[proxmark3-svn] / armsrc / iclass.c

//-----------------------------------------------------------------------------
// Gerhard de Koning Gans - May 2008
// Hagen Fritsch - June 2010
// Gerhard de Koning Gans - May 2011
// Gerhard de Koning Gans - June 2012 - Added iClass card and reader emulation
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Routines to support iClass.
//-----------------------------------------------------------------------------
// Based on ISO14443a implementation. Still in experimental phase.
// Contribution made during a security research at Radboud University Nijmegen
// 
// Please feel free to contribute and extend iClass support!!
//-----------------------------------------------------------------------------
//
// FIX:
// ====
// We still have sometimes a demodulation error when snooping iClass communication.
// The resulting trace of a read-block-03 command may look something like this:
//
//  +  22279:    :     0c  03  e8  01    
//
//    ...with an incorrect answer...
//
//  +     85:   0: TAG ff! ff! ff! ff! ff! ff! ff! ff! bb  33  bb  00  01! 0e! 04! bb     !crc
//
// We still left the error signalling bytes in the traces like 0xbb
//
// A correct trace should look like this:
//
// +  21112:    :     0c  03  e8  01    
// +     85:   0: TAG ff  ff  ff  ff  ff  ff  ff  ff  ea  f5    
//
//-----------------------------------------------------------------------------

#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "string.h"
#include "common.h"
#include "cmd.h"
// Needed for CRC in emulation mode;
// same construction as in ISO 14443;
// different initial value (CRC_ICLASS)
#include "iso14443crc.h"
#include "iso15693tools.h"
#include "protocols.h"
#include "optimized_cipher.h"

static int timeout = 4096;


static int SendIClassAnswer(uint8_t *resp, int respLen, int delay);

//-----------------------------------------------------------------------------
// The software UART that receives commands from the reader, and its state
// variables.
//-----------------------------------------------------------------------------
static struct {
    enum {
        STATE_UNSYNCD,
        STATE_START_OF_COMMUNICATION,
	STATE_RECEIVING
    }       state;
    uint16_t    shiftReg;
    int     bitCnt;
    int     byteCnt;
    int     byteCntMax;
    int     posCnt;
    int     nOutOfCnt;
    int     OutOfCnt;
    int     syncBit;
    int     samples;
    int     highCnt;
    int     swapper;
    int     counter;
    int     bitBuffer;
    int     dropPosition;
    uint8_t *output;
} Uart;

static RAMFUNC int OutOfNDecoding(int bit)
{
	//int error = 0;
	int bitright;

	if(!Uart.bitBuffer) {
		Uart.bitBuffer = bit ^ 0xFF0;
		return FALSE;
	}
	else {
		Uart.bitBuffer <<= 4;
		Uart.bitBuffer ^= bit;
	}
	
	/*if(Uart.swapper) {
		Uart.output[Uart.byteCnt] = Uart.bitBuffer & 0xFF;
		Uart.byteCnt++;
		Uart.swapper = 0;
		if(Uart.byteCnt > 15) { return TRUE; }
	}
	else {
		Uart.swapper = 1;
	}*/

	if(Uart.state != STATE_UNSYNCD) {
		Uart.posCnt++;

		if((Uart.bitBuffer & Uart.syncBit) ^ Uart.syncBit) {
			bit = 0x00;
		}
		else {
			bit = 0x01;
		}
		if(((Uart.bitBuffer << 1) & Uart.syncBit) ^ Uart.syncBit) {
			bitright = 0x00;
		}
		else {
			bitright = 0x01;
		}
		if(bit != bitright) { bit = bitright; }

		
		// So, now we only have to deal with *bit*, lets see...
		if(Uart.posCnt == 1) {
			// measurement first half bitperiod
			if(!bit) {
				// Drop in first half means that we are either seeing
				// an SOF or an EOF.

				if(Uart.nOutOfCnt == 1) {
					// End of Communication
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
					if(Uart.byteCnt == 0) {
						// Its not straightforward to show single EOFs
						// So just leave it and do not return TRUE
						Uart.output[0] = 0xf0;
						Uart.byteCnt++;
					}
					else {
						return TRUE;
					}
				}
				else if(Uart.state != STATE_START_OF_COMMUNICATION) {
					// When not part of SOF or EOF, it is an error
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
					//error = 4;
				}
			}
		}
		else {
			// measurement second half bitperiod
			// Count the bitslot we are in... (ISO 15693)
			Uart.nOutOfCnt++;
			
			if(!bit) {
				if(Uart.dropPosition) {
					if(Uart.state == STATE_START_OF_COMMUNICATION) {
						//error = 1;
					}
					else {
						//error = 7;
					}
					// It is an error if we already have seen a drop in current frame
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
				}
				else {
					Uart.dropPosition = Uart.nOutOfCnt;
				}
			}

			Uart.posCnt = 0;

			
			if(Uart.nOutOfCnt == Uart.OutOfCnt && Uart.OutOfCnt == 4) {
				Uart.nOutOfCnt = 0;
				
				if(Uart.state == STATE_START_OF_COMMUNICATION) {
					if(Uart.dropPosition == 4) {
						Uart.state = STATE_RECEIVING;
						Uart.OutOfCnt = 256;
					}
					else if(Uart.dropPosition == 3) {
						Uart.state = STATE_RECEIVING;
						Uart.OutOfCnt = 4;
						//Uart.output[Uart.byteCnt] = 0xdd;
						//Uart.byteCnt++;
					}
					else {
						Uart.state = STATE_UNSYNCD;
						Uart.highCnt = 0;
					}
					Uart.dropPosition = 0;
				}
				else {
					// RECEIVING DATA
					// 1 out of 4
					if(!Uart.dropPosition) {
						Uart.state = STATE_UNSYNCD;
						Uart.highCnt = 0;
						//error = 9;
					}
					else {
						Uart.shiftReg >>= 2;
						
						// Swap bit order
						Uart.dropPosition--;
						//if(Uart.dropPosition == 1) { Uart.dropPosition = 2; }
						//else if(Uart.dropPosition == 2) { Uart.dropPosition = 1; }
						
						Uart.shiftReg ^= ((Uart.dropPosition & 0x03) << 6);
						Uart.bitCnt += 2;
						Uart.dropPosition = 0;

						if(Uart.bitCnt == 8) {
							Uart.output[Uart.byteCnt] = (Uart.shiftReg & 0xff);
							Uart.byteCnt++;
							Uart.bitCnt = 0;
							Uart.shiftReg = 0;
						}
					}
				}
			}
			else if(Uart.nOutOfCnt == Uart.OutOfCnt) {
				// RECEIVING DATA
				// 1 out of 256
				if(!Uart.dropPosition) {
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
					//error = 3;
				}
				else {
					Uart.dropPosition--;
					Uart.output[Uart.byteCnt] = (Uart.dropPosition & 0xff);
					Uart.byteCnt++;
					Uart.bitCnt = 0;
					Uart.shiftReg = 0;
					Uart.nOutOfCnt = 0;
					Uart.dropPosition = 0;
				}
			}

			/*if(error) {
				Uart.output[Uart.byteCnt] = 0xAA;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = error & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = 0xAA;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = (Uart.bitBuffer >> 8) & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = Uart.bitBuffer & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = (Uart.syncBit >> 3) & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = 0xAA;
				Uart.byteCnt++;
				return TRUE;
			}*/
		}

	}
	else {
		bit = Uart.bitBuffer & 0xf0;
		bit >>= 4;
		bit ^= 0x0F; // drops become 1s ;-)
		if(bit) {
			// should have been high or at least (4 * 128) / fc
			// according to ISO this should be at least (9 * 128 + 20) / fc
			if(Uart.highCnt == 8) {
				// we went low, so this could be start of communication
				// it turns out to be safer to choose a less significant
				// syncbit... so we check whether the neighbour also represents the drop
				Uart.posCnt = 1;   // apparently we are busy with our first half bit period
				Uart.syncBit = bit & 8;
				Uart.samples = 3;
				if(!Uart.syncBit)	{ Uart.syncBit = bit & 4; Uart.samples = 2; }
				else if(bit & 4)	{ Uart.syncBit = bit & 4; Uart.samples = 2; bit <<= 2; }
				if(!Uart.syncBit)	{ Uart.syncBit = bit & 2; Uart.samples = 1; }
				else if(bit & 2)	{ Uart.syncBit = bit & 2; Uart.samples = 1; bit <<= 1; }
				if(!Uart.syncBit)	{ Uart.syncBit = bit & 1; Uart.samples = 0;
					if(Uart.syncBit && (Uart.bitBuffer & 8)) {
						Uart.syncBit = 8;

