X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/24aa0a57333c3467d141195b4e77167839bacadb..a39af1cb9cab6298fcf01d7243e9f48db0f45f26:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index d2e0fca4..76900047 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -10,8 +10,8 @@
 //
 // NOTES: 
 // LF Demod functions are placed here to allow the flexability to use client or
-// device side. Most BUT NOT ALL of these functions are currenlty safe for 
-// device side use currently. (DetectST for example...)
+// device side. Most BUT NOT ALL of these functions are currently safe for 
+// device side use. (DetectST for example...)
 //
 // There are likely many improvements to the code that could be made, please
 // make suggestions...
@@ -505,13 +505,14 @@ int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr) {
 	return bestStart[best];
 }
 
-int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
+int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low, bool *strong) {
 	//find shortest transition from high to low
+	*strong = false;
 	size_t i = 0;
 	size_t transition1 = 0;
 	int lowestTransition = 255;
 	bool lastWasHigh = false;
-
+	size_t transitionSampleCount = 0;
 	//find first valid beginning of a high or low wave
 	while ((dest[i] >= peak || dest[i] <= low) && (i < size))
 		++i;
@@ -527,10 +528,17 @@ int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
 			lastWasHigh = (dest[i] >= peak);
 			if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
 			transition1 = i;
+		} else if (dest[i] < peak && dest[i] > low) {
+			transitionSampleCount++;
 		}
 	}
 	if (lowestTransition == 255) lowestTransition = 0;
 	if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
+	// if less than 10% of the samples were not peaks (or 90% were peaks) then we have a strong wave
+	if (transitionSampleCount / size < 10) {
+		*strong = true;
+		lowestTransition = getClosestClock(lowestTransition);
+	}
 	return lowestTransition;
 }
 
@@ -550,7 +558,9 @@ int DetectNRZClock(uint8_t dest[], size_t size, int clock, size_t *clockStartIdx
 	int peak, low;
 	if (getHiLo(dest, loopCnt, &peak, &low, 90, 90) < 1) return 0;
 
-	int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
+	bool strong = false;
+	int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low, &strong);
+	if (strong) return lowestTransition;
 	size_t ii;
 	uint8_t clkCnt;
 	uint8_t tol = 0;
@@ -1767,22 +1777,53 @@ int IOdemodFSK(uint8_t *dest, size_t size, int *waveStartIdx) {
 } 
 
 // redesigned by marshmellow adjusted from existing decode functions
-// indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
-int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert) {
-	//26 bit 40134 format  (don't know other formats)
-	uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
-	uint8_t preamble_i[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0};
-	size_t startidx = 0; 
-	if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
-		// if didn't find preamble try again inverting
-		if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
+// indala id decoding
+int indala64decode(uint8_t *bitStream, size_t *size, uint8_t *invert) {
+	//standard 64 bit indala formats including 26 bit 40134 format
+	uint8_t preamble64[] = {1,0,1,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 1};
+	uint8_t preamble64_i[] = {0,1,0,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 0};
+	size_t startidx = 0;
+	size_t found_size = *size;
+	bool found = preambleSearch(bitStream, preamble64, sizeof(preamble64), &found_size, &startidx);
+	if (!found) {
+		found = preambleSearch(bitStream, preamble64_i, sizeof(preamble64_i), &found_size, &startidx);
+		if (!found) return -1;
 		*invert ^= 1;
-	} 
-	if (*size != 64 && *size != 224) return -2;
+	}
+	if (found_size != 64) return -2;
 	if (*invert==1)
-		for (size_t i = startidx; i < *size + startidx; i++) 
+		for (size_t i = startidx; i < found_size + startidx; i++) 
+			bitStream[i] ^= 1;
+
+	// note: don't change *size until we are sure we got it... 
+	*size = found_size;
+	return (int) startidx;
+}
+
+int indala224decode(uint8_t *bitStream, size_t *size, uint8_t *invert) {
+	//large 224 bit indala formats (different preamble too...)
+	uint8_t preamble224[] = {1,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,1};
+	uint8_t preamble224_i[] = {0,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,0};
+	size_t startidx = 0;
+	size_t found_size = *size;
+	bool found = preambleSearch(bitStream, preamble224, sizeof(preamble224), &found_size, &startidx);
+	if (!found) {
+		found = preambleSearch(bitStream, preamble224_i, sizeof(preamble224_i), &found_size, &startidx);
+		if (!found) return -1;
+		*invert ^= 1;
+	}
+	if (found_size != 224) return -2;
+	if (*invert==1 && startidx > 0)
+		for (size_t i = startidx-1; i < found_size + startidx + 2; i++) 
 			bitStream[i] ^= 1;
 
+	// 224 formats are typically PSK2 (afaik 2017 Marshmellow)
+	// note loses 1 bit at beginning of transformation...
+	// don't need to verify array is big enough as to get here there has to be a full preamble after all of our data
+	psk1TOpsk2(bitStream + (startidx-1), found_size+2);
+	startidx++;
+
+	*size = found_size;
 	return (int) startidx;
 }