               if(last == 0) {
-                                       // Sequence Z
-                                       Sequence(SEC_Z);
-                               }
-                               else {
+                               if (last == 0) {
+                               // Sequence Z
+                               ToSend[++ToSendMax] = SEC_Z;
+                               LastProxToAirDuration = 8 * (ToSendMax+1) - 6;
+                               } else {

                                        // Sequence Y
                                        // Sequence Y

-                                       Sequence(SEC_Y);
+                                       ToSend[++ToSendMax] = SEC_Y;

                                        last = 0;
                                }
                        }
                        b >>= 1;
                                        last = 0;
                                }
                        }
                        b >>= 1;

-

                }
 
                }
 

-               // Predefined parity bit, the flipper flips when needed, because of flips in byte sent
-               if(((parity >> (len - i - 1)) & 1)) {
-                       // Sequence X
-                       Sequence(SEC_X);
-                       last = 1;
-               } else {
-                       if(last == 0) {
-                               // Sequence Z
-                               Sequence(SEC_Z);
-                       }
-                       else {
-                               // Sequence Y
-                               Sequence(SEC_Y);
-                               last = 0;
+               // Only transmit (last) parity bit if we transmitted a complete byte
+               if (j == 8) {
+                       // Get the parity bit
+                       if ((dwParity >> i) & 0x01) {
+                               // Sequence X
+                               ToSend[++ToSendMax] = SEC_X;
+                               LastProxToAirDuration = 8 * (ToSendMax+1) - 2;
+                               last = 1;
+                       } else {
+                               if (last == 0) {
+                                       // Sequence Z
+                                       ToSend[++ToSendMax] = SEC_Z;
+                                       LastProxToAirDuration = 8 * (ToSendMax+1) - 6;
+                               } else {
+                                       // Sequence Y
+                                       ToSend[++ToSendMax] = SEC_Y;
+                                       last = 0;
+                               }

                        }
                }
        }
 
                        }
                }
        }
 

-       // End of Communication
-       if(last == 0) {
+       // End of Communication: Logic 0 followed by Sequence Y
+       if (last == 0) {

                // Sequence Z
                // Sequence Z

-               Sequence(SEC_Z);
-       }
-       else {
+               ToSend[++ToSendMax] = SEC_Z;
+               LastProxToAirDuration = 8 * (ToSendMax+1) - 6;
+       } else {

                // Sequence Y
                // Sequence Y

-               Sequence(SEC_Y);
+               ToSend[++ToSendMax] = SEC_Y;

                last = 0;
        }
                last = 0;
        }

-       // Sequence Y
-       Sequence(SEC_Y);
+       ToSend[++ToSendMax] = SEC_Y;

 
 

-       // Just to be sure!
-       Sequence(SEC_Y);
-       Sequence(SEC_Y);
-       Sequence(SEC_Y);
+       // Convert to length of command:
+       ToSendMax++;
+}

 
 

-    // Convert from last character reference to length
-    ToSendMax++;
+//-----------------------------------------------------------------------------
+// Prepare reader command to send to FPGA
+//-----------------------------------------------------------------------------
+void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
+{
+  CodeIso14443aBitsAsReaderPar(cmd,len*8,dwParity);

 }
 
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------

-// Code a 7-bit command without parity bit
-// This is especially for 0x26 and 0x52 (REQA and WUPA)
+// Wait for commands from reader
+// Stop when button is pressed (return 1) or field was gone (return 2)
+// Or return 0 when command is captured

 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------

-void ShortFrameFromReader(const uint8_t bt)
+static int EmGetCmd(uint8_t *received, int *len)

 {
 {

-       int j;
-       int last;
-  uint8_t b;
+       *len = 0;

 
 

-       ToSendReset();
+       uint32_t timer = 0, vtime = 0;
+       int analogCnt = 0;
+       int analogAVG = 0;

 
 

-       // Start of Communication (Seq. Z)
-       Sequence(SEC_Z);
-       last = 0;
+       // Set FPGA mode to "simulated ISO 14443 tag", no modulation (listen
+       // only, since we are receiving, not transmitting).
+       // Signal field is off with the appropriate LED
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);
+
+       // Set ADC to read field strength
+       AT91C_BASE_ADC->ADC_CR = AT91C_ADC_SWRST;
+       AT91C_BASE_ADC->ADC_MR =
+                               ADC_MODE_PRESCALE(32) |
+                               ADC_MODE_STARTUP_TIME(16) |
+                               ADC_MODE_SAMPLE_HOLD_TIME(8);
+       AT91C_BASE_ADC->ADC_CHER = ADC_CHANNEL(ADC_CHAN_HF);
+       // start ADC
+       AT91C_BASE_ADC->ADC_CR = AT91C_ADC_START;
+       
+       // Now run a 'software UART' on the stream of incoming samples.
+       UartReset();
+       Uart.output = received;
+
+       // Clear RXRDY:
+    uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;

 
 

-       b = bt;
-       for(j = 0; j < 7; j++) {
-               if(b & 1) {
-                       // Sequence X
-                       Sequence(SEC_X);
-                       last = 1;
-               } else {
-                       if(last == 0) {
-                               // Sequence Z
-                               Sequence(SEC_Z);
-                       }
-                       else {
-                               // Sequence Y
-                               Sequence(SEC_Y);
-                               last = 0;
+       for(;;) {
+               WDT_HIT();
+
+               if (BUTTON_PRESS()) return 1;
+
+               // test if the field exists
+               if (AT91C_BASE_ADC->ADC_SR & ADC_END_OF_CONVERSION(ADC_CHAN_HF)) {
+                       analogCnt++;
+                       analogAVG += AT91C_BASE_ADC->ADC_CDR[ADC_CHAN_HF];
+                       AT91C_BASE_ADC->ADC_CR = AT91C_ADC_START;
+                       if (analogCnt >= 32) {
+                               if ((33000 * (analogAVG / analogCnt) >> 10) < MF_MINFIELDV) {
+                                       vtime = GetTickCount();
+                                       if (!timer) timer = vtime;
+                                       // 50ms no field --> card to idle state
+                                       if (vtime - timer > 50) return 2;
+                               } else
+                                       if (timer) timer = 0;
+                               analogCnt = 0;
+                               analogAVG = 0;

                        }
                }
                        }
                }

-               b >>= 1;
+
+               // receive and test the miller decoding
+        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+            b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       if(MillerDecoding(b, 0)) {
+                               *len = Uart.len;
+                               return 0;
+                       }
+        }
+

        }
        }

+}

 
 

-       // End of Communication
-       if(last == 0) {
-               // Sequence Z
-               Sequence(SEC_Z);
+
+static int EmSendCmd14443aRaw(uint8_t *resp, int respLen, bool correctionNeeded)
+{
+       uint8_t b;
+       uint16_t i = 0;
+       uint32_t ThisTransferTime;
+       
+       // Modulate Manchester
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_MOD);
+
+       // include correction bit if necessary
+       if (Uart.parityBits & 0x01) {
+               correctionNeeded = TRUE;

        }
        }

-       else {
-               // Sequence Y
-               Sequence(SEC_Y);
-               last = 0;
+       if(correctionNeeded) {
+               // 1236, so correction bit needed
+               i = 0;
+       } else {
+               i = 1;
+       }
+
+       // clear receiving shift register and holding register
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
+       b = AT91C_BASE_SSC->SSC_RHR; (void) b;
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
+       b = AT91C_BASE_SSC->SSC_RHR; (void) b;
+       
+       // wait for the FPGA to signal fdt_indicator == 1 (the FPGA is ready to queue new data in its delay line)
+       for (uint16_t j = 0; j < 5; j++) {      // allow timeout - better late than never
+               while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
+               if (AT91C_BASE_SSC->SSC_RHR) break;

        }
        }

-       // Sequence Y
-       Sequence(SEC_Y);

 
 

-       // Just to be sure!
-       Sequence(SEC_Y);
-       Sequence(SEC_Y);
-       Sequence(SEC_Y);
+       while ((ThisTransferTime = GetCountSspClk()) & 0x00000007);
+
+       // Clear TXRDY:
+       AT91C_BASE_SSC->SSC_THR = SEC_F;
+
+       // send cycle
+       for(; i <= respLen; ) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = resp[i++];
+                       FpgaSendQueueDelay = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+               }
+       
+               if(BUTTON_PRESS()) {
+                       break;
+               }
+       }
+
+       // Ensure that the FPGA Delay Queue is empty before we switch to TAGSIM_LISTEN again:
+       for (i = 0; i < 2 ; ) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = SEC_F;
+                       FpgaSendQueueDelay = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       i++;
+               }
+       }
+       
+       LastTimeProxToAirStart = ThisTransferTime + (correctionNeeded?8:0);

 
 

-    // Convert from last character reference to length
-    ToSendMax++;
+       return 0;

 }
 
 }
 

-//-----------------------------------------------------------------------------
-// Prepare reader command to send to FPGA
-//
-//-----------------------------------------------------------------------------
-void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
-{
-  int i, j;
-  int last;
-  uint8_t b;
-
-  ToSendReset();
-
-  // Start of Communication (Seq. Z)
-  Sequence(SEC_Z);
-  last = 0;
-
-  // Generate send structure for the data bits
-  for (i = 0; i < len; i++) {
-    // Get the current byte to send
-    b = cmd[i];
-
-    for (j = 0; j < 8; j++) {
-      if (b & 1) {
-        // Sequence X
-        Sequence(SEC_X);
-        last = 1;
-      } else {
-        if (last == 0) {
-          // Sequence Z
-          Sequence(SEC_Z);
-        } else {
-          // Sequence Y
-          Sequence(SEC_Y);
-          last = 0;
-        }
-      }
-      b >>= 1;
-    }
+int EmSend4bitEx(uint8_t resp, bool correctionNeeded){
+       Code4bitAnswerAsTag(resp);
+       int res = EmSendCmd14443aRaw(ToSend, ToSendMax, correctionNeeded);
+       // do the tracing for the previous reader request and this tag answer:
+       EmLogTrace(Uart.output, 
+                               Uart.len, 
+                               Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, 
+                               Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 
+                               Uart.parityBits,
+                               &resp, 
+                               1, 
+                               LastTimeProxToAirStart*16 + DELAY_ARM2AIR_AS_TAG,
+                               (LastTimeProxToAirStart + LastProxToAirDuration)*16 + DELAY_ARM2AIR_AS_TAG, 
+                               SwapBits(GetParity(&resp, 1), 1));
+       return res;
+}

