]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - common/lfdemod.c
ADD: added the crc8legic to Lua. call it with core.crc8legic
[proxmark3-svn] / common / lfdemod.c
index 21b4cce520f1a107d52c30c9d7f88beceafd6e8e..306f3626d7fbc89a7c3b36f0a8b2d856834db969 100644 (file)
@@ -9,8 +9,22 @@
 //-----------------------------------------------------------------------------
 
 #include <stdlib.h>
-#include <string.h>
 #include "lfdemod.h"
+#include <string.h>
+
+//un_comment to allow debug print calls when used not on device
+void dummy(char *fmt, ...){}
+
+#ifndef ON_DEVICE
+#include "ui.h"
+#include "cmdparser.h"
+#include "cmddata.h"
+#define prnt PrintAndLog
+#else 
+       uint8_t g_debugMode=0;
+#define prnt dummy
+#endif
+
 uint8_t justNoise(uint8_t *BitStream, size_t size)
 {
        static const uint8_t THRESHOLD = 123;
@@ -52,6 +66,80 @@ uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
        return (ans == 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) 
+size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
+{
+       uint32_t parityWd = 0;
+       size_t j = 0, bitCnt = 0;
+       for (int word = 0; word < (bLen); word+=pLen){
+               for (int bit=0; bit < pLen; bit++){
+                       parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
+                       BitStream[j++] = (BitStream[startIdx+word+bit]);
+               }
+               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;                   
+               }
+               bitCnt+=(pLen-1);
+               parityWd = 0;
+       }
+       // if we got here then all the parities passed
+       //return ID start index and size
+       return bitCnt;
+}
+
+// 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)
+size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
+{
+       uint32_t parityWd = 0;
+       size_t j = 0, bitCnt = 0;
+       for (int word = 0; word < sourceLen; word+=pLen-1) {
+               for (int bit=0; bit < pLen-1; bit++){
+                       parityWd = (parityWd << 1) | BitSource[word+bit];
+                       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;
+               }
+               bitCnt += pLen;
+               parityWd = 0;
+       }
+       // if we got here then all the parities passed
+       //return ID start index and size
+       return bitCnt;
+}
+
+uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
+{
+       uint32_t num = 0;
+       for(int i = 0 ; i < numbits ; i++)
+       {
+               num = (num << 1) | (*src);
+               src++;
+       }
+       return num;
+}
+
+//least significant bit first
+uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
+{
+       uint32_t num = 0;
+       for(int i = 0 ; i < numbits ; i++) {
+               num = (num << 1) | *(src + (numbits-(i+1)));
+       }
+       return num;
+}
+
 //by marshmellow
 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
@@ -128,6 +216,7 @@ int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int
                                if (smplCnt > clk-(clk/4)-1) { //full clock
                                        if (smplCnt > clk + (clk/4)+1) { //too many samples
                                                errCnt++;
+                                               if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
                                                BinStream[bitCnt++]=7;
                                        } else if (waveHigh) {
                                                BinStream[bitCnt++] = invert;
@@ -184,6 +273,7 @@ int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr
        if (*clk==0 || start < 0) return -3;
        if (*invert != 1) *invert = 0;
        if (amp==1) askAmp(BinStream, *size);
+       if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
 
        uint8_t initLoopMax = 255;
        if (initLoopMax > *size) initLoopMax = *size;
@@ -196,19 +286,21 @@ int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr
        size_t errCnt = 0;
        // if clean clipped waves detected run alternate demod
        if (DetectCleanAskWave(BinStream, *size, high, low)) {
+               if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
                errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
                if (askType) //askman
                        return manrawdecode(BinStream, size, 0);        
                else //askraw
                        return errCnt;
        }
+       if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
 
        int lastBit;  //set first clock check - can go negative
        size_t i, bitnum = 0;     //output counter
        uint8_t midBit = 0;
        uint8_t tol = 0;  //clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave
        if (*clk <= 32) tol = 1;    //clock tolerance may not be needed anymore currently set to + or - 1 but could be increased for poor waves or removed entirely
-       size_t MaxBits = 1024;
+       size_t MaxBits = 3072;    //max bits to collect
        lastBit = start - *clk;
 