						// the first half bit period is expected in next sample
						Uart.posCnt = 0;
						Uart.samples = 3;
					}
				}
				else if(bit & 1)	{ Uart.syncBit = bit & 1; Uart.samples = 0; }

				Uart.syncBit <<= 4;
				Uart.state = STATE_START_OF_COMMUNICATION;
				Uart.bitCnt = 0;
				Uart.byteCnt = 0;
				Uart.nOutOfCnt = 0;
				Uart.OutOfCnt = 4; // Start at 1/4, could switch to 1/256
				Uart.dropPosition = 0;
				Uart.shiftReg = 0;
				//error = 0;
			}
			else {
				Uart.highCnt = 0;
			}
		}
		else {
			if(Uart.highCnt < 8) {
				Uart.highCnt++;
			}
		}
	}

    return FALSE;
}

//=============================================================================
// Manchester
//=============================================================================

static struct {
    enum {
        DEMOD_UNSYNCD,
		DEMOD_START_OF_COMMUNICATION,
		DEMOD_START_OF_COMMUNICATION2,
		DEMOD_START_OF_COMMUNICATION3,
		DEMOD_SOF_COMPLETE,
		DEMOD_MANCHESTER_D,
		DEMOD_MANCHESTER_E,
		DEMOD_END_OF_COMMUNICATION,
		DEMOD_END_OF_COMMUNICATION2,
		DEMOD_MANCHESTER_F,
        DEMOD_ERROR_WAIT
    }       state;
    int     bitCount;
    int     posCount;
	int     syncBit;
    uint16_t    shiftReg;
	int     buffer;
	int     buffer2;
	int	buffer3;
	int     buff;
	int     samples;
    int     len;
	enum {
		SUB_NONE,
		SUB_FIRST_HALF,
		SUB_SECOND_HALF,
		SUB_BOTH
	}		sub;
    uint8_t *output;
} Demod;

static RAMFUNC int ManchesterDecoding(int v)
{
	int bit;
	int modulation;
	int error = 0;

	bit = Demod.buffer;
	Demod.buffer = Demod.buffer2;
	Demod.buffer2 = Demod.buffer3;
	Demod.buffer3 = v;

	if(Demod.buff < 3) {
		Demod.buff++;
		return FALSE;
	}

	if(Demod.state==DEMOD_UNSYNCD) {
		Demod.output[Demod.len] = 0xfa;
		Demod.syncBit = 0;
		//Demod.samples = 0;
		Demod.posCount = 1;		// This is the first half bit period, so after syncing handle the second part

		if(bit & 0x08) {
			Demod.syncBit = 0x08;
		}

		if(bit & 0x04) {
			if(Demod.syncBit) {
				bit <<= 4;
			}
			Demod.syncBit = 0x04;
		}

		if(bit & 0x02) {
			if(Demod.syncBit) {
				bit <<= 2;
			}
			Demod.syncBit = 0x02;
		}

		if(bit & 0x01 && Demod.syncBit) {
			Demod.syncBit = 0x01;
		}
		
		if(Demod.syncBit) {
			Demod.len = 0;
			Demod.state = DEMOD_START_OF_COMMUNICATION;
			Demod.sub = SUB_FIRST_HALF;
			Demod.bitCount = 0;
			Demod.shiftReg = 0;
			Demod.samples = 0;
			if(Demod.posCount) {
				//if(trigger) LED_A_OFF();  // Not useful in this case...
				switch(Demod.syncBit) {
					case 0x08: Demod.samples = 3; break;
					case 0x04: Demod.samples = 2; break;
					case 0x02: Demod.samples = 1; break;
					case 0x01: Demod.samples = 0; break;
				}
				// SOF must be long burst... otherwise stay unsynced!!!
				if(!(Demod.buffer & Demod.syncBit) || !(Demod.buffer2 & Demod.syncBit)) {
					Demod.state = DEMOD_UNSYNCD;
				}
			}
			else {
				// SOF must be long burst... otherwise stay unsynced!!!
				if(!(Demod.buffer2 & Demod.syncBit) || !(Demod.buffer3 & Demod.syncBit)) {
					Demod.state = DEMOD_UNSYNCD;
					error = 0x88;
				}

			}
			error = 0;

		}
	}
	else {
		modulation = bit & Demod.syncBit;
		modulation |= ((bit << 1) ^ ((Demod.buffer & 0x08) >> 3)) & Demod.syncBit;

		Demod.samples += 4;

		if(Demod.posCount==0) {
			Demod.posCount = 1;
			if(modulation) {
				Demod.sub = SUB_FIRST_HALF;
			}
			else {
				Demod.sub = SUB_NONE;
			}
		}
		else {
			Demod.posCount = 0;
			/*(modulation && (Demod.sub == SUB_FIRST_HALF)) {
				if(Demod.state!=DEMOD_ERROR_WAIT) {
					Demod.state = DEMOD_ERROR_WAIT;
					Demod.output[Demod.len] = 0xaa;
					error = 0x01;
				}
			}*/
			//else if(modulation) {
			if(modulation) {
				if(Demod.sub == SUB_FIRST_HALF) {
					Demod.sub = SUB_BOTH;
				}
				else {
					Demod.sub = SUB_SECOND_HALF;
				}
			}
			else if(Demod.sub == SUB_NONE) {
				if(Demod.state == DEMOD_SOF_COMPLETE) {
					Demod.output[Demod.len] = 0x0f;
					Demod.len++;
					Demod.state = DEMOD_UNSYNCD;
//					error = 0x0f;
					return TRUE;
				}
				else {
					Demod.state = DEMOD_ERROR_WAIT;
					error = 0x33;
				}
				/*if(Demod.state!=DEMOD_ERROR_WAIT) {
					Demod.state = DEMOD_ERROR_WAIT;
					Demod.output[Demod.len] = 0xaa;
					error = 0x01;
				}*/
			}

			switch(Demod.state) {
				case DEMOD_START_OF_COMMUNICATION:
					if(Demod.sub == SUB_BOTH) {
						//Demod.state = DEMOD_MANCHESTER_D;
						Demod.state = DEMOD_START_OF_COMMUNICATION2;
						Demod.posCount = 1;
						Demod.sub = SUB_NONE;
					}
					else {
						Demod.output[Demod.len] = 0xab;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0xd2;
					}
					break;
				case DEMOD_START_OF_COMMUNICATION2:
					if(Demod.sub == SUB_SECOND_HALF) {
						Demod.state = DEMOD_START_OF_COMMUNICATION3;
					}
					else {
						Demod.output[Demod.len] = 0xab;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0xd3;
					}
					break;
				case DEMOD_START_OF_COMMUNICATION3:
					if(Demod.sub == SUB_SECOND_HALF) {
//						Demod.state = DEMOD_MANCHESTER_D;
						Demod.state = DEMOD_SOF_COMPLETE;
						//Demod.output[Demod.len] = Demod.syncBit & 0xFF;
						//Demod.len++;
					}
					else {
						Demod.output[Demod.len] = 0xab;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0xd4;
					}
					break;
				case DEMOD_SOF_COMPLETE:
				case DEMOD_MANCHESTER_D:
				case DEMOD_MANCHESTER_E:
					// OPPOSITE FROM ISO14443 - 11110000 = 0 (1 in 14443)
					//                          00001111 = 1 (0 in 14443)
					if(Demod.sub == SUB_SECOND_HALF) { // SUB_FIRST_HALF
						Demod.bitCount++;
						Demod.shiftReg = (Demod.shiftReg >> 1) ^ 0x100;
						Demod.state = DEMOD_MANCHESTER_D;
					}
					else if(Demod.sub == SUB_FIRST_HALF) { // SUB_SECOND_HALF
						Demod.bitCount++;
						Demod.shiftReg >>= 1;
						Demod.state = DEMOD_MANCHESTER_E;
					}
					else if(Demod.sub == SUB_BOTH) {
						Demod.state = DEMOD_MANCHESTER_F;
					}
					else {
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0x55;
					}
					break;

				case DEMOD_MANCHESTER_F:
					// Tag response does not need to be a complete byte!
					if(Demod.len > 0 || Demod.bitCount > 0) {
						if(Demod.bitCount > 1) {  // was > 0, do not interpret last closing bit, is part of EOF
							Demod.shiftReg >>= (9 - Demod.bitCount);	// right align data
							Demod.output[Demod.len] = Demod.shiftReg & 0xff;
							Demod.len++;
						}