 
 

-    // Get the parity bit
-    if ((dwParity >> i) & 0x01) {
-      // Sequence X
-      Sequence(SEC_X);
-      last = 1;
-    } else {
-      if (last == 0) {
-        // Sequence Z
-        Sequence(SEC_Z);
-      } else {
-        // Sequence Y
-        Sequence(SEC_Y);
-        last = 0;
-      }
-    }
-  }
+int EmSend4bit(uint8_t resp){
+       return EmSend4bitEx(resp, false);
+}

 
 

-  // End of Communication
-  if (last == 0) {
-    // Sequence Z
-    Sequence(SEC_Z);
-  } else {
-    // Sequence Y
-    Sequence(SEC_Y);
-    last = 0;
-  }
-  // Sequence Y
-  Sequence(SEC_Y);
+int EmSendCmdExPar(uint8_t *resp, int respLen, bool correctionNeeded, uint32_t par){
+       CodeIso14443aAsTagPar(resp, respLen, par);
+       int res = EmSendCmd14443aRaw(ToSend, ToSendMax, correctionNeeded);
+       // do the tracing for the previous reader request and this tag answer:
+       EmLogTrace(Uart.output, 
+                               Uart.len, 
+                               Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, 
+                               Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 
+                               Uart.parityBits,
+                               resp, 
+                               respLen, 
+                               LastTimeProxToAirStart*16 + DELAY_ARM2AIR_AS_TAG,
+                               (LastTimeProxToAirStart + LastProxToAirDuration)*16 + DELAY_ARM2AIR_AS_TAG, 
+                               SwapBits(GetParity(resp, respLen), respLen));
+       return res;
+}
+
+int EmSendCmdEx(uint8_t *resp, int respLen, bool correctionNeeded){
+       return EmSendCmdExPar(resp, respLen, correctionNeeded, GetParity(resp, respLen));
+}

 
 

-  // Just to be sure!
-  Sequence(SEC_Y);
-  Sequence(SEC_Y);
-  Sequence(SEC_Y);
+int EmSendCmd(uint8_t *resp, int respLen){
+       return EmSendCmdExPar(resp, respLen, false, GetParity(resp, respLen));
+}

 
 

-  // Convert from last character reference to length
-  ToSendMax++;
+int EmSendCmdPar(uint8_t *resp, int respLen, uint32_t par){
+       return EmSendCmdExPar(resp, respLen, false, par);
+}
+
+bool EmLogTrace(uint8_t *reader_data, uint16_t reader_len, uint32_t reader_StartTime, uint32_t reader_EndTime, uint32_t reader_Parity,
+                                uint8_t *tag_data, uint16_t tag_len, uint32_t tag_StartTime, uint32_t tag_EndTime, uint32_t tag_Parity)
+{
+       if (tracing) {
+               // we cannot exactly measure the end and start of a received command from reader. However we know that the delay from
+               // end of the received command to start of the tag's (simulated by us) answer is n*128+20 or n*128+84 resp.
+               // with n >= 9. The start of the tags answer can be measured and therefore the end of the received command be calculated:
+               uint16_t reader_modlen = reader_EndTime - reader_StartTime;
+               uint16_t approx_fdt = tag_StartTime - reader_EndTime;
+               uint16_t exact_fdt = (approx_fdt - 20 + 32)/64 * 64 + 20;
+               reader_EndTime = tag_StartTime - exact_fdt;
+               reader_StartTime = reader_EndTime - reader_modlen;
+               if (!LogTrace(reader_data, reader_len, reader_StartTime, reader_Parity, TRUE)) {
+                       return FALSE;
+               } else if (!LogTrace(NULL, 0, reader_EndTime, 0, TRUE)) {
+                       return FALSE;
+               } else if (!LogTrace(tag_data, tag_len, tag_StartTime, tag_Parity, FALSE)) {
+                       return FALSE;
+               } else {
+                       return (!LogTrace(NULL, 0, tag_EndTime, 0, FALSE));
+               }
+       } else {
+               return TRUE;
+       }

 }
 
 //-----------------------------------------------------------------------------
 // Wait a certain time for tag response
 //  If a response is captured return TRUE
 }
 
 //-----------------------------------------------------------------------------
 // Wait a certain time for tag response
 //  If a response is captured return TRUE

-//  If it takes to long return FALSE
+//  If it takes too long return FALSE

 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------

-static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, int maxLen, int *samples, int *elapsed) //uint8_t *buffer
+static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, uint16_t offset, int maxLen)

 {
 {

-       // buffer needs to be 512 bytes
-       int c;
-
+       uint16_t c;
+       

        // Set FPGA mode to "reader listen mode", no modulation (listen
        // Set FPGA mode to "reader listen mode", no modulation (listen

-    // only, since we are receiving, not transmitting).
-    // Signal field is on with the appropriate LED
-    LED_D_ON();
-    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_LISTEN);
-
-    // Now get the answer from the card
-    Demod.output = receivedResponse;
-    Demod.len = 0;
-    Demod.state = DEMOD_UNSYNCD;
-
-       uint8_t b;
-       if (elapsed) *elapsed = 0;
-
+       // only, since we are receiving, not transmitting).
+       // Signal field is on with the appropriate LED
+       LED_D_ON();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_LISTEN);
+       
+       // Now get the answer from the card
+       DemodReset();
+       Demod.output = receivedResponse;
+
+       // clear RXRDY:
+    uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+       

        c = 0;
        for(;;) {
        c = 0;
        for(;;) {

-        WDT_HIT();
+               WDT_HIT();

 
 

-        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-            AT91C_BASE_SSC->SSC_THR = 0x00;  // To make use of exact timing of next command from reader!!
-                       if (elapsed) (*elapsed)++;
-        }
-        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       if(c < 512) { c++; } else { return FALSE; }
-            b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                       if(ManchesterDecoding((b & 0xf0) >> 4)) {
-                               *samples = ((c - 1) << 3) + 4;
-                               return TRUE;
-                       }
-                       if(ManchesterDecoding(b & 0x0f)) {
-                               *samples = c << 3;
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                       b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       if(ManchesterDecoding(b, offset, 0)) {
+                               NextTransferTime = MAX(NextTransferTime, Demod.endTime - (DELAY_AIR2ARM_AS_READER + DELAY_ARM2AIR_AS_READER)/16 + FRAME_DELAY_TIME_PICC_TO_PCD);

                                return TRUE;
                                return TRUE;

+                       } else if(c++ > iso14a_timeout) {
+                               return FALSE; 

                        }
                        }

-        }
-    }
+               }
+       }

 }
 
 }
 

-void ReaderTransmitShort(const uint8_t* bt)
+void ReaderTransmitBitsPar(uint8_t* frame, int bits, uint32_t par, uint32_t *timing)

 {
 {

-  int wait = 0;
-  int samples = 0;

 
 

-  ShortFrameFromReader(*bt);
+       CodeIso14443aBitsAsReaderPar(frame,bits,par);
+  
+       // Send command to tag
+       TransmitFor14443a(ToSend, ToSendMax, timing);
+       if(trigger)
+               LED_A_ON();
+  
+       // Log reader command in trace buffer
+       if (tracing) {
+               LogTrace(frame, nbytes(bits), LastTimeProxToAirStart*16 + DELAY_ARM2AIR_AS_READER, par, TRUE);
+               LogTrace(NULL, 0, (LastTimeProxToAirStart + LastProxToAirDuration)*16 + DELAY_ARM2AIR_AS_READER, 0, TRUE);
+       }
+}

 
 

-  // Select the card
-  TransmitFor14443a(ToSend, ToSendMax, &samples, &wait);
+void ReaderTransmitPar(uint8_t* frame, int len, uint32_t par, uint32_t *timing)
+{
+  ReaderTransmitBitsPar(frame,len*8,par, timing);
+}

 
 

-  // Store reader command in buffer
-  if (tracing) LogTrace(bt,1,0,GetParity(bt,1),TRUE);
+void ReaderTransmitBits(uint8_t* frame, int len, uint32_t *timing)
+{
+  // Generate parity and redirect
+  ReaderTransmitBitsPar(frame,len,GetParity(frame,len/8), timing);

 }
 
 }
 

-void ReaderTransmitPar(uint8_t* frame, int len, uint32_t par)
+void ReaderTransmit(uint8_t* frame, int len, uint32_t *timing)

 {
 {

-  int wait = 0;
-  int samples = 0;
+  // Generate parity and redirect
+  ReaderTransmitBitsPar(frame,len*8,GetParity(frame,len), timing);
+}

 
 

-  // This is tied to other size changes
-  //   uint8_t* frame_addr = ((uint8_t*)BigBuf) + 2024;
-  CodeIso14443aAsReaderPar(frame,len,par);
+int ReaderReceiveOffset(uint8_t* receivedAnswer, uint16_t offset)
+{
+       if (!GetIso14443aAnswerFromTag(receivedAnswer,offset,160)) return FALSE;
+       if (tracing) {
+               LogTrace(receivedAnswer, Demod.len, Demod.startTime*16 - DELAY_AIR2ARM_AS_READER, Demod.parityBits, FALSE);
+               LogTrace(NULL, 0, Demod.endTime*16 - DELAY_AIR2ARM_AS_READER, 0, FALSE);
+       }
+       return Demod.len;
+}

