From 489ef36cf67e8b882682542b8ad16eea6a41531e Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Tue, 2 Jun 2015 12:17:34 +0200
Subject: [PATCH] ADD: @pwpiwi 's fixes for 14b.   Including a rename from
 iso14443.c -> iso14443b.c

---
 armsrc/Makefile    |    2 +-
 armsrc/iso14443b.c | 1259 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 1260 insertions(+), 1 deletion(-)
 create mode 100644 armsrc/iso14443b.c

diff --git a/armsrc/Makefile b/armsrc/Makefile
index 2ddad17ea..83a4ab949 100644
--- a/armsrc/Makefile
+++ b/armsrc/Makefile
@@ -17,7 +17,7 @@ APP_CFLAGS	= -DWITH_LF -DWITH_ISO15693 -DWITH_ISO14443a -DWITH_ISO14443b -DWITH_
 SRC_LF = lfops.c hitag2.c lfsampling.c
 SRC_ISO15693 = iso15693.c iso15693tools.c
 SRC_ISO14443a = epa.c iso14443a.c mifareutil.c mifarecmd.c mifaresniff.c
-SRC_ISO14443b = iso14443.c
+SRC_ISO14443b = iso14443b.c
 SRC_CRAPTO1 = crapto1.c crypto1.c des.c aes.c desfire_key.c desfire_crypto.c mifaredesfire.c
 SRC_CRC = iso14443crc.c crc.c crc16.c crc32.c 
 
diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
new file mode 100644
index 000000000..8add8f9c3
--- /dev/null
+++ b/armsrc/iso14443b.c
@@ -0,0 +1,1259 @@
+//-----------------------------------------------------------------------------
+// Jonathan Westhues, split Nov 2006
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// Routines to support ISO 14443. This includes both the reader software and
+// the `fake tag' modes. At the moment only the Type B modulation is
+// supported.
+//-----------------------------------------------------------------------------
+
+#include "proxmark3.h"
+#include "apps.h"
+#include "util.h"
+#include "string.h"
+
+#include "iso14443crc.h"
+
+//static void GetSamplesFor14443(int weTx, int n);
+
+/*#define DEMOD_TRACE_SIZE 4096
+#define READER_TAG_BUFFER_SIZE 2048
+#define TAG_READER_BUFFER_SIZE 2048
+#define DEMOD_DMA_BUFFER_SIZE 1024
+*/
+
+#define RECEIVE_SAMPLES_TIMEOUT 2000
+
+//=============================================================================
+// An ISO 14443 Type B tag. We listen for commands from the reader, using
+// a UART kind of thing that's implemented in software. When we get a
+// frame (i.e., a group of bytes between SOF and EOF), we check the CRC.
+// If it's good, then we can do something appropriate with it, and send
+// a response.
+//=============================================================================
+
+//-----------------------------------------------------------------------------
+// Code up a string of octets at layer 2 (including CRC, we don't generate
+// that here) so that they can be transmitted to the reader. Doesn't transmit
+// them yet, just leaves them ready to send in ToSend[].
+//-----------------------------------------------------------------------------
+static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
+{
+	int i;
+
+	ToSendReset();
+
+	// Transmit a burst of ones, as the initial thing that lets the
+	// reader get phase sync. This (TR1) must be > 80/fs, per spec,
+	// but tag that I've tried (a Paypass) exceeds that by a fair bit,
+	// so I will too.
+	for(i = 0; i < 20; i++) {
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+	}
+
+	// Send SOF.
+	for(i = 0; i < 10; i++) {
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+	}
+	for(i = 0; i < 2; i++) {
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+	}
+
+	for(i = 0; i < len; i++) {
+		int j;
+		uint8_t b = cmd[i];
+
+		// Start bit
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+
+		// Data bits
+		for(j = 0; j < 8; j++) {
+			if(b & 1) {
+				ToSendStuffBit(1);
+				ToSendStuffBit(1);
+				ToSendStuffBit(1);
+				ToSendStuffBit(1);
+			} else {
+				ToSendStuffBit(0);
+				ToSendStuffBit(0);
+				ToSendStuffBit(0);
+				ToSendStuffBit(0);
+			}
+			b >>= 1;
+		}
+
+		// Stop bit
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+	}
+
+	// Send SOF.
+	for(i = 0; i < 10; i++) {
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+		ToSendStuffBit(0);
+	}
+	for(i = 0; i < 10; i++) {
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+	}
+
+	// Convert from last byte pos to length
+	ToSendMax++;
+
+	// Add a few more for slop
+	ToSendMax += 2;
+}
+
+//-----------------------------------------------------------------------------
+// The software UART that receives commands from the reader, and its state
+// variables.
