X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/5b12974a7f01a94c40552402b66b01bf8ec0e214..refs/pull/862/head:/armsrc/iso15693.c?ds=inline

diff --git a/armsrc/iso15693.c b/armsrc/iso15693.c
index f33e0156..85af0859 100644
--- a/armsrc/iso15693.c
+++ b/armsrc/iso15693.c
@@ -246,6 +246,8 @@ static void CodeIso15693AsReader256(uint8_t *cmd, int n)
 	// }
 // }
 
+static const uint8_t encode_4bits[16] = { 0xaa, 0x6a, 0x9a, 0x5a, 0xa6, 0x66, 0x96, 0x56, 0xa9, 0x69, 0x99, 0x59, 0xa5, 0x65, 0x95, 0x55 };
+
 void CodeIso15693AsTag(uint8_t *cmd, size_t len) {
 	/*
 	 * SOF comprises 3 parts;
@@ -280,16 +282,9 @@ void CodeIso15693AsTag(uint8_t *cmd, size_t len) {
 	ToSend[++ToSendMax] = 0x1D;  // 00011101
 
 	// data
-	for(int i = 0; i < len; i++) {
-		for(int j = 0; j < 8; j++) {
-			if ((cmd[i] >> j) & 0x01) {
-					ToSendStuffBit(0);
-					ToSendStuffBit(1);
-			} else {
-					ToSendStuffBit(1);
-					ToSendStuffBit(0);
-			}
-		}
+	for (int i = 0; i < len; i++) {
+		ToSend[++ToSendMax] = encode_4bits[cmd[i] & 0xF];
+		ToSend[++ToSendMax] = encode_4bits[cmd[i] >> 4];
 	}
 
 	// EOF
@@ -327,19 +322,32 @@ static void TransmitTo15693Tag(const uint8_t *cmd, int len, uint32_t start_time)
 //-----------------------------------------------------------------------------
 // Transmit the tag response (to the reader) that was placed in cmd[].
 //-----------------------------------------------------------------------------
-void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start_time, bool slow) {
+void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t *start_time, uint32_t slot_time, bool slow) {
 	// don't use the FPGA_HF_SIMULATOR_MODULATE_424K_8BIT minor mode. It would spoil GetCountSspClk()
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_424K);
 
-	uint8_t shift_delay = start_time & 0x00000007;
+	uint32_t modulation_start_time = *start_time + 3 * 8;  // no need to transfer the unmodulated start of SOF
+	
+	while (GetCountSspClk() > (modulation_start_time & 0xfffffff8) + 3) { // we will miss the intended time
+		if (slot_time) {
+			modulation_start_time += slot_time; // use next available slot
+		} else {
+			modulation_start_time = (modulation_start_time & 0xfffffff8) + 8; // next possible time
+		}
+	}
+
+	while (GetCountSspClk() < (modulation_start_time & 0xfffffff8)) 
+		/* wait */ ;
 
-	while (GetCountSspClk() < (start_time & 0xfffffff8)) ;
+	uint8_t shift_delay = modulation_start_time & 0x00000007;
+
+	*start_time = modulation_start_time - 3 * 8;
 
 	LED_C_ON();
 	uint8_t bits_to_shift = 0x00;
 	uint8_t bits_to_send = 0x00;
-	for(size_t c = 0; c < len; c++) {
-		for (int i = 7; i >= 0; i--) {
+	for (size_t c = 0; c < len; c++) {
+		for (int i = (c==0?4:7); i >= 0; i--) {
 			uint8_t cmd_bits = ((cmd[c] >> i) & 0x01) ? 0xff : 0x00;
 			for (int j = 0; j < (slow?4:1); ) {
 				if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
@@ -361,7 +369,6 @@ void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start_time,
 		}
 	}
 	LED_C_OFF();
-
 }
 
 
@@ -827,6 +834,7 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			break;
 
 		case STATE_READER_RECEIVE_DATA_1_OUT_OF_4:
+			bit = !!bit;
 			DecodeReader->posCount++;
 			if (DecodeReader->posCount == 1) {
 				DecodeReader->sum1 = bit;
@@ -839,17 +847,14 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			}
 			if (DecodeReader->posCount == 8) {
 				DecodeReader->posCount = 0;
-				int corr10 = DecodeReader->sum1 - DecodeReader->sum2;
-				int corr01 = DecodeReader->sum2 - DecodeReader->sum1;
-				int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
-				if (corr01 > corr11 && corr01 > corr10) { // EOF
+				if (DecodeReader->sum1 <= 1 && DecodeReader->sum2 >= 3) { // EOF
 					LED_B_OFF(); // Finished receiving
 					DecodeReaderReset(DecodeReader);
 					if (DecodeReader->byteCount != 0) {
 						return true;
 					}
 				}
-				if (corr10 > corr11) { // detected a 2bit position
+				if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected a 2bit position
 					DecodeReader->shiftReg >>= 2;
 					DecodeReader->shiftReg |= (DecodeReader->bitCount << 6);
 				}
@@ -869,6 +874,7 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			break;
 
 		case STATE_READER_RECEIVE_DATA_1_OUT_OF_256:
+			bit = !!bit;
 			DecodeReader->posCount++;
 			if (DecodeReader->posCount == 1) {
 				DecodeReader->sum1 = bit;
@@ -881,17 +887,14 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			}
 			if (DecodeReader->posCount == 8) {
 				DecodeReader->posCount = 0;
-				int corr10 = DecodeReader->sum1 - DecodeReader->sum2;
-				int corr01 = DecodeReader->sum2 - DecodeReader->sum1;
-				int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
-				if (corr01 > corr11 && corr01 > corr10) { // EOF
+				if (DecodeReader->sum1 <= 1 && DecodeReader->sum2 >= 3) { // EOF
 					LED_B_OFF(); // Finished receiving
 					DecodeReaderReset(DecodeReader);
 					if (DecodeReader->byteCount != 0) {
 						return true;
 					}
 				}
-				if (corr10 > corr11) { // detected the bit position
+				if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected the bit position
 					DecodeReader->shiftReg = DecodeReader->bitCount;
 				}
 				if (DecodeReader->bitCount == 255) { // we have a full byte
@@ -1533,7 +1536,7 @@ void SimTagIso15693(uint32_t parameter, uint8_t *uid)
 		if ((cmd_len >= 5) && (cmd[0] & ISO15693_REQ_INVENTORY) && (cmd[1] == ISO15693_INVENTORY)) { // TODO: check more flags
 			bool slow = !(cmd[0] & ISO15693_REQ_DATARATE_HIGH);
 			start_time = eof_time + DELAY_ISO15693_VCD_TO_VICC_SIM - DELAY_ARM_TO_READER_SIM;
-			TransmitTo15693Reader(ToSend, ToSendMax, start_time, slow);
+			TransmitTo15693Reader(ToSend, ToSendMax, &start_time, 0, slow);
 		}
 
 		Dbprintf("%d bytes read from reader:", cmd_len);