X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/01d7272d5bf2f07752d0fd79e95ac28dfaf6cb1b..6923d3f14ff7c6439d708470f4da2edcc3eca854:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 7398f1b2..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;
@@ -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)