+//-----------------------------------------------------------------------------
+static struct {
+	enum {
+		STATE_UNSYNCD,
+		STATE_GOT_FALLING_EDGE_OF_SOF,
+		STATE_AWAITING_START_BIT,
+		STATE_RECEIVING_DATA,
+		STATE_ERROR_WAIT
+	}       state;
+	uint16_t    shiftReg;
+	int     bitCnt;
+	int     byteCnt;
+	int     byteCntMax;
+	int     posCnt;
+	uint8_t   *output;
+} Uart;
+
+/* Receive & handle a bit coming from the reader.
+ *
+ * LED handling:
+ * LED A -> ON once we have received the SOF and are expecting the rest.
+ * LED A -> OFF once we have received EOF or are in error state or unsynced
+ *
+ * Returns: true if we received a EOF
+ *          false if we are still waiting for some more
+ */
+static int Handle14443UartBit(int bit)
+{
+	switch(Uart.state) {
+		case STATE_UNSYNCD:
+			LED_A_OFF();
+			if(!bit) {
+				// we went low, so this could be the beginning
+				// of an SOF
+				Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
+				Uart.posCnt = 0;
+				Uart.bitCnt = 0;
+			}
+			break;
+
+		case STATE_GOT_FALLING_EDGE_OF_SOF:
+			Uart.posCnt++;
+			if(Uart.posCnt == 2) {
+				if(bit) {
+					if(Uart.bitCnt >= 10) {
+						// we've seen enough consecutive
+						// zeros that it's a valid SOF
+						Uart.posCnt = 0;
+						Uart.byteCnt = 0;
+						Uart.state = STATE_AWAITING_START_BIT;
+						LED_A_ON(); // Indicate we got a valid SOF
+					} else {
+						// didn't stay down long enough
+						// before going high, error
+						Uart.state = STATE_ERROR_WAIT;
+					}
+				} else {
+					// do nothing, keep waiting
+				}
+				Uart.bitCnt++;
+			}
+			if(Uart.posCnt >= 4) Uart.posCnt = 0;
+			if(Uart.bitCnt > 14) {
+				// Give up if we see too many zeros without
+				// a one, too.
+				Uart.state = STATE_ERROR_WAIT;
+			}
+			break;
+
+		case STATE_AWAITING_START_BIT:
+			Uart.posCnt++;
+			if(bit) {
+				if(Uart.posCnt > 25) {
+					// stayed high for too long between
+					// characters, error
+					Uart.state = STATE_ERROR_WAIT;
+				}
+			} else {
+				// falling edge, this starts the data byte
+				Uart.posCnt = 0;
+				Uart.bitCnt = 0;
+				Uart.shiftReg = 0;
+				Uart.state = STATE_RECEIVING_DATA;
+				LED_A_ON(); // Indicate we're receiving
+			}
+			break;
+
+		case STATE_RECEIVING_DATA:
+			Uart.posCnt++;
+			if(Uart.posCnt == 2) {
+				// time to sample a bit
+				Uart.shiftReg >>= 1;
+				if(bit) {
+					Uart.shiftReg |= 0x200;
+				}
+				Uart.bitCnt++;
+			}
+			if(Uart.posCnt >= 4) {
+				Uart.posCnt = 0;
+			}
+			if(Uart.bitCnt == 10) {
+				if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
+				{
+					// this is a data byte, with correct
+					// start and stop bits
+					Uart.output[Uart.byteCnt] = (Uart.shiftReg >> 1) & 0xff;
+					Uart.byteCnt++;
+
+					if(Uart.byteCnt >= Uart.byteCntMax) {
+						// Buffer overflowed, give up
+						Uart.posCnt = 0;
+						Uart.state = STATE_ERROR_WAIT;
+					} else {
+						// so get the next byte now
+						Uart.posCnt = 0;
+						Uart.state = STATE_AWAITING_START_BIT;
+					}
+				} else if(Uart.shiftReg == 0x000) {
+					// this is an EOF byte
+					LED_A_OFF(); // Finished receiving
+					return TRUE;
+				} else {
+					// this is an error
+					Uart.posCnt = 0;
+					Uart.state = STATE_ERROR_WAIT;
+				}
+			}
+			break;
+
+		case STATE_ERROR_WAIT:
+			// We're all screwed up, so wait a little while
+			// for whatever went wrong to finish, and then
+			// start over.
