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;
+}
+
+// find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
+size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_t expWaveSize) {
+ size_t i = 0;
+ size_t waveSizeCnt = 0;
+ uint8_t thresholdCnt = 0;
+ bool isAboveThreshold = dest[i++] >= threshold_value;
+ for (; i < size-20; i++ ) {
+ if(dest[i] < threshold_value && isAboveThreshold) {
+ thresholdCnt++;
+ if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
+ isAboveThreshold = false;
+ waveSizeCnt = 0;
+ } else if (dest[i] >= threshold_value && !isAboveThreshold) {
+ thresholdCnt++;
+ if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
+ isAboveThreshold = true;
+ waveSizeCnt = 0;
+ } else {
+ waveSizeCnt++;
+ }
+ if (thresholdCnt > 10) break;
+ }
+ if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at %u, count: %u",i, thresholdCnt);
+ return i;
+}
+
//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)
{
size_t last_transition = 0;
size_t idx = 1;
- //uint32_t maxVal=0;
if (fchigh==0) fchigh=10;
if (fclow==0) fclow=8;
//set the threshold close to 0 (graph) or 128 std to avoid static
size_t preLastSample = 0;
size_t LastSample = 0;
size_t currSample = 0;
- // sync to first lo-hi transition, and threshold
+ if ( size < 1024 ) return 0; // not enough samples
+
+ //find start of modulating data in trace
+ idx = findModStart(dest, size, threshold_value, fchigh);
// Need to threshold first sample
- // skip 160 samples to allow antenna/samples to settle
- if(dest[160] < threshold_value) dest[0] = 0;
+ if(dest[idx] < threshold_value) dest[0] = 0;
else dest[0] = 1;
-
+ idx++;
+
size_t numBits = 0;
// count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
// or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
// (could also be fc/5 && fc/7 for fsk1 = 4-9)
- for(idx = 161; idx < size-20; idx++) {
+ for(; idx < size-20; idx++) {
// threshold current value
if (dest[idx] < threshold_value) dest[idx] = 0;
//do nothing with extra garbage
} else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
//correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
- if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
+ if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1))){
dest[numBits-1]=1;
}
dest[numBits++]=1;
- } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
- //do nothing with beginning garbage
+ } else if (currSample > (fchigh+1) && numBits < 3) { //12 + and first two bit = unusable garbage
+ //do nothing with beginning garbage and reset.. should be rare..
+ numBits = 0;
} else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
dest[numBits++]=1;
} else { //9+ = 10 sample waves (or 6+ = 7)
continue;
// else new peak
// if we got less than the small fc + tolerance then set it to the small fc
- if (fcCounter < fcLow+fcTol)
+ // if it is inbetween set it to the last counter
+ if (fcCounter < fcHigh && fcCounter > fcLow)
+ fcCounter = lastFCcnt;
+ else if (fcCounter < fcLow+fcTol)
fcCounter = fcLow;
else //set it to the large fc
fcCounter = fcHigh;
}
}
- if (ii<0) return 0; // oops we went too far
+ if (ii<2) return 0; // oops we went too far
return clk[ii];
}
size_t numBits=0;
uint8_t curPhase = *invert;
- size_t i, 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);
+ size_t i=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
+ uint16_t fc=0, fullWaveLen=0, tol=1;
+ uint16_t errCnt=0, waveLenCnt=0, errCnt2=0;
+ fc = countFC(dest, *size, 1);
+ uint8_t fc2 = fc >> 8;
+ if (fc2 == 10) return -1; //fsk found - quit
+ fc = fc & 0xFF;
if (fc!=2 && fc!=4 && fc!=8) return -1;
//PrintAndLog("DEBUG: FC: %d",fc);
*clock = DetectPSKClock(dest, *size, *clock);
if (*clock == 0) return -1;
- int avgWaveVal=0, lastAvgWaveVal=0;
+
+ //find start of modulating data in trace
+ uint8_t threshold_value = 123; //-5
+ i = findModStart(dest, *size, threshold_value, fc);
+
//find first phase shift
- for (i=0; i<loopCnt; i++){
+ int avgWaveVal=0, lastAvgWaveVal=0;
+ waveStart = i;
+ for (; i<loopCnt; i++) {
+ // find peak
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 average wave value is > graph 0 then it is an up wave or a 1 (could cause inverting)
+ if (lastAvgWaveVal > threshold_value) curPhase ^= 1;
break;
}
waveStart = i+1;
//set start of wave as clock align
lastClkBit = firstFullWave;
if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
- if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
+ if (g_debugMode==2) prnt("DEBUG PSK: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
waveStart = 0;
dest[numBits++] = curPhase; //set first read bit
for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
} else if (i+1 > lastClkBit + *clock + tol + fc){
lastClkBit += *clock; //no phase shift but clock bit
dest[numBits++] = curPhase;
+ } else if (waveLenCnt < fc - 1) { //wave is smaller than field clock (shouldn't happen often)
+ errCnt2++;
+ if(errCnt2 > 101) return errCnt2;
}
avgWaveVal = 0;
waveStart = i+1;
projects / proxmark3-svn / blobdiff