Merge pull request #134 from VERTCraig/master

[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
// 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 "usb_cdc.h"


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

	int divisor_used = 95; // 125 KHz
	// see if 'h' was specified

	if (command[strlen((char *) command) - 1] == 'h')
		divisor_used = 88; // 134.8 KHz

	sample_config sc = { 0,0,1, divisor_used, 0};
	setSamplingConfig(&sc);

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

	LFSetupFPGAForADC(sc.divisor, 1);

	// And a little more time for the tag to fully power up
	SpinDelay(2000);

	// now modulate the reader field
	while(*command != '\0' && *command != ' ') {
		FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
		LED_D_OFF();
		SpinDelayUs(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')
			SpinDelayUs(period_0);
		else
			SpinDelayUs(period_1);
	}
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	LED_D_OFF();
	SpinDelayUs(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);
}



/* 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();
	memset(BigBuf,0,BigBuf_max_traceLen()/sizeof(uint32_t));

	// 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 tiread to check");
}

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

	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
		while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)) {
			if(BUTTON_PRESS() || (usb_poll_validate_length() )) {
				DbpString("Stopped");
				return;
			}
			WDT_HIT();
		}
		if (ledcontrol)
			LED_D_ON();

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

		if (ledcontrol)
			LED_D_OFF();
		//wait until SSC_CLK goes LOW
		while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK) {
			if(BUTTON_PRESS()) {
				DbpString("Stopped");
				return;
			}
			WDT_HIT();
		}

		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 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 (hi>0xFFF) {
		DbpString("Tags can only have 44 bits. - USE lf simfsk for larger tags");
		return;
	}
	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();
	// 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;

	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;
	}

}

// 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;

	if (encoding==2){  //biphase
		uint8_t phase=0;
		for (i=0; i<size; i++){
			biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
		}
		if (BitStream[0]==BitStream[size-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 biphase phase)
			for (i=0; i<size; i++){
				askSimBit(BitStream[i]^invert^1, &n, clk, encoding);
			}
		}
	}
	
	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;
	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 *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;
	// Configure to go in 125Khz listen mode
	LFSetupFPGAForADC(95, true);

	while(!BUTTON_PRESS()) {

		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);
		
		if (idx>0 && lo>0 && (size==96 || size==192)){
			// go over previously decoded manchester data and decode into usable tag ID
			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 {  //standard HID tags 44/96 bits
				//Dbprintf("TAG ID: %x%08x (%d)",(unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF); //old print cmd
				uint8_t bitlen = 0;
				uint32_t fc = 0;
				uint32_t cardnum = 0;
				if (((hi>>5)&1) == 1){//if bit 38 is set then < 37 bit format is used
					uint32_t lo2=0;
					lo2=(((hi & 31) << 12) | (lo>>20)); //get bits 21-37 to check for format len bit
					uint8_t idx3 = 1;
					while(lo2 > 1){ //find last bit set to 1 (format len bit)
						lo2=lo2 >> 1;
						idx3++;
					}
					bitlen = idx3+19;
					fc =0;
					cardnum=0;
					if(bitlen == 26){
						cardnum = (lo>>1)&0xFFFF;
						fc = (lo>>17)&0xFF;
					}
					if(bitlen == 37){
						cardnum = (lo>>1)&0x7FFFF;
						fc = ((hi&0xF)<<12)|(lo>>20);
					}
					if(bitlen == 34){
						cardnum = (lo>>1)&0xFFFF;
						fc= ((hi&1)<<15)|(lo>>17);
					}
					if(bitlen == 35){
						cardnum = (lo>>1)&0xFFFFF;
						fc = ((hi&1)<<11)|(lo>>21);
					}
				}
				else { //if bit 38 is not set then 37 bit format is used
					bitlen= 37;
					fc =0;
					cardnum=0;
					if(bitlen==37){
						cardnum = (lo>>1)&0x7FFFF;
						fc = ((hi&0xF)<<12)|(lo>>20);
					}
				}
				//Dbprintf("TAG ID: %x%08x (%d)",
				// (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
				Dbprintf("TAG ID: %x%08x (%d) - Format Len: %dbit - FC: %d - Card: %d",
						 (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF,
						 (unsigned int) bitlen, (unsigned int) fc, (unsigned int) cardnum);
			}
			if (findone){
				if (ledcontrol)	LED_A_OFF();
				*high = hi;
				*low = lo;
				return;
			}
			// reset
		}
		hi2 = hi = lo = idx = 0;
		WDT_HIT();
	}
	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();
	//const size_t sizeOfBigBuff = BigBuf_max_traceLen();
	size_t size; 
	int idx=0;
	// Configure to go in 125Khz listen mode
	LFSetupFPGAForADC(95, true);