        for (i = start; i < *size; ++i) {
@@ -219,6 +311,7 @@ int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr
                                BinStream[bitnum++] = *invert ^ 1;
                        } else if (i-lastBit >= *clk+tol) {
                                if (bitnum > 0) {
+                                       if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
                                        BinStream[bitnum++]=7;
                                        errCnt++;                                               
                                } 
@@ -385,15 +478,15 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
        // sync to first lo-hi transition, and threshold
 
        // Need to threshold first sample
-
-       if(dest[0] < threshold_value) dest[0] = 0;
+       // skip 160 samples to allow antenna/samples to settle
+       if(dest[160] < threshold_value) dest[0] = 0;
        else dest[0] = 1;
 
        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 with anywhere
        // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
-       for(idx = 1; idx < size; idx++) {
+       for(idx = 161; idx < size-20; idx++) {
                // threshold current value
 
                if (dest[idx] < threshold_value) dest[idx] = 0;
@@ -404,15 +497,15 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
                        preLastSample = LastSample;
                        LastSample = currSample;
                        currSample = idx-last_transition;
-                       if (currSample < (fclow-2)){            //0-5 = garbage noise
+                       if (currSample < (fclow-2)){            //0-5 = garbage noise (or 0-3)
                                //do nothing with extra garbage
-                       } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves
-                               if (LastSample > (fchigh-2) && preLastSample < (fchigh-1)){
-                                       dest[numBits-1]=1;  //correct last 9 wave surrounded by 8 waves
+                       } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves  or 3-6 = 5
+                               if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample     == 0 )){
+                                       dest[numBits-1]=1;  //correct previous 9 wave surrounded by 8 waves
                                }
                                dest[numBits++]=1;
 
-                       } else if (currSample > (fchigh+1) && !numBits) { //12 + and first bit = garbage 
+                       } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage 
                                //do nothing with beginning garbage
                        } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
                                dest[numBits++]=1;
@@ -439,19 +532,8 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
                
                //if lastval was 1, we have a 1->0 crossing
                if (dest[idx-1]==1) {
-                       if (!numBits && n < rfLen/fclow) {
-                               n=0;
-                               lastval = dest[idx];
-                               continue;
-                       }
                        n = (n * fclow + rfLen/2) / rfLen;
                } else {// 0->1 crossing 
-                       //test first bitsample too small
-                       if (!numBits && n < rfLen/fchigh) {
-                               n=0;
-                               lastval = dest[idx];
-                               continue;
-                       }
                        n = (n * fchigh + rfLen/2) / rfLen; 
                }
                if (n == 0) n = 1;
@@ -473,6 +555,7 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
        }
        return numBits;
 }
+
 //by marshmellow  (from holiman's base)
 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
@@ -547,28 +630,6 @@ int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, ui
        return (int)startIdx;
 }
 
-uint32_t bytebits_to_byte(uint8_t* src, size_t numbits)
-{
-       uint32_t num = 0;
-       for(int i = 0 ; i < numbits ; i++)
-       {
-               num = (num << 1) | (*src);
-               src++;
-       }
-       return num;
-}
-
-//least significant bit first
-uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
-{
-       uint32_t num = 0;
-       for(int i = 0 ; i < numbits ; i++)
-       {
-               num = (num << 1) | *(src + (numbits-(i+1)));
-       }
-       return num;
-}
-
 int IOdemodFSK(uint8_t *dest, size_t size)
 {
        if (justNoise(dest, size)) return -1;
@@ -618,33 +679,20 @@ int VikingDemod_AM(uint8_t *dest, size_t *size) {
        return (int) startIdx;
 }
 