 
 

-  // Select the card
-  TransmitFor14443a(ToSend, ToSendMax, &samples, &wait);
+int ReaderReceive(uint8_t* receivedAnswer)
+{
+       return ReaderReceiveOffset(receivedAnswer, 0);
+}

 
 

-  // Store reader command in buffer
-  if (tracing) LogTrace(frame,len,0,par,TRUE);
+int ReaderReceivePar(uint8_t *receivedAnswer, uint32_t *parptr)
+{
+       if (!GetIso14443aAnswerFromTag(receivedAnswer,0,160)) return FALSE;
+       if (tracing) {
+               LogTrace(receivedAnswer, Demod.len, Demod.startTime*16 - DELAY_AIR2ARM_AS_READER, Demod.parityBits, FALSE);
+               LogTrace(NULL, 0, Demod.endTime*16 - DELAY_AIR2ARM_AS_READER, 0, FALSE);
+       }
+       *parptr = Demod.parityBits;
+       return Demod.len;

 }
 
 }
 

+/* performs iso14443a anticollision procedure
+ * fills the uid pointer unless NULL
+ * fills resp_data unless NULL */
+int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, uint32_t* cuid_ptr) {
+  uint8_t wupa[]       = { 0x52 };  // 0x26 - REQA  0x52 - WAKE-UP
+  uint8_t sel_all[]    = { 0x93,0x20 };
+  uint8_t sel_uid[]    = { 0x93,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
+  uint8_t rats[]       = { 0xE0,0x80,0x00,0x00 }; // FSD=256, FSDI=8, CID=0
+  uint8_t* resp = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);  // was 3560 - tied to other size changes
+  byte_t uid_resp[4];
+  size_t uid_resp_len;
+
+  uint8_t sak = 0x04; // cascade uid
+  int cascade_level = 0;
+  int len;
+        
+  // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
+    ReaderTransmitBitsPar(wupa,7,0, NULL);
+       
+  // Receive the ATQA
+  if(!ReaderReceive(resp)) return 0;
+  // Dbprintf("atqa: %02x %02x",resp[0],resp[1]);

 
 

-void ReaderTransmit(uint8_t* frame, int len)
-{
-  // Generate parity and redirect
-  ReaderTransmitPar(frame,len,GetParity(frame,len));
+  if(p_hi14a_card) {
+    memcpy(p_hi14a_card->atqa, resp, 2);
+    p_hi14a_card->uidlen = 0;
+    memset(p_hi14a_card->uid,0,10);
+  }
+
+  // clear uid
+  if (uid_ptr) {
+    memset(uid_ptr,0,10);
+  }
+
+  // OK we will select at least at cascade 1, lets see if first byte of UID was 0x88 in
+  // which case we need to make a cascade 2 request and select - this is a long UID
+  // While the UID is not complete, the 3nd bit (from the right) is set in the SAK.
+  for(; sak & 0x04; cascade_level++) {
+    // SELECT_* (L1: 0x93, L2: 0x95, L3: 0x97)
+    sel_uid[0] = sel_all[0] = 0x93 + cascade_level * 2;
+
+    // SELECT_ALL
+    ReaderTransmit(sel_all,sizeof(sel_all), NULL);
+    if (!ReaderReceive(resp)) return 0;
+
+       if (Demod.collisionPos) {                       // we had a collision and need to construct the UID bit by bit
+               memset(uid_resp, 0, 4);
+               uint16_t uid_resp_bits = 0;
+               uint16_t collision_answer_offset = 0;
+               // anti-collision-loop:
+               while (Demod.collisionPos) {
+                       Dbprintf("Multiple tags detected. Collision after Bit %d", Demod.collisionPos);
+                       for (uint16_t i = collision_answer_offset; i < Demod.collisionPos; i++, uid_resp_bits++) {      // add valid UID bits before collision point
+                               uint16_t UIDbit = (resp[i/8] >> (i % 8)) & 0x01;
+                               uid_resp[uid_resp_bits & 0xf8] |= UIDbit << (uid_resp_bits % 8);
+                       }
+                       uid_resp[uid_resp_bits/8] |= 1 << (uid_resp_bits % 8);                                  // next time select the card(s) with a 1 in the collision position
+                       uid_resp_bits++;
+                       // construct anticollosion command:
+                       sel_uid[1] = ((2 + uid_resp_bits/8) << 4) | (uid_resp_bits & 0x07);     // length of data in bytes and bits
+                       for (uint16_t i = 0; i <= uid_resp_bits/8; i++) {
+                               sel_uid[2+i] = uid_resp[i];
+                       }
+                       collision_answer_offset = uid_resp_bits%8;
+                       ReaderTransmitBits(sel_uid, 16 + uid_resp_bits, NULL);
+                       if (!ReaderReceiveOffset(resp, collision_answer_offset)) return 0;
+               }
+               // finally, add the last bits and BCC of the UID
+               for (uint16_t i = collision_answer_offset; i < (Demod.len-1)*8; i++, uid_resp_bits++) {
+                       uint16_t UIDbit = (resp[i/8] >> (i%8)) & 0x01;
+                       uid_resp[uid_resp_bits/8] |= UIDbit << (uid_resp_bits % 8);
+               }
+
+       } else {                // no collision, use the response to SELECT_ALL as current uid
+               memcpy(uid_resp,resp,4);
+       }
+       uid_resp_len = 4;
+       // Dbprintf("uid: %02x %02x %02x %02x",uid_resp[0],uid_resp[1],uid_resp[2],uid_resp[3]);
+
+    // calculate crypto UID. Always use last 4 Bytes.
+    if(cuid_ptr) {
+        *cuid_ptr = bytes_to_num(uid_resp, 4);
+    }
+
+    // Construct SELECT UID command
+       sel_uid[1] = 0x70;                                                                                                      // transmitting a full UID (1 Byte cmd, 1 Byte NVB, 4 Byte UID, 1 Byte BCC, 2 Bytes CRC)
+    memcpy(sel_uid+2,uid_resp,4);                                                                              // the UID
+       sel_uid[6] = sel_uid[2] ^ sel_uid[3] ^ sel_uid[4] ^ sel_uid[5];         // calculate and add BCC
+    AppendCrc14443a(sel_uid,7);                                                                                        // calculate and add CRC
+    ReaderTransmit(sel_uid,sizeof(sel_uid), NULL);
+
+    // Receive the SAK
+    if (!ReaderReceive(resp)) return 0;
+    sak = resp[0];
+
+    // Test if more parts of the uid are comming
+    if ((sak & 0x04) /* && uid_resp[0] == 0x88 */) {
+      // Remove first byte, 0x88 is not an UID byte, it CT, see page 3 of:
+      // http://www.nxp.com/documents/application_note/AN10927.pdf
+      memcpy(uid_resp, uid_resp + 1, 3);
+      uid_resp_len = 3;
+    }
+
+    if(uid_ptr) {
+      memcpy(uid_ptr + (cascade_level*3), uid_resp, uid_resp_len);
+    }
+
+    if(p_hi14a_card) {
+      memcpy(p_hi14a_card->uid + (cascade_level*3), uid_resp, uid_resp_len);
+      p_hi14a_card->uidlen += uid_resp_len;
+    }
+  }
+
+  if(p_hi14a_card) {
+    p_hi14a_card->sak = sak;
+    p_hi14a_card->ats_len = 0;
+  }
+
+  if( (sak & 0x20) == 0) {
+    return 2; // non iso14443a compliant tag
+  }
+
+  // Request for answer to select
+  AppendCrc14443a(rats, 2);
+  ReaderTransmit(rats, sizeof(rats), NULL);
+
+  if (!(len = ReaderReceive(resp))) return 0;
+
+  if(p_hi14a_card) {
+    memcpy(p_hi14a_card->ats, resp, sizeof(p_hi14a_card->ats));
+    p_hi14a_card->ats_len = len;
+  }
+
+  // reset the PCB block number
+  iso14_pcb_blocknum = 0;
+  return 1;

 }
 
 }
 

-int ReaderReceive(uint8_t* receivedAnswer)
-{
-  int samples = 0;
-  if (!GetIso14443aAnswerFromTag(receivedAnswer,100,&samples,0)) return FALSE;
-  if (tracing) LogTrace(receivedAnswer,Demod.len,samples,Demod.parityBits,FALSE);
-  return TRUE;
+void iso14443a_setup(uint8_t fpga_minor_mode) {
+       // Set up the synchronous serial port
+       FpgaSetupSsc();
+       // connect Demodulated Signal to ADC:
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+       // Signal field is on with the appropriate LED
+       if (fpga_minor_mode == FPGA_HF_ISO14443A_READER_MOD
+               || fpga_minor_mode == FPGA_HF_ISO14443A_READER_LISTEN) {
+               LED_D_ON();
+       } else {
+               LED_D_OFF();
+       }
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | fpga_minor_mode);
+
+       // Start the timer
+       StartCountSspClk();
+       
+       DemodReset();
+       UartReset();
+       NextTransferTime = 2*DELAY_ARM2AIR_AS_READER;
+       iso14a_set_timeout(1050); // 10ms default
+}
+
+int iso14_apdu(uint8_t * cmd, size_t cmd_len, void * data) {
+       uint8_t real_cmd[cmd_len+4];
+       real_cmd[0] = 0x0a; //I-Block
+       // put block number into the PCB
+       real_cmd[0] |= iso14_pcb_blocknum;
+       real_cmd[1] = 0x00; //CID: 0 //FIXME: allow multiple selected cards
+       memcpy(real_cmd+2, cmd, cmd_len);
+       AppendCrc14443a(real_cmd,cmd_len+2);
+ 
+       ReaderTransmit(real_cmd, cmd_len+4, NULL);
+       size_t len = ReaderReceive(data);
+       uint8_t * data_bytes = (uint8_t *) data;
+       if (!len)
+               return 0; //DATA LINK ERROR
+       // if we received an I- or R(ACK)-Block with a block number equal to the
+       // current block number, toggle the current block number
+       else if (len >= 4 // PCB+CID+CRC = 4 bytes
+                && ((data_bytes[0] & 0xC0) == 0 // I-Block
+                    || (data_bytes[0] & 0xD0) == 0x80) // R-Block with ACK bit set to 0
+                && (data_bytes[0] & 0x01) == iso14_pcb_blocknum) // equal block numbers
+       {
+               iso14_pcb_blocknum ^= 1;
+       }
+
+       return len;