+			Uart.posCnt++;
+			if(Uart.posCnt > 10) {
+				Uart.state = STATE_UNSYNCD;
+			}
+			break;
+
+		default:
+			Uart.state = STATE_UNSYNCD;
+			break;
+	}
+
+	// This row make the error blew circular buffer in hf 14b snoop
+	//if (Uart.state == STATE_ERROR_WAIT) LED_A_OFF(); // Error
+
+	return FALSE;
+}
+
+//-----------------------------------------------------------------------------
+// Receive a command (from the reader to us, where we are the simulated tag),
+// and store it in the given buffer, up to the given maximum length. Keeps
+// spinning, waiting for a well-framed command, until either we get one
+// (returns TRUE) or someone presses the pushbutton on the board (FALSE).
+//
+// Assume that we're called with the SSC (to the FPGA) and ADC path set
+// correctly.
+//-----------------------------------------------------------------------------
+static int GetIso14443CommandFromReader(uint8_t *received, int *len, int maxLen)
+{
+	uint8_t mask;
+	int i, bit;
+
+	// 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_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
+
+
+	// 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;
+
+			mask = 0x80;
+			for(i = 0; i < 8; i++, mask >>= 1) {
+				bit = (b & mask);
+				if(Handle14443UartBit(bit)) {
+					*len = Uart.byteCnt;
+					return TRUE;
+				}
+			}
+		}
+	}
+}
+
+//-----------------------------------------------------------------------------
+// Main loop of simulated tag: receive commands from reader, decide what
+// response to send, and send it.
+//-----------------------------------------------------------------------------
+void SimulateIso14443Tag(void)
+{
+	static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+	static const uint8_t response1[] = {
+		0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
+		0x00, 0x21, 0x85, 0x5e, 0xd7
+	};
+
+	uint8_t *resp;
+	int respLen;
+
+	uint8_t *resp1 = BigBuf_get_addr() + 800;
+	int resp1Len;
+
+	uint8_t *receivedCmd = BigBuf_get_addr();
+	int len;
+
+	int i;
+
+	int cmdsRecvd = 0;
+
+	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+	memset(receivedCmd, 0x44, 400);
+
+	CodeIso14443bAsTag(response1, sizeof(response1));
+	memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
+
+	// We need to listen to the high-frequency, peak-detected path.
+	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+	FpgaSetupSsc();
+
+	cmdsRecvd = 0;
+
+	for(;;) {
+		uint8_t b1, b2;
+
+		if(!GetIso14443CommandFromReader(receivedCmd, &len, 100)) {
+		Dbprintf("button pressed, received %d commands", cmdsRecvd);
+		break;
+		}
+
+		// Good, look at the command now.
+
+		if(len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len)==0) {
+			resp = resp1; respLen = resp1Len;
+		} else {
+			Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
+			// And print whether the CRC fails, just for good measure
+			ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
+			if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
+				// Not so good, try again.
+				DbpString("+++CRC fail");
+			} else {
+				DbpString("CRC passes");
+			}
+			break;
+		}
+
+		memset(receivedCmd, 0x44, 32);
+
+		cmdsRecvd++;
+
+		if(cmdsRecvd > 0x30) {
+			DbpString("many commands later...");
+			break;
+		}
+
+		if(respLen <= 0) continue;
+
+		// Modulate BPSK
+		// Signal field is off with the appropriate LED
+		LED_D_OFF();
+		FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
+		AT91C_BASE_SSC->SSC_THR = 0xff;
+		FpgaSetupSsc();
+
+		// Transmit the response.
+		i = 0;
+		for(;;) {
+			if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+				uint8_t b = resp[i];
+
+				AT91C_BASE_SSC->SSC_THR = b;
+
+				i++;
+				if(i > respLen) {
+					break;
+				}
+			}
+			if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+				volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+				(void)b;
+			}
+		}
+	}
+}
+
+//=============================================================================
+// An ISO 14443 Type B reader. We take layer two commands, code them
+// appropriately, and then send them to the tag. We then listen for the
+// tag's response, which we leave in the buffer to be demodulated on the
+// PC side.
+//=============================================================================
+
+static struct {
+	enum {
+		DEMOD_UNSYNCD,
+		DEMOD_PHASE_REF_TRAINING,
+		DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
+		DEMOD_GOT_FALLING_EDGE_OF_SOF,
+		DEMOD_AWAITING_START_BIT,
+		DEMOD_RECEIVING_DATA,
+		DEMOD_ERROR_WAIT
+	}       state;
+	int     bitCount;
+	int     posCount;
+	int     thisBit;
+	int     metric;
+	int     metricN;
+	uint16_t    shiftReg;
+	uint8_t   *output;
+	int     len;
+	int     sumI;
+	int     sumQ;
+} Demod;
+
+/*
+ * Handles reception of a bit from the tag
+ *
+ * LED handling:
+ * LED C -> ON once we have received the SOF and are expecting the rest.