						Demod.state = DEMOD_UNSYNCD;
						return TRUE;
					}
					else {
						Demod.output[Demod.len] = 0xad;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0x03;
					}
					break;

				case DEMOD_ERROR_WAIT:
					Demod.state = DEMOD_UNSYNCD;
					break;

				default:
					Demod.output[Demod.len] = 0xdd;
					Demod.state = DEMOD_UNSYNCD;
					break;
			}

			/*if(Demod.bitCount>=9) {
				Demod.output[Demod.len] = Demod.shiftReg & 0xff;
				Demod.len++;

				Demod.parityBits <<= 1;
				Demod.parityBits ^= ((Demod.shiftReg >> 8) & 0x01);

				Demod.bitCount = 0;
				Demod.shiftReg = 0;
			}*/
			if(Demod.bitCount>=8) {
				Demod.shiftReg >>= 1;
				Demod.output[Demod.len] = (Demod.shiftReg & 0xff);
				Demod.len++;
				Demod.bitCount = 0;
				Demod.shiftReg = 0;
			}

			if(error) {
				Demod.output[Demod.len] = 0xBB;
				Demod.len++;
				Demod.output[Demod.len] = error & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = 0xBB;
				Demod.len++;
				Demod.output[Demod.len] = bit & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = Demod.buffer & 0xFF;
				Demod.len++;
				// Look harder ;-)
				Demod.output[Demod.len] = Demod.buffer2 & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = Demod.syncBit & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = 0xBB;
				Demod.len++;
				return TRUE;
			}

		}

	} // end (state != UNSYNCED)

    return FALSE;
}

//=============================================================================
// Finally, a `sniffer' for iClass communication
// Both sides of communication!
//=============================================================================

//-----------------------------------------------------------------------------
// Record the sequence of commands sent by the reader to the tag, with
// triggering so that we start recording at the point that the tag is moved
// near the reader.
//-----------------------------------------------------------------------------
void RAMFUNC SnoopIClass(void)
{


    // We won't start recording the frames that we acquire until we trigger;
    // a good trigger condition to get started is probably when we see a
    // response from the tag.
    //int triggered = FALSE; // FALSE to wait first for card

    // The command (reader -> tag) that we're receiving.
	// The length of a received command will in most cases be no more than 18 bytes.
	// So 32 should be enough!
	#define ICLASS_BUFFER_SIZE 32
	uint8_t readerToTagCmd[ICLASS_BUFFER_SIZE];
    // The response (tag -> reader) that we're receiving.
	uint8_t tagToReaderResponse[ICLASS_BUFFER_SIZE];
	
    FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
 	// free all BigBuf memory
	BigBuf_free();
    // The DMA buffer, used to stream samples from the FPGA
    uint8_t *dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);
 
	set_tracing(TRUE);
	clear_trace();
    iso14a_set_trigger(FALSE);

	int lastRxCounter;
    uint8_t *upTo;
    int smpl;
    int maxBehindBy = 0;

    // Count of samples received so far, so that we can include timing
    // information in the trace buffer.
    int samples = 0;
    rsamples = 0;

    // Set up the demodulator for tag -> reader responses.
	Demod.output = tagToReaderResponse;
    Demod.len = 0;
    Demod.state = DEMOD_UNSYNCD;

    // Setup for the DMA.
    FpgaSetupSsc();
    upTo = dmaBuf;
    lastRxCounter = DMA_BUFFER_SIZE;
    FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);

    // And the reader -> tag commands
    memset(&Uart, 0, sizeof(Uart));
	Uart.output = readerToTagCmd;
    Uart.byteCntMax = 32; // was 100 (greg)////////////////////////////////////////////////////////////////////////
    Uart.state = STATE_UNSYNCD;

    // And put the FPGA in the appropriate mode
    // Signal field is off with the appropriate LED
    LED_D_OFF();
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_SNIFFER);
    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

	uint32_t time_0 = GetCountSspClk();
	uint32_t time_start = 0;
	uint32_t time_stop  = 0;

    int div = 0;
    //int div2 = 0;
    int decbyte = 0;
    int decbyter = 0;

    // And now we loop, receiving samples.
    for(;;) {
        LED_A_ON();
        WDT_HIT();
        int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
                                (DMA_BUFFER_SIZE-1);
        if(behindBy > maxBehindBy) {
            maxBehindBy = behindBy;
            if(behindBy > (9 * DMA_BUFFER_SIZE / 10)) {
                Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
                goto done;
            }
        }
        if(behindBy < 1) continue;

	LED_A_OFF();
        smpl = upTo[0];
        upTo++;
        lastRxCounter -= 1;
        if(upTo - dmaBuf > DMA_BUFFER_SIZE) {
            upTo -= DMA_BUFFER_SIZE;
            lastRxCounter += DMA_BUFFER_SIZE;
            AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
            AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
        }

        //samples += 4;
	samples += 1;

	if(smpl & 0xF) {
		decbyte ^= (1 << (3 - div));
	}
	
	// FOR READER SIDE COMMUMICATION...

	decbyter <<= 2;
	decbyter ^= (smpl & 0x30);

	div++;
	
	if((div + 1) % 2 == 0) {
		smpl = decbyter;	
		if(OutOfNDecoding((smpl & 0xF0) >> 4)) {
		    rsamples = samples - Uart.samples;
			time_stop = (GetCountSspClk()-time_0) << 4;
		    LED_C_ON();

			//if(!LogTrace(Uart.output,Uart.byteCnt, rsamples, Uart.parityBits,TRUE)) break;
			//if(!LogTrace(NULL, 0, Uart.endTime*16 - DELAY_READER_AIR2ARM_AS_SNIFFER, 0, TRUE)) break;
			if(tracing)	{
				uint8_t parity[MAX_PARITY_SIZE];
				GetParity(Uart.output, Uart.byteCnt, parity);
				LogTrace(Uart.output,Uart.byteCnt, time_start, time_stop, parity, TRUE);
			}


			/* And ready to receive another command. */
		    Uart.state = STATE_UNSYNCD;
		    /* And also reset the demod code, which might have been */
		    /* false-triggered by the commands from the reader. */
		    Demod.state = DEMOD_UNSYNCD;
		    LED_B_OFF();
		    Uart.byteCnt = 0;
		}else{
			time_start = (GetCountSspClk()-time_0) << 4;
		}
		decbyter = 0;
	}

	if(div > 3) {
		smpl = decbyte;
		if(ManchesterDecoding(smpl & 0x0F)) {
			time_stop = (GetCountSspClk()-time_0) << 4;

			rsamples = samples - Demod.samples;
		    LED_B_ON();

			if(tracing)	{
				uint8_t parity[MAX_PARITY_SIZE];
				GetParity(Demod.output, Demod.len, parity);
				LogTrace(Demod.output, Demod.len, time_start, time_stop, parity, FALSE);
			}

		    // And ready to receive another response.
		    memset(&Demod, 0, sizeof(Demod));
			Demod.output = tagToReaderResponse;
		    Demod.state = DEMOD_UNSYNCD;
		    LED_C_OFF();
		}else{
			time_start = (GetCountSspClk()-time_0) << 4;
		}
		
		div = 0;
		decbyte = 0x00;
	}
	//}

        if(BUTTON_PRESS()) {
            DbpString("cancelled_a");
            goto done;
        }
    }

