Update lfops.c

[proxmark3-svn] / armsrc / lfops.c

//-----------------------------------------------------------------------------
// 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.
//-----------------------------------------------------------------------------
// Miscellaneous routines for low frequency tag operations.
// Tags supported here so far are Texas Instruments (TI), HID, EM4x05, EM410x
// Also routines for raw mode reading/simulating of LF waveform
//-----------------------------------------------------------------------------

#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "hitag2.h"
#include "crc16.h"
#include "string.h"
#include "lfdemod.h"
#include "lfsampling.h"
#include "protocols.h"
#include "usb_cdc.h" // for usb_poll_validate_length
#include "fpgaloader.h"

/**
 * Function to do a modulation and then get samples.
 * @param delay_off
 * @param period_0
 * @param period_1
 * @param command
 */
void ModThenAcquireRawAdcSamples125k(uint32_t delay_off, uint32_t period_0, uint32_t period_1, uint8_t *command)
{
        // start timer
        StartTicks();

        // use lf config settings
        sample_config *sc = getSamplingConfig();

        // Make sure the tag is reset
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        WaitMS(2500);

        // clear read buffer (after fpga bitstream loaded...)
        BigBuf_Clear_keep_EM();

        // power on
        LFSetupFPGAForADC(sc->divisor, 1);

        // And a little more time for the tag to fully power up
        WaitMS(2000);
        // if delay_off = 0 then just bitbang 1 = antenna on 0 = off for respective periods.
        bool bitbang = delay_off == 0;
        // now modulate the reader field

        if (bitbang) {
                // HACK it appears the loop and if statements take up about 7us so adjust waits accordingly...
                uint8_t hack_cnt = 7;
                if (period_0 < hack_cnt || period_1 < hack_cnt) {
                        DbpString("Warning periods cannot be less than 7us in bit bang mode");
                        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                        LED_D_OFF();
                        return;
                }

                // hack2 needed---  it appears to take about 8-16us to turn the antenna back on 
                // leading to ~ 1 to 2 125khz samples extra in every off period 
                // so we should test for last 0 before next 1 and reduce period_0 by this extra amount...
                // but is this time different for every antenna or other hw builds???  more testing needed

                // prime cmd_len to save time comparing strings while modulating
                int cmd_len = 0;
                while(command[cmd_len] != '\0' && command[cmd_len] != ' ')
                        cmd_len++;

                int counter = 0;
                bool off = false;
                for (counter = 0; counter < cmd_len; counter++) {
                        // if cmd = 0 then turn field off
                        if (command[counter] == '0') {
                                // if field already off leave alone (affects timing otherwise)
                                if (off == false) {
                                        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                                        LED_D_OFF();
                                        off = true;
                                }
                                // note we appear to take about 7us to switch over (or run the if statements/loop...)
                                WaitUS(period_0-hack_cnt);
                        // else if cmd = 1 then turn field on
                        } else {
                                // if field already on leave alone (affects timing otherwise)
                                if (off) {
                                        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
                                        LED_D_ON();
                                        off = false;
                                }
                                // note we appear to take about 7us to switch over (or run the if statements/loop...)
                                WaitUS(period_1-hack_cnt);
                        }
                }
        } else { // old mode of cmd read using delay as off period
                while(*command != '\0' && *command != ' ') {
                        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                        LED_D_OFF();
                        WaitUS(delay_off);
                        FpgaSendCommand(FPGA_CMD_SET_DIVISOR, sc->divisor);
                        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
                        LED_D_ON();
                        if(*(command++) == '0') {
                                WaitUS(period_0);
                        } else {
                                WaitUS(period_1);
                        }
                }
                FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                LED_D_OFF();
                WaitUS(delay_off);
                FpgaSendCommand(FPGA_CMD_SET_DIVISOR, sc->divisor);
        }

        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);

        // now do the read
        DoAcquisition_config(false, 0);

        // Turn off antenna
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        // tell client we are done
        cmd_send(CMD_ACK,0,0,0,0,0);
}

/* blank r/w tag data stream
...0000000000000000 01111111
1010101010101010101010101010101010101010101010101010101010101010
0011010010100001
01111111
101010101010101[0]000...

[5555fe852c5555555555555555fe0000]
*/
void ReadTItag(void)
{
        // some hardcoded initial params
        // when we read a TI tag we sample the zerocross line at 2Mhz
        // TI tags modulate a 1 as 16 cycles of 123.2Khz
        // TI tags modulate a 0 as 16 cycles of 134.2Khz
 #define FSAMPLE 2000000
 #define FREQLO 123200
 #define FREQHI 134200

        signed char *dest = (signed char *)BigBuf_get_addr();
        uint16_t n = BigBuf_max_traceLen();
        // 128 bit shift register [shift3:shift2:shift1:shift0]
        uint32_t shift3 = 0, shift2 = 0, shift1 = 0, shift0 = 0;

        int i, cycles=0, samples=0;
        // how many sample points fit in 16 cycles of each frequency
        uint32_t sampleslo = (FSAMPLE<<4)/FREQLO, sampleshi = (FSAMPLE<<4)/FREQHI;
        // when to tell if we're close enough to one freq or another
        uint32_t threshold = (sampleslo - sampleshi + 1)>>1;

        // TI tags charge at 134.2Khz
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
        FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz

        // Place FPGA in passthrough mode, in this mode the CROSS_LO line
        // connects to SSP_DIN and the SSP_DOUT logic level controls
        // whether we're modulating the antenna (high)
        // or listening to the antenna (low)
        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);

        // get TI tag data into the buffer
        AcquireTiType();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

        for (i=0; i<n-1; i++) {
                // count cycles by looking for lo to hi zero crossings
                if ( (dest[i]<0) && (dest[i+1]>0) ) {
                        cycles++;
                        // after 16 cycles, measure the frequency
                        if (cycles>15) {
                                cycles=0;
                                samples=i-samples; // number of samples in these 16 cycles

                                // TI bits are coming to us lsb first so shift them
                                // right through our 128 bit right shift register
                                shift0 = (shift0>>1) | (shift1 << 31);
                                shift1 = (shift1>>1) | (shift2 << 31);
                                shift2 = (shift2>>1) | (shift3 << 31);
                                shift3 >>= 1;

                                // check if the cycles fall close to the number
                                // expected for either the low or high frequency
                                if ( (samples>(sampleslo-threshold)) && (samples<(sampleslo+threshold)) ) {
                                        // low frequency represents a 1
                                        shift3 |= (1<<31);
                                } else if ( (samples>(sampleshi-threshold)) && (samples<(sampleshi+threshold)) ) {
                                        // high frequency represents a 0
                                } else {
                                        // probably detected a gay waveform or noise
                                        // use this as gaydar or discard shift register and start again
                                        shift3 = shift2 = shift1 = shift0 = 0;
                                }
                                samples = i;

                                // for each bit we receive, test if we've detected a valid tag

                                // if we see 17 zeroes followed by 6 ones, we might have a tag
                                // remember the bits are backwards
                                if ( ((shift0 & 0x7fffff) == 0x7e0000) ) {
                                        // if start and end bytes match, we have a tag so break out of the loop
                                        if ( ((shift0>>16)&0xff) == ((shift3>>8)&0xff) ) {
                                                cycles = 0xF0B; //use this as a flag (ugly but whatever)
                                                break;
                                        }
                                }
                        }
                }
        }

        // if flag is set we have a tag
        if (cycles!=0xF0B) {
                DbpString("Info: No valid tag detected.");
        } else {
                // put 64 bit data into shift1 and shift0
                shift0 = (shift0>>24) | (shift1 << 8);
                shift1 = (shift1>>24) | (shift2 << 8);

                // align 16 bit crc into lower half of shift2
                shift2 = ((shift2>>24) | (shift3 << 8)) & 0x0ffff;

                // if r/w tag, check ident match
                if (shift3 & (1<<15) ) {
                        DbpString("Info: TI tag is rewriteable");
                        // only 15 bits compare, last bit of ident is not valid
                        if (((shift3 >> 16) ^ shift0) & 0x7fff ) {
                                DbpString("Error: Ident mismatch!");
                        } else {
                                DbpString("Info: TI tag ident is valid");
                        }
                } else {
                        DbpString("Info: TI tag is readonly");
                }

                // WARNING the order of the bytes in which we calc crc below needs checking
                // i'm 99% sure the crc algorithm is correct, but it may need to eat the
                // bytes in reverse or something
                // calculate CRC
                uint32_t crc=0;

                crc = update_crc16(crc, (shift0)&0xff);
                crc = update_crc16(crc, (shift0>>8)&0xff);
                crc = update_crc16(crc, (shift0>>16)&0xff);
                crc = update_crc16(crc, (shift0>>24)&0xff);
                crc = update_crc16(crc, (shift1)&0xff);
                crc = update_crc16(crc, (shift1>>8)&0xff);
                crc = update_crc16(crc, (shift1>>16)&0xff);
                crc = update_crc16(crc, (shift1>>24)&0xff);

                Dbprintf("Info: Tag data: %x%08x, crc=%x",
                                 (unsigned int)shift1, (unsigned int)shift0, (unsigned int)shift2 & 0xFFFF);
                if (crc != (shift2&0xffff)) {
                        Dbprintf("Error: CRC mismatch, expected %x", (unsigned int)crc);
                } else {
                        DbpString("Info: CRC is good");
                }
        }
}

void WriteTIbyte(uint8_t b)
{
        int i = 0;