 }
 
 //-----------------------------------------------------------------------------
 // Read an ISO 14443a tag. Send out commands and store answers.
 //
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------
 // Read an ISO 14443a tag. Send out commands and store answers.
 //
 //-----------------------------------------------------------------------------

-void ReaderIso14443a(uint32_t parameter)
+void ReaderIso14443a(UsbCommand *c)

 {
 {

-       // Anticollision
-       uint8_t wupa[]       = { 0x52 };
-       uint8_t sel_all[]    = { 0x93,0x20 };
-       uint8_t sel_uid[]    = { 0x93,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
-       uint8_t sel_all_c2[] = { 0x95,0x20 };
-       uint8_t sel_uid_c2[] = { 0x95,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+       iso14a_command_t param = c->arg[0];
+       uint8_t *cmd = c->d.asBytes;
+       size_t len = c->arg[1];
+       size_t lenbits = c->arg[2];
+       uint32_t arg0 = 0;
+       byte_t buf[USB_CMD_DATA_SIZE];
+  
+       if(param & ISO14A_CONNECT) {
+               iso14a_clear_trace();
+       }

 
 

-       // Mifare AUTH
-       uint8_t mf_auth[]    = { 0x60,0x00,0xf5,0x7b };
-//     uint8_t mf_nr_ar[]   = { 0x00,0x00,0x00,0x00 };
+       iso14a_set_tracing(TRUE);

 
 

-  uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + 3560);      // was 3560 - tied to other size changes
-  traceLen = 0;
+       if(param & ISO14A_REQUEST_TRIGGER) {
+               iso14a_set_trigger(TRUE);
+       }

 
 

-       // Setup SSC
-       FpgaSetupSsc();
+       if(param & ISO14A_CONNECT) {
+               iso14443a_setup(FPGA_HF_ISO14443A_READER_LISTEN);
+               if(!(param & ISO14A_NO_SELECT)) {
+                       iso14a_card_select_t *card = (iso14a_card_select_t*)buf;
+                       arg0 = iso14443a_select_card(NULL,card,NULL);
+                       cmd_send(CMD_ACK,arg0,card->uidlen,0,buf,sizeof(iso14a_card_select_t));
+               }
+       }

 
 

-       // Start from off (no field generated)
-  // Signal field is off with the appropriate LED
-  LED_D_OFF();
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-  SpinDelay(200);
+       if(param & ISO14A_SET_TIMEOUT) {
+               iso14a_timeout = c->arg[2];
+       }

 
 

-  SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-  FpgaSetupSsc();
+       if(param & ISO14A_APDU) {
+               arg0 = iso14_apdu(cmd, len, buf);
+               cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
+       }

 
 

-       // Now give it time to spin up.
-  // Signal field is on with the appropriate LED
-  LED_D_ON();
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
-       SpinDelay(200);
+       if(param & ISO14A_RAW) {
+               if(param & ISO14A_APPEND_CRC) {
+                       AppendCrc14443a(cmd,len);
+                       len += 2;
+               }
+               if(lenbits>0) {
+                       ReaderTransmitBitsPar(cmd,lenbits,GetParity(cmd,lenbits/8), NULL);
+               } else {
+                       ReaderTransmit(cmd,len, NULL);
+               }
+               arg0 = ReaderReceive(buf);
+               cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
+       }
+
+       if(param & ISO14A_REQUEST_TRIGGER) {
+               iso14a_set_trigger(FALSE);
+       }
+
+       if(param & ISO14A_NO_DISCONNECT) {
+               return;
+       }
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LEDsoff();
+}
+
+
+// Determine the distance between two nonces.
+// Assume that the difference is small, but we don't know which is first.
+// Therefore try in alternating directions.
+int32_t dist_nt(uint32_t nt1, uint32_t nt2) {
+
+       uint16_t i;
+       uint32_t nttmp1, nttmp2;
+
+       if (nt1 == nt2) return 0;
+
+       nttmp1 = nt1;
+       nttmp2 = nt2;
+       
+       for (i = 1; i < 32768; i++) {
+               nttmp1 = prng_successor(nttmp1, 1);
+               if (nttmp1 == nt2) return i;
+               nttmp2 = prng_successor(nttmp2, 1);
+                       if (nttmp2 == nt1) return -i;
+               }
+       
+       return(-99999); // either nt1 or nt2 are invalid nonces
+}
+
+
+//-----------------------------------------------------------------------------
+// Recover several bits of the cypher stream. This implements (first stages of)
+// the algorithm described in "The Dark Side of Security by Obscurity and
+// Cloning MiFare Classic Rail and Building Passes, Anywhere, Anytime"
+// (article by Nicolas T. Courtois, 2009)
+//-----------------------------------------------------------------------------
+void ReaderMifare(bool first_try)
+{
+       // Mifare AUTH
+       uint8_t mf_auth[]    = { 0x60,0x00,0xf5,0x7b };
+       uint8_t mf_nr_ar[]   = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+       static uint8_t mf_nr_ar3;
+
+       uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);
+
+       iso14a_clear_trace();
+       iso14a_set_tracing(TRUE);
+
+       byte_t nt_diff = 0;
+       byte_t par = 0;
+       //byte_t par_mask = 0xff;
+       static byte_t par_low = 0;
+       bool led_on = TRUE;
+       uint8_t uid[10];
+       uint32_t cuid;
+
+       uint32_t nt, previous_nt;
+       static uint32_t nt_attacked = 0;
+       byte_t par_list[8] = {0,0,0,0,0,0,0,0};
+       byte_t ks_list[8] = {0,0,0,0,0,0,0,0};
+
+       static uint32_t sync_time;
+       static uint32_t sync_cycles;
+       int catch_up_cycles = 0;
+       int last_catch_up = 0;
+       uint16_t consecutive_resyncs = 0;
+       int isOK = 0;
+
+
+
+       if (first_try) { 
+               mf_nr_ar3 = 0;
+               iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);
+               sync_time = GetCountSspClk() & 0xfffffff8;
+               sync_cycles = 65536;                                                                    // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the nonces).
+               nt_attacked = 0;
+               nt = 0;
+               par = 0;
+       }
+       else {
+               // we were unsuccessful on a previous call. Try another READER nonce (first 3 parity bits remain the same)
+               // nt_attacked = prng_successor(nt_attacked, 1);
+               mf_nr_ar3++;
+               mf_nr_ar[3] = mf_nr_ar3;
+               par = par_low;
+       }

 
        LED_A_ON();
        LED_B_OFF();
        LED_C_OFF();
 
        LED_A_ON();
        LED_B_OFF();
        LED_C_OFF();

+       
+  
+       for(uint16_t i = 0; TRUE; i++) {
+               
+               WDT_HIT();

 
 

-       while(traceLen < TRACE_LENGTH)
-  {
-    // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
-    ReaderTransmitShort(wupa);
+               // Test if the action was cancelled
+               if(BUTTON_PRESS()) {
+                       break;
+               }
+               
+               LED_C_ON();

 
 

-    // Test if the action was cancelled
-    if(BUTTON_PRESS()) {
-      break;
-    }
+               if(!iso14443a_select_card(uid, NULL, &cuid)) {
+                       if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Can't select card");
+                       continue;
+               }

 
 

-    // Receive the ATQA
-    if (!ReaderReceive(receivedAnswer)) continue;
+               sync_time = (sync_time & 0xfffffff8) + sync_cycles + catch_up_cycles;
+               catch_up_cycles = 0;

 
 

-    // Transmit SELECT_ALL
-    ReaderTransmit(sel_all,sizeof(sel_all));
+               // if we missed the sync time already, advance to the next nonce repeat
+               while(GetCountSspClk() > sync_time) {
+                       sync_time = (sync_time & 0xfffffff8) + sync_cycles;
+               }

 
 

-    // Receive the UID
-    if (!ReaderReceive(receivedAnswer)) continue;
+               // Transmit MIFARE_CLASSIC_AUTH at synctime. Should result in returning the same tag nonce (== nt_attacked) 
+               ReaderTransmit(mf_auth, sizeof(mf_auth), &sync_time);

 
 

-               // Construct SELECT UID command
-               // First copy the 5 bytes (Mifare Classic) after the 93 70
-               memcpy(sel_uid+2,receivedAnswer,5);
-               // Secondly compute the two CRC bytes at the end
-    AppendCrc14443a(sel_uid,7);
+               // Receive the (4 Byte) "random" nonce
+               if (!ReaderReceive(receivedAnswer)) {
+                       if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Couldn't receive tag nonce");
+                       continue;
+                 }

 
 

-    // Transmit SELECT_UID
-    ReaderTransmit(sel_uid,sizeof(sel_uid));
+               previous_nt = nt;
+               nt = bytes_to_num(receivedAnswer, 4);

