Fido U2F complete (#716)

[proxmark3-svn] / armsrc / iso15693.c

diff --git a/armsrc/iso15693.c b/armsrc/iso15693.c
index e11e5a9ccc6e232fa7374bf2c7f5fb1e2390ec66..da2aab69bfa1d6971bc3c3a88edac8340e7f88f2 100644 (file)
--- a/armsrc/iso15693.c
+++ b/armsrc/iso15693.c
@@ -2,33 +2,31 @@
 // Jonathan Westhues, split Nov 2006
 // Modified by Greg Jones, Jan 2009
 // Modified by Adrian Dabrowski "atrox", Mar-Sept 2010,Oct 2011
 // Jonathan Westhues, split Nov 2006
 // Modified by Greg Jones, Jan 2009
 // Modified by Adrian Dabrowski "atrox", Mar-Sept 2010,Oct 2011

+// Modified by piwi, Oct 2018 

 //
 // 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 15693. This includes both the reader software and
 //
 // 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 15693. This includes both the reader software and

-// the `fake tag' modes, but at the moment I've implemented only the reader
-// stuff, and that barely.
-// Modified to perform modulation onboard in arm rather than on PC
-// Also added additional reader commands (SELECT, READ etc.)
+// the `fake tag' modes.

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

-// The ISO 15693 describes two transmission modes from reader to tag, and 4 
-// transmission modes from tag to reader. As of Mar 2010 this code only 
-// supports one of each: "1of4" mode from reader to tag, and the highspeed 
-// variant with one subcarrier from card to reader.
-// As long, as the card fully support ISO 15693 this is no problem, since the 
-// reader chooses both data rates, but some non-standard tags do not. Further for 
-// the simulation to work, we will need to support all data rates.
+
+// The ISO 15693 describes two transmission modes from reader to tag, and four
+// transmission modes from tag to reader. As of Oct 2018 this code supports
+// both reader modes and the high speed variant with one subcarrier from card to reader.
+// As long as the card fully support ISO 15693 this is no problem, since the
+// reader chooses both data rates, but some non-standard tags do not. 
+// For card simulation, the code supports both high and low speed modes with one subcarrier.

 //
 // VCD (reader) -> VICC (tag)
 // 1 out of 256:
 //
 // VCD (reader) -> VICC (tag)
 // 1 out of 256:

-//     data rate: 1,66 kbit/s (fc/8192) 
+//     data rate: 1,66 kbit/s (fc/8192)

 //     used for long range
 // 1 out of 4:
 //     data rate: 26,48 kbit/s (fc/512)
 //     used for short range, high speed
 //     used for long range
 // 1 out of 4:
 //     data rate: 26,48 kbit/s (fc/512)
 //     used for short range, high speed

-// 
+//

 // VICC (tag) -> VCD (reader)
 // Modulation:
 //             ASK / one subcarrier (423,75 khz)
 // VICC (tag) -> VCD (reader)
 // Modulation:
 //             ASK / one subcarrier (423,75 khz)


@@ -39,22 +37,17 @@
 //     high ASK: 26,48 kbit/s
 //     high FSK: 26,69 kbit/s
 //-----------------------------------------------------------------------------
 //     high ASK: 26,48 kbit/s
 //     high FSK: 26,69 kbit/s
 //-----------------------------------------------------------------------------

-// added "1 out of 256" mode (for VCD->PICC) - atrox 20100911

 
 
 // Random Remarks:
 // *) UID is always used "transmission order" (LSB), which is reverse to display order
 
 // TODO / BUGS / ISSUES:
 
 
 // Random Remarks:
 // *) UID is always used "transmission order" (LSB), which is reverse to display order
 
 // TODO / BUGS / ISSUES:

-// *) writing to tags takes longer: we miss the answer from the tag in most cases
-//    -> tweak the read-timeout times
-// *) signal decoding from the card is still a bit shaky. 
-// *) signal decoding is unable to detect collissions.
-// *) add anti-collission support for inventory-commands 
+// *) signal decoding is unable to detect collisions.
+// *) add anti-collision support for inventory-commands

 // *) read security status of a block
 // *) read security status of a block

-// *) sniffing and simulation do only support one transmission mode. need to support 
-//             all 8 transmission combinations
-//     *) remove or refactor code under "depricated"
+// *) sniffing and simulation do not support two subcarrier modes.
+// *) remove or refactor code under "depricated"

 // *) document all the functions
 
 
 // *) document all the functions
 
 


@@ -63,10 +56,13 @@
 #include "apps.h"
 #include "string.h"
 #include "iso15693tools.h"
 #include "apps.h"
 #include "string.h"
 #include "iso15693tools.h"

+#include "protocols.h"

 #include "cmd.h"
 
 #define arraylen(x) (sizeof(x)/sizeof((x)[0]))
 
 #include "cmd.h"
 
 #define arraylen(x) (sizeof(x)/sizeof((x)[0]))
 

+static int DEBUG = 0;
+

 ///////////////////////////////////////////////////////////////////////
 // ISO 15693 Part 2 - Air Interface
 // This section basicly contains transmission and receiving of bits
 ///////////////////////////////////////////////////////////////////////
 // ISO 15693 Part 2 - Air Interface
 // This section basicly contains transmission and receiving of bits


@@ -81,15 +77,25 @@
 #define AddCrc(data,datalen)  Iso15693AddCrc(data,datalen)
 #define sprintUID(target,uid)  Iso15693sprintUID(target,uid)
 
 #define AddCrc(data,datalen)  Iso15693AddCrc(data,datalen)
 #define sprintUID(target,uid)  Iso15693sprintUID(target,uid)
 

-int DEBUG=0;
+// approximate amplitude=sqrt(ci^2+cq^2) by amplitude = max(|ci|,|cq|) + 1/2*min(|ci|,|cq|)
+#define AMPLITUDE(ci, cq) (MAX(ABS(ci), ABS(cq)) + MIN(ABS(ci), ABS(cq))/2)

 
 

+// buffers
+#define ISO15693_DMA_BUFFER_SIZE     128
+#define ISO15693_MAX_RESPONSE_LENGTH  36 // allows read single block with the maximum block size of 256bits. Read multiple blocks not supported yet
+#define ISO15693_MAX_COMMAND_LENGTH   45 // allows write single block with the maximum block size of 256bits. Write multiple blocks not supported yet
+
+// timing. Delays in SSP_CLK ticks.
+#define DELAY_READER_TO_ARM            8
+#define DELAY_ARM_TO_READER            1
+#define DELAY_ISO15693_VCD_TO_VICC   132 // 132/423.75kHz = 311.5us from end of EOF to start of tag response

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

-// Signal Processing 
+// Signal Processing

 // ---------------------------
 
 // prepare data using "1 out of 4" code for later transmission
 // ---------------------------
 
 // prepare data using "1 out of 4" code for later transmission

-// resulting data rate is 26,48 kbit/s (fc/512)
+// resulting data rate is 26.48 kbit/s (fc/512)

 // cmd ... data
 // n ... length of data
 static void CodeIso15693AsReader(uint8_t *cmd, int n)
 // cmd ... data
 // n ... length of data
 static void CodeIso15693AsReader(uint8_t *cmd, int n)


@@ -165,14 +171,16 @@ static void CodeIso15693AsReader(uint8_t *cmd, int n)
        ToSendStuffBit(0);
        ToSendStuffBit(1);
 
        ToSendStuffBit(0);
        ToSendStuffBit(1);
 

-       // And slack at the end, too.
-       for(i = 0; i < 24; i++) {
+       // Fill remainder of last byte with 1
+       for(i = 0; i < 4; i++) {

                ToSendStuffBit(1);
        }
                ToSendStuffBit(1);
        }

+       
+       ToSendMax++;

 }
 
 }
 

-// encode data using "1 out of 256" sheme
-// data rate is 1,66 kbit/s (fc/8192) 
+// encode data using "1 out of 256" scheme
+// data rate is 1,66 kbit/s (fc/8192)

 // is designed for more robust communication over longer distances
 static void CodeIso15693AsReader256(uint8_t *cmd, int n)
 {
 // is designed for more robust communication over longer distances
 static void CodeIso15693AsReader256(uint8_t *cmd, int n)
 {


@@ -194,7 +202,7 @@ static void CodeIso15693AsReader256(uint8_t *cmd, int n)
        ToSendStuffBit(1);
        ToSendStuffBit(1);
        ToSendStuffBit(0);
        ToSendStuffBit(1);
        ToSendStuffBit(1);
        ToSendStuffBit(0);

-       
+

        for(i = 0; i < n; i++) {
                for (j = 0; j<=255; j++) {
                        if (cmd[i]==j) {
        for(i = 0; i < n; i++) {
                for (j = 0; j<=255; j++) {
                        if (cmd[i]==j) {


@@ -203,8 +211,8 @@ static void CodeIso15693AsReader256(uint8_t *cmd, int n)
                        } else {
                                ToSendStuffBit(1);
                                ToSendStuffBit(1);
                        } else {
                                ToSendStuffBit(1);
                                ToSendStuffBit(1);

-                       }                       
-               }       
+                       }
+               }

        }
        // EOF
        ToSendStuffBit(1);
        }
        // EOF
        ToSendStuffBit(1);


@@ -212,357 +220,722 @@ static void CodeIso15693AsReader256(uint8_t *cmd, int n)
        ToSendStuffBit(0);
        ToSendStuffBit(1);
 
        ToSendStuffBit(0);
        ToSendStuffBit(1);
 

-       // And slack at the end, too.
-       for(i = 0; i < 24; i++) {
+       // Fill remainder of last byte with 1
+       for(i = 0; i < 4; i++) {

