X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/c728b2b4cf2ce9fe4eebf0e46d74ef8542e56c16..ac42d5be8559300b88f0974fc14008010a4368a7:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 862d05ba..d9a87583 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;
@@ -148,8 +147,11 @@ uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
 {
-	uint8_t foundCnt=0;
-	for (int idx=0; idx < *size - pLen; idx++){
+	// Sanity check.  If preamble length is bigger than bitstream length.
+	if ( *size <= pLen ) return 0;
+	
+	uint8_t foundCnt = 0;
+	for (int idx = 0; idx < *size - pLen; idx++){
 		if (memcmp(BitStream+idx, preamble, pLen) == 0){
 			//first index found
 			foundCnt++;
@@ -259,13 +261,15 @@ int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int
 //by marshmellow
 void askAmp(uint8_t *BitStream, size_t size)
 {
-	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;
+	uint8_t last = 128;
+	for(size_t i = 1; i < size; ++i){
+		if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
+			last = 255;
+		else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
+			last = 0;
+		
+		BitStream[i] = last;
 	}
-	return;
 }
 
 //by marshmellow
@@ -463,10 +467,10 @@ 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;
@@ -490,6 +494,7 @@ 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
 
@@ -497,23 +502,24 @@ 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)
 				//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;
@@ -523,6 +529,7 @@ 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)
 {
@@ -534,6 +541,7 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 		n++;
 		if (dest[idx]==lastval) continue; 
 		
+		//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;
@@ -542,6 +550,7 @@ 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;
@@ -575,7 +584,7 @@ int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32
 {
 	if (justNoise(dest, *size)) return -1;
 
-	size_t numStart=0, size2=*size, startIdx=0; 
+	size_t numStart=0, size2 = *size, startIdx=0; 
 	// FSK demodulator
 	*size = fskdemod(dest, size2,50,1,10,8); //fsk2a
 	if (*size < 96*2) return -2;
@@ -607,7 +616,7 @@ int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, ui
 {
 	if (justNoise(dest, *size)) return -1;
 	
-	size_t numStart=0, size2=*size, startIdx=0;
+	size_t numStart=0, size2 = *size, startIdx=0;
 	// FSK demodulator
 	*size = fskdemod(dest, size2,50,1,10,8); //fsk2a
 	if (*size < 96) return -2;
@@ -674,10 +683,15 @@ int VikingDemod_AM(uint8_t *dest, size_t *size) {
 	uint8_t preamble[] = {1,1,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
 	uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
 	if (errChk == 0) return -4; //preamble not found
-	uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
-	    ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8) 
-	    ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
-	if ( checkCalc != 0xA8 ) return -5;
+	uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ 
+						 bytebits_to_byte(dest+startIdx+8,8) ^ 
+						 bytebits_to_byte(dest+startIdx+16,8) ^ 
+						 bytebits_to_byte(dest+startIdx+24,8) ^ 
+						 bytebits_to_byte(dest+startIdx+32,8) ^ 
+						 bytebits_to_byte(dest+startIdx+40,8) ^ 
+						 bytebits_to_byte(dest+startIdx+48,8) ^ 
+						 bytebits_to_byte(dest+startIdx+56,8);
+	if ( checkCalc != 0xA8 ) return -5;	
 	if (*size != 64) return -6;
 	//return start position
 	return (int) startIdx;
@@ -696,7 +710,6 @@ int PrescoDemod(uint8_t *dest, size_t *size) {
 	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)
@@ -712,6 +725,39 @@ int FDXBdemodBI(uint8_t *dest, size_t *size)
 	return (int)startIdx;
 }
 
+// ASK/Diphase fc/64 (inverted Biphase)
+// Note: this i s not a demod, this is only a detection
+// the parameter *dest needs to be demoded before call
+int JablotronDemod(uint8_t *dest, size_t *size){
+	//make sure buffer has enough data
+	if (*size < 64) return -1;
+
+	size_t startIdx = 0;
+	// 0xFFFF preamble, 64bits
+	uint8_t preamble[] = {
+		        1,1,1,1,
+	            1,1,1,1,
+				1,1,1,1,
+				1,1,1,1,
+				0
+		};
+
+	uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
+	if (errChk == 0) return -4; //preamble not found
+	if (*size != 64) return -3;
+	
+	uint8_t checkchksum = 0;
+	for (int i=16; i < 56; i += 8) {
+		checkchksum += bytebits_to_byte(dest+startIdx+i,8);
+	}
+	checkchksum ^= 0x3A;
+
+	uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
+	
+	if ( checkchksum != crc ) return -5;	
+	return (int)startIdx;
+}
+
 // by marshmellow
 // FSK Demod then try to locate an AWID ID
 int AWIDdemodFSK(uint8_t *dest, size_t *size)
@@ -755,6 +801,19 @@ int PyramiddemodFSK(uint8_t *dest, size_t *size)
 	return (int)startIdx;
 }
 
+// find nedap preamble in already demoded data
+int NedapDemod(uint8_t *dest, size_t *size) {
+	//make sure buffer has data
+	if (*size < 128) return -3;
+
+	size_t startIdx = 0;
+	//uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
+	uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
+	uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
+	if (errChk == 0) return -4; //preamble not found
+	return (int) startIdx;
+}
+
 // by marshmellow
 // to detect a wave that has heavily clipped (clean) samples
 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
@@ -1495,8 +1554,8 @@ 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++){
@@ -1679,7 +1738,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	i=0;
 	// 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;
@@ -1694,7 +1753,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 			}
 		}
 		newloc += i;
-		//skip next ST
+		//skip next ST  -  we just assume it will be there from now on...
 		dataloc += clk*4;
 	}
 	*size = newloc;