speed up the em4x05 cmds by only getting 6k...

[proxmark3-svn] / common / lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index a32d3b85e492401c2d04ea971789d23378bf8f3f..fbed6a9a8431fa913a4d56cba47b19297571ff4e 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -170,6 +170,23 @@ uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_
        return 0;
 }
 
+// search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found)
+// does not look for a repeating preamble
+// em4x05/4x69 only sends preamble once, so look for it once in the first pLen bits
+// leave it generic so it could be reused later...
+bool onePreambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t size, size_t *startIdx) {
+       // Sanity check.  If preamble length is bigger than bitstream length.
+       if ( size <= pLen ) return false;
+       for (size_t idx = 0; idx < size - pLen; idx++) {
+               if (memcmp(BitStream+idx, preamble, pLen) == 0) {
+                       if (g_debugMode) prnt("DEBUG: preamble found at %u", idx);
+                       *startIdx = idx;
+                       return true;
+               }
+       }
+       return false;
+}
+
 //by marshmellow
 //takes 1s and 0s and searches for EM410x format - output EM ID
 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
@@ -493,16 +510,16 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
        // in case you have junk or noise at the beginning of the trace...
        uint8_t thresholdCnt = 0;
        size_t waveSizeCnt = 0;
-       bool isAboveThreshold = dest[idx] >= threshold_value;
+       bool isAboveThreshold = dest[idx++] >= threshold_value;
        for (; idx < size-20; idx++ ) {
                if(dest[idx] < threshold_value && isAboveThreshold) {
                        thresholdCnt++;
-                       if (thresholdCnt > 4 && waveSizeCnt < fchigh+1) break;                  
+                       if (thresholdCnt > 2 && waveSizeCnt < fchigh+1) break;                  
                        isAboveThreshold = false;
                        waveSizeCnt = 0;
                } else if (dest[idx] >= threshold_value && !isAboveThreshold) {
                        thresholdCnt++;
-                       if (thresholdCnt > 4 && waveSizeCnt < fchigh+1) break;                  
+                       if (thresholdCnt > 2 && waveSizeCnt < fchigh+1) break;                  
                        isAboveThreshold = true;
                        waveSizeCnt = 0;
                } else {
@@ -1491,7 +1508,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
 
        size_t numBits=0;
        uint8_t curPhase = *invert;
-       size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
+       size_t i=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
        uint8_t fc=0, fullWaveLen=0, tol=1;
        uint16_t errCnt=0, waveLenCnt=0;
        fc = countFC(dest, *size, 0);
@@ -1499,19 +1516,45 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
        //PrintAndLog("DEBUG: FC: %d",fc);
        *clock = DetectPSKClock(dest, *size, *clock);
        if (*clock == 0) return -1;
+       // jump to modulating data by finding the first 2 threshold crossings (or first 1 waves)
+       // in case you have junk or noise at the beginning of the trace...
+       uint8_t thresholdCnt = 0;
+       size_t waveSizeCnt = 0;
+       uint8_t threshold_value = 123; //-5
+       bool isAboveThreshold = dest[i++] >= threshold_value;
+       for (; i < *size-20; i++ ) {
+               if(dest[i] < threshold_value && isAboveThreshold) {
+                       thresholdCnt++;
+                       if (thresholdCnt > 2 && waveSizeCnt < fc+1) break;                      
+                       isAboveThreshold = false;
+                       waveSizeCnt = 0;
+               } else if (dest[i] >= threshold_value && !isAboveThreshold) {
+                       thresholdCnt++;
+                       if (thresholdCnt > 2 && waveSizeCnt < fc+1) break;                      
+                       isAboveThreshold = true;
+                       waveSizeCnt = 0;
+               } else {
+                       waveSizeCnt++;
+               }
+               if (thresholdCnt > 10) break;
+       }
+       if (g_debugMode == 2) prnt("DEBUG PSK: threshold Count reached at %u, count: %u",i, thresholdCnt);
+
+
        int avgWaveVal=0, lastAvgWaveVal=0;
+       waveStart = i+1;
        //find first phase shift
-       for (i=0; i<loopCnt; i++){
+       for (; i<loopCnt; i++){
                if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
                        waveEnd = i+1;
-                       //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
+                       if (g_debugMode == 2) prnt("DEBUG PSK: waveEnd: %u, waveStart: %u",waveEnd, waveStart);
                        waveLenCnt = waveEnd-waveStart;
-                       if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
+                       if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+3)){ //not first peak and is a large wave but not out of whack
                                lastAvgWaveVal = avgWaveVal/(waveLenCnt);
                                firstFullWave = waveStart;
                                fullWaveLen=waveLenCnt;
                                //if average wave value is > graph 0 then it is an up wave or a 1
-                               if (lastAvgWaveVal > 123) curPhase ^= 1;  //fudge graph 0 a little 123 vs 128
+                               if (lastAvgWaveVal > threshold_value) curPhase ^= 1;  //fudge graph 0 a little 123 vs 128
                                break;
                        } 
                        waveStart = i+1;