                ToSendStuffBit(1);
        }
                ToSendStuffBit(1);
        }

+
+       ToSendMax++;

 }
 
 
 }
 
 

-// Transmit the command (to the tag) that was placed in ToSend[].
-static void TransmitTo15693Tag(const uint8_t *cmd, int len, int *samples, int *wait)
+static void CodeIso15693AsTag(uint8_t *cmd, int n)

 {
 {

-    int c;
+       ToSendReset();
+
+       // SOF
+       ToSendStuffBit(0);
+       ToSendStuffBit(0);
+       ToSendStuffBit(0);
+       ToSendStuffBit(1);
+       ToSendStuffBit(1);
+       ToSendStuffBit(1);
+       ToSendStuffBit(0);
+       ToSendStuffBit(1);
+
+       // data
+       for(int i = 0; i < n; i++) {
+               for(int j = 0; j < 8; j++) {
+                       if ((cmd[i] >> j) & 0x01) {
+                                       ToSendStuffBit(0);
+                                       ToSendStuffBit(1);
+                       } else {
+                                       ToSendStuffBit(1);
+                                       ToSendStuffBit(0);
+                       }
+               }
+       }
+
+       // EOF
+       ToSendStuffBit(1);
+       ToSendStuffBit(0);
+       ToSendStuffBit(1);
+       ToSendStuffBit(1);
+       ToSendStuffBit(1);
+       ToSendStuffBit(0);
+       ToSendStuffBit(0);
+       ToSendStuffBit(0);
+
+       ToSendMax++;
+}
+

 
 

-//    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
+// Transmit the command (to the tag) that was placed in cmd[].
+static void TransmitTo15693Tag(const uint8_t *cmd, int len)
+{
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);

-       if(*wait < 10) { *wait = 10; }
-
-//    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();
-//    }
-
-    c = 0;
-    for(;;) {
+
+       LED_B_ON();
+    for(int c = 0; c < len; ) {

         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {

-            AT91C_BASE_SSC->SSC_THR = cmd[c];
+            AT91C_BASE_SSC->SSC_THR = ~cmd[c];

             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();
     }
         }
         WDT_HIT();
     }

-       *samples = (c + *wait) << 3;
+       LED_B_OFF();

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

-// Transmit the command (to the reader) that was placed in ToSend[].
+// Transmit the tag response (to the reader) that was placed in cmd[].

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

-static void TransmitTo15693Reader(const uint8_t *cmd, int len, int *samples, int *wait)
+static void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start_time, bool slow)

 {
 {

-    int c = 0;
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR|FPGA_HF_SIMULATOR_MODULATE_424K);
-       if(*wait < 10) { *wait = 10; }
+       // don't use the FPGA_HF_SIMULATOR_MODULATE_424K_8BIT minor mode. It would spoil GetCountSspClk()
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_424K);

 
 

-    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;
+       uint8_t shift_delay = start_time & 0x00000007;
+       uint8_t bitmask = 0x00;
+       for (int i = 0; i < shift_delay; i++) {
+               bitmask |= (0x01 << i);
+       }
+
+       while (GetCountSspClk() < (start_time & 0xfffffff8)) ;
+       AT91C_BASE_SSC->SSC_THR = 0x00; // clear TXRDY
+
+       LED_C_ON();
+       uint8_t bits_to_shift = 0x00;
+    for(size_t c = 0; c <= len; c++) {
+               uint8_t bits_to_send = bits_to_shift << (8 - shift_delay) | (c==len?0x00:cmd[c]) >> shift_delay;
+               bits_to_shift = cmd[c] & bitmask;
+               for (int i = 7; i >= 0; i--) {
+                       for (int j = 0; j < (slow?4:1); ) {
+                               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+                                       if (bits_to_send >> i & 0x01) {
+                                               AT91C_BASE_SSC->SSC_THR = 0xff;
+                                       } else {
+                                               AT91C_BASE_SSC->SSC_THR = 0x00;
+                                       }
+                                       j++;
+                               }
+                               WDT_HIT();
+                       }

         }
         }

-        WDT_HIT();

     }
     }

-       *samples = (c + *wait) << 3;
+       LED_C_OFF();

 }
 
 
 }
 
 

-// Read from Tag
-// Parameters:
-//             receivedResponse
-//             maxLen
-//             samples
-//             elapsed
-// returns: 
-//             number of decoded bytes
-static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *samples, int *elapsed)
+//=============================================================================
+// An ISO 15693 decoder for tag responses (one subcarrier only).
+// Uses cross correlation to identify the SOF, each bit, and EOF.
+// This function is called 8 times per bit (every 2 subcarrier cycles).
+// Subcarrier frequency fs is 424kHz, 1/fs = 2,36us,
+// i.e. function is called every 4,72us
+// LED handling:
+//    LED C -> ON once we have received the SOF and are expecting the rest.
+//    LED C -> OFF once we have received EOF or are unsynced
+//
+// Returns: true if we received a EOF
+//          false if we are still waiting for some more
+//=============================================================================
+
+#define SUBCARRIER_DETECT_THRESHOLD    2
+#define SOF_CORRELATOR_LEN (1<<5)
+
+typedef struct DecodeTag {
+       enum {
+               STATE_TAG_UNSYNCD,
+               STATE_TAG_AWAIT_SOF_1,
+               STATE_TAG_AWAIT_SOF_2,
+               STATE_TAG_RECEIVING_DATA,
+               STATE_TAG_AWAIT_EOF
+       }         state;
+       int       bitCount;
+       int       posCount;
+       enum {
+               LOGIC0,
+               LOGIC1,
+               SOF_PART1,
+               SOF_PART2
+       }         lastBit;
+       uint16_t  shiftReg;
+       uint8_t   *output;
+       int       len;
+       int       sum1, sum2;
+       uint8_t   SOF_low;
+       uint8_t   SOF_high;
+       uint8_t   SOF_last;
+       int32_t   SOF_corr;
+       int32_t   SOF_corr_prev;
+       uint8_t   SOF_correlator[SOF_CORRELATOR_LEN];
+} DecodeTag_t;
+
+static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTag)

 {
 {

-       int c = 0;
-       uint8_t *dest = BigBuf_get_addr();
-       int getNext = 0;
+       switch(DecodeTag->state) {
+               case STATE_TAG_UNSYNCD:
+                       // initialize SOF correlator. We are looking for 12 samples low and 12 samples high.
+                       DecodeTag->SOF_low = 0;
+                       DecodeTag->SOF_high = 12;
+                       DecodeTag->SOF_last = 23;
+                       memset(DecodeTag->SOF_correlator, 0x00, DecodeTag->SOF_last + 1);
+                       DecodeTag->SOF_correlator[DecodeTag->SOF_last] = AMPLITUDE(ci,cq);
+                       DecodeTag->SOF_corr = DecodeTag->SOF_correlator[DecodeTag->SOF_last];
+                       DecodeTag->SOF_corr_prev = DecodeTag->SOF_corr;
+                       // initialize Decoder
+                       DecodeTag->posCount = 0;
+                       DecodeTag->bitCount = 0;
+                       DecodeTag->len = 0;
+                       DecodeTag->state = STATE_TAG_AWAIT_SOF_1;
+                       break;
+
+               case STATE_TAG_AWAIT_SOF_1:
+                       // calculate the correlation in real time. Look at differences only.
+                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_low++];
+                       DecodeTag->SOF_corr -= 2*DecodeTag->SOF_correlator[DecodeTag->SOF_high++];
+                       DecodeTag->SOF_last++;
+                       DecodeTag->SOF_low &= (SOF_CORRELATOR_LEN-1);
+                       DecodeTag->SOF_high &= (SOF_CORRELATOR_LEN-1);
+                       DecodeTag->SOF_last &= (SOF_CORRELATOR_LEN-1);
+                       DecodeTag->SOF_correlator[DecodeTag->SOF_last] = AMPLITUDE(ci,cq);
+                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_last];
+
+                       // if correlation increases for 10 consecutive samples, we are close to maximum correlation
+                       if (DecodeTag->SOF_corr > DecodeTag->SOF_corr_prev + SUBCARRIER_DETECT_THRESHOLD) {
+                               DecodeTag->posCount++;
+                       } else {
+                               DecodeTag->posCount = 0;
+                       }

 
 

-       int8_t prev = 0;
+                       if (DecodeTag->posCount == 10) {        // correlation increased 10 times
+                               DecodeTag->state = STATE_TAG_AWAIT_SOF_2;
+                       }

 
 

-// NOW READ RESPONSE
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
-       //spindelay(60);        // greg - experiment to get rid of some of the 0 byte/failed reads
-       c = 0;
-       getNext = FALSE;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       int8_t b;
-                       b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
+                       DecodeTag->SOF_corr_prev = DecodeTag->SOF_corr;

 
 

-                       // The samples are correlations against I and Q versions of the
-                       // tone that the tag AM-modulates, so every other sample is I,
-                       // every other is Q. We just want power, so abs(I) + abs(Q) is
-                       // close to what we want.
-                       if(getNext) {
-                               uint8_t r = ABS(b) + ABS(prev);
+                       break;

 
 

-                               dest[c++] = (uint8_t)r;
+               case STATE_TAG_AWAIT_SOF_2:
+                       // calculate the correlation in real time. Look at differences only.
+                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_low++];
+                       DecodeTag->SOF_corr -= 2*DecodeTag->SOF_correlator[DecodeTag->SOF_high++];
+                       DecodeTag->SOF_last++;
+                       DecodeTag->SOF_low &= (SOF_CORRELATOR_LEN-1);
+                       DecodeTag->SOF_high &= (SOF_CORRELATOR_LEN-1);
+                       DecodeTag->SOF_last &= (SOF_CORRELATOR_LEN-1);
+                       DecodeTag->SOF_correlator[DecodeTag->SOF_last] = AMPLITUDE(ci,cq);
+                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_last];