 
 

-    // Receive the SAK
-    if (!ReaderReceive(receivedAnswer)) continue;
+               // Transmit reader nonce with fake par
+               ReaderTransmitPar(mf_nr_ar, sizeof(mf_nr_ar), par, NULL);

 
 

-    // OK we have selected at least at cascade 1, lets see if first byte of UID was 0x88 in
-    // which case we need to make a cascade 2 request and select - this is a long UID
-    // When the UID is not complete, the 3nd bit (from the right) is set in the SAK.
-               if (receivedAnswer[0] &= 0x04)
+               if (first_try && previous_nt && !nt_attacked) { // we didn't calibrate our clock yet
+                       int nt_distance = dist_nt(previous_nt, nt);
+                       if (nt_distance == 0) {
+                               nt_attacked = nt;
+                       }
+                       else {
+                               if (nt_distance == -99999) { // invalid nonce received, try again
+                                       continue;
+                               }
+                               sync_cycles = (sync_cycles - nt_distance);
+                               if (MF_DBGLEVEL >= 3) Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
+                               continue;
+                       }
+               }
+
+               if ((nt != nt_attacked) && nt_attacked) {       // we somehow lost sync. Try to catch up again...
+                       catch_up_cycles = -dist_nt(nt_attacked, nt);
+                       if (catch_up_cycles == 99999) {                 // invalid nonce received. Don't resync on that one.
+                               catch_up_cycles = 0;
+                               continue;
+                       }
+                       if (catch_up_cycles == last_catch_up) {
+                               consecutive_resyncs++;
+                       }
+                       else {
+                               last_catch_up = catch_up_cycles;
+                           consecutive_resyncs = 0;
+                       }
+                       if (consecutive_resyncs < 3) {
+                               if (MF_DBGLEVEL >= 3) Dbprintf("Lost sync in cycle %d. nt_distance=%d. Consecutive Resyncs = %d. Trying one time catch up...\n", i, -catch_up_cycles, consecutive_resyncs);
+                       }
+                       else {  
+                               sync_cycles = sync_cycles + catch_up_cycles;
+                               if (MF_DBGLEVEL >= 3) Dbprintf("Lost sync in cycle %d for the fourth time consecutively (nt_distance = %d). Adjusting sync_cycles to %d.\n", i, -catch_up_cycles, sync_cycles);
+                       }
+                       continue;
+               }
+ 
+               consecutive_resyncs = 0;
+               
+               // Receive answer. This will be a 4 Bit NACK when the 8 parity bits are OK after decoding
+               if (ReaderReceive(receivedAnswer))

                {
                {

-      // Transmit SELECT_ALL
-      ReaderTransmit(sel_all_c2,sizeof(sel_all_c2));
+                       catch_up_cycles = 8;    // the PRNG is delayed by 8 cycles due to the NAC (4Bits = 0x05 encrypted) transfer
+       
+                       if (nt_diff == 0)
+                       {
+                               par_low = par & 0x07; // there is no need to check all parities for other nt_diff. Parity Bits for mf_nr_ar[0..2] won't change
+                       }

 
 

-      // Receive the UID
-      if (!ReaderReceive(receivedAnswer)) continue;
+                       led_on = !led_on;
+                       if(led_on) LED_B_ON(); else LED_B_OFF();

 
 

-      // Construct SELECT UID command
-      memcpy(sel_uid_c2+2,receivedAnswer,5);
-      // Secondly compute the two CRC bytes at the end
-      AppendCrc14443a(sel_uid_c2,7);
+                       par_list[nt_diff] = par;
+                       ks_list[nt_diff] = receivedAnswer[0] ^ 0x05;

 
 

-      // Transmit SELECT_UID
-      ReaderTransmit(sel_uid_c2,sizeof(sel_uid_c2));
+                       // Test if the information is complete
+                       if (nt_diff == 0x07) {
+                               isOK = 1;
+                               break;
+                       }

 
 

-      // Receive the SAK
-      if (!ReaderReceive(receivedAnswer)) continue;
+                       nt_diff = (nt_diff + 1) & 0x07;
+                       mf_nr_ar[3] = (mf_nr_ar[3] & 0x1F) | (nt_diff << 5);
+                       par = par_low;
+               } else {
+                       if (nt_diff == 0 && first_try)
+                       {
+                               par++;
+                       } else {
+                               par = (((par >> 3) + 1) << 3) | par_low;
+                       }

                }
                }

+       }

 
 

-    // Transmit MIFARE_CLASSIC_AUTH
-    ReaderTransmit(mf_auth,sizeof(mf_auth));

 
 

-    // Receive the (16 bit) "random" nonce
-    if (!ReaderReceive(receivedAnswer)) continue;
-       }
+       mf_nr_ar[3] &= 0x1F;
+       
+       byte_t buf[28];
+       memcpy(buf + 0,  uid, 4);
+       num_to_bytes(nt, 4, buf + 4);
+       memcpy(buf + 8,  par_list, 8);
+       memcpy(buf + 16, ks_list, 8);
+       memcpy(buf + 24, mf_nr_ar, 4);
+               
+       cmd_send(CMD_ACK,isOK,0,0,buf,28);

 
 

-  // Thats it...
+       // Thats it...

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();

-       Dbprintf("%x %x %x", rsamples, 0xCC, 0xCC);
-       DbpString("ready..");
+
+       iso14a_set_tracing(FALSE);

 }
 
 }
 

-//-----------------------------------------------------------------------------
-// Read an ISO 14443a tag. Send out commands and store answers.
-//
-//-----------------------------------------------------------------------------
-void ReaderMifare(uint32_t parameter)
+/**
+  *MIFARE 1K simulate.
+  *
+  *@param flags :
+  *    FLAG_INTERACTIVE - In interactive mode, we are expected to finish the operation with an ACK
+  * 4B_FLAG_UID_IN_DATA - means that there is a 4-byte UID in the data-section, we're expected to use that
+  * 7B_FLAG_UID_IN_DATA - means that there is a 7-byte UID in the data-section, we're expected to use that
+  *    FLAG_NR_AR_ATTACK  - means we should collect NR_AR responses for bruteforcing later
+  *@param exitAfterNReads, exit simulation after n blocks have been read, 0 is inifite
+  */
+void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *datain)

 {
 {

+       int cardSTATE = MFEMUL_NOFIELD;
+       int _7BUID = 0;
+       int vHf = 0;    // in mV
+       int res;
+       uint32_t selTimer = 0;
+       uint32_t authTimer = 0;
+       uint32_t par = 0;
+       int len = 0;
+       uint8_t cardWRBL = 0;
+       uint8_t cardAUTHSC = 0;
+       uint8_t cardAUTHKEY = 0xff;  // no authentication
+       uint32_t cardRr = 0;
+       uint32_t cuid = 0;
+       //uint32_t rn_enc = 0;
+       uint32_t ans = 0;
+       uint32_t cardINTREG = 0;
+       uint8_t cardINTBLOCK = 0;
+       struct Crypto1State mpcs = {0, 0};
+       struct Crypto1State *pcs;
+       pcs = &mpcs;
+       uint32_t numReads = 0;//Counts numer of times reader read a block
+       uint8_t* receivedCmd = eml_get_bigbufptr_recbuf();
+       uint8_t *response = eml_get_bigbufptr_sendbuf();
+       
+       uint8_t rATQA[] = {0x04, 0x00}; // Mifare classic 1k 4BUID
+       uint8_t rUIDBCC1[] = {0xde, 0xad, 0xbe, 0xaf, 0x62};
+       uint8_t rUIDBCC2[] = {0xde, 0xad, 0xbe, 0xaf, 0x62}; // !!!
+       uint8_t rSAK[] = {0x08, 0xb6, 0xdd};
+       uint8_t rSAK1[] = {0x04, 0xda, 0x17};
+
+       uint8_t rAUTH_NT[] = {0x01, 0x02, 0x03, 0x04};
+       uint8_t rAUTH_AT[] = {0x00, 0x00, 0x00, 0x00};
+               
+       //Here, we collect UID,NT,AR,NR,UID2,NT2,AR2,NR2
+       // This can be used in a reader-only attack.
+       // (it can also be retrieved via 'hf 14a list', but hey...
+       uint32_t ar_nr_responses[] = {0,0,0,0,0,0,0,0};
+       uint8_t ar_nr_collected = 0;
+
+       // clear trace
+    iso14a_clear_trace();
+       iso14a_set_tracing(TRUE);
+
+       // Authenticate response - nonce
+       uint32_t nonce = bytes_to_num(rAUTH_NT, 4);
+       
+       //-- Determine the UID
+       // Can be set from emulator memory, incoming data
+       // and can be 7 or 4 bytes long
+       if (flags & FLAG_4B_UID_IN_DATA)
+       {
+               // 4B uid comes from data-portion of packet
+               memcpy(rUIDBCC1,datain,4);
+               rUIDBCC1[4] = rUIDBCC1[0] ^ rUIDBCC1[1] ^ rUIDBCC1[2] ^ rUIDBCC1[3];
+
+       } else if (flags & FLAG_7B_UID_IN_DATA) {
+               // 7B uid comes from data-portion of packet
+               memcpy(&rUIDBCC1[1],datain,3);
+               memcpy(rUIDBCC2, datain+3, 4);
+               _7BUID = true;
+       } else {
+               // get UID from emul memory
+               emlGetMemBt(receivedCmd, 7, 1);
+               _7BUID = !(receivedCmd[0] == 0x00);
+               if (!_7BUID) {                     // ---------- 4BUID
+                       emlGetMemBt(rUIDBCC1, 0, 4);
+               } else {                           // ---------- 7BUID
+                       emlGetMemBt(&rUIDBCC1[1], 0, 3);
+                       emlGetMemBt(rUIDBCC2, 3, 4);
+               }
+       }

