X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/6923d3f14ff7c6439d708470f4da2edcc3eca854..7666f4608e8ade0ada08777d1cc33469c5d9471d:/common/lfdemod.c?ds=sidebyside

diff --git a/common/lfdemod.c b/common/lfdemod.c
index d6c024fa..8324c440 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -81,10 +81,9 @@ 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
 		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;
+			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: if (parityTest(parityWd, pLen, pType) == 0) {return 0;} break; //test parity
 		}
 		bitCnt+=(pLen-1);
 		parityWd = 0;
@@ -260,15 +259,18 @@ int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int
 //by marshmellow
 void askAmp(uint8_t *BitStream, size_t size)
 {
+	uint8_t Last = 128;
 	for(size_t i = 1; i<size; i++){
 		if (BitStream[i]-BitStream[i-1]>=30) //large jump up
-			BitStream[i]=127;
-		else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
-			BitStream[i]=-127;
+			Last = 255;
+		else if(BitStream[i-1]-BitStream[i]>=20) //large jump down
+			Last = 0;
+
+		BitStream[i-1] = Last;
 	}
 	return;
 }
-
+ 
 //by marshmellow
 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
@@ -278,7 +280,7 @@ int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr
 	if (*clk==0 || start < 0) return -3;
 	if (*invert != 1) *invert = 0;
 	if (amp==1) askAmp(BinStream, *size);
-	if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
+	if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d, amp %d", *clk, start, amp);
 
 	uint8_t initLoopMax = 255;
 	if (initLoopMax > *size) initLoopMax = *size;
@@ -464,10 +466,10 @@ int gProxII_Demod(uint8_t BitStream[], size_t *size)
 		//return start position
 		return (int) startIdx;
 	}
-	return -5;
+	return -5; //spacer bits not found - not a valid gproxII
 }
 
-//translate wave to 11111100000 (1 for each short wave 0 for each long wave)
+//translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
 {
 	size_t last_transition = 0;
@@ -491,6 +493,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 	// 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 anywhere
 	// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
+	//  (could also be fc/5 && fc/7 for fsk1 = 4-9)
 	for(idx = 161; idx < size-20; idx++) {
 		// threshold current value
 
@@ -498,23 +501,24 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 		else dest[idx] = 1;
 
 		// Check for 0->1 transition
-		if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
+		if (dest[idx-1] < dest[idx]) {
 			preLastSample = LastSample;
 			LastSample = currSample;
 			currSample = idx-last_transition;
-			if (currSample < (fclow-2)){            //0-5 = garbage noise (or 0-3)
+			if (currSample < (fclow-2)) {                   //0-5 = garbage noise (or 0-3)
 				//do nothing with extra garbage
-			} else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves  or 3-6 = 5
+			} else if (currSample < (fchigh-1)) {           //6-8 = 8 sample waves  (or 3-6 = 5)
+				//correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
 				if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample	== 0 )){
-					dest[numBits-1]=1;  //correct previous 9 wave surrounded by 8 waves
+					dest[numBits-1]=1;
 				}
 				dest[numBits++]=1;
 
-			} else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage 
+			} else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage 
 				//do nothing with beginning garbage
-			} else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
+			} else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
 				dest[numBits++]=1;
-			} else {                                         //9+ = 10 sample waves
+			} else {                                        //9+ = 10 sample waves (or 6+ = 7)
 				dest[numBits++]=0;
 			}
 			last_transition = idx;
@@ -524,6 +528,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 }
 
 //translate 11111100000 to 10
+//rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 		uint8_t invert, uint8_t fchigh, uint8_t fclow)
 {
@@ -533,8 +538,9 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 	uint32_t n=1;
 	for( idx=1; idx < size; idx++) {
 		n++;
-		if (dest[idx]==lastval) continue; 
+		if (dest[idx]==lastval) continue; //skip until we hit a transition
 		
+		//find out how many bits (n) we collected
 		//if lastval was 1, we have a 1->0 crossing
 		if (dest[idx-1]==1) {
 			n = (n * fclow + rfLen/2) / rfLen;
@@ -543,6 +549,7 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 		}
 		if (n == 0) n = 1;
 