 
 

-                               if(c >= 2000) {
-                                       break;
+                       if (DecodeTag->SOF_corr >= DecodeTag->SOF_corr_prev) { // we are looking for the maximum correlation
+                               DecodeTag->SOF_corr_prev = DecodeTag->SOF_corr;
+                       } else {
+                               DecodeTag->lastBit = SOF_PART1;  // detected 1st part of SOF
+                               DecodeTag->sum1 = DecodeTag->SOF_correlator[DecodeTag->SOF_last];
+                               DecodeTag->sum2 = 0;
+                               DecodeTag->posCount = 2;
+                               DecodeTag->state = STATE_TAG_RECEIVING_DATA;
+                               LED_C_ON();
+                       }
+
+                       break;
+
+               case STATE_TAG_RECEIVING_DATA:
+                       if (DecodeTag->posCount == 1) {
+                               DecodeTag->sum1 = 0;
+                               DecodeTag->sum2 = 0;
+                       }
+
+                       if (DecodeTag->posCount <= 4) {
+                               DecodeTag->sum1 += AMPLITUDE(ci, cq);
+                       } else {
+                               DecodeTag->sum2 += AMPLITUDE(ci, cq);
+                       }
+
+                       if (DecodeTag->posCount == 8) {
+                               int16_t corr_1 = (DecodeTag->sum2 - DecodeTag->sum1) / 4;
+                               int16_t corr_0 = (DecodeTag->sum1 - DecodeTag->sum2) / 4;
+                               int16_t corr_EOF = (DecodeTag->sum1 + DecodeTag->sum2) / 8;
+                               if (corr_EOF > corr_0 && corr_EOF > corr_1) {
+                                       DecodeTag->state = STATE_TAG_AWAIT_EOF;
+                               } else if (corr_1 > corr_0) {
+                                       // logic 1
+                                       if (DecodeTag->lastBit == SOF_PART1) { // still part of SOF
+                                               DecodeTag->lastBit = SOF_PART2;
+                                       } else {
+                                               DecodeTag->lastBit = LOGIC1;
+                                               DecodeTag->shiftReg >>= 1;
+                                               DecodeTag->shiftReg |= 0x80;
+                                               DecodeTag->bitCount++;
+                                               if (DecodeTag->bitCount == 8) {
+                                                       DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
+                                                       DecodeTag->len++;
+                                                       DecodeTag->bitCount = 0;
+                                                       DecodeTag->shiftReg = 0;
+                                               }
+                                       }
+                               } else {
+                                       // logic 0
+                                       if (DecodeTag->lastBit == SOF_PART1) { // incomplete SOF
+                                               DecodeTag->state = STATE_TAG_UNSYNCD;
+                                               LED_C_OFF();
+                                       } else {
+                                               DecodeTag->lastBit = LOGIC0;
+                                               DecodeTag->shiftReg >>= 1;
+                                               DecodeTag->bitCount++;
+                                               if (DecodeTag->bitCount == 8) {
+                                                       DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
+                                                       DecodeTag->len++;
+                                                       DecodeTag->bitCount = 0;
+                                                       DecodeTag->shiftReg = 0;
+                                               }
+                                       }

                                }
                                }

+                               DecodeTag->posCount = 0;
+                       }
+                       DecodeTag->posCount++;
+                       break;
+
+               case STATE_TAG_AWAIT_EOF:
+                       if (DecodeTag->lastBit == LOGIC0) {  // this was already part of EOF
+                               LED_C_OFF();
+                               return true;

                        } else {
                        } else {

-                               prev = b;
+                               DecodeTag->state = STATE_TAG_UNSYNCD;
+                               LED_C_OFF();

                        }
                        }

+                       break;

 
 

-                       getNext = !getNext;
-               }
+               default:
+                       DecodeTag->state = STATE_TAG_UNSYNCD;
+                       LED_C_OFF();
+                       break;

        }
 
        }
 

-       //////////////////////////////////////////
-       /////////// DEMODULATE ///////////////////
-       //////////////////////////////////////////
+       return false;
+}

 
 

-       int i, j;
-       int max = 0, maxPos=0;

 
 

-       int skip = 4;
+static void DecodeTagInit(DecodeTag_t *DecodeTag, uint8_t *data)
+{
+       DecodeTag->output = data;
+       DecodeTag->state = STATE_TAG_UNSYNCD;
+}
+
+/*
+ *  Receive and decode the tag response, also log to tracebuffer
+ */
+static int GetIso15693AnswerFromTag(uint8_t* response, int timeout)
+{
+       int maxBehindBy = 0;
+       int lastRxCounter, samples = 0;
+       int8_t ci, cq;
+       bool gotFrame = false;
+
+       uint16_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
+
+       // the Decoder data structure
+       DecodeTag_t DecodeTag;
+       DecodeTagInit(&DecodeTag, response);
+
+       // wait for last transfer to complete
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
+
+       // And put the FPGA in the appropriate mode
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+
+       // Setup and start DMA.
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+       uint16_t *upTo = dmaBuf;
+       lastRxCounter = ISO15693_DMA_BUFFER_SIZE;
+
+       for(;;) {
+               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO15693_DMA_BUFFER_SIZE-1);
+               if(behindBy > maxBehindBy) {
+                       maxBehindBy = behindBy;
+               }
+
+               if (behindBy < 1) continue;
+
+               ci = (int8_t)(*upTo >> 8);
+               cq = (int8_t)(*upTo & 0xff);

 
 

-       //      if(GraphTraceLen < 1000) return;        // THIS CHECKS FOR A BUFFER TO SMALL
+               upTo++;
+               lastRxCounter--;
+               if(upTo >= dmaBuf + ISO15693_DMA_BUFFER_SIZE) {                // we have read all of the DMA buffer content.
+                       upTo = dmaBuf;                                             // start reading the circular buffer from the beginning
+                       lastRxCounter += ISO15693_DMA_BUFFER_SIZE;
+               }
+               if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
+               }
+               samples++;

 
 

-       // First, correlate for SOF
-       for(i = 0; i < 100; i++) {
-               int corr = 0;
-               for(j = 0; j < arraylen(FrameSOF); j += skip) {
-                       corr += FrameSOF[j]*dest[i+(j/skip)];
+               if (Handle15693SamplesFromTag(ci, cq, &DecodeTag)) {
+                       gotFrame = true;
+                       break;

                }
                }

-               if(corr > max) {
-                       max = corr;
-                       maxPos = i;
+
+               if(samples > timeout && DecodeTag.state < STATE_TAG_RECEIVING_DATA) {
+                       DecodeTag.len = 0;
+                       break;

                }
                }

+

        }
        }

-               // Dbprintf("SOF at %d, correlation %d", maxPos,max/(arraylen(FrameSOF)/skip));

 
 

-       int k = 0; // this will be our return value
+       FpgaDisableSscDma();

 
 

-       // greg - If correlation is less than 1 then there's little point in continuing
-       if ((max/(arraylen(FrameSOF)/skip)) >= 1)
-       {
+       if (DEBUG) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Decoder: state = %d, len = %d, bitCount = %d, posCount = %d",
+                           maxBehindBy, samples, gotFrame, DecodeTag.state, DecodeTag.len, DecodeTag.bitCount, DecodeTag.posCount);

 
 

-               i = maxPos + arraylen(FrameSOF)/skip;
-       
-               uint8_t outBuf[20];
-               memset(outBuf, 0, sizeof(outBuf));
-               uint8_t mask = 0x01;
-               for(;;) {
-                       int corr0 = 0, corr1 = 0, corrEOF = 0;
-                       for(j = 0; j < arraylen(Logic0); j += skip) {
-                               corr0 += Logic0[j]*dest[i+(j/skip)];
+       if (tracing && DecodeTag.len > 0) {
+               LogTrace(DecodeTag.output, DecodeTag.len, 0, 0, NULL, false);
+       }
+
+       return DecodeTag.len;
+}
+
+
+//=============================================================================
+// An ISO15693 decoder for reader commands.
+//
+// This function is called 4 times per bit (every 2 subcarrier cycles).
+// Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
+// LED handling:
+//    LED B -> ON once we have received the SOF and are expecting the rest.
+//    LED B -> OFF once we have received EOF or are in error state or unsynced
+//
+// Returns: true  if we received a EOF
+//          false if we are still waiting for some more
+//=============================================================================
+
+typedef struct DecodeReader {
+       enum {
+               STATE_READER_UNSYNCD,
+               STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF,
+               STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF,
+               STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF,
+               STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4,
+               STATE_READER_RECEIVE_DATA_1_OUT_OF_4,
+               STATE_READER_RECEIVE_DATA_1_OUT_OF_256
+       }           state;
+       enum {
+               CODING_1_OUT_OF_4,
+               CODING_1_OUT_OF_256
+       }           Coding;
+       uint8_t     shiftReg;
+       uint8_t     bitCount;
+       int         byteCount;
+       int         byteCountMax;
+       int         posCount;
+       int                     sum1, sum2;
+       uint8_t     *output;
+} DecodeReader_t;
+
+
+static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader)
+{
+       switch(DecodeReader->state) {
+               case STATE_READER_UNSYNCD:
+                       if(!bit) {
+                               // we went low, so this could be the beginning of a SOF
+                               DecodeReader->state = STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF;
+                               DecodeReader->posCount = 1;