        // modulate 8 bits out to the antenna
        for (i=0; i<8; i++)
        {
                if (b&(1<<i)) {
                        // stop modulating antenna
                        LOW(GPIO_SSC_DOUT);
                        SpinDelayUs(1000);
                        // modulate antenna
                        HIGH(GPIO_SSC_DOUT);
                        SpinDelayUs(1000);
                } else {
                        // stop modulating antenna
                        LOW(GPIO_SSC_DOUT);
                        SpinDelayUs(300);
                        // modulate antenna
                        HIGH(GPIO_SSC_DOUT);
                        SpinDelayUs(1700);
                }
        }
}

void AcquireTiType(void)
{
        int i, j, n;
        // tag transmission is <20ms, sampling at 2M gives us 40K samples max
        // each sample is 1 bit stuffed into a uint32_t so we need 1250 uint32_t
 #define TIBUFLEN 1250

        // clear buffer
        uint32_t *BigBuf = (uint32_t *)BigBuf_get_addr();
        BigBuf_Clear_ext(false);

        // Set up the synchronous serial port
        AT91C_BASE_PIOA->PIO_PDR = GPIO_SSC_DIN;
        AT91C_BASE_PIOA->PIO_ASR = GPIO_SSC_DIN;

        // steal this pin from the SSP and use it to control the modulation
        AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
        AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;

        AT91C_BASE_SSC->SSC_CR = AT91C_SSC_SWRST;
        AT91C_BASE_SSC->SSC_CR = AT91C_SSC_RXEN | AT91C_SSC_TXEN;

        // Sample at 2 Mbit/s, so TI tags are 16.2 vs. 14.9 clocks long
        // 48/2 = 24 MHz clock must be divided by 12
        AT91C_BASE_SSC->SSC_CMR = 12;

        AT91C_BASE_SSC->SSC_RCMR = SSC_CLOCK_MODE_SELECT(0);
        AT91C_BASE_SSC->SSC_RFMR = SSC_FRAME_MODE_BITS_IN_WORD(32) | AT91C_SSC_MSBF;
        AT91C_BASE_SSC->SSC_TCMR = 0;
        AT91C_BASE_SSC->SSC_TFMR = 0;

        LED_D_ON();

        // modulate antenna
        HIGH(GPIO_SSC_DOUT);

        // Charge TI tag for 50ms.
        SpinDelay(50);

        // stop modulating antenna and listen
        LOW(GPIO_SSC_DOUT);

        LED_D_OFF();

        i = 0;
        for(;;) {
                if(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
                        BigBuf[i] = AT91C_BASE_SSC->SSC_RHR;    // store 32 bit values in buffer
                        i++; if(i >= TIBUFLEN) break;
                }
                WDT_HIT();
        }

        // return stolen pin to SSP
        AT91C_BASE_PIOA->PIO_PDR = GPIO_SSC_DOUT;
        AT91C_BASE_PIOA->PIO_ASR = GPIO_SSC_DIN | GPIO_SSC_DOUT;

        char *dest = (char *)BigBuf_get_addr();
        n = TIBUFLEN*32;
        // unpack buffer
        for (i=TIBUFLEN-1; i>=0; i--) {
                for (j=0; j<32; j++) {
                        if(BigBuf[i] & (1 << j)) {
                                dest[--n] = 1;
                        } else {
                                dest[--n] = -1;
                        }
                }
        }
}

// arguments: 64bit data split into 32bit idhi:idlo and optional 16bit crc
// if crc provided, it will be written with the data verbatim (even if bogus)
// if not provided a valid crc will be computed from the data and written.
void WriteTItag(uint32_t idhi, uint32_t idlo, uint16_t crc)
{
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
        if(crc == 0) {
                crc = update_crc16(crc, (idlo)&0xff);
                crc = update_crc16(crc, (idlo>>8)&0xff);
                crc = update_crc16(crc, (idlo>>16)&0xff);
                crc = update_crc16(crc, (idlo>>24)&0xff);
                crc = update_crc16(crc, (idhi)&0xff);
                crc = update_crc16(crc, (idhi>>8)&0xff);
                crc = update_crc16(crc, (idhi>>16)&0xff);
                crc = update_crc16(crc, (idhi>>24)&0xff);
        }
        Dbprintf("Writing to tag: %x%08x, crc=%x",
                        (unsigned int) idhi, (unsigned int) idlo, crc);

        // TI tags charge at 134.2Khz
        FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
        // Place FPGA in passthrough mode, in this mode the CROSS_LO line
        // connects to SSP_DIN and the SSP_DOUT logic level controls
        // whether we're modulating the antenna (high)
        // or listening to the antenna (low)
        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);
        LED_A_ON();

        // steal this pin from the SSP and use it to control the modulation
        AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
        AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;

        // writing algorithm:
        // a high bit consists of a field off for 1ms and field on for 1ms
        // a low bit consists of a field off for 0.3ms and field on for 1.7ms
        // initiate a charge time of 50ms (field on) then immediately start writing bits
        // start by writing 0xBB (keyword) and 0xEB (password)
        // then write 80 bits of data (or 64 bit data + 16 bit crc if you prefer)
        // finally end with 0x0300 (write frame)
        // all data is sent lsb firts
        // finish with 15ms programming time

        // modulate antenna
        HIGH(GPIO_SSC_DOUT);
        SpinDelay(50);  // charge time

        WriteTIbyte(0xbb); // keyword
        WriteTIbyte(0xeb); // password
        WriteTIbyte( (idlo    )&0xff );
        WriteTIbyte( (idlo>>8 )&0xff );
        WriteTIbyte( (idlo>>16)&0xff );
        WriteTIbyte( (idlo>>24)&0xff );
        WriteTIbyte( (idhi    )&0xff );
        WriteTIbyte( (idhi>>8 )&0xff );
        WriteTIbyte( (idhi>>16)&0xff );
        WriteTIbyte( (idhi>>24)&0xff ); // data hi to lo
        WriteTIbyte( (crc     )&0xff ); // crc lo
        WriteTIbyte( (crc>>8  )&0xff ); // crc hi
        WriteTIbyte(0x00); // write frame lo
        WriteTIbyte(0x03); // write frame hi
        HIGH(GPIO_SSC_DOUT);
        SpinDelay(50);  // programming time

        LED_A_OFF();

        // get TI tag data into the buffer
        AcquireTiType();

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        DbpString("Now use `lf ti read` to check");
}

void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
{
        int i;
        uint8_t *tab = BigBuf_get_addr();

        //note FpgaDownloadAndGo destroys the bigbuf so be sure this is called before now...
        //FpgaDownloadAndGo(FPGA_BITSTREAM_LF);  
        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);

        AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT | GPIO_SSC_CLK;

        AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
        AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_CLK;

 #define SHORT_COIL()   LOW(GPIO_SSC_DOUT)
 #define OPEN_COIL()    HIGH(GPIO_SSC_DOUT)

        i = 0;
        for(;;) {
                //wait until SSC_CLK goes HIGH
                int ii = 0;
                while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)) {
                        //only check every 1000th time (usb_poll_validate_length on some systems was too slow)
                        if ( ii == 1000 ) {
                                if (BUTTON_PRESS() || usb_poll_validate_length() ) {
                                        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                                        DbpString("Stopped");
                                        return;
                                }
                                ii=0;
                        }
                        WDT_HIT();
                        ii++;
                }
                if (ledcontrol)
                        LED_D_ON();

                if(tab[i])
                        OPEN_COIL();
                else
                        SHORT_COIL();

                if (ledcontrol)
                        LED_D_OFF();
                ii=0;
                //wait until SSC_CLK goes LOW
                while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK) {
                        //only check every 1000th time (usb_poll_validate_length on some systems was too slow)
                        if ( ii == 1000 ) { 
                                if (BUTTON_PRESS() || usb_poll_validate_length() ) {
                                        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                                        DbpString("Stopped");
                                        return;
                                }
                                ii=0;
                        }
                        WDT_HIT();
                        ii++;
                }

                i++;
                if(i == period) {

                        i = 0;
                        if (gap) {
                                SHORT_COIL();
                                SpinDelayUs(gap);
                        }
                }

        }
}

#define DEBUG_FRAME_CONTENTS 1
void SimulateTagLowFrequencyBidir(int divisor, int t0)
{
}

// compose fc/8 fc/10 waveform (FSK2)
static void fc(int c, int *n)
{
        uint8_t *dest = BigBuf_get_addr();
        int idx;

        // for when we want an fc8 pattern every 4 logical bits
        if(c==0) {
                dest[((*n)++)]=1;
                dest[((*n)++)]=1;
                dest[((*n)++)]=1;
                dest[((*n)++)]=1;
                dest[((*n)++)]=0;
                dest[((*n)++)]=0;
                dest[((*n)++)]=0;
                dest[((*n)++)]=0;
        }

        //      an fc/8  encoded bit is a bit pattern of  11110000  x6 = 48 samples
        if(c==8) {
                for (idx=0; idx<6; idx++) {
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                }
        }