    DbpString("COMMAND FINISHED");

    Dbprintf("%x %x %x", maxBehindBy, Uart.state, Uart.byteCnt);
	Dbprintf("%x %x %x", Uart.byteCntMax, BigBuf_get_traceLen(), (int)Uart.output[0]);

done:
    AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
    Dbprintf("%x %x %x", maxBehindBy, Uart.state, Uart.byteCnt);
	Dbprintf("%x %x %x", Uart.byteCntMax, BigBuf_get_traceLen(), (int)Uart.output[0]);
    LED_A_OFF();
    LED_B_OFF();
    LED_C_OFF();
    LED_D_OFF();
}

void rotateCSN(uint8_t* originalCSN, uint8_t* rotatedCSN) {
	int i; 
	for(i = 0; i < 8; i++) {
		rotatedCSN[i] = (originalCSN[i] >> 3) | (originalCSN[(i+1)%8] << 5);
	}
}

//-----------------------------------------------------------------------------
// Wait for commands from reader
// Stop when button is pressed
// Or return TRUE when command is captured
//-----------------------------------------------------------------------------
static int GetIClassCommandFromReader(uint8_t *received, int *len, int maxLen)
{
    // Set FPGA mode to "simulated ISO 14443 tag", no modulation (listen
    // only, since we are receiving, not transmitting).
    // Signal field is off with the appropriate LED
    LED_D_OFF();
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);

    // Now run a `software UART' on the stream of incoming samples.
    Uart.output = received;
    Uart.byteCntMax = maxLen;
    Uart.state = STATE_UNSYNCD;

    for(;;) {
        WDT_HIT();

        if(BUTTON_PRESS()) return FALSE;

        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
            AT91C_BASE_SSC->SSC_THR = 0x00;
        }
        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
            uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;

			if(OutOfNDecoding(b & 0x0f)) {
				*len = Uart.byteCnt;
				return TRUE;
			}
        }
    }
}

static uint8_t encode4Bits(const uint8_t b)
{
	uint8_t c = b & 0xF;
	// OTA, the least significant bits first
	//         The columns are
	//               1 - Bit value to send
	//               2 - Reversed (big-endian)
	//               3 - Encoded
	//               4 - Hex values

	switch(c){
	//                          1       2         3         4
	  case 15: return 0x55; // 1111 -> 1111 -> 01010101 -> 0x55
	  case 14: return 0x95; // 1110 -> 0111 -> 10010101 -> 0x95
	  case 13: return 0x65; // 1101 -> 1011 -> 01100101 -> 0x65
	  case 12: return 0xa5; // 1100 -> 0011 -> 10100101 -> 0xa5
	  case 11: return 0x59; // 1011 -> 1101 -> 01011001 -> 0x59
	  case 10: return 0x99; // 1010 -> 0101 -> 10011001 -> 0x99
	  case 9:  return 0x69; // 1001 -> 1001 -> 01101001 -> 0x69
	  case 8:  return 0xa9; // 1000 -> 0001 -> 10101001 -> 0xa9
	  case 7:  return 0x56; // 0111 -> 1110 -> 01010110 -> 0x56
	  case 6:  return 0x96; // 0110 -> 0110 -> 10010110 -> 0x96
	  case 5:  return 0x66; // 0101 -> 1010 -> 01100110 -> 0x66
	  case 4:  return 0xa6; // 0100 -> 0010 -> 10100110 -> 0xa6
	  case 3:  return 0x5a; // 0011 -> 1100 -> 01011010 -> 0x5a
	  case 2:  return 0x9a; // 0010 -> 0100 -> 10011010 -> 0x9a
	  case 1:  return 0x6a; // 0001 -> 1000 -> 01101010 -> 0x6a
	  default: return 0xaa; // 0000 -> 0000 -> 10101010 -> 0xaa

	}
}

//-----------------------------------------------------------------------------
// Prepare tag messages
//-----------------------------------------------------------------------------
static void CodeIClassTagAnswer(const uint8_t *cmd, int len)
{

	/*
	 * SOF comprises 3 parts;
	 * * An unmodulated time of 56.64 us
	 * * 24 pulses of 423.75 KHz (fc/32)
	 * * A logic 1, which starts with an unmodulated time of 18.88us
	 *   followed by 8 pulses of 423.75kHz (fc/32)
	 *
	 *
	 * EOF comprises 3 parts:
	 * - A logic 0 (which starts with 8 pulses of fc/32 followed by an unmodulated
	 *   time of 18.88us.
	 * - 24 pulses of fc/32
	 * - An unmodulated time of 56.64 us
	 *
	 *
	 * A logic 0 starts with 8 pulses of fc/32
	 * followed by an unmodulated time of 256/fc (~18,88us).
	 *
	 * A logic 0 starts with unmodulated time of 256/fc (~18,88us) followed by
	 * 8 pulses of fc/32 (also 18.88us)
	 *
	 * The mode FPGA_HF_SIMULATOR_MODULATE_424K_8BIT which we use to simulate tag,
	 * works like this.
	 * - A 1-bit input to the FPGA becomes 8 pulses on 423.5kHz (fc/32) (18.88us).
	 * - A 0-bit inptu to the FPGA becomes an unmodulated time of 18.88us
	 *
	 * In this mode the SOF can be written as 00011101 = 0x1D
	 * The EOF can be written as 10111000 = 0xb8
	 * A logic 1 is 01
	 * A logic 0 is 10
	 *
	 * */

	int i;

	ToSendReset();

	// Send SOF
	ToSend[++ToSendMax] = 0x1D;

	for(i = 0; i < len; i++) {
		uint8_t b = cmd[i];
		ToSend[++ToSendMax] = encode4Bits(b & 0xF); //Least significant half
		ToSend[++ToSendMax] = encode4Bits((b >>4) & 0xF);//Most significant half
	}

	// Send EOF
	ToSend[++ToSendMax] = 0xB8;
	//lastProxToAirDuration  = 8*ToSendMax - 3*8 - 3*8;//Not counting zeroes in the beginning or end
	// Convert from last byte pos to length
	ToSendMax++;
}

// Only SOF 
static void CodeIClassTagSOF()
{
	//So far a dummy implementation, not used
	//int lastProxToAirDuration =0;

	ToSendReset();
	// Send SOF
	ToSend[++ToSendMax] = 0x1D;
//	lastProxToAirDuration  = 8*ToSendMax - 3*8;//Not counting zeroes in the beginning

	// Convert from last byte pos to length
	ToSendMax++;
}
#define MODE_SIM_CSN        0
#define MODE_EXIT_AFTER_MAC 1
#define MODE_FULLSIM        2

int doIClassSimulation(int simulationMode, uint8_t *reader_mac_buf);
/**
 * @brief SimulateIClass simulates an iClass card.
 * @param arg0 type of simulation
 *			- 0 uses the first 8 bytes in usb data as CSN
 *			- 2 "dismantling iclass"-attack. This mode iterates through all CSN's specified
 *			in the usb data. This mode collects MAC from the reader, in order to do an offline
 *			attack on the keys. For more info, see "dismantling iclass" and proxclone.com.
 *			- Other : Uses the default CSN (031fec8af7ff12e0)
 * @param arg1 - number of CSN's contained in datain (applicable for mode 2 only)
 * @param arg2
 * @param datain
 */
void SimulateIClass(uint32_t arg0, uint32_t arg1, uint32_t arg2, uint8_t *datain)
{
	uint32_t simType = arg0;
	uint32_t numberOfCSNS = arg1;
	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);