+		//add to our destination the bits we collected		
 		memset(dest+numBits, dest[idx-1]^invert , n);
 		numBits += n;
 		n=0;
@@ -1495,8 +1502,8 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
 	numBits += (firstFullWave / *clock);
 	//set start of wave as clock align
 	lastClkBit = firstFullWave;
-	//PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);  
-	//PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
+	if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);  
+	if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
 	waveStart = 0;
 	dest[numBits++] = curPhase; //set first read bit
 	for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
@@ -1548,8 +1555,8 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	int tol = 0;
 	int i, j, skip, start, end, low, high, minClk, waveStart;
 	bool complete = false;
-	int tmpbuff[bufsize / 64];
-	int waveLen[bufsize / 64];
+	int tmpbuff[bufsize / 32]; //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
+	int waveLen[bufsize / 32]; //  if clock is larger then we waste memory in array size that is not needed...
 	size_t testsize = (bufsize < 512) ? bufsize : 512;
 	int phaseoff = 0;
 	high = low = 128;
@@ -1581,7 +1588,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 		waveStart = i;
 		while ((buffer[i] > low) && (i < bufsize))
 			++i;
-		if (j >= (bufsize/64)) {
+		if (j >= (bufsize/32)) {
 			break;
 		}
 		waveLen[j] = i - waveStart; //first high to first low
@@ -1627,6 +1634,8 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	if (start < 0) {
 		if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
 		return false;
+	} else {
+		if (g_debugMode==2) prnt("DEBUG STT: first STT found at: %d, j=%d",start, j);
 	}
 	if (waveLen[i+2] > clk*1+tol)
 		phaseoff = 0;
@@ -1640,7 +1649,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	end = skip;
 	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] >= 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
@@ -1662,12 +1671,15 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	start = skip;
 	size_t datalen = end - start;
 	// check validity of datalen (should be even clock increments)  - use a tolerance of up to 1/8th a clock
-	if (datalen % clk > clk/8) {
+	if ( clk - (datalen % clk) <= clk/8) {
+		// padd the amount off - could be problematic...  but shouldn't happen often
+		datalen += clk - (datalen % clk);
+	} else if ( (datalen % clk) <= clk/8 ) {
+		// padd the amount off - could be problematic...  but shouldn't happen often
+		datalen -= datalen % clk;
+	} else {
 		if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
 		return false;
-	} else {
-		// padd the amount off - could be problematic...  but shouldn't happen often
-		datalen += datalen % clk;
 	}
 	// if datalen is less than one t55xx block - ERROR
 	if (datalen/clk < 8*4) {
@@ -1675,11 +1687,23 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 		return false;
 	}
 	size_t dataloc = start;
+	if (buffer[dataloc-(clk*4)-(clk/8)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
+		//we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start 
+		for ( i=0; i <= (clk/8); ++i ) {
+			if ( buffer[dataloc - (clk*4) - i] <= low ) {
+				dataloc -= i;
+				break;
+			}
+		}
+	}
+	
 	size_t newloc = 0;
 	i=0;
+	if (g_debugMode==2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);		
+
 	// warning - overwriting buffer given with raw wave data with ST removed...
 	while ( dataloc < bufsize-(clk/2) ) {
-		//compensate for long high at end of ST not being high... (we cut out the high part)
+		//compensate for long high at end of ST not being high due to signal loss... (and we cut out the start of wave high part)
 		if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
 			for(i=0; i < clk/2-tol; ++i) {
 				buffer[dataloc+i] = high+5;
@@ -1690,11 +1714,12 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 				if (i+newloc < dataloc)
 					buffer[i+newloc] = buffer[dataloc];
 
-				dataloc++;				
+				dataloc++;
 			}
 		}
 		newloc += i;
-		//skip next ST
+		//skip next ST  -  we just assume it will be there from now on...
+		if (g_debugMode==2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
 		dataloc += clk*4;
 	}
 	*size = newloc;