X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/d1869c3336e82b7f2eb68b7fa9a5bdb865ff6b23..6923d3f14ff7c6439d708470f4da2edcc3eca854:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 5ed2d16c..d6c024fa 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -68,7 +68,7 @@ uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
 
 // by marshmellow
 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
-//   Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run) 
+//   Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run) 
 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
 {
 	uint32_t parityWd = 0;
@@ -80,10 +80,11 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
 		}
 		j--; // overwrite parity with next data
 		// if parity fails then return 0
-		if (pType == 2) { // then marker bit which should be a 1
-			if (!BitStream[j]) return 0;
-		} else {
-			if (parityTest(parityWd, pLen, pType) == 0) return 0;			
+		switch (pType) {
+			case 3: if (BitStream[j]==1) return 0; break; //should be 0 spacer bit
+			case 2: if (BitStream[j]==0) return 0; break; //should be 1 spacer bit
+			default: //test parity
+				if (parityTest(parityWd, pLen, pType) == 0) return 0; break;
 		}
 		bitCnt+=(pLen-1);
 		parityWd = 0;
@@ -95,7 +96,8 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
 
 // by marshmellow
 // takes a array of binary values, length of bits per parity (includes parity bit),
-//   Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
+//   Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
+//   Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
 {
 	uint32_t parityWd = 0;
@@ -106,10 +108,12 @@ size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t p
 			dest[j++] = (BitSource[word+bit]);
 		}
 		// if parity fails then return 0
-		if (pType == 2) { // then marker bit which should be a 1
-			dest[j++]=1;
-		} else {
-			dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
+		switch (pType) {
+			case 3: dest[j++]=0; break; // marker bit which should be a 0
+			case 2: dest[j++]=1; break; // marker bit which should be a 1
+			default: 
+				dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
+				break;
 		}
 		bitCnt += pLen;
 		parityWd = 0;
@@ -485,7 +489,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 
 	size_t numBits = 0;
 	// count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
-	// or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
+	// or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
 	// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
 	for(idx = 161; idx < size-20; idx++) {
 		// threshold current value
@@ -680,6 +684,19 @@ int VikingDemod_AM(uint8_t *dest, size_t *size) {
 	return (int) startIdx;
 }
 
+// find presco preamble 0x10D in already demoded data
+int PrescoDemod(uint8_t *dest, size_t *size) {
+	//make sure buffer has data
+	if (*size < 64*2) return -2;
+
+	size_t startIdx = 0;
+	uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
+	uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
+	if (errChk == 0) return -4; //preamble not found
+	//return start position
+	return (int) startIdx;
+}
+
 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
 // BitStream must contain previously askrawdemod and biphasedemoded data
 int FDXBdemodBI(uint8_t *dest, size_t *size)
@@ -1529,11 +1546,12 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	uint8_t fndClk[] = {8,16,32,40,50,64,128};
 	int clk = 0; 
 	int tol = 0;
-	int i, j, skip, start, end, low, high, minClk;
+	int i, j, skip, start, end, low, high, minClk, waveStart;
 	bool complete = false;
 	int tmpbuff[bufsize / 64];
+	int waveLen[bufsize / 64];
 	size_t testsize = (bufsize < 512) ? bufsize : 512;
-	//int phaseoff = 0;
+	int phaseoff = 0;
 	high = low = 128;
 	memset(tmpbuff, 0, sizeof(tmpbuff));
 
@@ -1541,7 +1559,6 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 		if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
 		return false; //just noise
 	}
-
 	i = 0;
 	j = 0;
 	minClk = 255;
@@ -1560,11 +1577,14 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 		start= i;
 		while ((buffer[i] < high) && (i < bufsize))
 			++i;
+		//first high point for this wave
+		waveStart = i;
 		while ((buffer[i] > low) && (i < bufsize))
 			++i;
 		if (j >= (bufsize/64)) {
 			break;
 		}
+		waveLen[j] = i - waveStart; //first high to first low
 		tmpbuff[j++] = i - start;
 		if (i-start < minClk && i < bufsize) {
 			minClk = i - start;
@@ -1592,10 +1612,10 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	start = -1;
 	for (i = 0; i < j - 4; ++i) {
 		skip += tmpbuff[i];
-		if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) {           //1 to 2 clocks depending on 2 bits prior
-			if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol) {       //2 clocks
-				if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol) { //1 1/2 to 2 clocks
-					if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= (clk*3)/2+tol) { //1 to 1 1/2 clocks for end of ST + first bit
+		if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) {           //1 to 2 clocks depending on 2 bits prior
+			if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) {       //2 clocks and wave size is 1 1/2
+				if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
+					if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
 						start = i + 3;
 						break;
 					}
@@ -1608,7 +1628,11 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 		if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
 		return false;
 	}
-
+	if (waveLen[i+2] > clk*1+tol)
+		phaseoff = 0;
+	else
+		phaseoff = clk/2;
+	
 	// skip over the remainder of ST
 	skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
 
@@ -1617,9 +1641,9 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	for (i += 3; i < j - 4; ++i) {
 		end += tmpbuff[i];
 		if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) {           //1 to 2 clocks depending on 2 bits prior
-			if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol) {       //2 clocks
-				if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol) { //1 1/2 to 2 clocks
-					if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= (clk*3)/2+tol) { //1 to 1 1/2 clocks for end of ST + first bit
+			if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) {       //2 clocks and wave size is 1 1/2
+				if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
+					if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
 						complete = true;
 						break;
 					}
@@ -1627,12 +1651,13 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 			}
 		}
 	}
+	end -= phaseoff;
 	//didn't find second ST - ERROR
 	if (!complete) {
 		if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
 		return false;
 	}
-	if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d", skip, end, end-skip, clk, (end-skip)/clk);
+	if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d, phaseoff: %d", skip, end, end-skip, clk, (end-skip)/clk, phaseoff);
 	//now begin to trim out ST so we can use normal demod cmds
 	start = skip;
 	size_t datalen = end - start;