	// Enable and clear the trace
	set_tracing(TRUE);
	clear_trace();
	//Use the emulator memory for SIM
	uint8_t *emulator = BigBuf_get_EM_addr();

	if(simType == 0) {
		// Use the CSN from commandline
		memcpy(emulator, datain, 8);
		doIClassSimulation(MODE_SIM_CSN,NULL);
	}else if(simType == 1)
	{
		//Default CSN
		uint8_t csn_crc[] = { 0x03, 0x1f, 0xec, 0x8a, 0xf7, 0xff, 0x12, 0xe0, 0x00, 0x00 };
		// Use the CSN from commandline
		memcpy(emulator, csn_crc, 8);
		doIClassSimulation(MODE_SIM_CSN,NULL);
	}
	else if(simType == 2)
	{

		uint8_t mac_responses[USB_CMD_DATA_SIZE] = { 0 };
		Dbprintf("Going into attack mode, %d CSNS sent", numberOfCSNS);
		// In this mode, a number of csns are within datain. We'll simulate each one, one at a time
		// in order to collect MAC's from the reader. This can later be used in an offlne-attack
		// in order to obtain the keys, as in the "dismantling iclass"-paper.
		int i = 0;
		for( ; i < numberOfCSNS && i*8+8 < USB_CMD_DATA_SIZE; i++)
		{
			// The usb data is 512 bytes, fitting 65 8-byte CSNs in there.

			memcpy(emulator, datain+(i*8), 8);
			if(doIClassSimulation(MODE_EXIT_AFTER_MAC,mac_responses+i*8))
			{
				cmd_send(CMD_ACK,CMD_SIMULATE_TAG_ICLASS,i,0,mac_responses,i*8);
				return; // Button pressed
			}
		}
		cmd_send(CMD_ACK,CMD_SIMULATE_TAG_ICLASS,i,0,mac_responses,i*8);

	}else if(simType == 3){
		//This is 'full sim' mode, where we use the emulator storage for data.
		doIClassSimulation(MODE_FULLSIM, NULL);
	}
	else{
		// We may want a mode here where we hardcode the csns to use (from proxclone).
		// That will speed things up a little, but not required just yet.
		Dbprintf("The mode is not implemented, reserved for future use");
	}
	Dbprintf("Done...");

}

/**
 * @brief Does the actual simulation
 * @param csn - csn to use
 * @param breakAfterMacReceived if true, returns after reader MAC has been received.
 */
int doIClassSimulation( int simulationMode, uint8_t *reader_mac_buf)
{
	// free eventually allocated BigBuf memory
	BigBuf_free_keep_EM();

	State cipher_state;
//	State cipher_state_reserve;
	uint8_t *csn = BigBuf_get_EM_addr();
	uint8_t *emulator = csn;
	uint8_t sof_data[] = { 0x0F} ;
	// CSN followed by two CRC bytes
	uint8_t anticoll_data[10] = { 0 };
	uint8_t csn_data[10] = { 0 };
	memcpy(csn_data,csn,sizeof(csn_data));
	Dbprintf("Simulating CSN %02x%02x%02x%02x%02x%02x%02x%02x",csn[0],csn[1],csn[2],csn[3],csn[4],csn[5],csn[6],csn[7]);

	// Construct anticollision-CSN
	rotateCSN(csn_data,anticoll_data);

	// Compute CRC on both CSNs
	ComputeCrc14443(CRC_ICLASS, anticoll_data, 8, &anticoll_data[8], &anticoll_data[9]);
	ComputeCrc14443(CRC_ICLASS, csn_data, 8, &csn_data[8], &csn_data[9]);

	//The diversified key should be stored on block 3
	uint8_t diversified_key[8] = { 0 };
	//Get the diversified key from emulator memory
	memcpy(diversified_key, emulator+(8*3),8);
	// e-Purse
	uint8_t card_challenge_data[8] = { 0x00 };
	if(simulationMode == MODE_FULLSIM)
	{
		//Card challenge, a.k.a e-purse is on block 2
		memcpy(card_challenge_data,emulator + (8 * 2) , 8);
		//Precalculate the cipher state, feeding it the CC
		opt_doTagMAC_1(card_challenge_data,diversified_key);
	}

	int exitLoop = 0;
	// Reader 0a
	// Tag    0f
	// Reader 0c
	// Tag    anticoll. CSN
	// Reader 81 anticoll. CSN
	// Tag    CSN

	uint8_t *modulated_response;
	int modulated_response_size = 0;
	uint8_t* trace_data = NULL;
	int trace_data_size = 0;


	// Respond SOF -- takes 1 bytes
	uint8_t *resp_sof = BigBuf_malloc(2);
	int resp_sof_Len;

	// Anticollision CSN (rotated CSN)
	// 22: Takes 2 bytes for SOF/EOF and 10 * 2 = 20 bytes (2 bytes/byte)
	uint8_t *resp_anticoll = BigBuf_malloc(28);
	int resp_anticoll_len;

	// CSN
	// 22: Takes 2 bytes for SOF/EOF and 10 * 2 = 20 bytes (2 bytes/byte)
	uint8_t *resp_csn = BigBuf_malloc(30);
	int resp_csn_len;

	// e-Purse
	// 18: Takes 2 bytes for SOF/EOF and 8 * 2 = 16 bytes (2 bytes/bit)
	uint8_t *resp_cc = BigBuf_malloc(20);
	int resp_cc_len;

	uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
	memset(receivedCmd, 0x44, MAX_FRAME_SIZE);
	int len;

	// Prepare card messages
	ToSendMax = 0;

	// First card answer: SOF
	CodeIClassTagSOF();
	memcpy(resp_sof, ToSend, ToSendMax); resp_sof_Len = ToSendMax;

	// Anticollision CSN
	CodeIClassTagAnswer(anticoll_data, sizeof(anticoll_data));
	memcpy(resp_anticoll, ToSend, ToSendMax); resp_anticoll_len = ToSendMax;

	// CSN
	CodeIClassTagAnswer(csn_data, sizeof(csn_data));
	memcpy(resp_csn, ToSend, ToSendMax); resp_csn_len = ToSendMax;

	// e-Purse
	CodeIClassTagAnswer(card_challenge_data, sizeof(card_challenge_data));
	memcpy(resp_cc, ToSend, ToSendMax); resp_cc_len = ToSendMax;

	//This is used for responding to READ-block commands or other data which is dynamically generated
	uint8_t *data_response = BigBuf_malloc(8 * 2 + 2);
	//This is used for responding to READ-block commands or other data which is dynamically generated
	uint8_t *data_generic_trace = BigBuf_malloc(8 * 2 + 2);

	// Start from off (no field generated)
	//FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	//SpinDelay(200);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);
	SpinDelay(100);
	StartCountSspClk();
	// We need to listen to the high-frequency, peak-detected path.
	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
	FpgaSetupSsc();

	// To control where we are in the protocol
	int cmdsRecvd = 0;
	uint32_t time_0 = GetCountSspClk();
	uint32_t t2r_time =0;
	uint32_t r2t_time =0;

	LED_A_ON();
	bool buttonPressed = false;

	while(!exitLoop) {

		LED_B_OFF();
		//Signal tracer
		// Can be used to get a trigger for an oscilloscope..
		LED_C_OFF();

		if(!GetIClassCommandFromReader(receivedCmd, &len, 100)) {
			buttonPressed = true;
			break;
		}
		r2t_time = GetCountSspClk();
		//Signal tracer
		LED_C_ON();