+ * LED C -> OFF once we have received EOF or are unsynced
+ *
+ * Returns: true if we received a EOF
+ *          false if we are still waiting for some more
+ *
+ */
+static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
+{
+	int v;
+
+	// The soft decision on the bit uses an estimate of just the
+	// quadrant of the reference angle, not the exact angle.
+#define MAKE_SOFT_DECISION() { \
+		if(Demod.sumI > 0) { \
+			v = ci; \
+		} else { \
+			v = -ci; \
+		} \
+		if(Demod.sumQ > 0) { \
+			v += cq; \
+		} else { \
+			v -= cq; \
+		} \
+	}
+
+	switch(Demod.state) {
+		case DEMOD_UNSYNCD:
+			v = ci;
+			if(v < 0) v = -v;
+			if(cq > 0) {
+				v += cq;
+			} else {
+				v -= cq;
+			}
+			if(v > 40) {
+				Demod.posCount = 0;
+				Demod.state = DEMOD_PHASE_REF_TRAINING;
+				Demod.sumI = 0;
+				Demod.sumQ = 0;
+			}
+			break;
+
+		case DEMOD_PHASE_REF_TRAINING:
+			if(Demod.posCount < 8) {
+				Demod.sumI += ci;
+				Demod.sumQ += cq;
+			} else if(Demod.posCount > 100) {
+				// error, waited too long
+				Demod.state = DEMOD_UNSYNCD;
+			} else {
+				MAKE_SOFT_DECISION();
+				if(v < 0) {
+					Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
+					Demod.posCount = 0;
+				}
+			}
+			Demod.posCount++;
+			break;
+
+		case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
+			MAKE_SOFT_DECISION();
+			if(v < 0) {
+				Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
+				Demod.posCount = 0;
+			} else {
+				if(Demod.posCount > 100) {
+					Demod.state = DEMOD_UNSYNCD;
+				}
+			}
+			Demod.posCount++;
+			break;
+
+		case DEMOD_GOT_FALLING_EDGE_OF_SOF:
+			MAKE_SOFT_DECISION();
+			if(v > 0) {
+				if(Demod.posCount < 12) {
+					Demod.state = DEMOD_UNSYNCD;
+				} else {
+					LED_C_ON(); // Got SOF
+					Demod.state = DEMOD_AWAITING_START_BIT;
+					Demod.posCount = 0;
+					Demod.len = 0;
+					Demod.metricN = 0;
+					Demod.metric = 0;
+				}
+			} else {
+				if(Demod.posCount > 100) {
+					Demod.state = DEMOD_UNSYNCD;
+				}
+			}
+			Demod.posCount++;
+			break;
+
+		case DEMOD_AWAITING_START_BIT:
+			MAKE_SOFT_DECISION();
+			if(v > 0) {
+				if(Demod.posCount > 10) {
+					Demod.state = DEMOD_UNSYNCD;
+				}
+			} else {
+				Demod.bitCount = 0;
+				Demod.posCount = 1;
+				Demod.thisBit = v;
+				Demod.shiftReg = 0;
+				Demod.state = DEMOD_RECEIVING_DATA;
+			}
+			break;
+
+		case DEMOD_RECEIVING_DATA:
+			MAKE_SOFT_DECISION();
+			if(Demod.posCount == 0) {
+				Demod.thisBit = v;
+				Demod.posCount = 1;
+			} else {
+				Demod.thisBit += v;
+
+				if(Demod.thisBit > 0) {
+					Demod.metric += Demod.thisBit;
+				} else {
+					Demod.metric -= Demod.thisBit;
+				}
+				(Demod.metricN)++;
+
+				Demod.shiftReg >>= 1;
+				if(Demod.thisBit > 0) {
+					Demod.shiftReg |= 0x200;
+				}
+
+				Demod.bitCount++;
+				if(Demod.bitCount == 10) {
+					uint16_t s = Demod.shiftReg;
+					if((s & 0x200) && !(s & 0x001)) {
+						uint8_t b = (s >> 1);
+						Demod.output[Demod.len] = b;
+						Demod.len++;
+						Demod.state = DEMOD_AWAITING_START_BIT;
+					} else if(s == 0x000) {
+						// This is EOF
+						LED_C_OFF();
+						Demod.state = DEMOD_UNSYNCD;
+						return TRUE;
+					} else {
+						Demod.state = DEMOD_UNSYNCD;
+					}
+				}
+				Demod.posCount = 0;
+			}
+			break;
+
+		default:
+			Demod.state = DEMOD_UNSYNCD;
+			break;
+	}
+
+	if (Demod.state == DEMOD_UNSYNCD) LED_C_OFF(); // Not synchronized...