-// 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) 
-size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
-{
-       uint32_t parityWd = 0;
-       size_t j = 0, bitCnt = 0;
-       for (int word = 0; word < (bLen); word+=pLen){
-               for (int bit=0; bit < pLen; bit++){
-                       parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
-                       BitStream[j++] = (BitStream[startIdx+word+bit]);
-               }
-               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;                   
-               }
-               bitCnt+=(pLen-1);
-               parityWd = 0;
-       }
-       // if we got here then all the parities passed
-       //return ID start index and size
-       return bitCnt;
+// 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)
@@ -682,7 +730,7 @@ int AWIDdemodFSK(uint8_t *dest, size_t *size)
 }
 
 // by marshmellow
-// FSK Demod then try to locate an Farpointe Data (pyramid) ID
+// FSK Demod then try to locate a Farpointe Data (pyramid) ID
 int PyramiddemodFSK(uint8_t *dest, size_t *size)
 {
        //make sure buffer has data
@@ -707,22 +755,21 @@ int PyramiddemodFSK(uint8_t *dest, size_t *size)
 // to detect a wave that has heavily clipped (clean) samples
 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
 {
-       uint16_t allPeaks=1;
+       bool allArePeaks = true;
        uint16_t cntPeaks=0;
-       size_t loopEnd = 512+60;
+       size_t loopEnd = 512+160;
        if (loopEnd > size) loopEnd = size;
-       for (size_t i=60; i<loopEnd; i++){
+       for (size_t i=160; i<loopEnd; i++){
                if (dest[i]>low && dest[i]<high) 
-                       allPeaks=0;
+                       allArePeaks = false;
                else
                        cntPeaks++;
        }
-       if (allPeaks == 0){
-               if (cntPeaks > 300) return 1;
+       if (!allArePeaks){
+               if (cntPeaks > 300) return true;
        }
-       return allPeaks;
+       return allArePeaks;
 }
-
 // by marshmellow
 // to help detect clocks on heavily clipped samples
 // based on count of low to low
@@ -730,7 +777,7 @@ int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
 {
        uint8_t fndClk[] = {8,16,32,40,50,64,128};
        size_t startwave;
-       size_t i = 0;
+       size_t i = 100;
        size_t minClk = 255;
                // get to first full low to prime loop and skip incomplete first pulse
        while ((dest[i] < high) && (i < size))
@@ -753,6 +800,7 @@ int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
                        minClk = i - startwave;
        }
        // set clock
+       if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
        for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
                if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
                        return fndClk[clkCnt];
@@ -770,8 +818,8 @@ int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
        uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
        uint8_t clkEnd = 9;
        uint8_t loopCnt = 255;  //don't need to loop through entire array...
-       if (size <= loopCnt) return -1; //not enough samples
-
+       if (size <= loopCnt+60) return -1; //not enough samples
+       size -= 60; //sometimes there is a strange end wave - filter out this....
        //if we already have a valid clock
        uint8_t clockFnd=0;
        for (;i<clkEnd;++i)
@@ -786,6 +834,7 @@ int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
        if (!clockFnd){
                if (DetectCleanAskWave(dest, size, peak, low)==1){
                        int ans = DetectStrongAskClock(dest, size, peak, low);
+                       if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
                        for (i=clkEnd-1; i>0; i--){
                                if (clk[i] == ans) {
                                        *clock = ans;
@@ -796,7 +845,6 @@ int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
                        }
                }
        }
-       
        uint8_t ii;
        uint8_t clkCnt, tol = 0;
        uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
@@ -838,7 +886,7 @@ int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
                        }
                        //if we found no errors then we can stop here and a low clock (common clocks)
                        //  this is correct one - return this clock
-                                       //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
+                       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;
@@ -860,8 +908,8 @@ int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
                                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 (bestErr[best] > maxErr) return -1;
        if (!clockFnd) *clock = clk[best];
        return bestStart[best];
 }
@@ -874,7 +922,7 @@ int DetectPSKClock(uint8_t dest[], size_t size, int clock)
        uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
        uint16_t loopCnt = 4096;  //don't need to loop through entire array...
        if (size == 0) return 0;
-       if (size<loopCnt) loopCnt = size;
+       if (size<loopCnt) loopCnt = size-20;
 