                        }
                        }

-                       for(j = 0; j < arraylen(Logic1); j += skip) {
-                               corr1 += Logic1[j]*dest[i+(j/skip)];
+                       break;
+
+               case STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF:
+                       DecodeReader->posCount++;
+                       if(bit) { // detected rising edge
+                               if(DecodeReader->posCount < 4) { // rising edge too early (nominally expected at 5)
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                               } else { // SOF
+                                       DecodeReader->state = STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF;
+                               }
+                       } else {
+                               if(DecodeReader->posCount > 5) { // stayed low for too long
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                               } else {
+                                       // do nothing, keep waiting
+                               }

                        }
                        }

-                       for(j = 0; j < arraylen(FrameEOF); j += skip) {
-                               corrEOF += FrameEOF[j]*dest[i+(j/skip)];
+                       break;
+
+               case STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF:
+                       DecodeReader->posCount++;
+                       if(!bit) { // detected a falling edge
+                               if (DecodeReader->posCount < 20) {         // falling edge too early (nominally expected at 21 earliest)
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                               } else if (DecodeReader->posCount < 23) {  // SOF for 1 out of 4 coding
+                                       DecodeReader->Coding = CODING_1_OUT_OF_4;
+                                       DecodeReader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
+                               } else if (DecodeReader->posCount < 28) {  // falling edge too early (nominally expected at 29 latest)
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                               } else {                                 // SOF for 1 out of 4 coding
+                                       DecodeReader->Coding = CODING_1_OUT_OF_256;
+                                       DecodeReader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
+                               }
+                       } else {
+                               if(DecodeReader->posCount > 29) { // stayed high for too long
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                               } else {
+                                       // do nothing, keep waiting
+                               }

                        }
                        }

-                       // Even things out by the length of the target waveform.
-                       corr0 *= 4;
-                       corr1 *= 4;
-       
-                       if(corrEOF > corr1 && corrEOF > corr0) {
-                               // Dbprintf("EOF at %d", i);
-                               break;
-                       } else if(corr1 > corr0) {
-                               i += arraylen(Logic1)/skip;
-                               outBuf[k] |= mask;
+                       break;
+
+               case STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF:
+                       DecodeReader->posCount++;
+                       if (bit) { // detected rising edge
+                               if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
+                                       if (DecodeReader->posCount < 32) { // rising edge too early (nominally expected at 33)
+                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       } else {
+                                               DecodeReader->posCount = 1;
+                                               DecodeReader->bitCount = 0;
+                                               DecodeReader->byteCount = 0;
+                                               DecodeReader->sum1 = 1;
+                                               DecodeReader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_256;
+                                               LED_B_ON();
+                                       }
+                               } else { // CODING_1_OUT_OF_4
+                                       if (DecodeReader->posCount < 24) { // rising edge too early (nominally expected at 25)
+                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       } else {
+                                               DecodeReader->state = STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4;
+                                       }
+                               }

                        } else {
                        } else {

-                               i += arraylen(Logic0)/skip;
+                               if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
+                                       if (DecodeReader->posCount > 34) { // signal stayed low for too long
+                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       } else {
+                                               // do nothing, keep waiting
+                                       }
+                               } else { // CODING_1_OUT_OF_4
+                                       if (DecodeReader->posCount > 26) { // signal stayed low for too long
+                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       } else {
+                                               // do nothing, keep waiting
+                                       }
+                               }

                        }
                        }

-                       mask <<= 1;
-                       if(mask == 0) {
-                               k++;
-                               mask = 0x01;
+                       break;
+
+               case STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4:
+                       DecodeReader->posCount++;
+                       if (bit) {
+                               if (DecodeReader->posCount == 33) {
+                                       DecodeReader->posCount = 1;
+                                       DecodeReader->bitCount = 0;
+                                       DecodeReader->byteCount = 0;
+                                       DecodeReader->sum1 = 1;
+                                       DecodeReader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_4;
+                                       LED_B_ON();
+                               } else {
+                                       // do nothing, keep waiting
+                               }
+                       } else { // unexpected falling edge
+                               DecodeReader->state = STATE_READER_UNSYNCD;

                        }
                        }

-                       if((i+(int)arraylen(FrameEOF)) >= 2000) {
-                               DbpString("ran off end!");
-                               break;
+                       break;
+
+               case STATE_READER_RECEIVE_DATA_1_OUT_OF_4:
+                       DecodeReader->posCount++;
+                       if (DecodeReader->posCount == 1) {
+                               DecodeReader->sum1 = bit;
+                       } else if (DecodeReader->posCount <= 4) {
+                               DecodeReader->sum1 += bit;
+                       } else if (DecodeReader->posCount == 5) {
+                               DecodeReader->sum2 = bit;
+                       } else {
+                               DecodeReader->sum2 += bit;

                        }
                        }

-               }
-               if(mask != 0x01) { // this happens, when we miss the EOF
-                       // TODO: for some reason this happens quite often
-                       if (DEBUG) Dbprintf("error, uneven octet! (extra bits!) mask=%02x", mask);
-                       if (mask<0x08) k--; // discard the last uneven octet;
-                       // 0x08 is an assumption - but works quite often
-               }
-       //      uint8_t str1 [8];
-       //      itoa(k,str1);
-       //      strncat(str1," octets read",8);
-       
-       //      DbpString(  str1);    // DbpString("%d octets", k);
-       
-       //      for(i = 0; i < k; i+=3) {
-       //              //DbpString("# %2d: %02x ", i, outBuf[i]);
-       //              DbpIntegers(outBuf[i],outBuf[i+1],outBuf[i+2]);
-       //      }
-       
-               for(i = 0; i < k; i++) {
-                       receivedResponse[i] = outBuf[i];
-               }
-       } // "end if correlation > 0"   (max/(arraylen(FrameSOF)/skip))
-       return k; // return the number of bytes demodulated
+                       if (DecodeReader->posCount == 8) {
+                               DecodeReader->posCount = 0;
+                               int corr10 = DecodeReader->sum1 - DecodeReader->sum2;
+                               int corr01 = DecodeReader->sum2 - DecodeReader->sum1;
+                               int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
+                               if (corr01 > corr11 && corr01 > corr10) { // EOF
+                                       LED_B_OFF(); // Finished receiving
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       if (DecodeReader->byteCount != 0) {
+                                               return true;
+                                       }
+                               }
+                               if (corr10 > corr11) { // detected a 2bit position
+                                       DecodeReader->shiftReg >>= 2;
+                                       DecodeReader->shiftReg |= (DecodeReader->bitCount << 6);
+                               }
+                               if (DecodeReader->bitCount == 15) { // we have a full byte
+                                       DecodeReader->output[DecodeReader->byteCount++] = DecodeReader->shiftReg;
+                                       if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
+                                               // buffer overflow, give up
+                                               LED_B_OFF();
+                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       }
+                                       DecodeReader->bitCount = 0;
+                               } else {
+                                       DecodeReader->bitCount++;
+                               }
+                       }
+                       break;
+
+               case STATE_READER_RECEIVE_DATA_1_OUT_OF_256:
+                       DecodeReader->posCount++;
+                       if (DecodeReader->posCount == 1) {
+                               DecodeReader->sum1 = bit;
+                       } else if (DecodeReader->posCount <= 4) {
+                               DecodeReader->sum1 += bit;
+                       } else if (DecodeReader->posCount == 5) {
+                               DecodeReader->sum2 = bit;
+                       } else {
+                               DecodeReader->sum2 += bit;
+                       }
+                       if (DecodeReader->posCount == 8) {
+                               DecodeReader->posCount = 0;
+                               int corr10 = DecodeReader->sum1 - DecodeReader->sum2;
+                               int corr01 = DecodeReader->sum2 - DecodeReader->sum1;
+                               int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
+                               if (corr01 > corr11 && corr01 > corr10) { // EOF
+                                       LED_B_OFF(); // Finished receiving
+                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       if (DecodeReader->byteCount != 0) {
+                                               return true;
+                                       }
+                               }
+                               if (corr10 > corr11) { // detected the bit position
+                                       DecodeReader->shiftReg = DecodeReader->bitCount;
+                               }
+                               if (DecodeReader->bitCount == 255) { // we have a full byte
+                                       DecodeReader->output[DecodeReader->byteCount++] = DecodeReader->shiftReg;
+                                       if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
+                                               // buffer overflow, give up
+                                               LED_B_OFF();
+                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       }
+                               }
+                               DecodeReader->bitCount++;
+                       }
+                       break;

 
 

-///    DbpString("CRC=%04x", Iso15693Crc(outBuf, k-2));
+               default:
+                       LED_B_OFF();
+                       DecodeReader->state = STATE_READER_UNSYNCD;
+                       break;
+       }

 
 

+       return false;

 }
 
 
 }
 
 

-// Now the GetISO15693 message from sniffing command
-static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int *samples, int *elapsed)
+static void DecodeReaderInit(uint8_t *data, uint16_t max_len, DecodeReader_t* DecodeReader)

 {
 {

-       int c = 0;
-       uint8_t *dest = BigBuf_get_addr();
-       int getNext = 0;
+       DecodeReader->output = data;
+       DecodeReader->byteCountMax = max_len;
+       DecodeReader->state = STATE_READER_UNSYNCD;
+       DecodeReader->byteCount = 0;
+       DecodeReader->bitCount = 0;
+       DecodeReader->posCount = 0;
+       DecodeReader->shiftReg = 0;
+}

 
 

-       int8_t prev = 0;

 
 