+	return FALSE;
+}
+
+
+static void DemodReset()
+{
+	// Clear out the state of the "UART" that receives from the tag.
+	Demod.len = 0;
+	Demod.state = DEMOD_UNSYNCD;
+	memset(Demod.output, 0x00, MAX_FRAME_SIZE);
+}
+
+
+static void DemodInit(uint8_t *data)
+{
+	Demod.output = data;
+	DemodReset();
+}
+
+
+static void UartReset()
+{
+	Uart.byteCntMax = MAX_FRAME_SIZE;
+	Uart.state = STATE_UNSYNCD;
+	Uart.byteCnt = 0;
+	Uart.bitCnt = 0;
+}
+
+
+static void UartInit(uint8_t *data)
+{
+	Uart.output = data;
+	UartReset();
+}
+
+
+/*
+ *  Demodulate the samples we received from the tag, also log to tracebuffer
+ *  weTx: set to 'TRUE' if we behave like a reader
+ *        set to 'FALSE' if we behave like a snooper
+ *  quiet: set to 'TRUE' to disable debug output
+ */
+static void GetSamplesFor14443Demod(int weTx, int n, int quiet)
+{
+	int max = 0;
+	int gotFrame = FALSE;
+	int lastRxCounter, ci, cq, samples = 0;
+
+	// Allocate memory from BigBuf for some buffers
+	// free all previous allocations first
+	BigBuf_free();
+	
+	// The response (tag -> reader) that we're receiving.
+	uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
+	
+	// The DMA buffer, used to stream samples from the FPGA
+	int8_t *dmaBuf = (int8_t*) BigBuf_malloc(DMA_BUFFER_SIZE);
+
+	// Set up the demodulator for tag -> reader responses.
+	DemodInit(receivedResponse);
+
+	// Setup and start DMA.
+	FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
+
+	int8_t *upTo = dmaBuf;
+	lastRxCounter = DMA_BUFFER_SIZE;
+
+	// Signal field is ON with the appropriate LED:
+	if (weTx) LED_D_ON(); else LED_D_OFF();
+	// And put the FPGA in the appropriate mode
+	FpgaWriteConfWord(
+		FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
+		(weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
+
+	for(;;) {
+		int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
+		if(behindBy > max) max = behindBy;
+
+		while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (DMA_BUFFER_SIZE-1))
+					> 2)
+		{
+			ci = upTo[0];
+			cq = upTo[1];
+			upTo += 2;
+			if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
+				upTo = dmaBuf;
+				AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
+				AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+			}
+			lastRxCounter -= 2;
+			if(lastRxCounter <= 0) {
+				lastRxCounter += DMA_BUFFER_SIZE;
+			}
+
+			samples += 2;
+
+			if(Handle14443SamplesDemod(ci, cq)) {
+				gotFrame = 1;
+			}
+		}
+
+		if(samples > n) {
+			break;
+		}
+	}
+	AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+	if (!quiet) Dbprintf("%x %x %x", max, gotFrame, Demod.len);
+	//Tracing
+	if (tracing && Demod.len > 0) {
+		uint8_t parity[MAX_PARITY_SIZE];
+		GetParity(Demod.output, Demod.len, parity);
+		LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
+	}
+}
+
+
+//-----------------------------------------------------------------------------
+// Read the tag's response. We just receive a stream of slightly-processed
+// samples from the FPGA, which we will later do some signal processing on,
+// to get the bits.
+//-----------------------------------------------------------------------------
+/*static void GetSamplesFor14443(int weTx, int n)
+{
+	uint8_t *dest = (uint8_t *)BigBuf;
+	int c;
+
+	FpgaWriteConfWord(
+		FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
+		(weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
+
+	c = 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)) {
+			int8_t b;
+			b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
+
+			dest[c++] = (uint8_t)b;
+
+			if(c >= n) {
+				break;
+			}
+		}
+	}
+}*/
+
+
+//-----------------------------------------------------------------------------
+// Transmit the command (to the tag) that was placed in ToSend[].