	while(!BUTTON_PRESS()) {

		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 = AWIDdemodFSK(dest, &size);
		
		if (idx>0 && size==96){
	        // 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);
	        // 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();
				return;
			}
			// reset
		}
		idx = 0;
		WDT_HIT();
	}
	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;
	// Configure to go in 125Khz listen mode
	LFSetupFPGAForADC(95, true);

	while(!BUTTON_PRESS()) {

		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;
				return;
			}
		}
		WDT_HIT();
		hi = lo = size = idx = 0;
		clk = invert = errCnt = 0;
	}
	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;
	// Configure to go in 125Khz listen mode
	LFSetupFPGAForADC(95, true);

	while(!BUTTON_PRESS()) {
		WDT_HIT();
		if (ledcontrol) LED_A_ON();
		DoAcquisition_default(-1,true);
		//fskdemod and get start index
		WDT_HIT();
		idx = IOdemodFSK(dest, BigBuf_max_traceLen());
		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;
			return;
		}
		code=code2=0;
		version=facilitycode=0;
		number=0;
		idx=0;

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

/*------------------------------
 * T5555/T5557/T5567 routines
 *------------------------------
 */

/* T55x7 configuration register definitions */
#define T55x7_POR_DELAY			0x00000001
#define T55x7_ST_TERMINATOR		0x00000008
#define T55x7_PWD			0x00000010
#define T55x7_MAXBLOCK_SHIFT		5
#define T55x7_AOR			0x00000200
#define T55x7_PSKCF_RF_2		0
#define T55x7_PSKCF_RF_4		0x00000400
#define T55x7_PSKCF_RF_8		0x00000800
#define T55x7_MODULATION_DIRECT		0
#define T55x7_MODULATION_PSK1		0x00001000
#define T55x7_MODULATION_PSK2		0x00002000
#define T55x7_MODULATION_PSK3		0x00003000
#define T55x7_MODULATION_FSK1		0x00004000
#define T55x7_MODULATION_FSK2		0x00005000
#define T55x7_MODULATION_FSK1a		0x00006000
#define T55x7_MODULATION_FSK2a		0x00007000
#define T55x7_MODULATION_MANCHESTER	0x00008000
#define T55x7_MODULATION_BIPHASE	0x00010000
#define T55x7_BITRATE_RF_8		0
#define T55x7_BITRATE_RF_16		0x00040000
#define T55x7_BITRATE_RF_32		0x00080000
#define T55x7_BITRATE_RF_40		0x000C0000
#define T55x7_BITRATE_RF_50		0x00100000
#define T55x7_BITRATE_RF_64		0x00140000
#define T55x7_BITRATE_RF_100		0x00180000
#define T55x7_BITRATE_RF_128		0x001C0000