-// NOW READ RESPONSE
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
-       //spindelay(60);        // greg - experiment to get rid of some of the 0 byte/failed reads
-       c = 0;
-       getNext = FALSE;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       int8_t b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
+//-----------------------------------------------------------------------------
+// Receive a command (from the reader to us, where we are the simulated tag),
+// and store it in the given buffer, up to the given maximum length. Keeps
+// spinning, waiting for a well-framed command, until either we get one
+// (returns true) or someone presses the pushbutton on the board (false).
+//
+// Assume that we're called with the SSC (to the FPGA) and ADC path set
+// correctly.
+//-----------------------------------------------------------------------------

 
 

-                       // The samples are correlations against I and Q versions of the
-                       // tone that the tag AM-modulates, so every other sample is I,
-                       // every other is Q. We just want power, so abs(I) + abs(Q) is
-                       // close to what we want.
-                       if(getNext) {
-                               uint8_t r = ABS(b) + ABS(prev);
+static int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eof_time)
+{
+       int maxBehindBy = 0;
+       int lastRxCounter, samples = 0;
+       bool gotFrame = false;
+       uint8_t b;

 
 

-                               dest[c++] = (uint8_t)r;
+       uint8_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];

 
 

-                               if(c >= 20000) {
-                                       break;
-                               }
-                       } else {
-                               prev = b;
-                       }
+       // the decoder data structure
+       DecodeReader_t DecodeReader = {0};
+       DecodeReaderInit(received, max_len, &DecodeReader);

 
 

-                       getNext = !getNext;
-               }
-       }
+       // wait for last transfer to complete
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));

 
 

-       //////////////////////////////////////////
-       /////////// DEMODULATE ///////////////////
-       //////////////////////////////////////////
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);

 
 

-       int i, j;
-       int max = 0, maxPos=0;
+       // clear receive register and wait for next transfer
+       uint32_t temp = AT91C_BASE_SSC->SSC_RHR;
+       (void) temp;
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) ;

 
 

-       int skip = 4;
+       uint32_t bit_time = GetCountSspClk() & 0xfffffff8;

 
 

-//     if(GraphTraceLen < 1000) return;        // THIS CHECKS FOR A BUFFER TO SMALL
+       // Setup and start DMA.
+       FpgaSetupSscDma(dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+       uint8_t *upTo = dmaBuf;
+       lastRxCounter = ISO15693_DMA_BUFFER_SIZE;

 
 

-       // First, correlate for SOF
-       for(i = 0; i < 19000; i++) {
-               int corr = 0;
-               for(j = 0; j < arraylen(FrameSOF); j += skip) {
-                       corr += FrameSOF[j]*dest[i+(j/skip)];
-               }
-               if(corr > max) {
-                       max = corr;
-                       maxPos = i;
+       for(;;) {
+               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO15693_DMA_BUFFER_SIZE-1);
+               if(behindBy > maxBehindBy) {
+                       maxBehindBy = behindBy;

                }
                }

-       }
-//     DbpString("SOF at %d, correlation %d", maxPos,max/(arraylen(FrameSOF)/skip));

 
 

-       int k = 0; // this will be our return value
+               if (behindBy < 1) continue;

 
 

-       // greg - If correlation is less than 1 then there's little point in continuing
-       if ((max/(arraylen(FrameSOF)/skip)) >= 1)       // THIS SHOULD BE 1
-       {
-       
-               i = maxPos + arraylen(FrameSOF)/skip;
-       
-               uint8_t outBuf[20];
-               memset(outBuf, 0, sizeof(outBuf));
-               uint8_t mask = 0x01;
-               for(;;) {
-                       int corr0 = 0, corr1 = 0, corrEOF = 0;
-                       for(j = 0; j < arraylen(Logic0); j += skip) {
-                               corr0 += Logic0[j]*dest[i+(j/skip)];
-                       }
-                       for(j = 0; j < arraylen(Logic1); j += skip) {
-                               corr1 += Logic1[j]*dest[i+(j/skip)];
-                       }
-                       for(j = 0; j < arraylen(FrameEOF); j += skip) {
-                               corrEOF += FrameEOF[j]*dest[i+(j/skip)];
-                       }
-                       // Even things out by the length of the target waveform.
-                       corr0 *= 4;
-                       corr1 *= 4;
-       
-                       if(corrEOF > corr1 && corrEOF > corr0) {
-       //                      DbpString("EOF at %d", i);
-                               break;
-                       } else if(corr1 > corr0) {
-                               i += arraylen(Logic1)/skip;
-                               outBuf[k] |= mask;
-                       } else {
-                               i += arraylen(Logic0)/skip;
-                       }
-                       mask <<= 1;
-                       if(mask == 0) {
-                               k++;
-                               mask = 0x01;
-                       }
-                       if((i+(int)arraylen(FrameEOF)) >= 2000) {
-                               DbpString("ran off end!");
+               b = *upTo++;
+               lastRxCounter--;
+               if(upTo >= dmaBuf + ISO15693_DMA_BUFFER_SIZE) {                // we have read all of the DMA buffer content.
+                       upTo = dmaBuf;                                             // start reading the circular buffer from the beginning
+                       lastRxCounter += ISO15693_DMA_BUFFER_SIZE;
+               }
+               if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
+               }
+
+               for (int i = 7; i >= 0; i--) {
+                       if (Handle15693SampleFromReader((b >> i) & 0x01, &DecodeReader)) {
+                               *eof_time = bit_time + samples - DELAY_READER_TO_ARM; // end of EOF
+                               gotFrame = true;

                                break;
                        }
                                break;
                        }

+                       samples++;

                }
                }

-               if(mask != 0x01) {
-                       DbpString("sniff: error, uneven octet! (discard extra bits!)");
-       ///             DbpString("   mask=%02x", mask);
+
+               if (gotFrame) {
+                       break;

                }
                }

-       //      uint8_t str1 [8];
-       //      itoa(k,str1);
-       //      strncat(str1," octets read",8);
-       
-       //      DbpString(  str1);    // DbpString("%d octets", k);
-       
-       //      for(i = 0; i < k; i+=3) {
-       //              //DbpString("# %2d: %02x ", i, outBuf[i]);
-       //              DbpIntegers(outBuf[i],outBuf[i+1],outBuf[i+2]);
-       //      }
-       
-               for(i = 0; i < k; i++) {
-                       receivedResponse[i] = outBuf[i];
+
+               if (BUTTON_PRESS()) {
+                       DecodeReader.byteCount = 0;
+                       break;

                }
                }

-       } // "end if correlation > 0"   (max/(arraylen(FrameSOF)/skip))
-       return k; // return the number of bytes demodulated

 
 

-///    DbpString("CRC=%04x", Iso15693Crc(outBuf, k-2));
+               WDT_HIT();
+       }
+
+
+       FpgaDisableSscDma();
+
+       if (DEBUG) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Decoder: state = %d, len = %d, bitCount = %d, posCount = %d",
+                           maxBehindBy, samples, gotFrame, DecodeReader.state, DecodeReader.byteCount, DecodeReader.bitCount, DecodeReader.posCount);
+
+       if (tracing && DecodeReader.byteCount > 0) {
+               LogTrace(DecodeReader.output, DecodeReader.byteCount, 0, 0, NULL, true);
+       }
+
+       return DecodeReader.byteCount;

 }
 
 
 }
 
 


@@ -574,11 +947,10 @@ static void BuildIdentifyRequest(void);
 //-----------------------------------------------------------------------------
 void AcquireRawAdcSamplesIso15693(void)
 {
 //-----------------------------------------------------------------------------
 void AcquireRawAdcSamplesIso15693(void)
 {

-       uint8_t *dest = BigBuf_get_addr();
+       LEDsoff();
+       LED_A_ON();

 
 

-       int c = 0;
-       int getNext = 0;
-       int8_t prev = 0;
+       uint8_t *dest = BigBuf_get_addr();

 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        BuildIdentifyRequest();
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        BuildIdentifyRequest();


@@ -586,151 +958,118 @@ void AcquireRawAdcSamplesIso15693(void)
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // Give the tags time to energize
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // Give the tags time to energize

+       LED_D_ON();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(100);
 
        // Now send the command
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(100);
 
        // Now send the command

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
 

-       c = 0;
-       for(;;) {
+       LED_B_ON();
+       for(int c = 0; c < ToSendMax; ) {

                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {

-                       AT91C_BASE_SSC->SSC_THR = ToSend[c];
+                       AT91C_BASE_SSC->SSC_THR = ~ToSend[c];

                        c++;
                        c++;

-                       if(c == ToSendMax+3) {
-                               break;
-                       }
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;

                }
                WDT_HIT();
        }
                }
                WDT_HIT();
        }

+       LED_B_OFF();
+
+       // wait for last transfer to complete
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));

 
 

+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
 

-       c = 0;
-       getNext = FALSE;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
-               }
+       for(int c = 0; c < 4000; ) {

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

-                       int8_t b;
-                       b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
-
+                       uint16_t iq = AT91C_BASE_SSC->SSC_RHR;

                        // The samples are correlations against I and Q versions of the
                        // The samples are correlations against I and Q versions of the

-                       // tone that the tag AM-modulates, so every other sample is I,
-                       // every other is Q. We just want power, so abs(I) + abs(Q) is
-                       // close to what we want.
-                       if(getNext) {
-                               uint8_t r = ABS(b) + ABS(prev);
-
-                               dest[c++] = (uint8_t)r;
-
-                               if(c >= 2000) {
-                                       break;
-                               }
-                       } else {
-                               prev = b;
-                       }
-
-                       getNext = !getNext;
+                       // tone that the tag AM-modulates. We just want power,
+                       // so abs(I) + abs(Q) is close to what we want.
+                       int8_t i = (int8_t)(iq >> 8);
+                       int8_t q = (int8_t)(iq & 0xff);
+                       uint8_t r = AMPLITUDE(i, q);
+                       dest[c++] = r;