+//-----------------------------------------------------------------------------
+static void TransmitFor14443(void)
+{
+	int c;
+
+	FpgaSetupSsc();
+
+	while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+		AT91C_BASE_SSC->SSC_THR = 0xff;
+	}
+
+	// Signal field is ON with the appropriate Red LED
+	LED_D_ON();
+	// Signal we are transmitting with the Green LED
+	LED_B_ON();
+	FpgaWriteConfWord(
+		FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
+
+	for(c = 0; c < 10;) {
+		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+			AT91C_BASE_SSC->SSC_THR = 0xff;
+			c++;
+		}
+		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+			volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
+			(void)r;
+		}
+		WDT_HIT();
+	}
+
+	c = 0;
+	for(;;) {
+		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+			AT91C_BASE_SSC->SSC_THR = ToSend[c];
+			c++;
+			if(c >= ToSendMax) {
+				break;
+			}
+		}
+		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+			volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
+			(void)r;
+		}
+		WDT_HIT();
+	}
+	LED_B_OFF(); // Finished sending
+}
+
+
+//-----------------------------------------------------------------------------
+// Code a layer 2 command (string of octets, including CRC) into ToSend[],
+// so that it is ready to transmit to the tag using TransmitFor14443().
+//-----------------------------------------------------------------------------
+static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
+{
+	int i, j;
+	uint8_t b;
+
+	ToSendReset();
+
+	// Establish initial reference level
+	for(i = 0; i < 40; i++) {
+		ToSendStuffBit(1);
+	}
+	// Send SOF
+	for(i = 0; i < 10; i++) {
+		ToSendStuffBit(0);
+	}
+
+	for(i = 0; i < len; i++) {
+		// Stop bits/EGT
+		ToSendStuffBit(1);
+		ToSendStuffBit(1);
+		// Start bit
+		ToSendStuffBit(0);
+		// Data bits
+		b = cmd[i];
+		for(j = 0; j < 8; j++) {
+			if(b & 1) {
+				ToSendStuffBit(1);
+			} else {
+				ToSendStuffBit(0);
+			}
+			b >>= 1;
+		}
+	}
+	// Send EOF
+	ToSendStuffBit(1);
+	for(i = 0; i < 10; i++) {
+		ToSendStuffBit(0);
+	}
+	for(i = 0; i < 8; i++) {
+		ToSendStuffBit(1);
+	}
+
+	// And then a little more, to make sure that the last character makes
+	// it out before we switch to rx mode.
+	for(i = 0; i < 24; i++) {
+		ToSendStuffBit(1);
+	}
+
+	// Convert from last character reference to length
+	ToSendMax++;
+}
+
+
+//-----------------------------------------------------------------------------
+// Read an ISO 14443 tag. We send it some set of commands, and record the
+// responses.
+// The command name is misleading, it actually decodes the reponse in HEX
+// into the output buffer (read the result using hexsamples, not hisamples)
+//
+// obsolete function only for test
+//-----------------------------------------------------------------------------
+void AcquireRawAdcSamplesIso14443(uint32_t parameter)
+{
+	uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+
+	SendRawCommand14443B(sizeof(cmd1),1,1,cmd1);
+}
+
+
+/**
+  Convenience function to encode, transmit and trace iso 14443b comms
+  **/
+static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
+{
+	CodeIso14443bAsReader(cmd, len);
+	TransmitFor14443();
+	if (tracing) {
+		uint8_t parity[MAX_PARITY_SIZE];
+		GetParity(cmd, len, parity);
+		LogTrace(cmd,len, 0, 0, parity, TRUE);
+	}
+}
+
+
+//-----------------------------------------------------------------------------
+// Read a SRI512 ISO 14443 tag.
+//
+// SRI512 tags are just simple memory tags, here we're looking at making a dump
+// of the contents of the memory. No anticollision algorithm is done, we assume
+// we have a single tag in the field.
+//
+// I tried to be systematic and check every answer of the tag, every CRC, etc...
+//-----------------------------------------------------------------------------
+void ReadSTMemoryIso14443(uint32_t dwLast)
+{
+	clear_trace();
+	set_tracing(TRUE);
+
+	uint8_t i = 0x00;
+
+	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+	// Make sure that we start from off, since the tags are stateful;
+	// confusing things will happen if we don't reset them between reads.
+	LED_D_OFF();
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+	SpinDelay(200);
+
+	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+	FpgaSetupSsc();
+
+	// Now give it time to spin up.