/* T5555 (Q5) configuration register definitions */
#define T5555_ST_TERMINATOR		0x00000001
#define T5555_MAXBLOCK_SHIFT		0x00000001
#define T5555_MODULATION_MANCHESTER	0
#define T5555_MODULATION_PSK1		0x00000010
#define T5555_MODULATION_PSK2		0x00000020
#define T5555_MODULATION_PSK3		0x00000030
#define T5555_MODULATION_FSK1		0x00000040
#define T5555_MODULATION_FSK2		0x00000050
#define T5555_MODULATION_BIPHASE	0x00000060
#define T5555_MODULATION_DIRECT		0x00000070
#define T5555_INVERT_OUTPUT		0x00000080
#define T5555_PSK_RF_2			0
#define T5555_PSK_RF_4			0x00000100
#define T5555_PSK_RF_8			0x00000200
#define T5555_USE_PWD			0x00000400
#define T5555_USE_AOR			0x00000800
#define T5555_BITRATE_SHIFT		12
#define T5555_FAST_WRITE		0x00004000
#define T5555_PAGE_SELECT		0x00008000

/*
 * Relevant times in microsecond
 * To compensate antenna falling times shorten the write times
 * and enlarge the gap ones.
 */
#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 T55xx_SAMPLES_SIZE      12000 // 32 x 32 x 10  (32 bit times numofblock (7), times clock skip..)

// Write one bit to card
void T55xxWriteBit(int bit)
{
	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
	if (bit == 0)
		SpinDelayUs(WRITE_0);
	else
		SpinDelayUs(WRITE_1);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	SpinDelayUs(WRITE_GAP);
}

// Write one card block in page 0, no lock
void T55xxWriteBlock(uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
{
	uint32_t i = 0;

	// Set up FPGA, 125kHz
	// Wait for config.. (192+8190xPOW)x8 == 67ms
	LFSetupFPGAForADC(0, true);

	// Now start writting
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	SpinDelayUs(START_GAP);

	// Opcode
	T55xxWriteBit(1);
	T55xxWriteBit(0); //Page 0
	if (PwdMode == 1){
		// Pwd
		for (i = 0x80000000; i != 0; i >>= 1)
			T55xxWriteBit(Pwd & i);
	}
	// Lock bit
	T55xxWriteBit(0);

	// Data
	for (i = 0x80000000; i != 0; i >>= 1)
		T55xxWriteBit(Data & i);

	// Block
	for (i = 0x04; i != 0; i >>= 1)
		T55xxWriteBit(Block & i);

	// Now perform write (nominal is 5.6 ms for T55x7 and 18ms for E5550,
	// so wait a little more)
	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
	SpinDelay(20);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
}

void TurnReadLFOn(){
	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
	// Give it a bit of time for the resonant antenna to settle.
	SpinDelayUs(8*150);
}


// Read one card block in page 0
void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
{
	uint32_t i = 0;
	uint8_t *dest = BigBuf_get_addr();
	uint16_t bufferlength = BigBuf_max_traceLen();
	if ( bufferlength > T55xx_SAMPLES_SIZE )
		bufferlength = T55xx_SAMPLES_SIZE;

	// Clear destination buffer before sending the command
	memset(dest, 0x80, bufferlength);

	// Set up FPGA, 125kHz
	// Wait for config.. (192+8190xPOW)x8 == 67ms
	LFSetupFPGAForADC(0, true);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	SpinDelayUs(START_GAP);

	// Opcode
	T55xxWriteBit(1);
	T55xxWriteBit(0); //Page 0
	if (PwdMode == 1){
		// Pwd
		for (i = 0x80000000; i != 0; i >>= 1)
			T55xxWriteBit(Pwd & i);
	}
	// Lock bit
	T55xxWriteBit(0);
	// Block
	for (i = 0x04; i != 0; i >>= 1)
		T55xxWriteBit(Block & i);

	// Turn field on to read the response
	TurnReadLFOn();
	// Now do the acquisition
	i = 0;
	for(;;) {
		if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
			AT91C_BASE_SSC->SSC_THR = 0x43;
			LED_D_ON();
		}
		if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
			dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
			i++;
			LED_D_OFF();
			if (i >= bufferlength) break;
		}
	}

	cmd_send(CMD_ACK,0,0,0,0,0);    
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
	LED_D_OFF();
}