                }
        }
                }
        }

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

 }
 
 
 }
 
 

+// TODO: there is no trigger condition. The 14000 samples represent a time frame of 66ms.
+// It is unlikely that we get something meaningful.
+// TODO: Currently we only record tag answers. Add tracing of reader commands.
+// TODO: would we get something at all? The carrier is switched on...

 void RecordRawAdcSamplesIso15693(void)
 {
 void RecordRawAdcSamplesIso15693(void)
 {

-       uint8_t *dest = BigBuf_get_addr();
+       LEDsoff();
+       LED_A_ON();

 
 

-       int c = 0;
-       int getNext = 0;
-       int8_t prev = 0;
+       uint8_t *dest = BigBuf_get_addr();

 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        // Setup SSC
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        // Setup SSC

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

 
        // Start from off (no field generated)
 
        // Start from off (no field generated)

-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelay(200);

 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        SpinDelay(100);
 
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        SpinDelay(100);
 

+       LED_D_ON();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
 

-       c = 0;
-       getNext = FALSE;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
-               }
+       for(int c = 0; c < 14000;) {

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

-                       int8_t b;
-                       b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
-
+                       uint16_t iq = AT91C_BASE_SSC->SSC_RHR;

                        // The samples are correlations against I and Q versions of the
                        // The samples are correlations against I and Q versions of the

-                       // tone that the tag AM-modulates, so every other sample is I,
-                       // every other is Q. We just want power, so abs(I) + abs(Q) is
-                       // close to what we want.
-                       if(getNext) {
-                               uint8_t r = ABS(b) + ABS(prev);
-
-                               dest[c++] = (uint8_t)r;
-
-                               if(c >= 7000) {
-                                       break;
-                               }
-                       } else {
-                               prev = b;
-                       }
-
-                       getNext = !getNext;
-                       WDT_HIT();
+                       // tone that the tag AM-modulates. We just want power,
+                       // so abs(I) + abs(Q) is close to what we want.
+                       int8_t i = (int8_t)(iq >> 8);
+                       int8_t q = (int8_t)(iq & 0xff);
+                       uint8_t r = AMPLITUDE(i, q);
+                       dest[c++] = r;

                }
        }
                }
        }

-       Dbprintf("fin record");
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
+       Dbprintf("finished recording");
+       LED_A_OFF();

 }
 
 
 }
 
 

-// Initialize the proxmark as iso15k reader 
+// Initialize the proxmark as iso15k reader

 // (this might produces glitches that confuse some tags
 // (this might produces glitches that confuse some tags

-void Iso15693InitReader() {
-       LED_A_ON();
-       LED_B_ON();
-       LED_C_OFF();
-       LED_D_OFF();
-       
+static void Iso15693InitReader() {

        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        // Setup SSC
        // FpgaSetupSsc();
 
        // Start from off (no field generated)
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        // Setup SSC
        // FpgaSetupSsc();
 
        // Start from off (no field generated)

+       LED_D_OFF();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        SpinDelay(10);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        SpinDelay(10);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

 
        // Give the tags time to energize
 
        // Give the tags time to energize

+       LED_D_ON();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(250);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(250);

-
-       LED_A_ON();
-       LED_B_OFF();
-       LED_C_OFF();
-       LED_D_OFF();

 }
 
 ///////////////////////////////////////////////////////////////////////
 // ISO 15693 Part 3 - Air Interface
 }
 
 ///////////////////////////////////////////////////////////////////////
 // ISO 15693 Part 3 - Air Interface

-// This section basicly contains transmission and receiving of bits
+// This section basically contains transmission and receiving of bits

 ///////////////////////////////////////////////////////////////////////
 
 // Encode (into the ToSend buffers) an identify request, which is the first
 ///////////////////////////////////////////////////////////////////////
 
 // Encode (into the ToSend buffers) an identify request, which is the first


@@ -780,23 +1119,22 @@ static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )
        // Block number to read
        cmd[10] = blockNumber;//0x00;
        //Now the CRC
        // Block number to read
        cmd[10] = blockNumber;//0x00;
        //Now the CRC

-       crc = Crc(cmd, 11); // the crc needs to be calculated over 12 bytes
+       crc = Crc(cmd, 11); // the crc needs to be calculated over 11 bytes

        cmd[11] = crc & 0xff;
        cmd[12] = crc >> 8;
 
        CodeIso15693AsReader(cmd, sizeof(cmd));
 }
 
        cmd[11] = crc & 0xff;
        cmd[12] = crc >> 8;
 
        CodeIso15693AsReader(cmd, sizeof(cmd));
 }
 

+

 // Now the VICC>VCD responses when we are simulating a tag
 // Now the VICC>VCD responses when we are simulating a tag

- static void BuildInventoryResponse( uint8_t *uid)
+static void BuildInventoryResponse(uint8_t *uid)

 {
        uint8_t cmd[12];
 
        uint16_t crc;
 {
        uint8_t cmd[12];
 
        uint16_t crc;

-       // one sub-carrier, inventory, 1 slot, fast rate
-       // AFI is at bit 5 (1<<4) when doing an INVENTORY
-    //(1 << 2) | (1 << 5) | (1 << 1);
-       cmd[0] = 0; // 
+
+       cmd[0] = 0; // No error, no protocol format extension

        cmd[1] = 0; // DSFID (data storage format identifier).  0x00 = not supported
        // 64-bit UID
        cmd[2] = uid[7]; //0x32;
        cmd[1] = 0; // DSFID (data storage format identifier).  0x00 = not supported
        // 64-bit UID
        cmd[2] = uid[7]; //0x32;


@@ -812,31 +1150,25 @@ static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )
        cmd[10] = crc & 0xff;
        cmd[11] = crc >> 8;
 
        cmd[10] = crc & 0xff;
        cmd[11] = crc >> 8;
 

-       CodeIso15693AsReader(cmd, sizeof(cmd));
+       CodeIso15693AsTag(cmd, sizeof(cmd));

 }
 
 // Universal Method for sending to and recv bytes from a tag
 //     init ... should we initialize the reader?
 }
 
 // Universal Method for sending to and recv bytes from a tag
 //     init ... should we initialize the reader?

-//     speed ... 0 low speed, 1 hi speed 
+//     speed ... 0 low speed, 1 hi speed

 //     **recv will return you a pointer to the received data
 //     **recv will return you a pointer to the received data

-//     If you do not need the answer use NULL for *recv[] 
+//     If you do not need the answer use NULL for *recv[]

 //     return: lenght of received data
 //     return: lenght of received data

-int SendDataTag(uint8_t *send, int sendlen, int init, int speed, uint8_t **recv) {
+int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t **recv) {

 
 

-       int samples = 0;
-       int tsamples = 0;
-       int wait = 0;
-       int elapsed = 0;
-       

        LED_A_ON();
        LED_A_ON();

-       LED_B_ON();
+       LED_B_OFF();

        LED_C_OFF();
        LED_C_OFF();

-       LED_D_OFF();
-       
+

        if (init) Iso15693InitReader();
 
        int answerLen=0;
        if (init) Iso15693InitReader();
 
        int answerLen=0;

-       uint8_t *answer = BigBuf_get_addr() + 3660;
+       uint8_t *answer = BigBuf_get_addr() + 4000;

        if (recv != NULL) memset(answer, 0, 100);
 
        if (!speed) {
        if (recv != NULL) memset(answer, 0, 100);
 
        if (!speed) {


@@ -846,30 +1178,22 @@ int SendDataTag(uint8_t *send, int sendlen, int init, int speed, uint8_t **recv)
                // high speed (1 out of 4)
                CodeIso15693AsReader(send, sendlen);
        }
                // high speed (1 out of 4)
                CodeIso15693AsReader(send, sendlen);
        }

-       
-       LED_A_ON();
-       LED_B_OFF();
-       
-       TransmitTo15693Tag(ToSend,ToSendMax,&tsamples, &wait);  
+
+       TransmitTo15693Tag(ToSend,ToSendMax);

        // Now wait for a response
        if (recv!=NULL) {
        // Now wait for a response
        if (recv!=NULL) {

-               LED_A_OFF();
-               LED_B_ON();
-               answerLen = GetIso15693AnswerFromTag(answer, 100, &samples, &elapsed) ; 
+               answerLen = GetIso15693AnswerFromTag(answer, 100);

                *recv=answer;
        }
 
        LED_A_OFF();
                *recv=answer;
        }
 
        LED_A_OFF();

-       LED_B_OFF();
-       LED_C_OFF();
-       LED_D_OFF();
-       
+

        return answerLen;
 }
 
 
 // --------------------------------------------------------------------
        return answerLen;
 }
 
 
 // --------------------------------------------------------------------

-// Debug Functions 
+// Debug Functions

 // --------------------------------------------------------------------
 
 // Decodes a message from a tag and displays its metadata and content
 // --------------------------------------------------------------------
 
 // Decodes a message from a tag and displays its metadata and content


@@ -879,37 +1203,37 @@ void DbdecodeIso15693Answer(int len, uint8_t *d) {
        uint16_t crc;
 
        if (len>3) {
        uint16_t crc;
 
        if (len>3) {

-               if (d[0]&(1<<3)) 
+               if (d[0]&(1<<3))

                        strncat(status,"ProtExt ",DBD15STATLEN);
                        strncat(status,"ProtExt ",DBD15STATLEN);