+	// Signal field is on with the appropriate LED
+	LED_D_ON();
+	FpgaWriteConfWord(
+		FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+	SpinDelay(200);
+
+	// First command: wake up the tag using the INITIATE command
+	uint8_t cmd1[] = { 0x06, 0x00, 0x97, 0x5b};
+
+	CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
+//    LED_A_ON();
+	GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+//    LED_A_OFF();
+
+	if (Demod.len == 0) {
+	DbpString("No response from tag");
+	return;
+	} else {
+	Dbprintf("Randomly generated UID from tag (+ 2 byte CRC): %x %x %x",
+		Demod.output[0], Demod.output[1],Demod.output[2]);
+	}
+	// There is a response, SELECT the uid
+	DbpString("Now SELECT tag:");
+	cmd1[0] = 0x0E; // 0x0E is SELECT
+	cmd1[1] = Demod.output[0];
+	ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
+	CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
+
+//    LED_A_ON();
+	GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+//    LED_A_OFF();
+	if (Demod.len != 3) {
+	Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
+	return;
+	}
+	// Check the CRC of the answer:
+	ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
+	if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
+	DbpString("CRC Error reading select response.");
+	return;
+	}
+	// Check response from the tag: should be the same UID as the command we just sent:
+	if (cmd1[1] != Demod.output[0]) {
+	Dbprintf("Bad response to SELECT from Tag, aborting: %x %x", cmd1[1], Demod.output[0]);
+	return;
+	}
+	// Tag is now selected,
+	// First get the tag's UID:
+	cmd1[0] = 0x0B;
+	ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
+	CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
+
+//    LED_A_ON();
+	GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+//    LED_A_OFF();
+	if (Demod.len != 10) {
+	Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
+	return;
+	}
+	// The check the CRC of the answer (use cmd1 as temporary variable):
+	ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
+		   if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
+	Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
+		(cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
+	// Do not return;, let's go on... (we should retry, maybe ?)
+	}
+	Dbprintf("Tag UID (64 bits): %08x %08x",
+	(Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
+	(Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
+
+	// Now loop to read all 16 blocks, address from 0 to last block
+	Dbprintf("Tag memory dump, block 0 to %d",dwLast);
+	cmd1[0] = 0x08;
+	i = 0x00;
+	dwLast++;
+	for (;;) {
+		   if (i == dwLast) {
+			DbpString("System area block (0xff):");
+			i = 0xff;
+		}
+		cmd1[1] = i;
+		ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
+		CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
+
+//	    LED_A_ON();
+		GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+//	    LED_A_OFF();
+		if (Demod.len != 6) { // Check if we got an answer from the tag
+		DbpString("Expected 6 bytes from tag, got less...");
+		return;
+		}
+		// The check the CRC of the answer (use cmd1 as temporary variable):
+		ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
+			if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
+		Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
+			(cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
+		// Do not return;, let's go on... (we should retry, maybe ?)
+		}
+		// Now print out the memory location:
+		Dbprintf("Address=%x, Contents=%x, CRC=%x", i,
+		(Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
+		(Demod.output[4]<<8)+Demod.output[5]);
+		if (i == 0xff) {
+		break;
+		}
+		i++;
+	}
+}
+
+
+//=============================================================================
+// Finally, the `sniffer' combines elements from both the reader and
+// simulated tag, to show both sides of the conversation.
+//=============================================================================
+
+//-----------------------------------------------------------------------------
+// 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.
+//-----------------------------------------------------------------------------
+/*
+ * Memory usage for this function, (within BigBuf)
+ * 0-4095 : Demodulated samples receive (4096 bytes) - DEMOD_TRACE_SIZE
+ * 4096-6143 : Last Received command, 2048 bytes (reader->tag) - READER_TAG_BUFFER_SIZE
+ * 6144-8191 : Last Received command, 2048 bytes(tag->reader) - TAG_READER_BUFFER_SIZE
+ * 8192-9215 : DMA Buffer, 1024 bytes (samples) - DEMOD_DMA_BUFFER_SIZE
+ */
+void RAMFUNC SnoopIso14443(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 = TRUE;
+
+	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+	BigBuf_free();
+
+	clear_trace();
+	set_tracing(TRUE);
+
+	// The DMA buffer, used to stream samples from the FPGA
+	int8_t *dmaBuf = (int8_t*) BigBuf_malloc(DMA_BUFFER_SIZE);
+	int lastRxCounter;
+	int8_t *upTo;
+	int ci, cq;
+	int maxBehindBy = 0;
+
+	// Count of samples received so far, so that we can include timing
+	// information in the trace buffer.