// Read card traceability data (page 1)
void T55xxReadTrace(void){
	
	uint32_t i = 0;
	uint8_t *dest = BigBuf_get_addr();
	uint16_t bufferlength = BigBuf_max_traceLen();
	if ( bufferlength > T55xx_SAMPLES_SIZE )
		bufferlength= T55xx_SAMPLES_SIZE;

	// Clear destination buffer before sending the command
	memset(dest, 0x80, bufferlength);

	LFSetupFPGAForADC(0, true);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	SpinDelayUs(START_GAP);

	// Opcode
	T55xxWriteBit(1);
	T55xxWriteBit(1); //Page 1

	// Turn field on to read the response
	TurnReadLFOn();

	// Now do the acquisition
	for(;;) {
		if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
			AT91C_BASE_SSC->SSC_THR = 0x43;
			LED_D_ON();
		}
		if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
			dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
			i++;
			LED_D_OFF();

			if (i >= bufferlength) break;
		}
	}

	cmd_send(CMD_ACK,0,0,0,0,0);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
	LED_D_OFF();
}

/*-------------- Cloning routines -----------*/
// Copy HID id to card and setup block 0 config
void CopyHIDtoT55x7(uint32_t hi2, uint32_t hi, uint32_t lo, uint8_t longFMT)
{
	int data1=0, data2=0, data3=0, data4=0, data5=0, data6=0; //up to six blocks for long format
	int 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;
		data1 = 0x1D96A900; // load preamble (1D) & long format identifier (9E manchester encoded)
		for (int i=0;i<4;i++) {
			if (hi2 & (1<<(19-i)))
				data1 |= (1<<(((3-i)*2)+1)); // 1 -> 10
			else
				data1 |= (1<<((3-i)*2)); // 0 -> 01
		}

		data2 = 0;
		for (int i=0;i<16;i++) {
			if (hi2 & (1<<(15-i)))
				data2 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data2 |= (1<<((15-i)*2)); // 0 -> 01
		}

		data3 = 0;
		for (int i=0;i<16;i++) {
			if (hi & (1<<(31-i)))
				data3 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data3 |= (1<<((15-i)*2)); // 0 -> 01
		}

		data4 = 0;
		for (int i=0;i<16;i++) {
			if (hi & (1<<(15-i)))
				data4 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data4 |= (1<<((15-i)*2)); // 0 -> 01
		}

		data5 = 0;
		for (int i=0;i<16;i++) {
			if (lo & (1<<(31-i)))
				data5 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data5 |= (1<<((15-i)*2)); // 0 -> 01
		}

		data6 = 0;
		for (int i=0;i<16;i++) {
			if (lo & (1<<(15-i)))
				data6 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data6 |= (1<<((15-i)*2)); // 0 -> 01
		}
	}
	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;

		data1 = 0x1D000000; // load preamble

		for (int i=0;i<12;i++) {
			if (hi & (1<<(11-i)))
				data1 |= (1<<(((11-i)*2)+1)); // 1 -> 10
			else
				data1 |= (1<<((11-i)*2)); // 0 -> 01
		}

		data2 = 0;
		for (int i=0;i<16;i++) {
			if (lo & (1<<(31-i)))
				data2 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data2 |= (1<<((15-i)*2)); // 0 -> 01
		}

		data3 = 0;
		for (int i=0;i<16;i++) {
			if (lo & (1<<(15-i)))
				data3 |= (1<<(((15-i)*2)+1)); // 1 -> 10
			else
				data3 |= (1<<((15-i)*2)); // 0 -> 01
		}
	}

	LED_D_ON();
	// Program the data blocks for supplied ID
	// and the block 0 for HID format
	T55xxWriteBlock(data1,1,0,0);
	T55xxWriteBlock(data2,2,0,0);
	T55xxWriteBlock(data3,3,0,0);

	if (longFMT) { // if long format there are 6 blocks
		T55xxWriteBlock(data4,4,0,0);
		T55xxWriteBlock(data5,5,0,0);
		T55xxWriteBlock(data6,6,0,0);
	}