-               if (d[0]&1) { 
+               if (d[0]&1) {

                        // error
                        strncat(status,"Error ",DBD15STATLEN);
                        switch (d[1]) {
                        // error
                        strncat(status,"Error ",DBD15STATLEN);
                        switch (d[1]) {

-                               case 0x01: 
+                               case 0x01:

                                        strncat(status,"01:notSupp",DBD15STATLEN);
                                        break;
                                        strncat(status,"01:notSupp",DBD15STATLEN);
                                        break;

-                               case 0x02: 
+                               case 0x02:

                                        strncat(status,"02:notRecog",DBD15STATLEN);
                                        break;
                                        strncat(status,"02:notRecog",DBD15STATLEN);
                                        break;

-                               case 0x03: 
+                               case 0x03:

                                        strncat(status,"03:optNotSupp",DBD15STATLEN);
                                        break;
                                        strncat(status,"03:optNotSupp",DBD15STATLEN);
                                        break;

-                               case 0x0f: 
+                               case 0x0f:

                                        strncat(status,"0f:noInfo",DBD15STATLEN);
                                        break;
                                        strncat(status,"0f:noInfo",DBD15STATLEN);
                                        break;

-                               case 0x10: 
+                               case 0x10:

                                        strncat(status,"10:dontExist",DBD15STATLEN);
                                        break;
                                        strncat(status,"10:dontExist",DBD15STATLEN);
                                        break;

-                               case 0x11: 
+                               case 0x11:

                                        strncat(status,"11:lockAgain",DBD15STATLEN);
                                        break;
                                        strncat(status,"11:lockAgain",DBD15STATLEN);
                                        break;

-                               case 0x12: 
+                               case 0x12:

                                        strncat(status,"12:locked",DBD15STATLEN);
                                        break;
                                        strncat(status,"12:locked",DBD15STATLEN);
                                        break;

-                               case 0x13: 
+                               case 0x13:

                                        strncat(status,"13:progErr",DBD15STATLEN);
                                        break;
                                        strncat(status,"13:progErr",DBD15STATLEN);
                                        break;

-                               case 0x14: 
+                               case 0x14:

                                        strncat(status,"14:lockErr",DBD15STATLEN);
                                        break;
                                default:
                                        strncat(status,"14:lockErr",DBD15STATLEN);
                                        break;
                                default:


@@ -919,12 +1243,12 @@ void DbdecodeIso15693Answer(int len, uint8_t *d) {
                } else {
                        strncat(status,"NoErr ",DBD15STATLEN);
                }
                } else {
                        strncat(status,"NoErr ",DBD15STATLEN);
                }

-                       
+

                crc=Crc(d,len-2);
                crc=Crc(d,len-2);

-               if ( (( crc & 0xff ) == d[len-2]) && (( crc >> 8 ) == d[len-1]) ) 
+               if ( (( crc & 0xff ) == d[len-2]) && (( crc >> 8 ) == d[len-1]) )

                        strncat(status,"CrcOK",DBD15STATLEN);
                else
                        strncat(status,"CrcOK",DBD15STATLEN);
                else

-                       strncat(status,"CrcFail!",DBD15STATLEN); 
+                       strncat(status,"CrcFail!",DBD15STATLEN);

 
                Dbprintf("%s",status);
        }
 
                Dbprintf("%s",status);
        }


@@ -942,64 +1266,46 @@ void SetDebugIso15693(uint32_t debug) {
        return;
 }
 
        return;
 }
 

-
-

 //-----------------------------------------------------------------------------
 // Simulate an ISO15693 reader, perform anti-collision and then attempt to read a sector
 // all demodulation performed in arm rather than host. - greg
 //-----------------------------------------------------------------------------
 void ReaderIso15693(uint32_t parameter)
 {
 //-----------------------------------------------------------------------------
 // Simulate an ISO15693 reader, perform anti-collision and then attempt to read a sector
 // all demodulation performed in arm rather than host. - greg
 //-----------------------------------------------------------------------------
 void ReaderIso15693(uint32_t parameter)
 {

+       LEDsoff();

        LED_A_ON();
        LED_A_ON();

-       LED_B_ON();
-       LED_C_OFF();
-       LED_D_OFF();

 
        int answerLen1 = 0;
 
        int answerLen1 = 0;

-       int answerLen2 = 0;
-       int answerLen3 = 0;
-       int i = 0;
-       int samples = 0;
-       int tsamples = 0;
-       int wait = 0;
-       int elapsed = 0;

        uint8_t TagUID[8] = {0x00};
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        uint8_t TagUID[8] = {0x00};
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 

-       uint8_t *answer1 = BigBuf_get_addr() + 3660;
-       uint8_t *answer2 = BigBuf_get_addr() + 3760;
-       uint8_t *answer3 = BigBuf_get_addr() + 3860;
-       // Blank arrays
-       memset(answer1, 0x00, 300);
+       uint8_t *answer1 = BigBuf_get_addr() + 4000;
+       memset(answer1, 0x00, 200);

 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        // Setup SSC
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        // Setup SSC

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

 
        // Start from off (no field generated)
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        SpinDelay(200);
 
        // Give the tags time to energize
 
        // Start from off (no field generated)
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        SpinDelay(200);
 
        // Give the tags time to energize

+       LED_D_ON();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(200);
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(200);
 

-       LED_A_ON();
-       LED_B_OFF();
-       LED_C_OFF();
-       LED_D_OFF();
-

        // FIRST WE RUN AN INVENTORY TO GET THE TAG UID
        // THIS MEANS WE CAN PRE-BUILD REQUESTS TO SAVE CPU TIME
 
        // Now send the IDENTIFY command
        BuildIdentifyRequest();
        // FIRST WE RUN AN INVENTORY TO GET THE TAG UID
        // THIS MEANS WE CAN PRE-BUILD REQUESTS TO SAVE CPU TIME
 
        // Now send the IDENTIFY command
        BuildIdentifyRequest();

-       
-       TransmitTo15693Tag(ToSend,ToSendMax,&tsamples, &wait);
-       
+
+       TransmitTo15693Tag(ToSend,ToSendMax);
+

        // Now wait for a response
        // Now wait for a response

-       answerLen1 = GetIso15693AnswerFromTag(answer1, 100, &samples, &elapsed) ;
+       answerLen1 = GetIso15693AnswerFromTag(answer1, 100) ;

 
        if (answerLen1 >=12) // we should do a better check than this
        {
 
        if (answerLen1 >=12) // we should do a better check than this
        {


@@ -1015,178 +1321,169 @@ void ReaderIso15693(uint32_t parameter)
        }
 
        Dbprintf("%d octets read from IDENTIFY request:", answerLen1);
        }
 
        Dbprintf("%d octets read from IDENTIFY request:", answerLen1);

-       DbdecodeIso15693Answer(answerLen1,answer1);
-       Dbhexdump(answerLen1,answer1,true);
+       DbdecodeIso15693Answer(answerLen1, answer1);
+       Dbhexdump(answerLen1, answer1, false);

 
        // UID is reverse
 
        // UID is reverse

-       if (answerLen1>=12) 
+       if (answerLen1 >= 12)

                Dbprintf("UID = %02hX%02hX%02hX%02hX%02hX%02hX%02hX%02hX",
                        TagUID[7],TagUID[6],TagUID[5],TagUID[4],
                        TagUID[3],TagUID[2],TagUID[1],TagUID[0]);
 
 
                Dbprintf("UID = %02hX%02hX%02hX%02hX%02hX%02hX%02hX%02hX",
                        TagUID[7],TagUID[6],TagUID[5],TagUID[4],
                        TagUID[3],TagUID[2],TagUID[1],TagUID[0]);
 
 

-       Dbprintf("%d octets read from SELECT request:", answerLen2);
-       DbdecodeIso15693Answer(answerLen2,answer2);
-       Dbhexdump(answerLen2,answer2,true);
+       // Dbprintf("%d octets read from SELECT request:", answerLen2);
+       // DbdecodeIso15693Answer(answerLen2,answer2);
+       // Dbhexdump(answerLen2,answer2,true);

 
 

-       Dbprintf("%d octets read from XXX request:", answerLen3);
-       DbdecodeIso15693Answer(answerLen3,answer3);
-       Dbhexdump(answerLen3,answer3,true);
+       // Dbprintf("%d octets read from XXX request:", answerLen3);
+       // DbdecodeIso15693Answer(answerLen3,answer3);
+       // Dbhexdump(answerLen3,answer3,true);

 
        // read all pages
 
        // read all pages

-       if (answerLen1>=12 && DEBUG) {
-               i=0;                    
-               while (i<32) {  // sanity check, assume max 32 pages
-                       BuildReadBlockRequest(TagUID,i);
-             TransmitTo15693Tag(ToSend,ToSendMax,&tsamples, &wait);  
-         answerLen2 = GetIso15693AnswerFromTag(answer2, 100, &samples, &elapsed);
-                       if (answerLen2>0) {
-                               Dbprintf("READ SINGLE BLOCK %d returned %d octets:",i,answerLen2);
-                               DbdecodeIso15693Answer(answerLen2,answer2);
-                               Dbhexdump(answerLen2,answer2,true);
-                               if ( *((uint32_t*) answer2) == 0x07160101 ) break; // exit on NoPageErr 
-                       } 
+       if (answerLen1 >= 12 && DEBUG) {
+               uint8_t *answer2 = BigBuf_get_addr() + 4100;
+               int i = 0;
+               while (i < 32) {  // sanity check, assume max 32 pages
+                       BuildReadBlockRequest(TagUID, i);
+                       TransmitTo15693Tag(ToSend, ToSendMax);
+                       int answerLen2 = GetIso15693AnswerFromTag(answer2, 100);
+                       if (answerLen2 > 0) {
+                               Dbprintf("READ SINGLE BLOCK %d returned %d octets:", i, answerLen2);
+                               DbdecodeIso15693Answer(answerLen2, answer2);
+                               Dbhexdump(answerLen2, answer2, false);
+                               if ( *((uint32_t*) answer2) == 0x07160101 ) break; // exit on NoPageErr
+                       }