        //      an fc/10 encoded bit is a bit pattern of 1111100000 x5 = 50 samples
        if(c==10) {
                for (idx=0; idx<5; idx++) {
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=1;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                        dest[((*n)++)]=0;
                }
        }
}
// compose fc/X fc/Y waveform (FSKx)
static void fcAll(uint8_t fc, int *n, uint8_t clock, uint16_t *modCnt) 
{
        uint8_t *dest = BigBuf_get_addr();
        uint8_t halfFC = fc/2;
        uint8_t wavesPerClock = clock/fc;
        uint8_t mod = clock % fc;    //modifier
        uint8_t modAdj = fc/mod;     //how often to apply modifier
        bool modAdjOk = !(fc % mod); //if (fc % mod==0) modAdjOk=true;
        // loop through clock - step field clock
        for (uint8_t idx=0; idx < wavesPerClock; idx++){
                // put 1/2 FC length 1's and 1/2 0's per field clock wave (to create the wave)
                memset(dest+(*n), 0, fc-halfFC);  //in case of odd number use extra here
                memset(dest+(*n)+(fc-halfFC), 1, halfFC);
                *n += fc;
        }
        if (mod>0) (*modCnt)++;
        if ((mod>0) && modAdjOk){  //fsk2 
                if ((*modCnt % modAdj) == 0){ //if 4th 8 length wave in a rf/50 add extra 8 length wave
                        memset(dest+(*n), 0, fc-halfFC);
                        memset(dest+(*n)+(fc-halfFC), 1, halfFC);
                        *n += fc;
                }
        }
        if (mod>0 && !modAdjOk){  //fsk1
                memset(dest+(*n), 0, mod-(mod/2));
                memset(dest+(*n)+(mod-(mod/2)), 1, mod/2);
                *n += mod;
        }
}

// prepare a waveform pattern in the buffer based on the ID given then
// simulate a HID tag until the button is pressed
void CmdHIDsimTAG(int hi2, int hi, int lo, int ledcontrol)
{
        int n=0, i=0;
        /*
         HID tag bitstream format
         The tag contains a 44bit unique code. This is sent out MSB first in sets of 4 bits
         A 1 bit is represented as 6 fc8 and 5 fc10 patterns
         A 0 bit is represented as 5 fc10 and 6 fc8 patterns
         A fc8 is inserted before every 4 bits
         A special start of frame pattern is used consisting a0b0 where a and b are neither 0
         nor 1 bits, they are special patterns (a = set of 12 fc8 and b = set of 10 fc10)
        */

        if (hi2>0x0FFFFFFF) {
                DbpString("Tags can only have 44 or 84 bits. - USE lf simfsk for larger tags");
                return;
        }
        // set LF so we don't kill the bigbuf we are setting with simulation data.
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);

        fc(0,&n);
        // special start of frame marker containing invalid bit sequences
        fc(8,  &n);     fc(8,  &n); // invalid
        fc(8,  &n);     fc(10, &n); // logical 0
        fc(10, &n);     fc(10, &n); // invalid
        fc(8,  &n);     fc(10, &n); // logical 0

        WDT_HIT();
        if (hi2 > 0 || hi > 0xFFF){
                // manchester encode bits 91 to 64 (91-84 are part of the header)
                for (i=27; i>=0; i--) {
                        if ((i%4)==3) fc(0,&n);
                        if ((hi2>>i)&1) {
                                fc(10, &n); fc(8,  &n);         // low-high transition
                        } else {
                                fc(8,  &n); fc(10, &n);         // high-low transition
                        }
                }
                WDT_HIT();
                // manchester encode bits 63 to 32
                for (i=31; i>=0; i--) {
                        if ((i%4)==3) fc(0,&n);
                        if ((hi>>i)&1) {
                                fc(10, &n); fc(8,  &n);         // low-high transition
                        } else {
                                fc(8,  &n); fc(10, &n);         // high-low transition
                        }
                }
        } else {
                // manchester encode bits 43 to 32
                for (i=11; i>=0; i--) {
                        if ((i%4)==3) fc(0,&n);
                        if ((hi>>i)&1) {
                                fc(10, &n); fc(8,  &n);         // low-high transition
                        } else {
                                fc(8,  &n); fc(10, &n);         // high-low transition
                        }
                }
        }

        WDT_HIT();
        // manchester encode bits 31 to 0
        for (i=31; i>=0; i--) {
                if ((i%4)==3) fc(0,&n);
                if ((lo>>i)&1) {
                        fc(10, &n); fc(8,  &n);         // low-high transition
                } else {
                        fc(8,  &n); fc(10, &n);         // high-low transition
                }
        }

        if (ledcontrol)
                LED_A_ON();
        SimulateTagLowFrequency(n, 0, ledcontrol);

        if (ledcontrol)
                LED_A_OFF();
}

// prepare a waveform pattern in the buffer based on the ID given then
// simulate a FSK tag until the button is pressed
// arg1 contains fcHigh and fcLow, arg2 contains invert and clock
void CmdFSKsimTAG(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
{
        int ledcontrol=1;
        int n=0, i=0;
        uint8_t fcHigh = arg1 >> 8;
        uint8_t fcLow = arg1 & 0xFF;
        uint16_t modCnt = 0;
        uint8_t clk = arg2 & 0xFF;
        uint8_t invert = (arg2 >> 8) & 1;

        // set LF so we don't kill the bigbuf we are setting with simulation data.
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);

        for (i=0; i<size; i++){
                if (BitStream[i] == invert){
                        fcAll(fcLow, &n, clk, &modCnt);
                } else {
                        fcAll(fcHigh, &n, clk, &modCnt);
                }
        }
        Dbprintf("Simulating with fcHigh: %d, fcLow: %d, clk: %d, invert: %d, n: %d",fcHigh, fcLow, clk, invert, n);
        /*Dbprintf("DEBUG: First 32:");
        uint8_t *dest = BigBuf_get_addr();
        i=0;
        Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
        i+=16;
        Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
        */
        if (ledcontrol)
                LED_A_ON();

        SimulateTagLowFrequency(n, 0, ledcontrol);

        if (ledcontrol)
                LED_A_OFF();
}

// compose ask waveform for one bit(ASK)
static void askSimBit(uint8_t c, int *n, uint8_t clock, uint8_t manchester)
{
        uint8_t *dest = BigBuf_get_addr();
        uint8_t halfClk = clock/2;
        // c = current bit 1 or 0
        if (manchester==1){
                memset(dest+(*n), c, halfClk);
                memset(dest+(*n) + halfClk, c^1, halfClk);
        } else {
                memset(dest+(*n), c, clock);
        }
        *n += clock;
}

static void biphaseSimBit(uint8_t c, int *n, uint8_t clock, uint8_t *phase)
{
        uint8_t *dest = BigBuf_get_addr();
        uint8_t halfClk = clock/2;
        if (c){
                memset(dest+(*n), c ^ 1 ^ *phase, halfClk);
                memset(dest+(*n) + halfClk, c ^ *phase, halfClk);
        } else {
                memset(dest+(*n), c ^ *phase, clock);
                *phase ^= 1;
        }
        *n += clock;
}

static void stAskSimBit(int *n, uint8_t clock) {
        uint8_t *dest = BigBuf_get_addr();
        uint8_t halfClk = clock/2;
        //ST = .5 high .5 low 1.5 high .5 low 1 high    
        memset(dest+(*n), 1, halfClk);
        memset(dest+(*n) + halfClk, 0, halfClk);
        memset(dest+(*n) + clock, 1, clock + halfClk);
        memset(dest+(*n) + clock*2 + halfClk, 0, halfClk);
        memset(dest+(*n) + clock*3, 1, clock);
        *n += clock*4;
}

// args clock, ask/man or askraw, invert, transmission separator
void CmdASKsimTag(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
{
        int ledcontrol = 1;
        int n=0, i=0;
        uint8_t clk = (arg1 >> 8) & 0xFF;
        uint8_t encoding = arg1 & 0xFF;
        uint8_t separator = arg2 & 1;
        uint8_t invert = (arg2 >> 8) & 1;

        // set LF so we don't kill the bigbuf we are setting with simulation data.
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);

        if (encoding==2){  //biphase
                uint8_t phase=0;
                for (i=0; i<size; i++){
                        biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
                }
                if (phase==1) { //run a second set inverted to keep phase in check
                        for (i=0; i<size; i++){
                                biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
                        }
                }
        } else {  // ask/manchester || ask/raw
                for (i=0; i<size; i++){
                        askSimBit(BitStream[i]^invert, &n, clk, encoding);
                }
                if (encoding==0 && BitStream[0]==BitStream[size-1]){ //run a second set inverted (for ask/raw || biphase phase)
                        for (i=0; i<size; i++){
                                askSimBit(BitStream[i]^invert^1, &n, clk, encoding);
                        }
                }
        }
        if (separator==1 && encoding == 1)
                stAskSimBit(&n, clk);
        else if (separator==1)
                Dbprintf("sorry but separator option not yet available");

        Dbprintf("Simulating with clk: %d, invert: %d, encoding: %d, separator: %d, n: %d",clk, invert, encoding, separator, n);
        //DEBUG
        //Dbprintf("First 32:");
        //uint8_t *dest = BigBuf_get_addr();
        //i=0;
        //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
        //i+=16;
        //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
        
        if (ledcontrol) LED_A_ON();
        SimulateTagLowFrequency(n, 0, ledcontrol);
        if (ledcontrol) LED_A_OFF();
}

//carrier can be 2,4 or 8
static void pskSimBit(uint8_t waveLen, int *n, uint8_t clk, uint8_t *curPhase, bool phaseChg)
{
        uint8_t *dest = BigBuf_get_addr();
        uint8_t halfWave = waveLen/2;
        //uint8_t idx;
        int i = 0;
        if (phaseChg){
                // write phase change
                memset(dest+(*n), *curPhase^1, halfWave);
                memset(dest+(*n) + halfWave, *curPhase, halfWave);
                *n += waveLen;
                *curPhase ^= 1;
                i += waveLen;
        }
        //write each normal clock wave for the clock duration
        for (; i < clk; i+=waveLen){
                memset(dest+(*n), *curPhase, halfWave);
                memset(dest+(*n) + halfWave, *curPhase^1, halfWave);
                *n += waveLen;
        }
}

