X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/13d77ef964cefe68750873d5268299a53c9e22a5..327a690813ff04d580a2630977f160b8ec809bd9:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 5b0bc29d..92ad633e 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -88,37 +88,34 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
     return 0;
   }
   // 111111111 bit pattern represent start of frame
-  uint8_t preamble[] = {1,1,1,1,1,1,1,1,1};
+  //  include 0 in front to help get start pos
+  uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
   uint32_t idx = 0;
   uint32_t parityBits = 0;
   uint8_t errChk = 0;
   uint8_t FmtLen = 10;
   *startIdx = 0;
-  for (uint8_t extraBitChk=0; extraBitChk<5; extraBitChk++){
-    errChk = preambleSearch(BitStream+extraBitChk+*startIdx, preamble, sizeof(preamble), size, startIdx);
-    if (errChk == 0) return 0;
-    if (*size>64) FmtLen = 22;
-    if (*size<64) return 0;
-    idx = *startIdx + 9;
-    for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
-      parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
-      //check even parity
-      if (parityTest(parityBits, 5, 0) == 0){
-        //parity failed try next bit (in the case of 1111111111) but last 9 = preamble
-        startIdx++;
-        errChk = 0;
-        break;
-      }
-      //set uint64 with ID from BitStream
-      for (uint8_t ii=0; ii<4; ii++){
-        *hi = (*hi << 1) | (*lo >> 63);
-        *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
-      }
+  errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
+  if (errChk == 0 || *size < 64) return 0;
+  if (*size > 64) FmtLen = 22;
+  *startIdx += 1; //get rid of 0 from preamble
+  idx = *startIdx + 9;
+  for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
+    parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
+    //check even parity
+    if (parityTest(parityBits, 5, 0) == 0){
+      //parity failed quit
+    	return 0;
+    }
+    //set uint64 with ID from BitStream
+    for (uint8_t ii=0; ii<4; ii++){
+      *hi = (*hi << 1) | (*lo >> 63);
+      *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
     }
-    if (errChk != 0) return 1;
-    //skip last 5 bit parity test for simplicity.
-    // *size = 64 | 128;
   }
+  if (errChk != 0) return 1;
+  //skip last 5 bit parity test for simplicity.
+  // *size = 64 | 128;
   return 0;
 }
 
@@ -375,34 +372,39 @@ int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int
 			smplCnt++;
 		} else if (BinStream[i] <= low && !waveHigh){
 			smplCnt++;
-		} else { //not high or low or a transition
-			if (smplCnt > clk-(clk/4)) { //full clock
-				if (smplCnt > clk + (clk/4)) { //too many samples
-					errCnt++;
-					BinStream[bitCnt++]=77;
-				} else if (waveHigh) {
-					BinStream[bitCnt++] = invert;
-					BinStream[bitCnt++] = invert;
-				} else if (!waveHigh) {
-					BinStream[bitCnt++] = invert ^ 1;
-					BinStream[bitCnt++] = invert ^ 1;
-				}
-				waveHigh ^= 1;  
-				smplCnt = 0;
-			} else if (smplCnt > (clk/2) - (clk/5)) {
-				if (waveHigh) {
-					BinStream[bitCnt++] = invert;
-				} else if (!waveHigh) {
-					BinStream[bitCnt++] = invert ^ 1;
+		} else { //transition
+			if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
+				if (smplCnt > clk-(clk/4)-1) { //full clock
+					if (smplCnt > clk + (clk/4)+1) { //too many samples
+						errCnt++;
+						BinStream[bitCnt++]=77;
+					} else if (waveHigh) {
+						BinStream[bitCnt++] = invert;
+						BinStream[bitCnt++] = invert;
+					} else if (!waveHigh) {
+						BinStream[bitCnt++] = invert ^ 1;
+						BinStream[bitCnt++] = invert ^ 1;
+					}
+					waveHigh ^= 1;  
+					smplCnt = 0;
+				} else if (smplCnt > (clk/2) - (clk/4)-1) {
+					if (waveHigh) {
+						BinStream[bitCnt++] = invert;
+					} else if (!waveHigh) {
+						BinStream[bitCnt++] = invert ^ 1;
+					}
+					waveHigh ^= 1;  
+					smplCnt = 0;
+				} else if (!bitCnt) {
+					//first bit
+					waveHigh = (BinStream[i] >= high);
+					smplCnt = 1;
+				} else {
+					smplCnt++;
+					//transition bit oops
 				}
-				waveHigh ^= 1;  
-				smplCnt = 0;
-			} else if (!bitCnt) {
-				//first bit
-				waveHigh = (BinStream[i] >= high);
-				smplCnt = 1;
-			} else {
-				//transition bit? ignore
+			} else { //haven't hit new high or new low yet
+				smplCnt++;
 			}
 		}
 	}
@@ -888,16 +890,18 @@ int PyramiddemodFSK(uint8_t *dest, size_t *size)
 
 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, int high, int low)
 {
-	uint8_t allPeaks=1;
+	uint16_t allPeaks=1;
 	uint16_t cntPeaks=0;
-	for (size_t i=30; i<255; i++){
+	size_t loopEnd = 572;
+	if (loopEnd > size) loopEnd = size;
+	for (size_t i=60; i<loopEnd; i++){
 		if (dest[i]>low && dest[i]<high) 
 			allPeaks=0;
 		else
 			cntPeaks++;
 	}
-	if (allPeaks==0){
-		if (cntPeaks>210) return 1;
+	if (allPeaks == 0){
+		if (cntPeaks > 300) return 1;
 	}
 	return allPeaks;
 }
@@ -939,10 +943,12 @@ int DetectStrongAskClock(uint8_t dest[], size_t size)
 			}
 		}
 	}
+	uint8_t tol;
 	for (idx=8; idx>0; idx--){
-		if (clk[idx] >= highCnt && clk[idx] <= highCnt+2)
+		tol = clk[idx]/8;
+		if (clk[idx] >= highCnt - tol && clk[idx] <= highCnt + tol)
 			return clk[idx];
-		if (clk[idx] >= highCnt2 && clk[idx] <= highCnt2+2)
+		if (clk[idx] >= highCnt2 - tol && clk[idx] <= highCnt2 + tol)
 			return clk[idx];
 	}
 	return -1;