	// Config for HID (RF/50, FSK2a, Maxblock=3 for short/6 for long)
	T55xxWriteBlock(T55x7_BITRATE_RF_50    |
					T55x7_MODULATION_FSK2a |
					last_block << T55x7_MAXBLOCK_SHIFT,
					0,0,0);

	LED_D_OFF();

	DbpString("DONE!");
}

void CopyIOtoT55x7(uint32_t hi, uint32_t lo, uint8_t longFMT)
{
	int data1=0, data2=0; //up to six blocks for long format

	data1 = hi;  // load preamble
	data2 = lo;

	LED_D_ON();
	// Program the data blocks for supplied ID
	// and the block 0 for HID format
	T55xxWriteBlock(data1,1,0,0);
	T55xxWriteBlock(data2,2,0,0);

	//Config Block
	T55xxWriteBlock(0x00147040,0,0,0);
	LED_D_OFF();

	DbpString("DONE!");
}

// 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
	T55xxWriteBlock((uint32_t)(id >> 32), 1, 0, 0);
	T55xxWriteBlock((uint32_t)id, 2, 0, 0);

	// Config for EM410x (RF/64, Manchester, Maxblock=2)
	if (card) {
		// Clock rate is stored in bits 8-15 of the card value
		clock = (card & 0xFF00) >> 8;
		Dbprintf("Clock rate: %d", clock);
		switch (clock)
		{
		case 32:
			clock = T55x7_BITRATE_RF_32;
			break;
		case 16:
			clock = T55x7_BITRATE_RF_16;
			break;
		case 0:
			// A value of 0 is assumed to be 64 for backwards-compatibility
			// Fall through...
		case 64:
			clock = T55x7_BITRATE_RF_64;
			break;
		default:
			Dbprintf("Invalid clock rate: %d", clock);
			return;
		}

		// Writing configuration for T55x7 tag
		T55xxWriteBlock(clock	    |
						T55x7_MODULATION_MANCHESTER |
						2 << T55x7_MAXBLOCK_SHIFT,
						0, 0, 0);
	}
	else
		// Writing configuration for T5555(Q5) tag
		T55xxWriteBlock(0x1F << T5555_BITRATE_SHIFT |
						T5555_MODULATION_MANCHESTER |
						2 << T5555_MAXBLOCK_SHIFT,
						0, 0, 0);

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

// Clone Indala 64-bit tag by UID to T55x7
void CopyIndala64toT55x7(int hi, int lo)
{

	//Program the 2 data blocks for supplied 64bit UID
	// and the block 0 for Indala64 format
	T55xxWriteBlock(hi,1,0,0);
	T55xxWriteBlock(lo,2,0,0);
	//Config for Indala (RF/32;PSK1 with RF/2;Maxblock=2)
	T55xxWriteBlock(T55x7_BITRATE_RF_32    |
					T55x7_MODULATION_PSK1 |
					2 << T55x7_MAXBLOCK_SHIFT,
					0, 0, 0);
	//Alternative config for Indala (Extended mode;RF/32;PSK1 with RF/2;Maxblock=2;Inverse data)
	//	T5567WriteBlock(0x603E1042,0);

	DbpString("DONE!");

}

void CopyIndala224toT55x7(int uid1, int uid2, int uid3, int uid4, int uid5, int uid6, int uid7)
{