// args clock, carrier, invert,
void CmdPSKsimTag(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
{
        int ledcontrol=1;
        int n=0, i=0;
        uint8_t clk = arg1 >> 8;
        uint8_t carrier = arg1 & 0xFF;
        uint8_t invert = arg2 & 0xFF;
        uint8_t curPhase = 0;
        // set LF so we don't kill the bigbuf we are setting with simulation data.
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);

        for (i=0; i<size; i++){
                if (BitStream[i] == curPhase){
                        pskSimBit(carrier, &n, clk, &curPhase, false);
                } else {
                        pskSimBit(carrier, &n, clk, &curPhase, true);
                }
        }
        Dbprintf("Simulating with Carrier: %d, clk: %d, invert: %d, n: %d",carrier, clk, invert, n);
        //Dbprintf("DEBUG: First 32:");
        //uint8_t *dest = BigBuf_get_addr();
        //i=0;
        //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
        //i+=16;
        //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
                   
        if (ledcontrol) LED_A_ON();
        SimulateTagLowFrequency(n, 0, ledcontrol);
        if (ledcontrol) LED_A_OFF();
}

// loop to get raw HID waveform then FSK demodulate the TAG ID from it
void CmdHIDdemodFSK(int findone, int *high2, int *high, int *low, int ledcontrol)
{
        uint8_t *dest = BigBuf_get_addr();
        //const size_t sizeOfBigBuff = BigBuf_max_traceLen();
        size_t size; 
        uint32_t hi2=0, hi=0, lo=0;
        int idx=0;
        int dummyIdx = 0;
        // Configure to go in 125Khz listen mode
        LFSetupFPGAForADC(95, true);

        //clear read buffer
        BigBuf_Clear_keep_EM();

        while(!BUTTON_PRESS() && !usb_poll_validate_length()) {
                WDT_HIT();
                if (ledcontrol) LED_A_ON();

                DoAcquisition_default(-1,true);
                // FSK demodulator
                //size = sizeOfBigBuff;  //variable size will change after demod so re initialize it before use
                size = 50*128*2; //big enough to catch 2 sequences of largest format
                idx = HIDdemodFSK(dest, &size, &hi2, &hi, &lo, &dummyIdx);
                
                if (idx>0 && lo>0 && (size==96 || size==192)){
                        uint8_t bitlen = 0;
                        uint32_t fc = 0;
                        uint32_t cardnum = 0;
                        bool decoded = false;

                        // go over previously decoded manchester data and decode into usable tag ID
                        if ((hi2 & 0x000FFFF) != 0){ //extra large HID tags  88/192 bits
                                uint32_t bp = hi2 & 0x000FFFFF;
                                bitlen = 63;
                                while (bp > 0) {
                                        bp = bp >> 1;
                                        bitlen++;
                                }
                        } else if ((hi >> 6) > 0) {
                                uint32_t bp = hi;
                                bitlen = 31;
                                while (bp > 0) {
                                        bp = bp >> 1;
                                        bitlen++;
                                }
                        } else if (((hi >> 5) & 1) == 0) {
                                bitlen = 37;
                        } else if ((hi & 0x0000001F) > 0 ) {
                                uint32_t bp = (hi & 0x0000001F);
                                bitlen = 31;
                                while (bp > 0) {
                                        bp = bp >> 1;
                                        bitlen++;
                                }
                        } else {
                                uint32_t bp = lo;
                                bitlen = 0;
                                while (bp > 0) {
                                        bp = bp >> 1;
                                        bitlen++;
                                }
                        }
                        switch (bitlen){
                                case 26:
                                        cardnum = (lo>>1)&0xFFFF;
                                        fc = (lo>>17)&0xFF;
                                        decoded = true;
                                        break;
                                case 35:
                                        cardnum = (lo>>1)&0xFFFFF;
                                        fc = ((hi&1)<<11)|(lo>>21);
                                        decoded = true;
                                        break;
                        }
                                
                        if (hi2 != 0) //extra large HID tags  88/192 bits
                                Dbprintf("TAG ID: %x%08x%08x (%d)",
                                        (unsigned int) hi2, (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
                        else 
                                Dbprintf("TAG ID: %x%08x (%d)",
                                        (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
                        
                        if (decoded)
                                Dbprintf("Format Len: %dbits - FC: %d - Card: %d",
                                        (unsigned int) bitlen, (unsigned int) fc, (unsigned int) cardnum);

                        if (findone){
                                if (ledcontrol) LED_A_OFF();
                                *high2 = hi2;
                                *high = hi;
                                *low = lo;
                                break;
                        }
                        // reset
                }
                hi2 = hi = lo = idx = 0;
                WDT_HIT();
        }

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        DbpString("Stopped");
        if (ledcontrol) LED_A_OFF();
}

// loop to get raw HID waveform then FSK demodulate the TAG ID from it
void CmdAWIDdemodFSK(int findone, int *high, int *low, int ledcontrol)
{
        uint8_t *dest = BigBuf_get_addr();
        size_t size; 
        int idx=0, dummyIdx=0;
        //clear read buffer
        BigBuf_Clear_keep_EM();
        // Configure to go in 125Khz listen mode
        LFSetupFPGAForADC(95, true);

        while(!BUTTON_PRESS() && !usb_poll_validate_length()) {

                WDT_HIT();
                if (ledcontrol) LED_A_ON();

                DoAcquisition_default(-1,true);
                // FSK demodulator
                size = 50*128*2; //big enough to catch 2 sequences of largest format
                idx = AWIDdemodFSK(dest, &size, &dummyIdx);
                
                if (idx<=0 || size!=96) continue;
                // Index map
                // 0            10            20            30              40            50              60
                // |            |             |             |               |             |               |
                // 01234567 890 1 234 5 678 9 012 3 456 7 890 1 234 5 678 9 012 3 456 7 890 1 234 5 678 9 012 3 - to 96
                // -----------------------------------------------------------------------------
                // 00000001 000 1 110 1 101 1 011 1 101 1 010 0 000 1 000 1 010 0 001 0 110 1 100 0 000 1 000 1
                // premable bbb o bbb o bbw o fff o fff o ffc o ccc o ccc o ccc o ccc o ccc o wxx o xxx o xxx o - to 96
                //          |---26 bit---|    |-----117----||-------------142-------------|
                // b = format bit len, o = odd parity of last 3 bits
                // f = facility code, c = card number
                // w = wiegand parity
                // (26 bit format shown)

                //get raw ID before removing parities
                uint32_t rawLo = bytebits_to_byte(dest+idx+64,32);
                uint32_t rawHi = bytebits_to_byte(dest+idx+32,32);
                uint32_t rawHi2 = bytebits_to_byte(dest+idx,32);

                size = removeParity(dest, idx+8, 4, 1, 88);
                if (size != 66) continue;
                // ok valid card found!

                // Index map
                // 0           10         20        30          40        50        60
                // |           |          |         |           |         |         |
                // 01234567 8 90123456 7890123456789012 3 456789012345678901234567890123456
                // -----------------------------------------------------------------------------
                // 00011010 1 01110101 0000000010001110 1 000000000000000000000000000000000
                // bbbbbbbb w ffffffff cccccccccccccccc w xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                // |26 bit|   |-117--| |-----142------|
                // b = format bit len, o = odd parity of last 3 bits
                // f = facility code, c = card number
                // w = wiegand parity
                // (26 bit format shown)

                uint32_t fc = 0;
                uint32_t cardnum = 0;
                uint32_t code1 = 0;
                uint32_t code2 = 0;
                uint8_t fmtLen = bytebits_to_byte(dest,8);
                if (fmtLen==26){
                        fc = bytebits_to_byte(dest+9, 8);
                        cardnum = bytebits_to_byte(dest+17, 16);
                        code1 = bytebits_to_byte(dest+8,fmtLen);
                        Dbprintf("AWID Found - BitLength: %d, FC: %d, Card: %d - Wiegand: %x, Raw: %08x%08x%08x", fmtLen, fc, cardnum, code1, rawHi2, rawHi, rawLo);
                } else {
                        cardnum = bytebits_to_byte(dest+8+(fmtLen-17), 16);
                        if (fmtLen>32){
                                code1 = bytebits_to_byte(dest+8,fmtLen-32);
                                code2 = bytebits_to_byte(dest+8+(fmtLen-32),32);
                                Dbprintf("AWID Found - BitLength: %d -unknown BitLength- (%d) - Wiegand: %x%08x, Raw: %08x%08x%08x", fmtLen, cardnum, code1, code2, rawHi2, rawHi, rawLo);
                        } else{
                                code1 = bytebits_to_byte(dest+8,fmtLen);
                                Dbprintf("AWID Found - BitLength: %d -unknown BitLength- (%d) - Wiegand: %x, Raw: %08x%08x%08x", fmtLen, cardnum, code1, rawHi2, rawHi, rawLo);
                        }
                }
                if (findone){
                        if (ledcontrol) LED_A_OFF();
                        break;
                }
                // reset
                idx = 0;
                WDT_HIT();
        }
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        DbpString("Stopped");
        if (ledcontrol) LED_A_OFF();
}

void CmdEM410xdemod(int findone, int *high, int *low, int ledcontrol)
{
        uint8_t *dest = BigBuf_get_addr();

        size_t size=0, idx=0;
        int clk=0, invert=0, errCnt=0, maxErr=20;
        uint32_t hi=0;
        uint64_t lo=0;
        //clear read buffer
        BigBuf_Clear_keep_EM();
        // Configure to go in 125Khz listen mode
        LFSetupFPGAForADC(95, true);

        while(!BUTTON_PRESS() && !usb_poll_validate_length()) {

                WDT_HIT();
                if (ledcontrol) LED_A_ON();