 
 

-       // Anticollision
-       uint8_t wupa[]       = { 0x52 };
-       uint8_t sel_all[]    = { 0x93,0x20 };
-       uint8_t sel_uid[]    = { 0x93,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+       /*
+        * Regardless of what method was used to set the UID, set fifth byte and modify
+        * the ATQA for 4 or 7-byte UID
+        */
+       rUIDBCC1[4] = rUIDBCC1[0] ^ rUIDBCC1[1] ^ rUIDBCC1[2] ^ rUIDBCC1[3];
+       if (_7BUID) {
+               rATQA[0] = 0x44;
+               rUIDBCC1[0] = 0x88;
+               rUIDBCC2[4] = rUIDBCC2[0] ^ rUIDBCC2[1] ^ rUIDBCC2[2] ^ rUIDBCC2[3];
+       }

 
 

-       // Mifare AUTH
-       uint8_t mf_auth[]    = { 0x60,0x00,0xf5,0x7b };
-  uint8_t mf_nr_ar[]   = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+       // We need to listen to the high-frequency, peak-detected path.
+       iso14443a_setup(FPGA_HF_ISO14443A_TAGSIM_LISTEN);

 
 

-  uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + 3560);      // was 3560 - tied to other size changes
-  traceLen = 0;
-  tracing = false;

 
 

-       // Setup SSC
-       FpgaSetupSsc();
+       if (MF_DBGLEVEL >= 1)   {
+               if (!_7BUID) {
+                       Dbprintf("4B UID: %02x%02x%02x%02x",rUIDBCC1[0] , rUIDBCC1[1] , rUIDBCC1[2] , rUIDBCC1[3]);
+               } else {
+                       Dbprintf("7B UID: (%02x)%02x%02x%02x%02x%02x%02x%02x",rUIDBCC1[0] , rUIDBCC1[1] , rUIDBCC1[2] , rUIDBCC1[3],rUIDBCC2[0],rUIDBCC2[1] ,rUIDBCC2[2] , rUIDBCC2[3]);
+               }
+       }

 
 

-       // Start from off (no field generated)
-  // Signal field is off with the appropriate LED
-  LED_D_OFF();
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-  SpinDelay(200);
+       bool finished = FALSE;
+       while (!BUTTON_PRESS() && !finished) {
+               WDT_HIT();

 
 

-  SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-  FpgaSetupSsc();
+               // find reader field
+               // Vref = 3300mV, and an 10:1 voltage divider on the input
+               // can measure voltages up to 33000 mV
+               if (cardSTATE == MFEMUL_NOFIELD) {
+                       vHf = (33000 * AvgAdc(ADC_CHAN_HF)) >> 10;
+                       if (vHf > MF_MINFIELDV) {
+                               cardSTATE_TO_IDLE();
+                               LED_A_ON();
+                       }
+               } 
+               if(cardSTATE == MFEMUL_NOFIELD) continue;
+
+               //Now, get data
+
+               res = EmGetCmd(receivedCmd, &len);
+               if (res == 2) { //Field is off!
+                       cardSTATE = MFEMUL_NOFIELD;
+                       LEDsoff();
+                       continue;
+               } else if (res == 1) {
+                       break;  //return value 1 means button press
+               }
+                       
+               // REQ or WUP request in ANY state and WUP in HALTED state
+               if (len == 1 && ((receivedCmd[0] == 0x26 && cardSTATE != MFEMUL_HALTED) || receivedCmd[0] == 0x52)) {
+                       selTimer = GetTickCount();
+                       EmSendCmdEx(rATQA, sizeof(rATQA), (receivedCmd[0] == 0x52));
+                       cardSTATE = MFEMUL_SELECT1;
+
+                       // init crypto block
+                       LED_B_OFF();
+                       LED_C_OFF();
+                       crypto1_destroy(pcs);
+                       cardAUTHKEY = 0xff;
+                       continue;
+               }
+               
+               switch (cardSTATE) {
+                       case MFEMUL_NOFIELD:
+                       case MFEMUL_HALTED:
+                       case MFEMUL_IDLE:{
+                               LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                               break;
+                       }
+                       case MFEMUL_SELECT1:{
+                               // select all
+                               if (len == 2 && (receivedCmd[0] == 0x93 && receivedCmd[1] == 0x20)) {
+                                       if (MF_DBGLEVEL >= 4)   Dbprintf("SELECT ALL received");
+                                       EmSendCmd(rUIDBCC1, sizeof(rUIDBCC1));
+                                       break;
+                               }

 
 

-       // Now give it time to spin up.
-  // Signal field is on with the appropriate LED
-  LED_D_ON();
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
-       SpinDelay(200);
+                               if (MF_DBGLEVEL >= 4 && len == 9 && receivedCmd[0] == 0x93 && receivedCmd[1] == 0x70 )
+                               {
+                                       Dbprintf("SELECT %02x%02x%02x%02x received",receivedCmd[2],receivedCmd[3],receivedCmd[4],receivedCmd[5]);
+                               }
+                               // select card
+                               if (len == 9 && 
+                                               (receivedCmd[0] == 0x93 && receivedCmd[1] == 0x70 && memcmp(&receivedCmd[2], rUIDBCC1, 4) == 0)) {
+                                       EmSendCmd(_7BUID?rSAK1:rSAK, sizeof(_7BUID?rSAK1:rSAK));
+                                       cuid = bytes_to_num(rUIDBCC1, 4);
+                                       if (!_7BUID) {
+                                               cardSTATE = MFEMUL_WORK;
+                                               LED_B_ON();
+                                               if (MF_DBGLEVEL >= 4)   Dbprintf("--> WORK. anticol1 time: %d", GetTickCount() - selTimer);
+                                               break;
+                                       } else {
+                                               cardSTATE = MFEMUL_SELECT2;
+                                       }
+                               }
+                               break;
+                       }
+                       case MFEMUL_AUTH1:{
+                               if( len != 8)
+                               {
+                                       cardSTATE_TO_IDLE();
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }
+                               uint32_t ar = bytes_to_num(receivedCmd, 4);
+                               uint32_t nr= bytes_to_num(&receivedCmd[4], 4);
+
+                               //Collect AR/NR
+                               if(ar_nr_collected < 2){
+                                       if(ar_nr_responses[2] != ar)
+                                       {// Avoid duplicates... probably not necessary, ar should vary. 
+                                               ar_nr_responses[ar_nr_collected*4] = cuid;
+                                               ar_nr_responses[ar_nr_collected*4+1] = nonce;
+                                               ar_nr_responses[ar_nr_collected*4+2] = ar;
+                                               ar_nr_responses[ar_nr_collected*4+3] = nr;
+                                               ar_nr_collected++;
+                                       }
+                               }

 
 

-       LED_A_ON();
-       LED_B_OFF();
-       LED_C_OFF();
+                               // --- crypto
+                               crypto1_word(pcs, ar , 1);
+                               cardRr = nr ^ crypto1_word(pcs, 0, 0);
+
+                               // test if auth OK
+                               if (cardRr != prng_successor(nonce, 64)){
+                                       if (MF_DBGLEVEL >= 2)   Dbprintf("AUTH FAILED. cardRr=%08x, succ=%08x",cardRr, prng_successor(nonce, 64));
+                                       // Shouldn't we respond anything here?
+                                       // Right now, we don't nack or anything, which causes the
+                                       // reader to do a WUPA after a while. /Martin
+                                       cardSTATE_TO_IDLE();
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }

 
 

-  // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
-  ReaderTransmitShort(wupa);
-  // Receive the ATQA
-  ReaderReceive(receivedAnswer);
-  // Transmit SELECT_ALL
-  ReaderTransmit(sel_all,sizeof(sel_all));
-  // Receive the UID
-  ReaderReceive(receivedAnswer);
-  // Construct SELECT UID command
-  // First copy the 5 bytes (Mifare Classic) after the 93 70
-  memcpy(sel_uid+2,receivedAnswer,5);
-  // Secondly compute the two CRC bytes at the end
-  AppendCrc14443a(sel_uid,7);
-
-  byte_t nt_diff = 0;
-  LED_A_OFF();
-  byte_t par = 0;
-  byte_t par_mask = 0xff;
-  byte_t par_low = 0;
-  int led_on = TRUE;
-
-  tracing = FALSE;
-  byte_t nt[4];
-  byte_t nt_attacked[4];
-  byte_t par_list[8];
-  byte_t ks_list[8];
-  num_to_bytes(parameter,4,nt_attacked);
-
-  while(TRUE)
-  {
-    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-    SpinDelay(200);
-    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
-
-    // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
-    ReaderTransmitShort(wupa);
-
-    // Test if the action was cancelled
-    if(BUTTON_PRESS()) {
-      break;
-    }
+                               ans = prng_successor(nonce, 96) ^ crypto1_word(pcs, 0, 0);

 
 

-    // Receive the ATQA
-    if (!ReaderReceive(receivedAnswer)) continue;
+                               num_to_bytes(ans, 4, rAUTH_AT);
+                               // --- crypto
+                               EmSendCmd(rAUTH_AT, sizeof(rAUTH_AT));
+                               LED_C_ON();
+                               cardSTATE = MFEMUL_WORK;
+                               if (MF_DBGLEVEL >= 4)   Dbprintf("AUTH COMPLETED. sector=%d, key=%d time=%d", cardAUTHSC, cardAUTHKEY, GetTickCount() - authTimer);
+                               break;
+                       }
+                       case MFEMUL_SELECT2:{
+                               if (!len) { 
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }
+                               if (len == 2 && (receivedCmd[0] == 0x95 && receivedCmd[1] == 0x20)) {
+                                       EmSendCmd(rUIDBCC2, sizeof(rUIDBCC2));
+                                       break;
+                               }