		// Okay, look at the command now.
		if(receivedCmd[0] == ICLASS_CMD_ACTALL ) {
			// Reader in anticollission phase
			modulated_response = resp_sof; modulated_response_size = resp_sof_Len; //order = 1;
			trace_data = sof_data;
			trace_data_size = sizeof(sof_data);
		} else if(receivedCmd[0] == ICLASS_CMD_READ_OR_IDENTIFY && len == 1) {
			// Reader asks for anticollission CSN
			modulated_response = resp_anticoll; modulated_response_size = resp_anticoll_len; //order = 2;
			trace_data = anticoll_data;
			trace_data_size = sizeof(anticoll_data);
			//DbpString("Reader requests anticollission CSN:");
		} else if(receivedCmd[0] == ICLASS_CMD_SELECT) {
			// Reader selects anticollission CSN.
			// Tag sends the corresponding real CSN
			modulated_response = resp_csn; modulated_response_size = resp_csn_len; //order = 3;
			trace_data = csn_data;
			trace_data_size = sizeof(csn_data);
			//DbpString("Reader selects anticollission CSN:");
		} else if(receivedCmd[0] == ICLASS_CMD_READCHECK_KD) {
			// Read e-purse (88 02)
			modulated_response = resp_cc; modulated_response_size = resp_cc_len; //order = 4;
			trace_data = card_challenge_data;
			trace_data_size = sizeof(card_challenge_data);
			LED_B_ON();
		} else if(receivedCmd[0] == ICLASS_CMD_CHECK) {
			// Reader random and reader MAC!!!
			if(simulationMode == MODE_FULLSIM)
			{
				//NR, from reader, is in receivedCmd +1
				opt_doTagMAC_2(cipher_state,receivedCmd+1,data_generic_trace,diversified_key);

				trace_data = data_generic_trace;
				trace_data_size = 4;
				CodeIClassTagAnswer(trace_data , trace_data_size);
				memcpy(data_response, ToSend, ToSendMax);
				modulated_response = data_response;
				modulated_response_size = ToSendMax;
				//exitLoop = true;
			}else
			{	//Not fullsim, we don't respond
				// We do not know what to answer, so lets keep quiet
				modulated_response = resp_sof; modulated_response_size = 0;
				trace_data = NULL;
				trace_data_size = 0;
				if (simulationMode == MODE_EXIT_AFTER_MAC){
					// dbprintf:ing ...
					Dbprintf("CSN: %02x %02x %02x %02x %02x %02x %02x %02x"
							   ,csn[0],csn[1],csn[2],csn[3],csn[4],csn[5],csn[6],csn[7]);
					Dbprintf("RDR:  (len=%02d): %02x %02x %02x %02x %02x %02x %02x %02x %02x",len,
							receivedCmd[0], receivedCmd[1], receivedCmd[2],
							receivedCmd[3], receivedCmd[4], receivedCmd[5],
							receivedCmd[6], receivedCmd[7], receivedCmd[8]);
					if (reader_mac_buf != NULL)
					{
						memcpy(reader_mac_buf,receivedCmd+1,8);
					}
					exitLoop = true;
				}
			}

		} else if(receivedCmd[0] == ICLASS_CMD_HALT && len == 1) {
			// Reader ends the session
			modulated_response = resp_sof; modulated_response_size = 0; //order = 0;
			trace_data = NULL;
			trace_data_size = 0;
		} else if(simulationMode == MODE_FULLSIM && receivedCmd[0] == ICLASS_CMD_READ_OR_IDENTIFY && len == 4){
			//Read block
			uint16_t blk = receivedCmd[1];
			trace_data = emulator+(blk << 3);
			trace_data_size = 8;
			CodeIClassTagAnswer(trace_data , trace_data_size);
			memcpy(data_response, ToSend, ToSendMax);
			modulated_response = data_response;
			modulated_response_size = ToSendMax;
		}
		else if(receivedCmd[0] == ICLASS_CMD_PAGESEL)
		{//Pagesel
			//Pagesel enables to select a page in the selected chip memory and return its configuration block
			//Chips with a single page will not answer to this command
			// It appears we're fine ignoring this.
			//Otherwise, we should answer 8bytes (block) + 2bytes CRC
		}
		else {
			//#db# Unknown command received from reader (len=5): 26 1 0 f6 a 44 44 44 44
			// Never seen this command before
			Dbprintf("Unknown command received from reader (len=%d): %x %x %x %x %x %x %x %x %x",
			len,
			receivedCmd[0], receivedCmd[1], receivedCmd[2],
			receivedCmd[3], receivedCmd[4], receivedCmd[5],
			receivedCmd[6], receivedCmd[7], receivedCmd[8]);
			// Do not respond
			modulated_response = resp_sof; modulated_response_size = 0; //order = 0;
			trace_data = NULL;
			trace_data_size = 0;
		}

		if(cmdsRecvd >  100) {
			//DbpString("100 commands later...");
			//break;
		}
		else {
			cmdsRecvd++;
		}
		/**
		A legit tag has about 380us delay between reader EOT and tag SOF.
		**/
		if(modulated_response_size > 0) {
			SendIClassAnswer(modulated_response, modulated_response_size, 1);
			t2r_time = GetCountSspClk();
		}

		if (tracing) {
			uint8_t parity[MAX_PARITY_SIZE];
			GetParity(receivedCmd, len, parity);
			LogTrace(receivedCmd,len, (r2t_time-time_0)<< 4, (r2t_time-time_0) << 4, parity, TRUE);

			if (trace_data != NULL) {
				GetParity(trace_data, trace_data_size, parity);
				LogTrace(trace_data, trace_data_size, (t2r_time-time_0) << 4, (t2r_time-time_0) << 4, parity, FALSE);
			}
			if(!tracing) {
				DbpString("Trace full");
				//break;
			}

		}
		memset(receivedCmd, 0x44, MAX_FRAME_SIZE);
	}

	//Dbprintf("%x", cmdsRecvd);
	LED_A_OFF();
	LED_B_OFF();
	LED_C_OFF();

	if(buttonPressed)
	{
		DbpString("Button pressed");
	}
	return buttonPressed;
}

static int SendIClassAnswer(uint8_t *resp, int respLen, int delay)
{
	int i = 0, d=0;//, u = 0, d = 0;
	uint8_t b = 0;

	//FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR|FPGA_HF_SIMULATOR_MODULATE_424K);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR|FPGA_HF_SIMULATOR_MODULATE_424K_8BIT);

	AT91C_BASE_SSC->SSC_THR = 0x00;
	FpgaSetupSsc();
	while(!BUTTON_PRESS()) {
		if((AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)){
			b = AT91C_BASE_SSC->SSC_RHR; (void) b;
		}
		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)){
			b = 0x00;
			if(d < delay) {
				d++;
			}
			else {
				if( i < respLen){
					b = resp[i];
					//Hack
					//b = 0xAC;
				}
				i++;
			}
			AT91C_BASE_SSC->SSC_THR = b;
		}

//		if (i > respLen +4) break;
		if (i > respLen +1) break;
	}

	return 0;
}

/// THE READER CODE

//-----------------------------------------------------------------------------
// Transmit the command (to the tag) that was placed in ToSend[].
//-----------------------------------------------------------------------------
static void TransmitIClassCommand(const uint8_t *cmd, int len, int *samples, int *wait)
{
  int c;
  FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
  AT91C_BASE_SSC->SSC_THR = 0x00;
  FpgaSetupSsc();

   if (wait)
   {
     if(*wait < 10) *wait = 10;
     
     for(c = 0; c < *wait;) {
       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
         AT91C_BASE_SSC->SSC_THR = 0x00;		// For exact timing!
         c++;
       }
       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
         volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
         (void)r;
       }
       WDT_HIT();
     }

   }


  uint8_t sendbyte;
  bool firstpart = TRUE;
  c = 0;
  for(;;) {
    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {

      // DOUBLE THE SAMPLES!
      if(firstpart) {
	sendbyte = (cmd[c] & 0xf0) | (cmd[c] >> 4); 
      }
      else {
	sendbyte = (cmd[c] & 0x0f) | (cmd[c] << 4);
        c++;
      }
      if(sendbyte == 0xff) {
	sendbyte = 0xfe;
      }
      AT91C_BASE_SSC->SSC_THR = sendbyte;
      firstpart = !firstpart;

      if(c >= len) {
        break;
      }
    }
    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
      volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
      (void)r;
    }
    WDT_HIT();
  }
  if (samples) *samples = (c + *wait) << 3;
}


//-----------------------------------------------------------------------------
// Prepare iClass reader command to send to FPGA
//-----------------------------------------------------------------------------
void CodeIClassCommand(const uint8_t * cmd, int len)
{
  int i, j, k;
  uint8_t b;

  ToSendReset();

  // Start of Communication: 1 out of 4
  ToSend[++ToSendMax] = 0xf0;
  ToSend[++ToSendMax] = 0x00;
  ToSend[++ToSendMax] = 0x0f;
  ToSend[++ToSendMax] = 0x00;