        //if we already have a valid clock quit
        size_t i=1;
@@ -888,17 +936,17 @@ int DetectPSKClock(uint8_t dest[], size_t size, int clock)
        uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
        fc = countFC(dest, size, 0);
        if (fc!=2 && fc!=4 && fc!=8) return -1;
-       //PrintAndLog("DEBUG: FC: %d",fc);
+       if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
 
        //find first full wave
-       for (i=0; i<loopCnt; i++){
+       for (i=160; i<loopCnt; i++){
                if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
                        if (waveStart == 0) {
                                waveStart = i+1;
-                               //PrintAndLog("DEBUG: waveStart: %d",waveStart);
+                               //prnt("DEBUG: waveStart: %d",waveStart);
                        } else {
                                waveEnd = i+1;
-                               //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
+                               //prnt("DEBUG: waveEnd: %d",waveEnd);
                                waveLenCnt = waveEnd-waveStart;
                                if (waveLenCnt > fc){
                                        firstFullWave = waveStart;
@@ -909,7 +957,7 @@ int DetectPSKClock(uint8_t dest[], size_t size, int clock)
                        }
                }
        }
-       //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
+       if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
        
        //test each valid clock from greatest to smallest to see which lines up
        for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
@@ -917,7 +965,7 @@ int DetectPSKClock(uint8_t dest[], size_t size, int clock)
                waveStart = 0;
                errCnt=0;
                peakcnt=0;
-               //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
+               if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
 
                for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
                        //top edge of wave = start of new wave 
@@ -930,7 +978,7 @@ int DetectPSKClock(uint8_t dest[], size_t size, int clock)
                                        waveLenCnt = waveEnd-waveStart;
                                        if (waveLenCnt > fc){ 
                                                //if this wave is a phase shift
-                                               //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
+                                               if (g_debugMode == 2) prnt("DEBUG PSK: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,i+1,fc);
                                                if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
                                                        peakcnt++;
                                                        lastClkBit+=clk[clkCnt];
@@ -959,11 +1007,40 @@ int DetectPSKClock(uint8_t dest[], size_t size, int clock)
                if (peaksdet[i] > peaksdet[best]) {
                        best = i;
                }
-               //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
+               if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
        }
        return clk[best];
 }
 
+int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
+       //find shortest transition from high to low
+       size_t i = 0;
+       size_t transition1 = 0;
+       int lowestTransition = 255;
+       bool lastWasHigh = false;
+
+       //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;
+               }
+       }
+       if (lowestTransition == 255) lowestTransition = 0;
+       if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",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)
@@ -972,8 +1049,7 @@ int DetectNRZClock(uint8_t dest[], size_t size, int clock)
        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;
-
+       if (size<loopCnt) loopCnt = size-20;
        //if we already have a valid clock quit
        for (; i < 8; ++i)
                if (clk[i] == clock) return clock;
@@ -982,38 +1058,82 @@ int DetectNRZClock(uint8_t dest[], size_t size, int clock)
        int peak, low;
        if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
 