 
 

-    // Transmit SELECT_ALL
-    ReaderTransmit(sel_all,sizeof(sel_all));
+                               // select 2 card
+                               if (len == 9 && 
+                                               (receivedCmd[0] == 0x95 && receivedCmd[1] == 0x70 && memcmp(&receivedCmd[2], rUIDBCC2, 4) == 0)) {
+                                       EmSendCmd(rSAK, sizeof(rSAK));
+                                       cuid = bytes_to_num(rUIDBCC2, 4);
+                                       cardSTATE = MFEMUL_WORK;
+                                       LED_B_ON();
+                                       if (MF_DBGLEVEL >= 4)   Dbprintf("--> WORK. anticol2 time: %d", GetTickCount() - selTimer);
+                                       break;
+                               }
+                               
+                               // i guess there is a command). go into the work state.
+                               if (len != 4) {
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }
+                               cardSTATE = MFEMUL_WORK;
+                               //goto lbWORK;
+                               //intentional fall-through to the next case-stmt
+                       }

 
 

-    // Receive the UID
-    if (!ReaderReceive(receivedAnswer)) continue;
+                       case MFEMUL_WORK:{
+                               if (len == 0) {
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }
+                               
+                               bool encrypted_data = (cardAUTHKEY != 0xFF) ;

 
 

-    // Transmit SELECT_UID
-    ReaderTransmit(sel_uid,sizeof(sel_uid));
+                               if(encrypted_data) {
+                                       // decrypt seqence
+                                       mf_crypto1_decrypt(pcs, receivedCmd, len);
+                               }
+                               
+                               if (len == 4 && (receivedCmd[0] == 0x60 || receivedCmd[0] == 0x61)) {
+                                       authTimer = GetTickCount();
+                                       cardAUTHSC = receivedCmd[1] / 4;  // received block num
+                                       cardAUTHKEY = receivedCmd[0] - 0x60;
+                                       crypto1_destroy(pcs);//Added by martin
+                                       crypto1_create(pcs, emlGetKey(cardAUTHSC, cardAUTHKEY));
+
+                                       if (!encrypted_data) { // first authentication
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader authenticating for block %d (0x%02x) with key %d",receivedCmd[1] ,receivedCmd[1],cardAUTHKEY  );
+
+                                               crypto1_word(pcs, cuid ^ nonce, 0);//Update crypto state
+                                               num_to_bytes(nonce, 4, rAUTH_AT); // Send nonce
+                                       } else { // nested authentication
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader doing nested authentication for block %d (0x%02x) with key %d",receivedCmd[1] ,receivedCmd[1],cardAUTHKEY );
+                                               ans = nonce ^ crypto1_word(pcs, cuid ^ nonce, 0); 
+                                               num_to_bytes(ans, 4, rAUTH_AT);
+                                       }
+                                       EmSendCmd(rAUTH_AT, sizeof(rAUTH_AT));
+                                       //Dbprintf("Sending rAUTH %02x%02x%02x%02x", rAUTH_AT[0],rAUTH_AT[1],rAUTH_AT[2],rAUTH_AT[3]);
+                                       cardSTATE = MFEMUL_AUTH1;
+                                       break;
+                               }
+                               
+                               // rule 13 of 7.5.3. in ISO 14443-4. chaining shall be continued
+                               // BUT... ACK --> NACK
+                               if (len == 1 && receivedCmd[0] == CARD_ACK) {
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                       break;
+                               }
+                               
+                               // rule 12 of 7.5.3. in ISO 14443-4. R(NAK) --> R(ACK)
+                               if (len == 1 && receivedCmd[0] == CARD_NACK_NA) {
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_ACK));
+                                       break;
+                               }
+                               
+                               if(len != 4) {
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }

 
 

-    // Receive the SAK
-    if (!ReaderReceive(receivedAnswer)) continue;
-
-    // Transmit MIFARE_CLASSIC_AUTH
-    ReaderTransmit(mf_auth,sizeof(mf_auth));
-
-    // Receive the (16 bit) "random" nonce
-    if (!ReaderReceive(receivedAnswer)) continue;
-    memcpy(nt,receivedAnswer,4);
-
-    // Transmit reader nonce and reader answer
-    ReaderTransmitPar(mf_nr_ar,sizeof(mf_nr_ar),par);
-
-    // Receive 4 bit answer
-    if (ReaderReceive(receivedAnswer))
-    {
-      if (nt_diff == 0)
-      {
-        LED_A_ON();
-        memcpy(nt_attacked,nt,4);
-        par_mask = 0xf8;
-        par_low = par & 0x07;
-      }
-
-      if (memcmp(nt,nt_attacked,4) != 0) continue;
-
-      led_on = !led_on;
-      if(led_on) LED_B_ON(); else LED_B_OFF();
-      par_list[nt_diff] = par;
-      ks_list[nt_diff] = receivedAnswer[0]^0x05;
-
-      // Test if the information is complete
-      if (nt_diff == 0x07) break;
-
-      nt_diff = (nt_diff+1) & 0x07;
-      mf_nr_ar[3] = nt_diff << 5;
-      par = par_low;
-    } else {
-      if (nt_diff == 0)
-      {
-        par++;
-      } else {
-        par = (((par>>3)+1) << 3) | par_low;
-      }
-    }
-  }
+                               if(receivedCmd[0] == 0x30 // read block
+                                               || receivedCmd[0] == 0xA0 // write block
+                                               || receivedCmd[0] == 0xC0
+                                               || receivedCmd[0] == 0xC1
+                                               || receivedCmd[0] == 0xC2 // inc dec restore
+                                               || receivedCmd[0] == 0xB0) { // transfer
+                                       if (receivedCmd[1] >= 16 * 4) {
+                                               EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate (0x%02) on out of range block: %d (0x%02x), nacking",receivedCmd[0],receivedCmd[1],receivedCmd[1]);
+                                               break;
+                                       }

 
 

-  LogTraceInfo(sel_uid+2,4);
-  LogTraceInfo(nt,4);
-  LogTraceInfo(par_list,8);
-  LogTraceInfo(ks_list,8);
+                                       if (receivedCmd[1] / 4 != cardAUTHSC) {
+                                               EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate (0x%02) on block (0x%02x) not authenticated for (0x%02x), nacking",receivedCmd[0],receivedCmd[1],cardAUTHSC);
+                                               break;
+                                       }
+                               }
+                               // read block
+                               if (receivedCmd[0] == 0x30) {
+                                       if (MF_DBGLEVEL >= 2) {
+                                               Dbprintf("Reader reading block %d (0x%02x)",receivedCmd[1],receivedCmd[1]);
+                                       }
+                                       emlGetMem(response, receivedCmd[1], 1);
+                                       AppendCrc14443a(response, 16);
+                                       mf_crypto1_encrypt(pcs, response, 18, &par);
+                                       EmSendCmdPar(response, 18, par);
+                                       numReads++;
+                                       if(exitAfterNReads > 0 && numReads == exitAfterNReads) {
+                                               Dbprintf("%d reads done, exiting", numReads);
+                                               finished = true;
+                                       }
+                                       break;
+                               }
+                               // write block
+                               if (receivedCmd[0] == 0xA0) {
+                                       if (MF_DBGLEVEL >= 2) Dbprintf("RECV 0xA0 write block %d (%02x)",receivedCmd[1],receivedCmd[1]);
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_ACK));
+                                       cardSTATE = MFEMUL_WRITEBL2;
+                                       cardWRBL = receivedCmd[1];
+                                       break;
+                               }
+                               // increment, decrement, restore
+                               if (receivedCmd[0] == 0xC0 || receivedCmd[0] == 0xC1 || receivedCmd[0] == 0xC2) {
+                                       if (MF_DBGLEVEL >= 2) Dbprintf("RECV 0x%02x inc(0xC1)/dec(0xC0)/restore(0xC2) block %d (%02x)",receivedCmd[0],receivedCmd[1],receivedCmd[1]);
+                                       if (emlCheckValBl(receivedCmd[1])) {
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate on block, but emlCheckValBl failed, nacking");
+                                               EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                               break;
+                                       }
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_ACK));
+                                       if (receivedCmd[0] == 0xC1)
+                                               cardSTATE = MFEMUL_INTREG_INC;
+                                       if (receivedCmd[0] == 0xC0)
+                                               cardSTATE = MFEMUL_INTREG_DEC;
+                                       if (receivedCmd[0] == 0xC2)
+                                               cardSTATE = MFEMUL_INTREG_REST;
+                                       cardWRBL = receivedCmd[1];
+                                       break;
+                               }
+                               // transfer
+                               if (receivedCmd[0] == 0xB0) {
+                                       if (MF_DBGLEVEL >= 2) Dbprintf("RECV 0x%02x transfer block %d (%02x)",receivedCmd[0],receivedCmd[1],receivedCmd[1]);
+                                       if (emlSetValBl(cardINTREG, cardINTBLOCK, receivedCmd[1]))
+                                               EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                       else
+                                               EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_ACK));
+                                       break;
+                               }
+                               // halt
+                               if (receivedCmd[0] == 0x50 && receivedCmd[1] == 0x00) {
+                                       LED_B_OFF();
+                                       LED_C_OFF();
+                                       cardSTATE = MFEMUL_HALTED;
+                                       if (MF_DBGLEVEL >= 4)   Dbprintf("--> HALTED. Selected time: %d ms",  GetTickCount() - selTimer);
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                                       break;
+                               }
+                               // RATS
+                               if (receivedCmd[0] == 0xe0) {//RATS
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                       break;
+                               }
+                               // command not allowed
+                               if (MF_DBGLEVEL >= 4)   Dbprintf("Received command not allowed, nacking");
+                               EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                               break;
+                       }
+                       case MFEMUL_WRITEBL2:{
+                               if (len == 18){
+                                       mf_crypto1_decrypt(pcs, receivedCmd, len);
+                                       emlSetMem(receivedCmd, cardWRBL, 1);
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_ACK));
+                                       cardSTATE = MFEMUL_WORK;
+                               } else {
+                                       cardSTATE_TO_IDLE();
+                                       LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                                       LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                               }
+                               break;
+                       }
+                       
+                       case MFEMUL_INTREG_INC:{
+                               mf_crypto1_decrypt(pcs, receivedCmd, len);
+                               memcpy(&ans, receivedCmd, 4);
+                               if (emlGetValBl(&cardINTREG, &cardINTBLOCK, cardWRBL)) {
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                       cardSTATE_TO_IDLE();
+                                       break;
+                               } 
+                               LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                               cardINTREG = cardINTREG + ans;
+                               cardSTATE = MFEMUL_WORK;
+                               break;
+                       }
+                       case MFEMUL_INTREG_DEC:{
+                               mf_crypto1_decrypt(pcs, receivedCmd, len);
+                               memcpy(&ans, receivedCmd, 4);
+                               if (emlGetValBl(&cardINTREG, &cardINTBLOCK, cardWRBL)) {
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                       cardSTATE_TO_IDLE();
+                                       break;
+                               }
+                               LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                               cardINTREG = cardINTREG - ans;
+                               cardSTATE = MFEMUL_WORK;
+                               break;
+                       }
+                       case MFEMUL_INTREG_REST:{
+                               mf_crypto1_decrypt(pcs, receivedCmd, len);
+                               memcpy(&ans, receivedCmd, 4);
+                               if (emlGetValBl(&cardINTREG, &cardINTBLOCK, cardWRBL)) {
+                                       EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
+                                       cardSTATE_TO_IDLE();
+                                       break;
+                               }
+                               LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parityBits, TRUE);
+                               LogTrace(NULL, 0, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, 0, TRUE);
+                               cardSTATE = MFEMUL_WORK;
+                               break;
+                       }
+               }
+       }