                DoAcquisition_default(-1,true);
                size  = BigBuf_max_traceLen();
                //askdemod and manchester decode
                if (size > 16385) size = 16385; //big enough to catch 2 sequences of largest format
                errCnt = askdemod(dest, &size, &clk, &invert, maxErr, 0, 1);
                WDT_HIT();

                if (errCnt<0) continue;
        
                errCnt = Em410xDecode(dest, &size, &idx, &hi, &lo);
                if (errCnt){
                        if (size>64){
                                Dbprintf("EM XL TAG ID: %06x%08x%08x - (%05d_%03d_%08d)",
                                  hi,
                                  (uint32_t)(lo>>32),
                                  (uint32_t)lo,
                                  (uint32_t)(lo&0xFFFF),
                                  (uint32_t)((lo>>16LL) & 0xFF),
                                  (uint32_t)(lo & 0xFFFFFF));
                        } else {
                                Dbprintf("EM TAG ID: %02x%08x - (%05d_%03d_%08d)",
                                  (uint32_t)(lo>>32),
                                  (uint32_t)lo,
                                  (uint32_t)(lo&0xFFFF),
                                  (uint32_t)((lo>>16LL) & 0xFF),
                                  (uint32_t)(lo & 0xFFFFFF));
                        }

                        if (findone){
                                if (ledcontrol) LED_A_OFF();
                                *high=lo>>32;
                                *low=lo & 0xFFFFFFFF;
                                break;
                        }
                }
                WDT_HIT();
                hi = lo = size = idx = 0;
                clk = invert = errCnt = 0;
        }
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        DbpString("Stopped");
        if (ledcontrol) LED_A_OFF();
}

void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
{
        uint8_t *dest = BigBuf_get_addr();
        int idx=0;
        uint32_t code=0, code2=0;
        uint8_t version=0;
        uint8_t facilitycode=0;
        uint16_t number=0;
        int dummyIdx=0;
        //clear read buffer
        BigBuf_Clear_keep_EM();
        // Configure to go in 125Khz listen mode
        LFSetupFPGAForADC(95, true);

        while(!BUTTON_PRESS() && !usb_poll_validate_length()) {
                WDT_HIT();
                if (ledcontrol) LED_A_ON();
                DoAcquisition_default(-1,true);
                //fskdemod and get start index
                WDT_HIT();
                idx = IOdemodFSK(dest, BigBuf_max_traceLen(), &dummyIdx);
                if (idx<0) continue;
                //valid tag found

                //Index map
                //0           10          20          30          40          50          60
                //|           |           |           |           |           |           |
                //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
                //-----------------------------------------------------------------------------
                //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
                //
                //XSF(version)facility:codeone+codetwo
                //Handle the data
                if(findone){ //only print binary if we are doing one
                        Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx],   dest[idx+1],   dest[idx+2],dest[idx+3],dest[idx+4],dest[idx+5],dest[idx+6],dest[idx+7],dest[idx+8]);
                        Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+9], dest[idx+10],dest[idx+11],dest[idx+12],dest[idx+13],dest[idx+14],dest[idx+15],dest[idx+16],dest[idx+17]);
                        Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+18],dest[idx+19],dest[idx+20],dest[idx+21],dest[idx+22],dest[idx+23],dest[idx+24],dest[idx+25],dest[idx+26]);
                        Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+27],dest[idx+28],dest[idx+29],dest[idx+30],dest[idx+31],dest[idx+32],dest[idx+33],dest[idx+34],dest[idx+35]);
                        Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+36],dest[idx+37],dest[idx+38],dest[idx+39],dest[idx+40],dest[idx+41],dest[idx+42],dest[idx+43],dest[idx+44]);
                        Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+45],dest[idx+46],dest[idx+47],dest[idx+48],dest[idx+49],dest[idx+50],dest[idx+51],dest[idx+52],dest[idx+53]);
                        Dbprintf("%d%d%d%d%d%d%d%d %d%d",dest[idx+54],dest[idx+55],dest[idx+56],dest[idx+57],dest[idx+58],dest[idx+59],dest[idx+60],dest[idx+61],dest[idx+62],dest[idx+63]);
                }
                code = bytebits_to_byte(dest+idx,32);
                code2 = bytebits_to_byte(dest+idx+32,32);
                version = bytebits_to_byte(dest+idx+27,8); //14,4
                facilitycode = bytebits_to_byte(dest+idx+18,8);
                number = (bytebits_to_byte(dest+idx+36,8)<<8)|(bytebits_to_byte(dest+idx+45,8)); //36,9

                Dbprintf("XSF(%02d)%02x:%05d (%08x%08x)",version,facilitycode,number,code,code2);
                // if we're only looking for one tag
                if (findone){
                        if (ledcontrol) LED_A_OFF();
                        //LED_A_OFF();
                        *high=code;
                        *low=code2;
                        break;
                }
                code=code2=0;
                version=facilitycode=0;
                number=0;
                idx=0;

                WDT_HIT();
        }
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        DbpString("Stopped");
        if (ledcontrol) LED_A_OFF();
}

/*------------------------------
 * T5555/T5557/T5567/T5577 routines
 *------------------------------
 * NOTE: T55x7/T5555 configuration register definitions moved to protocols.h
 *
 * Relevant communication times in microsecond
 * To compensate antenna falling times shorten the write times
 * and enlarge the gap ones.
 * Q5 tags seems to have issues when these values changes. 
 */
 /*
 // Original Timings for reference
 
#define START_GAP 31*8 // was 250 // SPEC:  1*8 to 50*8 - typ 15*8 (or 15fc)
#define WRITE_GAP 20*8 // was 160 // SPEC:  1*8 to 20*8 - typ 10*8 (or 10fc)
#define WRITE_0   18*8 // was 144 // SPEC: 16*8 to 32*8 - typ 24*8 (or 24fc)
#define WRITE_1   50*8 // was 400 // SPEC: 48*8 to 64*8 - typ 56*8 (or 56fc)  432 for T55x7; 448 for E5550
#define READ_GAP  15*8 
*/

// Structure to hold Timing values.  In future will be simplier to add user changable timings.
typedef struct  {
        uint16_t  START_GAP;
        uint16_t  WRITE_GAP;
        uint16_t  WRITE_0;
        uint16_t  WRITE_1;
        uint16_t  WRITE_2;
        uint16_t  WRITE_3;
        uint16_t  READ_GAP;
} T55xx_Timing;



// Set Initial/Default Values.  Note: *8 can occure when used.  This should keep things simplier here.
T55xx_Timing T55xx_Timing_FixedBit = { 31 * 8   , 20 * 8   , 18 * 8 , 50 * 8 , 0      , 0      , 15 * 8   };
T55xx_Timing T55xx_Timing_LLR      = { 31 * 8   , 20 * 8   , 18 * 8 , 50 * 8 , 0      , 0      , 15 * 8   };
T55xx_Timing T55xx_Timing_Leading0 = { 31 * 8   , 20 * 8   , 18 * 8 , 40 * 8 , 0      , 0      , 15 * 8   };
T55xx_Timing T55xx_Timing_1of4     = { 31 * 8   , 20 * 8   , 18 * 8 , 34 * 8 , 50 * 8 , 66 * 8 , 15 * 8   };


// Some defines for readability
#define T55xx_LongLeadingReference 4 // Value to tell Write Bit to send long reference
#define T55xx_DLMode_Fixed         0 // Default Mode
#define T55xx_DLMode_LLR           1 // Long Leading Reference
#define T55xx_DLMode_Leading0      2 // Leading Zero
#define T55xx_DLMode_1of4                  3 // 1 of 4

void TurnReadLFOn(int delay) {
        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
        // Give it a bit of time for the resonant antenna to settle.
        WaitUS(delay); //155*8 //50*8
}

// Write one bit to card
void T55xxWriteBit(int bit, T55xx_Timing *Timings) {

        // If bit = 4 Send Long Leading Reference which is 138 + WRITE_0        

        switch (bit){
                case 0 : TurnReadLFOn(Timings->WRITE_0);             break; // Send bit  0/00
                case 1 : TurnReadLFOn(Timings->WRITE_1);             break; // Send bit  1/01
                case 2 : TurnReadLFOn(Timings->WRITE_2);             break; // Send bits   10
                case 3 : TurnReadLFOn(Timings->WRITE_3);                     break; // Send bits   11
                case 4 : TurnReadLFOn(Timings->WRITE_0 + (136 * 8)); break; // Send Long Leading Reference 
        }               
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        WaitUS(Timings->WRITE_GAP);
}


// Function to abstract an Arbitrary length byte array to store bit pattern.
// bit_array    - Array to hold data/bit pattern
// start_offset - bit location to start storing new bits.
// data         - upto 32 bits of data to store
// num_bits     - how many bits (low x bits of data)  Max 32 bits at a time
// max_len         - how many bytes can the bit_array hold (ensure no buffer overflow)
// returns "Next" bit offset / bits stored (for next store)
int T55xx_SetBits (uint8_t *bit_array, int start_offset, uint32_t data      , int num_bits, int max_len)
{
        int bit,byte_idx, bit_idx;
    int offset;
    int NextOffset = start_offset;      

    // Check if data will fit.
    if ((start_offset + num_bits) <= (max_len*8))       {
                           