-       //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
+       int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
        size_t ii;
        uint8_t clkCnt;
        uint8_t tol = 0;
-       uint16_t peakcnt=0;
-       uint16_t peaksdet[]={0,0,0,0,0,0,0,0};
-       uint16_t maxPeak=0;
+       uint16_t smplCnt = 0;
+       int16_t peakcnt = 0;
+       int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
+       uint16_t maxPeak = 255;
+       bool firstpeak = false;
        //test for large clipped waves
        for (i=0; i<loopCnt; i++){
                if (dest[i] >= peak || dest[i] <= low){
-                       peakcnt++;
+                       if (!firstpeak) continue;
+                       smplCnt++;
                } else {
-                       if (peakcnt>0 && maxPeak < peakcnt){
-                               maxPeak = peakcnt;
+                       firstpeak=true;
+                       if (smplCnt > 6 ){
+                               if (maxPeak > smplCnt){
+                                       maxPeak = smplCnt;
+                                       //prnt("maxPk: %d",maxPeak);
+                               }
+                               peakcnt++;
+                               //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
+                               smplCnt=0;
                        }
-                       peakcnt=0;
                }
        }
+       bool errBitHigh = 0;
+       bool bitHigh = 0;
+       uint8_t ignoreCnt = 0;
+       uint8_t ignoreWindow = 4;
+       bool lastPeakHigh = 0;
+       int lastBit = 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 largest peak
-               if (clk[clkCnt]<maxPeak) continue;
-
+               //ignore clocks smaller than smallest peak
+               if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
                //try lining up the peaks by moving starting point (try first 256)
-               for (ii=0; ii< loopCnt; ++ii){
+               for (ii=20; ii < loopCnt; ++ii){
                        if ((dest[ii] >= peak) || (dest[ii] <= low)){
                                peakcnt=0;
-                               // now that we have the first one lined up test rest of wave array
-                               for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
-                                       if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
+                               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;
                                        }
                                }
                                if(peakcnt>peaksdet[clkCnt]) {
@@ -1025,11 +1145,16 @@ int DetectNRZClock(uint8_t dest[], size_t size, int clock)
        int iii=7;
        uint8_t best=0;
        for (iii=7; iii > 0; iii--){
-               if (peaksdet[iii] > peaksdet[best]){
+               if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
+                       if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
+                       best = iii;
+               }
+               } else if (peaksdet[iii] > peaksdet[best]){
                        best = iii;
                }
-               //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
+               if (g_debugMode==2) prnt("DEBUG NRZ: Clk: %d, peaks: %d, maxPeak: %d, bestClk: %d, lowestTrs: %d",clk[iii],peaksdet[iii],maxPeak, clk[best], lowestTransition);
        }
+
        return clk[best];
 }
 
@@ -1089,123 +1214,37 @@ int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
        return (int) startidx;
 }
 