 
 

-  // Thats it...

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();

-  tracing = TRUE;
+
+       if(flags & FLAG_INTERACTIVE)// Interactive mode flag, means we need to send ACK
+       {
+               //May just aswell send the collected ar_nr in the response aswell
+               cmd_send(CMD_ACK,CMD_SIMULATE_MIFARE_CARD,0,0,&ar_nr_responses,ar_nr_collected*4*4);
+       }
+
+       if(flags & FLAG_NR_AR_ATTACK)
+       {
+               if(ar_nr_collected > 1) {
+                       Dbprintf("Collected two pairs of AR/NR which can be used to extract keys from reader:");
+                       Dbprintf("../tools/mfkey/mfkey32 %08x %08x %08x %08x %08x %08x",
+                                        ar_nr_responses[0], // UID
+                                       ar_nr_responses[1], //NT
+                                       ar_nr_responses[2], //AR1
+                                       ar_nr_responses[3], //NR1
+                                       ar_nr_responses[6], //AR2
+                                       ar_nr_responses[7] //NR2
+                                       );
+               } else {
+                       Dbprintf("Failed to obtain two AR/NR pairs!");
+                       if(ar_nr_collected >0) {
+                               Dbprintf("Only got these: UID=%08x, nonce=%08x, AR1=%08x, NR1=%08x",
+                                               ar_nr_responses[0], // UID
+                                               ar_nr_responses[1], //NT
+                                               ar_nr_responses[2], //AR1
+                                               ar_nr_responses[3] //NR1
+                                               );
+                       }
+               }
+       }
+       if (MF_DBGLEVEL >= 1)   Dbprintf("Emulator stopped. Tracing: %d  trace length: %d ",    tracing, traceLen);
+}
+
+
+
+//-----------------------------------------------------------------------------
+// MIFARE sniffer. 
+// 
+//-----------------------------------------------------------------------------
+void RAMFUNC SniffMifare(uint8_t param) {
+       // param:
+       // bit 0 - trigger from first card answer
+       // bit 1 - trigger from first reader 7-bit request
+
+       // C(red) A(yellow) B(green)
+       LEDsoff();
+       // init trace buffer
+    iso14a_clear_trace();
+
+       // The command (reader -> tag) that we're receiving.
+       // The length of a received command will in most cases be no more than 18 bytes.
+       // So 32 should be enough!
+       uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
+       // The response (tag -> reader) that we're receiving.
+       uint8_t *receivedResponse = (((uint8_t *)BigBuf) + RECV_RES_OFFSET);
+
+       // As we receive stuff, we copy it from receivedCmd or receivedResponse
+       // into trace, along with its length and other annotations.
+       //uint8_t *trace = (uint8_t *)BigBuf;
+       
+       // The DMA buffer, used to stream samples from the FPGA
+       uint8_t *dmaBuf = ((uint8_t *)BigBuf) + DMA_BUFFER_OFFSET;
+       uint8_t *data = dmaBuf;
+       uint8_t previous_data = 0;
+       int maxDataLen = 0;
+       int dataLen = 0;
+       bool ReaderIsActive = FALSE;
+       bool TagIsActive = FALSE;
+
+       iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
+
+       // Set up the demodulator for tag -> reader responses.
+       Demod.output = receivedResponse;
+
+       // Set up the demodulator for the reader -> tag commands
+       Uart.output = receivedCmd;
+
+       // Setup for the DMA.
+       FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE); // set transfer address and number of bytes. Start transfer.
+
+       LED_D_OFF();
+       
+       // init sniffer
+       MfSniffInit();
+
+       // And now we loop, receiving samples.
+       for(uint32_t sniffCounter = 0; TRUE; ) {
+       
+               if(BUTTON_PRESS()) {
+                       DbpString("cancelled by button");
+                       break;
+               }
+
+               LED_A_ON();
+               WDT_HIT();
+               
+               if ((sniffCounter & 0x0000FFFF) == 0) { // from time to time
+                       // check if a transaction is completed (timeout after 2000ms).
+                       // if yes, stop the DMA transfer and send what we have so far to the client
+                       if (MfSniffSend(2000)) {                        
+                               // Reset everything - we missed some sniffed data anyway while the DMA was stopped
+                               sniffCounter = 0;
+                               data = dmaBuf;
+                               maxDataLen = 0;
+                               ReaderIsActive = FALSE;
+                               TagIsActive = FALSE;
+                               FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE); // set transfer address and number of bytes. Start transfer.
+                       }
+               }
+               
+               int register readBufDataP = data - dmaBuf;      // number of bytes we have processed so far
+               int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR; // number of bytes already transferred
+               if (readBufDataP <= dmaBufDataP){                       // we are processing the same block of data which is currently being transferred
+                       dataLen = dmaBufDataP - readBufDataP;   // number of bytes still to be processed
+               } else {                                                                        
+                       dataLen = DMA_BUFFER_SIZE - readBufDataP + dmaBufDataP; // number of bytes still to be processed
+               }
+               // test for length of buffer
+               if(dataLen > maxDataLen) {                                      // we are more behind than ever...
+                       maxDataLen = dataLen;                                   
+                       if(dataLen > 400) {
+                               Dbprintf("blew circular buffer! dataLen=0x%x", dataLen);
+                               break;
+                       }
+               }
+               if(dataLen < 1) continue;
+
+               // primary buffer was stopped ( <-- we lost data!
+               if (!AT91C_BASE_PDC_SSC->PDC_RCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
+                       Dbprintf("RxEmpty ERROR!!! data length:%d", dataLen); // temporary
+               }
+               // secondary buffer sets as primary, secondary buffer was stopped
+               if (!AT91C_BASE_PDC_SSC->PDC_RNCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+               }
+
+               LED_A_OFF();
+               
+               if (sniffCounter & 0x01) {
+
+                       if(!TagIsActive) {              // no need to try decoding tag data if the reader is sending
+                               uint8_t readerdata = (previous_data & 0xF0) | (*data >> 4);
+                               if(MillerDecoding(readerdata, (sniffCounter-1)*4)) {
+                                       LED_C_INV();
+                                       if (MfSniffLogic(receivedCmd, Uart.len, Uart.parityBits, Uart.bitCount, TRUE)) break;
+
+                                       /* And ready to receive another command. */
+                                       UartReset();
+                                       
+                                       /* And also reset the demod code */
+                                       DemodReset();
+                               }
+                               ReaderIsActive = (Uart.state != STATE_UNSYNCD);
+                       }
+                       
+                       if(!ReaderIsActive) {           // no need to try decoding tag data if the reader is sending
+                               uint8_t tagdata = (previous_data << 4) | (*data & 0x0F);
+                               if(ManchesterDecoding(tagdata, 0, (sniffCounter-1)*4)) {
+                                       LED_C_INV();
+
+                                       if (MfSniffLogic(receivedResponse, Demod.len, Demod.parityBits, Demod.bitCount, FALSE)) break;
+
+                                       // And ready to receive another response.
+                                       DemodReset();
+                               }
+                               TagIsActive = (Demod.state != DEMOD_UNSYNCD);
+                       }
+               }
+
+               previous_data = *data;
+               sniffCounter++;
+               data++;
+               if(data == dmaBuf + DMA_BUFFER_SIZE) {
+                       data = dmaBuf;
+               }
+
+       } // main cycle
+
+       DbpString("COMMAND FINISHED");
+
+       FpgaDisableSscDma();
+       MfSniffEnd();
+       
+       Dbprintf("maxDataLen=%x, Uart.state=%x, Uart.len=%x", maxDataLen, Uart.state, Uart.len);
+       LEDsoff();

 }
 }