	//Program the 7 data blocks for supplied 224bit UID
	// and the block 0 for Indala224 format
	T55xxWriteBlock(uid1,1,0,0);
	T55xxWriteBlock(uid2,2,0,0);
	T55xxWriteBlock(uid3,3,0,0);
	T55xxWriteBlock(uid4,4,0,0);
	T55xxWriteBlock(uid5,5,0,0);
	T55xxWriteBlock(uid6,6,0,0);
	T55xxWriteBlock(uid7,7,0,0);
	//Config for Indala (RF/32;PSK1 with RF/2;Maxblock=7)
	T55xxWriteBlock(T55x7_BITRATE_RF_32    |
					T55x7_MODULATION_PSK1 |
					7 << T55x7_MAXBLOCK_SHIFT,
					0,0,0);
	//Alternative config for Indala (Extended mode;RF/32;PSK1 with RF/2;Maxblock=7;Inverse data)
	//	T5567WriteBlock(0x603E10E2,0);

	DbpString("DONE!");

}


#define abs(x) ( ((x)<0) ? -(x) : (x) )
#define max(x,y) ( x<y ? y:x)

int DemodPCF7931(uint8_t **outBlocks) {
	uint8_t BitStream[256];
	uint8_t Blocks[8][16];
	uint8_t *GraphBuffer = BigBuf_get_addr();
	int GraphTraceLen = BigBuf_max_traceLen();
	int i, j, lastval, bitidx, half_switch;
	int clock = 64;
	int tolerance = clock / 8;
	int pmc, block_done;
	int lc, warnings = 0;
	int num_blocks = 0;
	int lmin=128, lmax=128;
	uint8_t dir;

	LFSetupFPGAForADC(95, true);
	DoAcquisition_default(0, 0);


	lmin = 64;
	lmax = 192;

	i = 2;

	/* Find first local max/min */
	if(GraphBuffer[1] > GraphBuffer[0]) {
		while(i < GraphTraceLen) {
			if( !(GraphBuffer[i] > GraphBuffer[i-1]) && GraphBuffer[i] > lmax)
				break;
			i++;
		}
		dir = 0;
	}
	else {
		while(i < GraphTraceLen) {
			if( !(GraphBuffer[i] < GraphBuffer[i-1]) && GraphBuffer[i] < lmin)
				break;
			i++;
		}
		dir = 1;
	}

	lastval = i++;
	half_switch = 0;
	pmc = 0;
	block_done = 0;

	for (bitidx = 0; i < GraphTraceLen; i++)
	{
		if ( (GraphBuffer[i-1] > GraphBuffer[i] && dir == 1 && GraphBuffer[i] > lmax) || (GraphBuffer[i-1] < GraphBuffer[i] && dir == 0 && GraphBuffer[i] < lmin))
		{
			lc = i - lastval;
			lastval = i;

			// Switch depending on lc length:
			// Tolerance is 1/8 of clock rate (arbitrary)
			if (abs(lc-clock/4) < tolerance) {
				// 16T0
				if((i - pmc) == lc) { /* 16T0 was previous one */
					/* It's a PMC ! */
					i += (128+127+16+32+33+16)-1;
					lastval = i;
					pmc = 0;
					block_done = 1;
				}
				else {
					pmc = i;
				}
			} else if (abs(lc-clock/2) < tolerance) {
				// 32TO
				if((i - pmc) == lc) { /* 16T0 was previous one */
					/* It's a PMC ! */
					i += (128+127+16+32+33)-1;
					lastval = i;
					pmc = 0;
					block_done = 1;
				}
				else if(half_switch == 1) {
					BitStream[bitidx++] = 0;
					half_switch = 0;
				}
				else
					half_switch++;
			} else if (abs(lc-clock) < tolerance) {
				// 64TO
				BitStream[bitidx++] = 1;
			} else {
				// Error
				warnings++;
				if (warnings > 10)
				{
					Dbprintf("Error: too many detection errors, aborting.");
					return 0;
				}
			}