        // Loop through the data and store                          
        for (offset = (num_bits-1); offset >= 0; offset--) {
                                                
                bit      = (data >> offset) & 1;                          // Get data bit value (0/1)
            byte_idx = (NextOffset / 8);                              // Get Array Byte Index to Store
            bit_idx  = NextOffset - (byte_idx * 8);                   // Get Bit Index to set/clr

            // If set (1) we OR, if clear (0) we AND with inverse
           // Dbprintf ("Add Bit : %d at byte %d bit %d",bit,byte_idx,bit_idx);
            if (bit == 1)
                bit_array[byte_idx] |= (1 << bit_idx);                // Set the bit to 1
                
            else  
                bit_array[byte_idx] &= (0xff ^ (1 << bit_idx));       // Set the bit to 0 (clr)

            NextOffset++;
        }
        }
        else
                Dbprintf ("Too Many Bits to fit into bit buffer");
    return NextOffset;          
}

// Send T5577 reset command then read stream (see if we can identify the start of the stream)
void T55xxResetRead(void) {
        LED_A_ON();
        //clear buffer now so it does not interfere with timing later
        BigBuf_Clear_keep_EM();

        // Set up FPGA, 125kHz
        LFSetupFPGAForADC(95, true);
        StartTicks();
        // make sure tag is fully powered up...
        WaitMS(5);
        
        // Trigger T55x7 in mode.
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        WaitUS(T55xx_Timing_FixedBit.START_GAP);

        // reset tag - op code 00
        T55xxWriteBit(0,&T55xx_Timing_FixedBit);
        T55xxWriteBit(0,&T55xx_Timing_FixedBit);

        TurnReadLFOn(T55xx_Timing_FixedBit.READ_GAP);

        // Acquisition
        DoPartialAcquisition(0, true, BigBuf_max_traceLen(), 0);

        // Turn the field off
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
        cmd_send(CMD_ACK,0,0,0,0,0);    
        LED_A_OFF();
}

// Send one downlink command to the card 
void T55xx_SendCMD (uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t arg) { //, bool read_cmd) {//, struct T55xx_Timing *Timing) {
        
        /*
                arg bits
                xxxxxxx1 0x01 PwdMode
                xxxxxx1x 0x02 Page
                xxxxx1xx 0x04 testMode
                xxx11xxx 0x18 downlink mode
                xx1xxxxx 0x20 reg_readmode
                x1xxxxxx 0x40 called for a read, so no data packet
                
        */
        bool    PwdMode                 = ((arg & 0x01) == 0x01);
        uint8_t Page                    =  (arg & 0x02) >> 1;
        bool    testMode                = ((arg & 0x04) == 0x04);
        uint8_t downlink_mode   =  (arg >> 3) & 0x03;;
        bool    reg_readmode    = ((arg & 0x20) == 0x20);
        bool    read_cmd                = ((arg & 0x40) == 0x40);
        
        int i = 0;
        uint8_t BitStream[10]; // Max Downlink Command size ~75 bits, so 10 bytes (80 bits)              
        uint8_t BitStreamLen;
        int byte_idx, bit_idx;
        T55xx_Timing *Timing;
        

        // Assigning Downlink Timeing for write
        switch (downlink_mode)
        {
                case T55xx_DLMode_Fixed    : Timing = &T55xx_Timing_FixedBit;  break; 
                case T55xx_DLMode_LLR      : Timing = &T55xx_Timing_LLR;           break;
                case T55xx_DLMode_Leading0 : Timing = &T55xx_Timing_Leading0;  break;
                case T55xx_DLMode_1of4     : Timing = &T55xx_Timing_1of4;      break;
                default:
                                Timing = &T55xx_Timing_FixedBit;
        }       

        // Build Bit Stream to send.
        memset (BitStream,0x00,sizeof(BitStream));
        
        BitStreamLen = 0;
        
        // Add Leading 0 and 1 of 4 reference bit
        if ((downlink_mode == T55xx_DLMode_Leading0) || (downlink_mode == T55xx_DLMode_1of4))  
                BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, 0, 1,sizeof(BitStream)); 

        // Add extra reference 0 for 1 of 4
        if (downlink_mode == T55xx_DLMode_1of4)                            
                BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, 0, 1,sizeof(BitStream)); 

        // Add Opcode
        if (testMode) Dbprintf("TestMODE");
        BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen,testMode ? 0 : 1    , 1,sizeof(BitStream));       
        BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen,testMode ? 1 : Page , 1,sizeof(BitStream));       
        
        if (PwdMode) {

                // Leading 0 and 1 of 4 00 fixed bits if passsword used         
                if ((downlink_mode == T55xx_DLMode_Leading0) || (downlink_mode == T55xx_DLMode_1of4)) {
                        BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, 0, 1,sizeof(BitStream)); 
                        BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, 0, 1,sizeof(BitStream)); 
                }
                BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, Pwd, 32,sizeof(BitStream)); 

        }
        // Add Lock bit
        BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, 0, 1,sizeof(BitStream)); 

        // Add Data if a write command
        if (!read_cmd)  BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, Data, 32,sizeof(BitStream)); 

        // Add Address
        if (!reg_readmode) BitStreamLen = T55xx_SetBits (BitStream, BitStreamLen, Block, 3,sizeof(BitStream)); 
        


        // Send Bits to T55xx
        
        // Set up FPGA, 125kHz
        LFSetupFPGAForADC(95, true);
        StartTicks();
        // make sure tag is fully powered up...
        WaitMS(5);
        // Trigger T55x7 in mode.
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        WaitUS(Timing->START_GAP);


        // If long leading 0 send long reference pulse
        if (downlink_mode ==  T55xx_DLMode_LLR) 
                T55xxWriteBit (T55xx_LongLeadingReference,Timing); // Send Long Leading Start Reference

        uint8_t SendBits;
        
        if (downlink_mode ==  T55xx_DLMode_1of4) { // 1 of 4 need to send 2 bits at a time
                for (i = 0; i < BitStreamLen; i+=2) {
                        byte_idx = i / 8;
                        bit_idx  = i - (byte_idx * 8);
                        SendBits = ((BitStream[byte_idx] >> bit_idx) & 1) << 1;
                        
                        byte_idx = (i+1) / 8;
                        bit_idx  = (i+1) - (byte_idx * 8);
                        SendBits += (BitStream[byte_idx] >> bit_idx) & 1;
                        
                        T55xxWriteBit (SendBits,Timing);
                }
        }
        else {
                for (i = 0; i < BitStreamLen; i++) {
                        byte_idx = i / 8;
                        bit_idx  = i - (byte_idx * 8);
                        SendBits = (BitStream[byte_idx] >> bit_idx) & 1;
                        T55xxWriteBit (SendBits,Timing);
        }               
        }
        
}

// Write one card block in page 0, no lock
void T55xxWriteBlock(uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t arg) {
        /*
                arg bits
                xxxxxxx1 0x01 PwdMode
                xxxxxx1x 0x02 Page
                xxxxx1xx 0x04 testMode
                xxx11xxx 0x18 downlink mode
                xx1xxxxx 0x20 reg_readmode
                x1xxxxxx 0x40 called for a read, so no data packet
        */
        
        bool    testMode                = ((arg & 0x04) == 0x04);
        arg &= (0xff ^ 0x40); // Called for a write, so ensure it is clear/0
        
        LED_A_ON ();
        T55xx_SendCMD (Data, Block, Pwd, arg) ;//, false); 

        // Perform write (nominal is 5.6 ms for T55x7 and 18ms for E5550,
        // so wait a little more)

        // "there is a clock delay before programming" 
        //  - programming takes ~5.6ms for t5577 ~18ms for E5550 or t5567
        //  so we should wait 1 clock + 5.6ms then read response? 
        //  but we need to know we are dealing with t5577 vs t5567 vs e5550 (or q5) marshmellow...
        if (testMode) {
                //TESTMODE TIMING TESTS: 
                // <566us does nothing 
                // 566-568 switches between wiping to 0s and doing nothing
                // 5184 wipes and allows 1 block to be programmed.
                // indefinite power on wipes and then programs all blocks with bitshifted data sent.
                TurnReadLFOn(5184); 

        } else {
                TurnReadLFOn(20 * 1000);
                //could attempt to do a read to confirm write took
                // as the tag should repeat back the new block 
                // until it is reset, but to confirm it we would 
                // need to know the current block 0 config mode for
                // modulation clock an other details to demod the response...
                // response should be (for t55x7) a 0 bit then (ST if on) 
                // block data written in on repeat until reset. 

