X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/c71f4da9bc3d8207e8308e3212345eb578e1a08f..a5d824656811693c9f31cf41766e419b2dd799f9:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 24336160..ff80b8b3 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -84,7 +84,9 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
 			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;
+				if (parityTest(parityWd, pLen, pType) == 0) 
+					return 0; 
+				break;
 		}
 		bitCnt+=(pLen-1);
 		parityWd = 0;
@@ -148,8 +150,11 @@ 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 +264,15 @@ 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]=255;
-		else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
-			BitStream[i]=0;
+	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
@@ -721,6 +728,39 @@ 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)
@@ -764,16 +804,16 @@ int PyramiddemodFSK(uint8_t *dest, size_t *size)
 	return (int)startIdx;
 }
 
-// find presco preamble 0x10D in already demoded data
+// 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[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
+	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 start position
 	return (int) startIdx;
 }