+	int samples = 0;
+
+	DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
+	UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
+
+	// Print some debug information about the buffer sizes
+	Dbprintf("Snooping buffers initialized:");
+	Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
+	Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
+	Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
+	Dbprintf("  DMA: %i bytes", DMA_BUFFER_SIZE);
+
+	// Signal field is off with the appropriate LED
+	LED_D_OFF();
+
+	// And put the FPGA in the appropriate mode
+	FpgaWriteConfWord(
+		FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
+		FPGA_HF_READER_RX_XCORR_SNOOP);
+	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+	// Setup for the DMA.
+	FpgaSetupSsc();
+	upTo = dmaBuf;
+	lastRxCounter = DMA_BUFFER_SIZE;
+	FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
+	uint8_t parity[MAX_PARITY_SIZE];
+	LED_A_ON();
+		
+	// And now we loop, receiving samples.
+	for(;;) {
+		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)) { // TODO: understand whether we can increase/decrease as we want or not?
+				Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
+				break;
+			}
+		}
+		if(behindBy < 2) continue;
+
+		ci = upTo[0];
+		cq = upTo[1];
+		upTo += 2;
+		lastRxCounter -= 2;
+		if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
+			upTo = dmaBuf;
+			lastRxCounter += DMA_BUFFER_SIZE;
+			AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
+			AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+		}
+
+		samples += 2;
+
+		if(Handle14443UartBit(ci & 1)) {
+			if(triggered && tracing) {
+				GetParity(Uart.output, Uart.byteCnt, parity);
+				LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
+			}
+			if(Uart.byteCnt==0) Dbprintf("[1] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
+
+			/* And ready to receive another command. */
+			UartReset();
+			/* And also reset the demod code, which might have been */
+			/* false-triggered by the commands from the reader. */
+			DemodReset();
+		}
+		if(Handle14443UartBit(cq & 1)) {
+			if(triggered && tracing) {
+				GetParity(Uart.output, Uart.byteCnt, parity);
+				LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
+			}
+			if(Uart.byteCnt==0) Dbprintf("[2] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
+
+			/* And ready to receive another command. */
+			UartReset();
+			/* And also reset the demod code, which might have been */
+			/* false-triggered by the commands from the reader. */
+			DemodReset();
+		}
+
+		if(Handle14443SamplesDemod(ci, cq)) {
+
+			//Use samples as a time measurement
+			if(tracing)
+			{
+				uint8_t parity[MAX_PARITY_SIZE];
+				GetParity(Demod.output, Demod.len, parity);
+				LogTrace(Demod.output, Demod.len,samples, samples, parity, FALSE);
+			}
+			triggered = TRUE;
+			LED_A_OFF();
+			LED_B_ON();
+
+			// And ready to receive another response.
+			DemodReset();
+		}
+		WDT_HIT();
+
+		if(!tracing) {
+			DbpString("Reached trace limit");
+			break;
+		}
+
+		if(BUTTON_PRESS()) {
+			DbpString("cancelled");
+			break;
+		}
+	}
+	FpgaDisableSscDma();
+	LED_A_OFF();
+	LED_B_OFF();
+	LED_C_OFF();
+	AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+	DbpString("Snoop statistics:");
+	Dbprintf("  Max behind by: %i", maxBehindBy);
+	Dbprintf("  Uart State: %x", Uart.state);
+	Dbprintf("  Uart ByteCnt: %i", Uart.byteCnt);
+	Dbprintf("  Uart ByteCntMax: %i", Uart.byteCntMax);
+	Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
+}
+
+
+/*
+ * Send raw command to tag ISO14443B
+ * @Input
+ * datalen     len of buffer data
+ * recv        bool when true wait for data from tag and send to client
+ * powerfield  bool leave the field on when true
+ * data        buffer with byte to send
+ *
+ * @Output
+ * none
+ *
+ */
+void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
+{
+	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+	if(!powerfield)
+	{
+		// Make sure that we start from off, since the tags are stateful;
+		// confusing things will happen if we don't reset them between reads.
+		FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+		LED_D_OFF();
+		SpinDelay(200);
+	}
+
+	if(!GETBIT(GPIO_LED_D))
+	{
+		SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+		FpgaSetupSsc();
+
+		// Now give it time to spin up.
+		// Signal field is on with the appropriate LED
+		LED_D_ON();
+		FpgaWriteConfWord(
+			FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+		SpinDelay(200);
+	}
+
+	CodeAndTransmit14443bAsReader(data, datalen);
+
+	if(recv)
+	{
+		GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+		uint16_t iLen = MIN(Demod.len,USB_CMD_DATA_SIZE);
+		cmd_send(CMD_ACK,iLen,0,0,Demod.output,iLen);
+	}
+	if(!powerfield)
+	{
+		FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+		LED_D_OFF();
+	}
+}
+