                //DoPartialAcquisition(20, true, 12000);
        }
        // turn field off
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                
        cmd_send(CMD_ACK,0,0,0,0,0);

        LED_A_OFF ();
}

// Read one card block in page [page]
void T55xxReadBlock (uint16_t arg0, uint8_t Block, uint32_t Pwd) {//, struct T55xx_Timing *Timing) {
        
        LED_A_ON();

        /*
                arg bits
                xxxxxxx1 0x01 PwdMode
                xxxxxx1x 0x02 Page
                xxxxx1xx 0x04 testMode
                xxx11xxx 0x18 downlink mode
                xx1xxxxx 0x20 reg_readmode
                x1xxxxxx 0x40 called for a read, so no data packet
        */
        
        // Set Read Flag to ensure SendCMD does not add "data" to the packet
        arg0 |= 0x40;

                
        if (Block == 0xff) arg0 |= 0x20;
        
        //make sure block is at max 7
        Block &= 0x7;
        //clear buffer now so it does not interfere with timing later
        BigBuf_Clear_ext(false);
        
        T55xx_SendCMD (0, Block, Pwd, arg0); //, true);
        
                
        // Turn field on to read the response
        // 137*8 seems to get to the start of data pretty well... 
        //  but we want to go past the start and let the repeating data settle in...
        TurnReadLFOn(210*8); 

        // Acquisition
        // Now do the acquisition
        DoPartialAcquisition(0, true, 12000, 0);

        // Turn the field off
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
        cmd_send(CMD_ACK,0,0,0,0,0);    

        LED_A_OFF();
}

void T55xxWakeUp(uint32_t Pwd){
        LED_B_ON();
        uint32_t i = 0;
        
        // Set up FPGA, 125kHz
        LFSetupFPGAForADC(95, true);
        StartTicks();
        // make sure tag is fully powered up...
        WaitMS(5);
        
        // Trigger T55x7 Direct Access Mode
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        WaitUS(T55xx_Timing_FixedBit.START_GAP);
        
        // Opcode 10
        T55xxWriteBit(1,&T55xx_Timing_FixedBit);
        T55xxWriteBit(0,&T55xx_Timing_FixedBit); //Page 0

        // Send Pwd
        
        for (i = 0x80000000; i != 0; i >>= 1)
                T55xxWriteBit(Pwd & i,&T55xx_Timing_FixedBit);

        // Turn and leave field on to let the begin repeating transmission
        TurnReadLFOn(20*1000);
}

/*-------------- Cloning routines -----------*/

void WriteT55xx(uint32_t *blockdata, uint8_t startblock, uint8_t numblocks) {
        // write last block first and config block last (if included)
        for (uint8_t i = numblocks+startblock; i > startblock; i--) {
                 T55xxWriteBlock(blockdata[i-1],i-1,0,0);//,false); //,&T55xx_Timing_FixedBit);
        //      T55xx_SendCMD (blockdata[i-1],i-1,0,0);//,false); //,&T55xx_Timing_FixedBit);
        }
}

// Copy a HID-like card (e.g. HID Proximity, Paradox) to a T55x7 compatible card
void CopyHIDtoT55x7(uint32_t hi2, uint32_t hi, uint32_t lo, uint8_t longFMT, uint8_t preamble) {
        uint32_t data[] = {0,0,0,0,0,0,0};
        uint8_t last_block = 0;

        if (longFMT) {
                // Ensure no more than 84 bits supplied
                if (hi2>0xFFFFF) {
                        DbpString("Tags can only have 84 bits.");
                        return;
                }
                // Build the 6 data blocks for supplied 84bit ID
                last_block = 6;
                // load preamble & long format identifier (9E manchester encoded)
                data[1] = (preamble << 24) | 0x96A900 | (manchesterEncode2Bytes((hi2 >> 16) & 0xF) & 0xFF);
                // load raw id from hi2, hi, lo to data blocks (manchester encoded)
                data[2] = manchesterEncode2Bytes(hi2 & 0xFFFF);
                data[3] = manchesterEncode2Bytes(hi >> 16);
                data[4] = manchesterEncode2Bytes(hi & 0xFFFF);
                data[5] = manchesterEncode2Bytes(lo >> 16);
                data[6] = manchesterEncode2Bytes(lo & 0xFFFF);
        } else {
                // Ensure no more than 44 bits supplied
                if (hi>0xFFF) {
                        DbpString("Tags can only have 44 bits.");
                        return;
                }
                // Build the 3 data blocks for supplied 44bit ID
                last_block = 3;
                // load preamble
                data[1] = (preamble << 24) | (manchesterEncode2Bytes(hi) & 0xFFFFFF);
                data[2] = manchesterEncode2Bytes(lo >> 16);
                data[3] = manchesterEncode2Bytes(lo & 0xFFFF);
        }
        // load chip config block
        data[0] = T55x7_BITRATE_RF_50 | T55x7_MODULATION_FSK2a | last_block << T55x7_MAXBLOCK_SHIFT;

        //TODO add selection of chip for Q5 or T55x7
        // data[0] = (((50-2)/2)<<T5555_BITRATE_SHIFT) | T5555_MODULATION_FSK2 | T5555_INVERT_OUTPUT | last_block << T5555_MAXBLOCK_SHIFT;

        LED_D_ON();
        // Program the data blocks for supplied ID
        // and the block 0 for HID format
        WriteT55xx(data, 0, last_block+1);

        LED_D_OFF();

        DbpString("DONE!");
}

void CopyIOtoT55x7(uint32_t hi, uint32_t lo) {
        uint32_t data[] = {T55x7_BITRATE_RF_64 | T55x7_MODULATION_FSK2a | (2 << T55x7_MAXBLOCK_SHIFT), hi, lo};
        //TODO add selection of chip for Q5 or T55x7
        // data[0] = (((64-2)/2)<<T5555_BITRATE_SHIFT) | T5555_MODULATION_FSK2 | T5555_INVERT_OUTPUT | 2 << T5555_MAXBLOCK_SHIFT;

        LED_D_ON();
        // Program the data blocks for supplied ID
        // and the block 0 config
        WriteT55xx(data, 0, 3);

        LED_D_OFF();

        DbpString("DONE!");
}

// Clone Indala 64-bit tag by UID to T55x7
void CopyIndala64toT55x7(uint32_t hi, uint32_t lo) {
        //Program the 2 data blocks for supplied 64bit UID
        // and the Config for Indala 64 format (RF/32;PSK1 with RF/2;Maxblock=2)
        uint32_t data[] = { T55x7_BITRATE_RF_32 | T55x7_MODULATION_PSK1 | (2 << T55x7_MAXBLOCK_SHIFT), hi, lo};
        //TODO add selection of chip for Q5 or T55x7
        // data[0] = (((32-2)/2)<<T5555_BITRATE_SHIFT) | T5555_MODULATION_PSK1 | 2 << T5555_MAXBLOCK_SHIFT;

        WriteT55xx(data, 0, 3);
        //Alternative config for Indala (Extended mode;RF/32;PSK1 with RF/2;Maxblock=2;Inverse data)
        //      T5567WriteBlock(0x603E1042,0);
        DbpString("DONE!");
}
// Clone Indala 224-bit tag by UID to T55x7
void CopyIndala224toT55x7(uint32_t uid1, uint32_t uid2, uint32_t uid3, uint32_t uid4, uint32_t uid5, uint32_t uid6, uint32_t uid7) {
        //Program the 7 data blocks for supplied 224bit UID
        uint32_t data[] = {0, uid1, uid2, uid3, uid4, uid5, uid6, uid7};
        // and the block 0 for Indala224 format 
        //Config for Indala (RF/32;PSK2 with RF/2;Maxblock=7)
        data[0] = T55x7_BITRATE_RF_32 | T55x7_MODULATION_PSK2 | (7 << T55x7_MAXBLOCK_SHIFT);
        //TODO add selection of chip for Q5 or T55x7
        // data[0] = (((32-2)>>1)<<T5555_BITRATE_SHIFT) | T5555_MODULATION_PSK2 | 7 << T5555_MAXBLOCK_SHIFT;
        WriteT55xx(data, 0, 8);
        //Alternative config for Indala (Extended mode;RF/32;PSK1 with RF/2;Maxblock=7;Inverse data)
        //      T5567WriteBlock(0x603E10E2,0);
        DbpString("DONE!");
}
// clone viking tag to T55xx
void CopyVikingtoT55xx(uint32_t block1, uint32_t block2, uint8_t Q5) {
        uint32_t data[] = {T55x7_BITRATE_RF_32 | T55x7_MODULATION_MANCHESTER | (2 << T55x7_MAXBLOCK_SHIFT), block1, block2};
        if (Q5) data[0] = T5555_SET_BITRATE(32) | T5555_MODULATION_MANCHESTER | 2 << T5555_MAXBLOCK_SHIFT;
        // Program the data blocks for supplied ID and the block 0 config
        WriteT55xx(data, 0, 3);
        LED_D_OFF();
        cmd_send(CMD_ACK,0,0,0,0,0);
}

// Define 9bit header for EM410x tags
#define EM410X_HEADER             0x1FF
#define EM410X_ID_LENGTH        40

void WriteEM410x(uint32_t card, uint32_t id_hi, uint32_t id_lo) {
        int i, id_bit;
        uint64_t id = EM410X_HEADER;
        uint64_t rev_id = 0;    // reversed ID
        int c_parity[4];        // column parity
        int r_parity = 0;       // row parity
        uint32_t clock = 0;

        // Reverse ID bits given as parameter (for simpler operations)
        for (i = 0; i < EM410X_ID_LENGTH; ++i) {
                if (i < 32) {
                        rev_id = (rev_id << 1) | (id_lo & 1);
                        id_lo >>= 1;
                } else {
                        rev_id = (rev_id << 1) | (id_hi & 1);
                        id_hi >>= 1;
                }
        }

        for (i = 0; i < EM410X_ID_LENGTH; ++i) {
                id_bit = rev_id & 1;

                if (i % 4 == 0) {
                        // Don't write row parity bit at start of parsing
                        if (i)
                                id = (id << 1) | r_parity;
                        // Start counting parity for new row
                        r_parity = id_bit;
                } else {
                        // Count row parity
                        r_parity ^= id_bit;
                }

                // First elements in column?
                if (i < 4)
                        // Fill out first elements
                        c_parity[i] = id_bit;
                else
                        // Count column parity
                        c_parity[i % 4] ^= id_bit;

                // Insert ID bit
                id = (id << 1) | id_bit;
                rev_id >>= 1;
        }