			if(block_done == 1) {
				if(bitidx == 128) {
					for(j=0; j<16; j++) {
						Blocks[num_blocks][j] = 128*BitStream[j*8+7]+
								64*BitStream[j*8+6]+
								32*BitStream[j*8+5]+
								16*BitStream[j*8+4]+
								8*BitStream[j*8+3]+
								4*BitStream[j*8+2]+
								2*BitStream[j*8+1]+
								BitStream[j*8];
					}
					num_blocks++;
				}
				bitidx = 0;
				block_done = 0;
				half_switch = 0;
			}
			if(i < GraphTraceLen)
			{
				if (GraphBuffer[i-1] > GraphBuffer[i]) dir=0;
				else dir = 1;
			}
		}
		if(bitidx==255)
			bitidx=0;
		warnings = 0;
		if(num_blocks == 4) break;
	}
	memcpy(outBlocks, Blocks, 16*num_blocks);
	return num_blocks;
}

int IsBlock0PCF7931(uint8_t *Block) {
	// Assume RFU means 0 :)
	if((memcmp(Block, "\x00\x00\x00\x00\x00\x00\x00\x01", 8) == 0) && memcmp(Block+9, "\x00\x00\x00\x00\x00\x00\x00", 7) == 0) // PAC enabled
		return 1;
	if((memcmp(Block+9, "\x00\x00\x00\x00\x00\x00\x00", 7) == 0) && Block[7] == 0) // PAC disabled, can it *really* happen ?
		return 1;
	return 0;
}

int IsBlock1PCF7931(uint8_t *Block) {
	// Assume RFU means 0 :)
	if(Block[10] == 0 && Block[11] == 0 && Block[12] == 0 && Block[13] == 0)
		if((Block[14] & 0x7f) <= 9 && Block[15] <= 9)
			return 1;

	return 0;
}

#define ALLOC 16

void ReadPCF7931() {
	uint8_t Blocks[8][17];
	uint8_t tmpBlocks[4][16];
	int i, j, ind, ind2, n;
	int num_blocks = 0;
	int max_blocks = 8;
	int ident = 0;
	int error = 0;
	int tries = 0;

	memset(Blocks, 0, 8*17*sizeof(uint8_t));

	do {
		memset(tmpBlocks, 0, 4*16*sizeof(uint8_t));
		n = DemodPCF7931((uint8_t**)tmpBlocks);
		if(!n)
			error++;
		if(error==10 && num_blocks == 0) {
			Dbprintf("Error, no tag or bad tag");
			return;
		}
		else if (tries==20 || error==10) {
			Dbprintf("Error reading the tag");
			Dbprintf("Here is the partial content");
			goto end;
		}