                        i++;
                        i++;

-               } 
+               }

        }
 
        }
 

-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_OFF();
+       // for the time being, switch field off to protect rdv4.0
+       // note: this prevents using hf 15 cmd with s option - which isn't implemented yet anyway
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

        LED_D_OFF();
        LED_D_OFF();

+
+       LED_A_OFF();

 }
 
 }
 

-// Simulate an ISO15693 TAG, perform anti-collision and then print any reader commands
-// all demodulation performed in arm rather than host. - greg
+
+// Simulate an ISO15693 TAG.
+// For Inventory command: print command and send Inventory Response with given UID
+// TODO: interpret other reader commands and send appropriate response

 void SimTagIso15693(uint32_t parameter, uint8_t *uid)
 {
 void SimTagIso15693(uint32_t parameter, uint8_t *uid)
 {

+       LEDsoff();

        LED_A_ON();
        LED_A_ON();

-       LED_B_ON();
-       LED_C_OFF();
-       LED_D_OFF();
-
-       int answerLen1 = 0;
-       int samples = 0;
-       int tsamples = 0;
-       int wait = 0;
-       int elapsed = 0;

 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);

-
-       uint8_t *buf = BigBuf_get_addr() + 3660;
-       memset(buf, 0x00, 100);
-       

        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);

 
 

-       // Start from off (no field generated)
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
+       StartCountSspClk();

 
 

-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_ON();
-       LED_D_OFF();
+       uint8_t cmd[ISO15693_MAX_COMMAND_LENGTH];
+
+       // Build a suitable response to the reader INVENTORY command
+       BuildInventoryResponse(uid);

 
        // Listen to reader
 
        // Listen to reader

-       answerLen1 = GetIso15693AnswerFromSniff(buf, 100, &samples, &elapsed) ;
+       while (!BUTTON_PRESS()) {
+               uint32_t eof_time = 0, start_time = 0;
+               int cmd_len = GetIso15693CommandFromReader(cmd, sizeof(cmd), &eof_time);
+
+               if ((cmd_len >= 5) && (cmd[0] & ISO15693_REQ_INVENTORY) && (cmd[1] == ISO15693_INVENTORY)) { // TODO: check more flags
+                       bool slow = !(cmd[0] & ISO15693_REQ_DATARATE_HIGH);
+                       start_time = eof_time + DELAY_ISO15693_VCD_TO_VICC - DELAY_ARM_TO_READER;
+                       TransmitTo15693Reader(ToSend, ToSendMax, start_time, slow);
+               }

 
 

-       if (answerLen1 >=1) // we should do a better check than this
-       {
-               // Build a suitable reponse to the reader INVENTORY cocmmand
-               // not so obsvious, but in the call to BuildInventoryResponse,  the command is copied to the global ToSend buffer used below.
-               
-               BuildInventoryResponse(uid);
-       
-               TransmitTo15693Reader(ToSend,ToSendMax, &tsamples, &wait);
+               Dbprintf("%d bytes read from reader:", cmd_len);
+               Dbhexdump(cmd_len, cmd, false);

        }
 
        }
 

-       Dbprintf("%d octets read from reader command: %x %x %x %x %x %x %x %x %x", answerLen1,
-               buf[0], buf[1], buf[2], buf[3],
-               buf[4], buf[5], buf[6], buf[7], buf[8]);
-
-       Dbprintf("Simulationg uid: %x %x %x %x %x %x %x %x",
-               uid[0], uid[1], uid[2], uid[3],
-               uid[4], uid[5], uid[6], uid[7]);
-
-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_OFF();
-       LED_D_OFF();
+       LEDsoff();

 }
 
 
 // Since there is no standardized way of reading the AFI out of a tag, we will brute force it
 // (some manufactures offer a way to read the AFI, though)
 }
 
 
 // Since there is no standardized way of reading the AFI out of a tag, we will brute force it
 // (some manufactures offer a way to read the AFI, though)

-void BruteforceIso15693Afi(uint32_t speed) 
-{      
+void BruteforceIso15693Afi(uint32_t speed)
+{
+       LEDsoff();
+       LED_A_ON();
+

        uint8_t data[20];
        uint8_t *recv=data;
        int datalen=0, recvlen=0;
        uint8_t data[20];
        uint8_t *recv=data;
        int datalen=0, recvlen=0;

-               
+

        Iso15693InitReader();
        Iso15693InitReader();

-       
+

        // first without AFI
        // first without AFI

-       // Tags should respond wihtout AFI and with AFI=0 even when AFI is active
-       
-       data[0]=ISO15_REQ_SUBCARRIER_SINGLE | ISO15_REQ_DATARATE_HIGH | 
-               ISO15_REQ_INVENTORY | ISO15_REQINV_SLOT1;
-       data[1]=ISO15_CMD_INVENTORY;
-       data[2]=0; // mask length
-       datalen=AddCrc(data,3);
-       recvlen=SendDataTag(data,datalen,0,speed,&recv);
+       // Tags should respond without AFI and with AFI=0 even when AFI is active
+
+       data[0] = ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_INVENTORY | ISO15693_REQINV_SLOT1;
+       data[1] = ISO15693_INVENTORY;
+       data[2] = 0; // mask length
+       datalen = AddCrc(data,3);
+       recvlen = SendDataTag(data, datalen, false, speed, &recv);

        WDT_HIT();
        if (recvlen>=12) {
                Dbprintf("NoAFI UID=%s",sprintUID(NULL,&recv[2]));
        }
        WDT_HIT();
        if (recvlen>=12) {
                Dbprintf("NoAFI UID=%s",sprintUID(NULL,&recv[2]));
        }

-       
+

        // now with AFI
        // now with AFI

-       
-       data[0]=ISO15_REQ_SUBCARRIER_SINGLE | ISO15_REQ_DATARATE_HIGH | 
-               ISO15_REQ_INVENTORY | ISO15_REQINV_AFI | ISO15_REQINV_SLOT1;
-       data[1]=ISO15_CMD_INVENTORY;
-       data[2]=0; // AFI
-       data[3]=0; // mask length
-       
+
+       data[0] = ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_INVENTORY | ISO15693_REQINV_AFI | ISO15693_REQINV_SLOT1;
+       data[1] = ISO15693_INVENTORY;
+       data[2] = 0; // AFI
+       data[3] = 0; // mask length
+

        for (int i=0;i<256;i++) {
                data[2]=i & 0xFF;
                datalen=AddCrc(data,4);
        for (int i=0;i<256;i++) {
                data[2]=i & 0xFF;
                datalen=AddCrc(data,4);

-               recvlen=SendDataTag(data,datalen,0,speed,&recv);
+               recvlen=SendDataTag(data, datalen, false, speed, &recv);

                WDT_HIT();
                if (recvlen>=12) {
                WDT_HIT();
                if (recvlen>=12) {

-                       Dbprintf("AFI=%i UID=%s",i,sprintUID(NULL,&recv[2]));
+                       Dbprintf("AFI=%i UID=%s", i, sprintUID(NULL,&recv[2]));

                }
                }

-       }       
+       }

        Dbprintf("AFI Bruteforcing done.");
        Dbprintf("AFI Bruteforcing done.");

-       
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LEDsoff();

 }
 
 // Allows to directly send commands to the tag via the client
 }
 
 // Allows to directly send commands to the tag via the client

-void DirectTag15693Command(uint32_t datalen,uint32_t speed, uint32_t recv, uint8_t data[]) {
+void DirectTag15693Command(uint32_t datalen, uint32_t speed, uint32_t recv, uint8_t data[]) {

 
        int recvlen=0;
        uint8_t *recvbuf = BigBuf_get_addr();
 
        int recvlen=0;
        uint8_t *recvbuf = BigBuf_get_addr();

-//     UsbCommand n;
-       
+
+       LED_A_ON();
+

        if (DEBUG) {
                Dbprintf("SEND");
        if (DEBUG) {
                Dbprintf("SEND");

-               Dbhexdump(datalen,data,true);
+               Dbhexdump(datalen, data, false);

        }
        }

-       
-       recvlen=SendDataTag(data,datalen,1,speed,(recv?&recvbuf:NULL));

 
 

-       if (recv) { 
-               LED_B_ON();
-    cmd_send(CMD_ACK,recvlen>48?48:recvlen,0,0,recvbuf,48);
-               LED_B_OFF();    
-               
+       recvlen = SendDataTag(data, datalen, true, speed, (recv?&recvbuf:NULL));
+
+       if (recv) {
+               cmd_send(CMD_ACK, recvlen>48?48:recvlen, 0, 0, recvbuf, 48);
+

                if (DEBUG) {
                        Dbprintf("RECV");
                if (DEBUG) {
                        Dbprintf("RECV");

-                       DbdecodeIso15693Answer(recvlen,recvbuf); 
-                       Dbhexdump(recvlen,recvbuf,true);
+                       DbdecodeIso15693Answer(recvlen,recvbuf);
+                       Dbhexdump(recvlen, recvbuf, false);

                }
        }
 
                }
        }
 

+       // for the time being, switch field off to protect rdv4.0
+       // note: this prevents using hf 15 cmd with s option - which isn't implemented yet anyway
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
+
+       LED_A_OFF();

 }
 
 
 }