        // Insert parity bit of last row
        id = (id << 1) | r_parity;

        // Fill out column parity at the end of tag
        for (i = 0; i < 4; ++i)
                id = (id << 1) | c_parity[i];

        // Add stop bit
        id <<= 1;

        Dbprintf("Started writing %s tag ...", card ? "T55x7":"T5555");
        LED_D_ON();

        // Write EM410x ID
        uint32_t data[] = {0, (uint32_t)(id>>32), (uint32_t)(id & 0xFFFFFFFF)};

        clock = (card & 0xFF00) >> 8;
        clock = (clock == 0) ? 64 : clock;
        Dbprintf("Clock rate: %d", clock);
        if (card & 0xFF) { //t55x7
                clock = GetT55xxClockBit(clock);                        
                if (clock == 0) {
                        Dbprintf("Invalid clock rate: %d", clock);
                        return;
                }
                data[0] = clock | T55x7_MODULATION_MANCHESTER | (2 << T55x7_MAXBLOCK_SHIFT);
        } else { //t5555 (Q5)
                data[0] = T5555_SET_BITRATE(clock) | T5555_MODULATION_MANCHESTER | (2 << T5555_MAXBLOCK_SHIFT);
        }

        WriteT55xx(data, 0, 3);

        LED_D_OFF();
        Dbprintf("Tag %s written with 0x%08x%08x\n", card ? "T55x7":"T5555",
                         (uint32_t)(id >> 32), (uint32_t)id);
}

//-----------------------------------
// EM4469 / EM4305 routines
//-----------------------------------
#define FWD_CMD_LOGIN 0xC //including the even parity, binary mirrored
#define FWD_CMD_WRITE 0xA
#define FWD_CMD_READ 0x9
#define FWD_CMD_DISABLE 0x5

uint8_t forwardLink_data[64]; //array of forwarded bits
uint8_t * forward_ptr; //ptr for forward message preparation
uint8_t fwd_bit_sz; //forwardlink bit counter
uint8_t * fwd_write_ptr; //forwardlink bit pointer

//====================================================================
// prepares command bits
// see EM4469 spec
//====================================================================
//--------------------------------------------------------------------
//  VALUES TAKEN FROM EM4x function: SendForward
//  START_GAP = 440;       (55*8) cycles at 125Khz (8us = 1cycle)
//  WRITE_GAP = 128;       (16*8)
//  WRITE_1   = 256 32*8;  (32*8) 

//  These timings work for 4469/4269/4305 (with the 55*8 above)
//  WRITE_0 = 23*8 , 9*8  SpinDelayUs(23*8); 

uint8_t Prepare_Cmd( uint8_t cmd ) {

        *forward_ptr++ = 0; //start bit
        *forward_ptr++ = 0; //second pause for 4050 code

        *forward_ptr++ = cmd;
        cmd >>= 1;
        *forward_ptr++ = cmd;
        cmd >>= 1;
        *forward_ptr++ = cmd;
        cmd >>= 1;
        *forward_ptr++ = cmd;

        return 6; //return number of emited bits
}

//====================================================================
// prepares address bits
// see EM4469 spec
//====================================================================
uint8_t Prepare_Addr( uint8_t addr ) {

        register uint8_t line_parity;

        uint8_t i;
        line_parity = 0;
        for(i=0;i<6;i++) {
                *forward_ptr++ = addr;
                line_parity ^= addr;
                addr >>= 1;
        }

        *forward_ptr++ = (line_parity & 1);

        return 7; //return number of emited bits
}

//====================================================================
// prepares data bits intreleaved with parity bits
// see EM4469 spec
//====================================================================
uint8_t Prepare_Data( uint16_t data_low, uint16_t data_hi) {

        register uint8_t line_parity;
        register uint8_t column_parity;
        register uint8_t i, j;
        register uint16_t data;

        data = data_low;
        column_parity = 0;

        for(i=0; i<4; i++) {
                line_parity = 0;
                for(j=0; j<8; j++) {
                        line_parity ^= data;
                        column_parity ^= (data & 1) << j;
                        *forward_ptr++ = data;
                        data >>= 1;
                }
                *forward_ptr++ = line_parity;
                if(i == 1)
                        data = data_hi;
        }

        for(j=0; j<8; j++) {
                *forward_ptr++ = column_parity;
                column_parity >>= 1;
        }
        *forward_ptr = 0;

        return 45; //return number of emited bits
}

//====================================================================
// Forward Link send function
// Requires: forwarLink_data filled with valid bits (1 bit per byte)
// fwd_bit_count set with number of bits to be sent
//====================================================================
void SendForward(uint8_t fwd_bit_count) {

        fwd_write_ptr = forwardLink_data;
        fwd_bit_sz = fwd_bit_count;

        // Set up FPGA, 125kHz or 95 divisor
        LFSetupFPGAForADC(95, true);

        // force 1st mod pulse (start gap must be longer for 4305)
        fwd_bit_sz--; //prepare next bit modulation
        fwd_write_ptr++;
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
        WaitUS(55*8); //55 cycles off (8us each)for 4305  //another reader has 37 here...
        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
        WaitUS(18*8); //18 cycles on (8us each)

        // now start writting
        while(fwd_bit_sz-- > 0) { //prepare next bit modulation
                if(((*fwd_write_ptr++) & 1) == 1)
                        WaitUS(32*8); //32 cycles at 125Khz (8us each)
                else {
                        //These timings work for 4469/4269/4305 (with the 55*8 above)
                        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
                        WaitUS(23*8); //23 cycles off (8us each)
                        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
                        WaitUS(18*8); //18 cycles on (8us each)
                }
        }
}

void EM4xLogin(uint32_t Password) {

        uint8_t fwd_bit_count;

        forward_ptr = forwardLink_data;
        fwd_bit_count = Prepare_Cmd( FWD_CMD_LOGIN );
        fwd_bit_count += Prepare_Data( Password&0xFFFF, Password>>16 );

        SendForward(fwd_bit_count);

        //Wait for command to complete
        SpinDelay(20);
}

void EM4xReadWord(uint8_t Address, uint32_t Pwd, uint8_t PwdMode) {

        uint8_t fwd_bit_count;

        // Clear destination buffer before sending the command
        BigBuf_Clear_ext(false);

        LED_A_ON();
        StartTicks();
        //If password mode do login
        if (PwdMode == 1) EM4xLogin(Pwd);

        forward_ptr = forwardLink_data;
        fwd_bit_count = Prepare_Cmd( FWD_CMD_READ );
        fwd_bit_count += Prepare_Addr( Address );

        SendForward(fwd_bit_count);
        WaitUS(400);
        // Now do the acquisition
        DoPartialAcquisition(20, true, 6000, 1000);
        
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
        LED_A_OFF();
        cmd_send(CMD_ACK,0,0,0,0,0);
}

void EM4xWriteWord(uint32_t flag, uint32_t Data, uint32_t Pwd) {
        
        bool PwdMode = (flag & 0xF);
        uint8_t Address = (flag >> 8) & 0xFF;
        uint8_t fwd_bit_count;

        //clear buffer now so it does not interfere with timing later
        BigBuf_Clear_ext(false);

        LED_A_ON();
        StartTicks();
        //If password mode do login
        if (PwdMode) EM4xLogin(Pwd);

        forward_ptr = forwardLink_data;
        fwd_bit_count = Prepare_Cmd( FWD_CMD_WRITE );
        fwd_bit_count += Prepare_Addr( Address );
        fwd_bit_count += Prepare_Data( Data&0xFFFF, Data>>16 );

        SendForward(fwd_bit_count);

        //Wait for write to complete
        //SpinDelay(10);

        WaitUS(6500);
        //Capture response if one exists
        DoPartialAcquisition(20, true, 6000, 1000);

        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
        LED_A_OFF();
        cmd_send(CMD_ACK,0,0,0,0,0);
}
/*
Reading a COTAG.

COTAG needs the reader to send a startsequence and the card has an extreme slow datarate.
because of this, we can "sample" the data signal but we interpreate it to Manchester direct.

READER START SEQUENCE:
burst 800 us,    gap   2.2 msecs
burst 3.6 msecs  gap   2.2 msecs
burst 800 us     gap   2.2 msecs
pulse 3.6 msecs

This triggers a COTAG tag to response
*/
void Cotag(uint32_t arg0) {

#define OFF     { FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); WaitUS(2035); }
#define ON(x)   { FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD); WaitUS((x)); }

        uint8_t rawsignal = arg0 & 0xF;

        LED_A_ON();

        // Switching to LF image on FPGA. This might empty BigBuff
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);

        //clear buffer now so it does not interfere with timing later
        BigBuf_Clear_ext(false);

        // Set up FPGA, 132kHz to power up the tag
        FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 89);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);

        // Connect the A/D to the peak-detected low-frequency path.
        SetAdcMuxFor(GPIO_MUXSEL_LOPKD);

        // Now set up the SSC to get the ADC samples that are now streaming at us.
        FpgaSetupSsc(FPGA_MAJOR_MODE_LF_ADC);

        // start clock - 1.5ticks is 1us
        StartTicks();

        //send COTAG start pulse
        ON(740)  OFF
        ON(3330) OFF
        ON(740)  OFF
        ON(1000)

        switch(rawsignal) {
                case 0: doCotagAcquisition(50000); break;
                case 1: doCotagAcquisitionManchester(); break;
                case 2: DoAcquisition_config(true, 0); break;
        }

        // Turn the field off
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
        cmd_send(CMD_ACK,0,0,0,0,0);
        LED_A_OFF();
}