+ //if we found no errors then we can stop here and a low clock (common clocks)
+ // this is correct one - return this clock
+ if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
+ if(errCnt==0 && clkCnt<7) {
+ if (!clockFnd) *clock = clk[clkCnt];
+ return ii;
+ }
+ //if we found errors see if it is lowest so far and save it as best run
+ if(errCnt<bestErr[clkCnt]){
+ bestErr[clkCnt]=errCnt;
+ bestStart[clkCnt]=ii;
+ }
+ }
+ }
+ uint8_t iii;
+ uint8_t best=0;
+ for (iii=1; iii<clkEnd; ++iii){
+ if (bestErr[iii] < bestErr[best]){
+ if (bestErr[iii] == 0) bestErr[iii]=1;
+ // current best bit to error ratio vs new bit to error ratio
+ if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
+ best = iii;
+ }
+ }
+ if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d",clk[iii],bestErr[iii],clk[best],bestStart[best]);
+ }
+ if (!clockFnd) *clock = clk[best];
+ return bestStart[best];
+}
+
+int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low, bool *strong) {
+ //find shortest transition from high to low
+ *strong = false;
+ size_t i = 0;
+ size_t transition1 = 0;
+ int lowestTransition = 255;
+ bool lastWasHigh = false;
+ size_t transitionSampleCount = 0;
+ //find first valid beginning of a high or low wave
+ while ((dest[i] >= peak || dest[i] <= low) && (i < size))
+ ++i;
+ while ((dest[i] < peak && dest[i] > low) && (i < size))
+ ++i;
+ lastWasHigh = (dest[i] >= peak);
+
+ if (i==size) return 0;
+ transition1 = i;
+
+ for (;i < size; i++) {
+ if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
+ lastWasHigh = (dest[i] >= peak);
+ if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
+ transition1 = i;
+ } else if (dest[i] < peak && dest[i] > low) {
+ transitionSampleCount++;
+ }
+ }
+ if (lowestTransition == 255) lowestTransition = 0;
+ if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
+ // if less than 10% of the samples were not peaks (or 90% were peaks) then we have a strong wave
+ if (transitionSampleCount / size < 10) {
+ *strong = true;
+ lowestTransition = getClosestClock(lowestTransition);
+ }
+ return lowestTransition;
+}
+
+//by marshmellow
+//detect nrz clock by reading #peaks vs no peaks(or errors)
+int DetectNRZClock(uint8_t dest[], size_t size, int clock, size_t *clockStartIdx) {
+ size_t i=0;
+ uint8_t clk[]={8,16,32,40,50,64,100,128,255};
+ size_t loopCnt = 4096; //don't need to loop through entire array...
+ if (size == 0) return 0;
+ if (size<loopCnt) loopCnt = size-20;
+ //if we already have a valid clock quit
+ for (; i < 8; ++i)
+ if (clk[i] == clock) return clock;
+
+ //get high and low peak
+ int peak, low;
+ if (getHiLo(dest, loopCnt, &peak, &low, 90, 90) < 1) return 0;
+
+ bool strong = false;
+ int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low, &strong);
+ if (strong) return lowestTransition;
+ size_t ii;
+ uint8_t clkCnt;
+ uint8_t tol = 0;
+ uint16_t smplCnt = 0;
+ int16_t peakcnt = 0;
+ int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
+ uint16_t minPeak = 255;
+ bool firstpeak = true;
+ //test for large clipped waves - ignore first peak
+ for (i=0; i<loopCnt; i++) {
+ if (dest[i] >= peak || dest[i] <= low) {
+ if (firstpeak) continue;
+ smplCnt++;
+ } else {
+ firstpeak = false;
+ if (smplCnt > 0) {
+ if (minPeak > smplCnt && smplCnt > 7) minPeak = smplCnt;
+ peakcnt++;
+ if (g_debugMode == 2) prnt("DEBUG NRZ: minPeak: %d, smplCnt: %d, peakcnt: %d",minPeak,smplCnt,peakcnt);
+ smplCnt = 0;
+ }
+ }
+ }
+ if (minPeak < 8) return 0;
+ bool errBitHigh = 0;
+ bool bitHigh = 0;
+ uint8_t ignoreCnt = 0;
+ uint8_t ignoreWindow = 4;
+ bool lastPeakHigh = 0;
+ int lastBit = 0;
+ size_t bestStart[]={0,0,0,0,0,0,0,0,0};
+ peakcnt=0;
+ //test each valid clock from smallest to greatest to see which lines up
+ for(clkCnt=0; clkCnt < 8; ++clkCnt) {
+ //ignore clocks smaller than smallest peak
+ if (clk[clkCnt] < minPeak - (clk[clkCnt]/4)) continue;
+ //try lining up the peaks by moving starting point (try first 256)
+ for (ii=20; ii < loopCnt; ++ii) {
+ if ((dest[ii] >= peak) || (dest[ii] <= low)) {
+ peakcnt = 0;
+ bitHigh = false;
+ ignoreCnt = 0;
+ lastBit = ii-clk[clkCnt];
+ //loop through to see if this start location works
+ for (i = ii; i < size-20; ++i) {
+ //if we are at a clock bit
+ if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
+ //test high/low
+ if (dest[i] >= peak || dest[i] <= low) {
+ //if same peak don't count it
+ if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
+ peakcnt++;
+ }
+ lastPeakHigh = (dest[i] >= peak);
+ bitHigh = true;
+ errBitHigh = false;
+ ignoreCnt = ignoreWindow;
+ lastBit += clk[clkCnt];
+ } else if (i == lastBit + clk[clkCnt] + tol) {
+ lastBit += clk[clkCnt];
+ }
+ //else if not a clock bit and no peaks
+ } else if (dest[i] < peak && dest[i] > low) {
+ if (ignoreCnt==0) {
+ bitHigh=false;
+ if (errBitHigh==true) peakcnt--;
+ errBitHigh=false;
+ } else {
+ ignoreCnt--;
+ }
+ // else if not a clock bit but we have a peak
+ } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
+ //error bar found no clock...
+ errBitHigh=true;
+ }
projects / proxmark3-svn / blobdiff