  // Modulate the bytes 
  for (i = 0; i < len; i++) {
    b = cmd[i];
    for(j = 0; j < 4; j++) {
      for(k = 0; k < 4; k++) {
			if(k == (b & 3)) {
				ToSend[++ToSendMax] = 0x0f;
			}
			else {
				ToSend[++ToSendMax] = 0x00;
			}
      }
      b >>= 2;
    }
  }

  // End of Communication
  ToSend[++ToSendMax] = 0x00;
  ToSend[++ToSendMax] = 0x00;
  ToSend[++ToSendMax] = 0xf0;
  ToSend[++ToSendMax] = 0x00;

  // Convert from last character reference to length
  ToSendMax++;
}

void ReaderTransmitIClass(uint8_t* frame, int len)
{
	int wait = 0;
	int samples = 0;

	// This is tied to other size changes
	CodeIClassCommand(frame,len);

	// Select the card
	TransmitIClassCommand(ToSend, ToSendMax, &samples, &wait);
	if(trigger)
		LED_A_ON();

	// Store reader command in buffer
	if (tracing) {
		uint8_t par[MAX_PARITY_SIZE];
		GetParity(frame, len, par);
		LogTrace(frame, len, rsamples, rsamples, par, TRUE);
	}
}

//-----------------------------------------------------------------------------
// Wait a certain time for tag response
//  If a response is captured return TRUE
//  If it takes too long return FALSE
//-----------------------------------------------------------------------------
static int GetIClassAnswer(uint8_t *receivedResponse, int maxLen, int *samples, int *elapsed) //uint8_t *buffer
{
	// buffer needs to be 512 bytes
	int c;

	// Set FPGA mode to "reader listen mode", no modulation (listen
	// only, since we are receiving, not transmitting).
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_LISTEN);

	// Now get the answer from the card
	Demod.output = receivedResponse;
	Demod.len = 0;
	Demod.state = DEMOD_UNSYNCD;

	uint8_t b;
	if (elapsed) *elapsed = 0;

	bool skip = FALSE;

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

	        if(BUTTON_PRESS()) return FALSE;

		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
			AT91C_BASE_SSC->SSC_THR = 0x00;  // To make use of exact timing of next command from reader!!
			if (elapsed) (*elapsed)++;
		}
		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
			if(c < timeout) { c++; } else { return FALSE; }
			b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
			skip = !skip;
			if(skip) continue;
		
			if(ManchesterDecoding(b & 0x0f)) {
				*samples = c << 3;
				return  TRUE;
			}
		}
	}
}

int ReaderReceiveIClass(uint8_t* receivedAnswer)
{
  int samples = 0;
  if (!GetIClassAnswer(receivedAnswer,160,&samples,0)) return FALSE;
  rsamples += samples;
  if (tracing) {
	uint8_t parity[MAX_PARITY_SIZE];
	GetParity(receivedAnswer, Demod.len, parity);
	LogTrace(receivedAnswer,Demod.len,rsamples,rsamples,parity,FALSE);
  }
  if(samples == 0) return FALSE;
  return Demod.len;
}

void setupIclassReader()
{
    FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
    // Reset trace buffer
	set_tracing(TRUE);
	clear_trace();

    // Setup SSC
    FpgaSetupSsc();
    // Start from off (no field generated)
    // Signal field is off with the appropriate LED
    LED_D_OFF();
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    SpinDelay(200);

    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

    // Now give it time to spin up.
    // Signal field is on with the appropriate LED
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
    SpinDelay(200);
    LED_A_ON();

}

size_t sendCmdGetResponseWithRetries(uint8_t* command, size_t cmdsize, uint8_t* resp, uint8_t expected_size, uint8_t retries)
{
	while(retries-- > 0)
	{
		ReaderTransmitIClass(command, cmdsize);
		if(expected_size == ReaderReceiveIClass(resp)){
			return 0;
		}
	}
	return 1;//Error
}

/**
 * @brief Talks to an iclass tag, sends the commands to get CSN and CC.
 * @param card_data where the CSN and CC are stored for return
 * @return 0 = fail
 *         1 = Got CSN
 *         2 = Got CSN and CC
 */
uint8_t handshakeIclassTag(uint8_t *card_data)
{
	static uint8_t act_all[]     = { 0x0a };
	static uint8_t identify[]    = { 0x0c };
	static uint8_t select[]      = { 0x81, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	static uint8_t readcheck_cc[]= { 0x88, 0x02 };
	uint8_t resp[ICLASS_BUFFER_SIZE];

	uint8_t read_status = 0;

	// Send act_all
	ReaderTransmitIClass(act_all, 1);
	// Card present?
	if(!ReaderReceiveIClass(resp)) return read_status;//Fail
	//Send Identify
	ReaderTransmitIClass(identify, 1);
	//We expect a 10-byte response here, 8 byte anticollision-CSN and 2 byte CRC
	uint8_t len  = ReaderReceiveIClass(resp);
	if(len != 10) return read_status;//Fail

	//Copy the Anti-collision CSN to our select-packet
	memcpy(&select[1],resp,8);
	//Select the card
	ReaderTransmitIClass(select, sizeof(select));
	//We expect a 10-byte response here, 8 byte CSN and 2 byte CRC
	len  = ReaderReceiveIClass(resp);
	if(len != 10) return read_status;//Fail

	//Success - level 1, we got CSN
	//Save CSN in response data
	memcpy(card_data,resp,8);

	//Flag that we got to at least stage 1, read CSN
	read_status = 1;

	// Card selected, now read e-purse (cc)
	ReaderTransmitIClass(readcheck_cc, sizeof(readcheck_cc));
	if(ReaderReceiveIClass(resp) == 8) {
		//Save CC (e-purse) in response data
		memcpy(card_data+8,resp,8);

		//Got both
		read_status = 2;
	}

	return read_status;
}

// Reader iClass Anticollission
void ReaderIClass(uint8_t arg0) {

    uint8_t card_data[24]={0};
    uint8_t last_csn[8]={0};
	
    int read_status= 0;
    bool abort_after_read = arg0 & FLAG_ICLASS_READER_ONLY_ONCE;
	bool get_cc = arg0 & FLAG_ICLASS_READER_GET_CC;
	set_tracing(TRUE);
    setupIclassReader();

    size_t datasize = 0;
    while(!BUTTON_PRESS())
    {

		if(!tracing) {
			DbpString("Trace full");
			break;
		}
		WDT_HIT();

		read_status = handshakeIclassTag(card_data);

		if(read_status == 0) continue;
		if(read_status == 1) datasize = 8;
		if(read_status == 2) datasize = 16;

		//Todo, read the public blocks 1,5 aswell:
		//
		// 0 : CSN (we already have)
		// 1 : Configuration
		// 2 : e-purse (we already have)
		// (3,4 write-only)
		// 5 Application issuer area
		//
		//Then we can 'ship' back the 8 * 5 bytes of data,
		// with 0xFF:s in block 3 and 4.