		for(i=0; i<n; i++)
			Dbprintf("(dbg) %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
					 tmpBlocks[i][0], tmpBlocks[i][1], tmpBlocks[i][2], tmpBlocks[i][3], tmpBlocks[i][4], tmpBlocks[i][5], tmpBlocks[i][6], tmpBlocks[i][7],
					tmpBlocks[i][8], tmpBlocks[i][9], tmpBlocks[i][10], tmpBlocks[i][11], tmpBlocks[i][12], tmpBlocks[i][13], tmpBlocks[i][14], tmpBlocks[i][15]);
		if(!ident) {
			for(i=0; i<n; i++) {
				if(IsBlock0PCF7931(tmpBlocks[i])) {
					// Found block 0 ?
					if(i < n-1 && IsBlock1PCF7931(tmpBlocks[i+1])) {
						// Found block 1!
						// \o/
						ident = 1;
						memcpy(Blocks[0], tmpBlocks[i], 16);
						Blocks[0][ALLOC] = 1;
						memcpy(Blocks[1], tmpBlocks[i+1], 16);
						Blocks[1][ALLOC] = 1;
						max_blocks = max((Blocks[1][14] & 0x7f), Blocks[1][15]) + 1;
						// Debug print
						Dbprintf("(dbg) Max blocks: %d", max_blocks);
						num_blocks = 2;
						// Handle following blocks
						for(j=i+2, ind2=2; j!=i; j++, ind2++, num_blocks++) {
							if(j==n) j=0;
							if(j==i) break;
							memcpy(Blocks[ind2], tmpBlocks[j], 16);
							Blocks[ind2][ALLOC] = 1;
						}
						break;
					}
				}
			}
		}
		else {
			for(i=0; i<n; i++) { // Look for identical block in known blocks
				if(memcmp(tmpBlocks[i], "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16)) { // Block is not full of 00
					for(j=0; j<max_blocks; j++) {
						if(Blocks[j][ALLOC] == 1 && !memcmp(tmpBlocks[i], Blocks[j], 16)) {
							// Found an identical block
							for(ind=i-1,ind2=j-1; ind >= 0; ind--,ind2--) {
								if(ind2 < 0)
									ind2 = max_blocks;
								if(!Blocks[ind2][ALLOC]) { // Block ind2 not already found
									// Dbprintf("Tmp %d -> Block %d", ind, ind2);
									memcpy(Blocks[ind2], tmpBlocks[ind], 16);
									Blocks[ind2][ALLOC] = 1;
									num_blocks++;
									if(num_blocks == max_blocks) goto end;
								}
							}
							for(ind=i+1,ind2=j+1; ind < n; ind++,ind2++) {
								if(ind2 > max_blocks)
									ind2 = 0;
								if(!Blocks[ind2][ALLOC]) { // Block ind2 not already found
									// Dbprintf("Tmp %d -> Block %d", ind, ind2);
									memcpy(Blocks[ind2], tmpBlocks[ind], 16);
									Blocks[ind2][ALLOC] = 1;
									num_blocks++;
									if(num_blocks == max_blocks) goto end;
								}
							}
						}
					}
				}
			}
		}
		tries++;
		if (BUTTON_PRESS()) return;
	} while (num_blocks != max_blocks);
 end:
	Dbprintf("-----------------------------------------");
	Dbprintf("Memory content:");
	Dbprintf("-----------------------------------------");
	for(i=0; i<max_blocks; i++) {
		if(Blocks[i][ALLOC]==1)
			Dbprintf("%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
					 Blocks[i][0], Blocks[i][1], Blocks[i][2], Blocks[i][3], Blocks[i][4], Blocks[i][5], Blocks[i][6], Blocks[i][7],
					Blocks[i][8], Blocks[i][9], Blocks[i][10], Blocks[i][11], Blocks[i][12], Blocks[i][13], Blocks[i][14], Blocks[i][15]);
		else
			Dbprintf("<missing block %d>", i);
	}
	Dbprintf("-----------------------------------------");

	return ;
}


//-----------------------------------
// 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
//====================================================================
//--------------------------------------------------------------------
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;

	LED_D_ON();

	//Field on
	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);

	// Give it a bit of time for the resonant antenna to settle.
	// And for the tag to fully power up
	SpinDelay(150);

	// 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
	SpinDelayUs(55*8); //55 cycles off (8us each)for 4305
	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
	SpinDelayUs(16*8); //16 cycles on (8us each)

	// now start writting
	while(fwd_bit_sz-- > 0) { //prepare next bit modulation
		if(((*fwd_write_ptr++) & 1) == 1)
			SpinDelayUs(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
			SpinDelayUs(23*8); //16-4 cycles off (8us each)
			FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
			FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
			SpinDelayUs(9*8); //16 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;
	uint8_t *dest = BigBuf_get_addr();
	int m=0, i=0;

	//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 );

	m = BigBuf_max_traceLen();
	// Clear destination buffer before sending the command
	memset(dest, 128, m);
	// 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();

	SendForward(fwd_bit_count);

	// Now do the acquisition
	i = 0;
	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) {
			dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
			i++;
			if (i >= m) break;
		}
	}
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
	LED_D_OFF();
}

void EM4xWriteWord(uint32_t Data, uint8_t Address, uint32_t Pwd, uint8_t PwdMode) {

	uint8_t fwd_bit_count;

	//If password mode do login
	if (PwdMode == 1) 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(20);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
	LED_D_OFF();
}