		LED_B_ON();
		//Send back to client, but don't bother if we already sent this
		if(memcmp(last_csn, card_data, 8) != 0)
		{

			if(!get_cc || (get_cc && read_status == 2))
			{
				cmd_send(CMD_ACK,read_status,0,0,card_data,datasize);
				if(abort_after_read) {
					LED_A_OFF();
					return;
				}
				//Save that we already sent this....
				memcpy(last_csn, card_data, 8);
			}
			//If 'get_cc' was specified and we didn't get a CC, we'll just keep trying...
		}
		LED_B_OFF();
    }
    cmd_send(CMD_ACK,0,0,0,card_data, 0);
    LED_A_OFF();
}

void ReaderIClass_Replay(uint8_t arg0, uint8_t *MAC) {

	uint8_t card_data[USB_CMD_DATA_SIZE]={0};
	uint16_t block_crc_LUT[255] = {0};

	{//Generate a lookup table for block crc
		for(int block = 0; block < 255; block++){
			char bl = block;
			block_crc_LUT[block] = iclass_crc16(&bl ,1);
		}
	}
	//Dbprintf("Lookup table: %02x %02x %02x" ,block_crc_LUT[0],block_crc_LUT[1],block_crc_LUT[2]);

	uint8_t check[]       = { 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	uint8_t read[]        = { 0x0c, 0x00, 0x00, 0x00 };
	
    uint16_t crc = 0;
	uint8_t cardsize=0;
	uint8_t mem=0;
	
	static struct memory_t{
	  int k16;
	  int book;
	  int k2;
	  int lockauth;
	  int keyaccess;
	} memory;
	
	uint8_t resp[ICLASS_BUFFER_SIZE];
	
    setupIclassReader();
	set_tracing(TRUE);

	while(!BUTTON_PRESS()) {
	
		WDT_HIT();

		if(!tracing) {
			DbpString("Trace full");
			break;
		}
		
		uint8_t read_status = handshakeIclassTag(card_data);
		if(read_status < 2) continue;

		//for now replay captured auth (as cc not updated)
		memcpy(check+5,MAC,4);

		if(sendCmdGetResponseWithRetries(check, sizeof(check),resp, 4, 5))
		{
			Dbprintf("Error: Authentication Fail!");
			continue;
		}

		//first get configuration block (block 1)
		crc = block_crc_LUT[1];
		read[1]=1;
		read[2] = crc >> 8;
		read[3] = crc & 0xff;

		if(sendCmdGetResponseWithRetries(read, sizeof(read),resp, 10, 10))
		{
			Dbprintf("Dump config (block 1) failed");
			continue;
		}

		mem=resp[5];
		memory.k16= (mem & 0x80);
		memory.book= (mem & 0x20);
		memory.k2= (mem & 0x8);
		memory.lockauth= (mem & 0x2);
		memory.keyaccess= (mem & 0x1);

		cardsize = memory.k16 ? 255 : 32;
		WDT_HIT();
		//Set card_data to all zeroes, we'll fill it with data
		memset(card_data,0x0,USB_CMD_DATA_SIZE);
		uint8_t failedRead =0;
		uint32_t stored_data_length =0;
		//then loop around remaining blocks
		for(int block=0; block < cardsize; block++){

			read[1]= block;
			crc = block_crc_LUT[block];
			read[2] = crc >> 8;
			read[3] = crc & 0xff;

			if(!sendCmdGetResponseWithRetries(read, sizeof(read), resp, 10, 10))
			{
				Dbprintf("     %02x: %02x %02x %02x %02x %02x %02x %02x %02x",
						 block, resp[0], resp[1], resp[2],
						resp[3], resp[4], resp[5],
						resp[6], resp[7]);

				//Fill up the buffer
				memcpy(card_data+stored_data_length,resp,8);
				stored_data_length += 8;
				if(stored_data_length +8 > USB_CMD_DATA_SIZE)
				{//Time to send this off and start afresh
					cmd_send(CMD_ACK,
							 stored_data_length,//data length
							 failedRead,//Failed blocks?
							 0,//Not used ATM
							 card_data, stored_data_length);
					//reset
					stored_data_length = 0;
					failedRead = 0;
				}

			}else{
				failedRead = 1;
				stored_data_length +=8;//Otherwise, data becomes misaligned
				Dbprintf("Failed to dump block %d", block);
			}
		}

		//Send off any remaining data
		if(stored_data_length > 0)
		{
			cmd_send(CMD_ACK,
					 stored_data_length,//data length
					 failedRead,//Failed blocks?
					 0,//Not used ATM
					 card_data, stored_data_length);
		}
		//If we got here, let's break
		break;
	}
	//Signal end of transmission
	cmd_send(CMD_ACK,
			 0,//data length
			 0,//Failed blocks?
			 0,//Not used ATM
			 card_data, 0);

	LED_A_OFF();
}

//2. Create Read method (cut-down from above) based off responses from 1. 
//   Since we have the MAC could continue to use replay function.
//3. Create Write method
/*
void IClass_iso14443A_write(uint8_t arg0, uint8_t blockNo, uint8_t *data, uint8_t *MAC) {
	uint8_t act_all[]     = { 0x0a };
	uint8_t identify[]    = { 0x0c };
	uint8_t select[]      = { 0x81, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	uint8_t readcheck_cc[]= { 0x88, 0x02 };
	uint8_t check[]       = { 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	uint8_t read[]        = { 0x0c, 0x00, 0x00, 0x00 };
	uint8_t write[]       = { 0x87, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	
    uint16_t crc = 0;
	
	uint8_t* resp = (((uint8_t *)BigBuf) + 3560);

	// Reset trace buffer
    memset(trace, 0x44, RECV_CMD_OFFSET);
	traceLen = 0;

	// Setup SSC
	FpgaSetupSsc();
	// Start from off (no field generated)
	// Signal field is off with the appropriate LED
	LED_D_OFF();
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	SpinDelay(200);

	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

	// Now give it time to spin up.
	// Signal field is on with the appropriate LED
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
	SpinDelay(200);

	LED_A_ON();

	for(int i=0;i<1;i++) {
	
		if(traceLen > TRACE_SIZE) {
			DbpString("Trace full");
			break;
		}
		
		if (BUTTON_PRESS()) break;

		// Send act_all
		ReaderTransmitIClass(act_all, 1);
		// Card present?
		if(ReaderReceiveIClass(resp)) {
			ReaderTransmitIClass(identify, 1);
			if(ReaderReceiveIClass(resp) == 10) {
				// Select card          
				memcpy(&select[1],resp,8);
				ReaderTransmitIClass(select, sizeof(select));

				if(ReaderReceiveIClass(resp) == 10) {
					Dbprintf("     Selected CSN: %02x %02x %02x %02x %02x %02x %02x %02x",
					resp[0], resp[1], resp[2],
					resp[3], resp[4], resp[5],
					resp[6], resp[7]);
				}
				// Card selected
				Dbprintf("Readcheck on Sector 2");
				ReaderTransmitIClass(readcheck_cc, sizeof(readcheck_cc));
				if(ReaderReceiveIClass(resp) == 8) {
				   Dbprintf("     CC: %02x %02x %02x %02x %02x %02x %02x %02x",
					resp[0], resp[1], resp[2],
					resp[3], resp[4], resp[5],
					resp[6], resp[7]);
				}else return;
				Dbprintf("Authenticate");
				//for now replay captured auth (as cc not updated)
				memcpy(check+5,MAC,4);
				Dbprintf("     AA: %02x %02x %02x %02x",
					check[5], check[6], check[7],check[8]);
				ReaderTransmitIClass(check, sizeof(check));
				if(ReaderReceiveIClass(resp) == 4) {
				   Dbprintf("     AR: %02x %02x %02x %02x",
					resp[0], resp[1], resp[2],resp[3]);
				}else {
				  Dbprintf("Error: Authentication Fail!");
				  return;
				}
				Dbprintf("Write Block");
				
				//read configuration for max block number
				read_success=false;
				read[1]=1;
				uint8_t *blockno=&read[1];
				crc = iclass_crc16((char *)blockno,1);
				read[2] = crc >> 8;
				read[3] = crc & 0xff;
				while(!read_success){
				      ReaderTransmitIClass(read, sizeof(read));
				      if(ReaderReceiveIClass(resp) == 10) {
					 read_success=true;
					 mem=resp[5];
					 memory.k16= (mem & 0x80);
					 memory.book= (mem & 0x20);
					 memory.k2= (mem & 0x8);
					 memory.lockauth= (mem & 0x2);
					 memory.keyaccess= (mem & 0x1);

				      }
				}
				if (memory.k16){
				  cardsize=255;
				}else cardsize=32;
				//check card_size
				
				memcpy(write+1,blockNo,1);
				memcpy(write+2,data,8);
				memcpy(write+10,mac,4);
				while(!send_success){
				  ReaderTransmitIClass(write, sizeof(write));
				  if(ReaderReceiveIClass(resp) == 10) {
				    write_success=true;
				}
			}//
		}
		WDT_HIT();
	}
	
	LED_A_OFF();
}*/