-// by marshmellow - demodulate NRZ wave (both similar enough)
+// by marshmellow - demodulate NRZ wave - requires a read with strong signal
 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
-// there probably is a much simpler way to do this.... 
-int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert, int maxErr)
-{
+int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
        if (justNoise(dest, *size)) return -1;
        *clk = DetectNRZClock(dest, *size, *clk);
        if (*clk==0) return -2;
        size_t i, gLen = 4096;
-       if (gLen>*size) gLen = *size;
+       if (gLen>*size) gLen = *size-20;
        int high, low;
        if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
-       int lastBit = 0;  //set first clock check
-       size_t iii = 0, bitnum = 0; //bitnum counter
-       uint16_t errCnt = 0, MaxBits = 1000;
-       size_t bestErrCnt = maxErr+1;
-       size_t bestPeakCnt = 0, bestPeakStart = 0;
-       uint8_t bestFirstPeakHigh=0, firstPeakHigh=0, curBit=0, bitHigh=0, errBitHigh=0;
-       uint8_t tol = 1;  //clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave
-       uint16_t peakCnt=0;
-       uint8_t ignoreWindow=4;
-       uint8_t ignoreCnt=ignoreWindow; //in case of noise near peak
-       //loop to find first wave that works - align to clock
-       for (iii=0; iii < gLen; ++iii){
-               if ((dest[iii]>=high) || (dest[iii]<=low)){
-                       if (dest[iii]>=high) firstPeakHigh=1;
-                       else firstPeakHigh=0;
-                       lastBit=iii-*clk;
-                       peakCnt=0;
-                       errCnt=0;
-                       //loop through to see if this start location works
-                       for (i = iii; i < *size; ++i) {
-                               // if we are at a clock bit
-                               if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
-                                       //test high/low
-                                       if (dest[i] >= high || dest[i] <= low) {
-                                               bitHigh = 1;
-                                               peakCnt++;
-                                               errBitHigh = 0;
-                                               ignoreCnt = ignoreWindow;
-                                               lastBit += *clk;
-                                       } else if (i == lastBit + *clk + tol) {
-                                               lastBit += *clk;
-                                       }
-                               //else if no bars found
-                               } else if (dest[i] < high && dest[i] > low){
-                                       if (ignoreCnt==0){
-                                               bitHigh=0;
-                                               if (errBitHigh==1) errCnt++;
-                                               errBitHigh=0;
-                                       } else {
-                                               ignoreCnt--;
-                                       }
-                               } else if ((dest[i]>=high || dest[i]<=low) && (bitHigh==0)) {
-                                       //error bar found no clock...
-                                       errBitHigh=1;
-                               }
-                               if (((i-iii) / *clk)>=MaxBits) break;
-                       }
-                       //we got more than 64 good bits and not all errors
-                       if (((i-iii) / *clk) > 64 && (errCnt <= (maxErr))) {
-                               //possible good read
-                               if (!errCnt || peakCnt > bestPeakCnt){
-                                       bestFirstPeakHigh=firstPeakHigh;
-                                       bestErrCnt = errCnt;
-                                       bestPeakCnt = peakCnt;
-                                       bestPeakStart = iii;
-                                       if (!errCnt) break;  //great read - finish
-                               }
-                       }
-               }
+
+       uint8_t bit=0;
+       //convert wave samples to 1's and 0's
+       for(i=20; i < *size-20; i++){
+               if (dest[i] >= high) bit = 1;
+               if (dest[i] <= low)  bit = 0;
+               dest[i] = bit;
        }
-       //PrintAndLog("DEBUG: bestErrCnt: %d, maxErr: %d, bestStart: %d, bestPeakCnt: %d, bestPeakStart: %d",bestErrCnt,maxErr,bestStart,bestPeakCnt,bestPeakStart);
-       if (bestErrCnt > maxErr) return bestErrCnt;             
-
-       //best run is good enough set to best run and set overwrite BinStream
-       lastBit = bestPeakStart - *clk;
-       memset(dest, bestFirstPeakHigh^1, bestPeakStart / *clk);
-       bitnum += (bestPeakStart / *clk);
-       for (i = bestPeakStart; i < *size; ++i) {
-               // if expecting a clock bit
-               if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
-                       // test high/low
-                       if (dest[i] >= high || dest[i] <= low) {
-                               peakCnt++;
-                               bitHigh = 1;
-                               errBitHigh = 0;
-                               ignoreCnt = ignoreWindow;
-                               curBit = *invert;
-                               if (dest[i] >= high) curBit ^= 1;
-                               dest[bitnum++] = curBit;
-                               lastBit += *clk;
-                       //else no bars found in clock area
-                       } else if (i == lastBit + *clk + tol) {
-                               dest[bitnum++] = curBit;
-                               lastBit += *clk;
-                       }
-               //else if no bars found
-               } else if (dest[i] < high && dest[i] > low){
-                       if (ignoreCnt == 0){
-                               bitHigh = 0;
-                               if (errBitHigh == 1){
-                                       dest[bitnum++] = 7;
-                                       errCnt++;
-                               }
-                               errBitHigh=0;
-                       } else {
-                               ignoreCnt--;
-                       }
-               } else if ((dest[i] >= high || dest[i] <= low) && (bitHigh == 0)) {
-                       //error bar found no clock...
-                       errBitHigh=1;
+       //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit) 
+       size_t lastBit = 0;
+       size_t numBits = 0;
+       for(i=21; i < *size-20; i++) {
+               //if transition detected or large number of same bits - store the passed bits
+               if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
+                       memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
+                       numBits += (i - lastBit + (*clk/4)) / *clk;
+                       lastBit = i-1;
                }
-               if (bitnum >= MaxBits) break;
        }
-       *size = bitnum;
-       return bestErrCnt;
+       *size = numBits;
+       return 0;
 }
 
 //by marshmellow
@@ -1223,18 +1262,18 @@ uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fc
        size_t i;
        if (size == 0) return 0;
 
-       uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
+       uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
        rfLensFnd=0;
        fcCounter=0;
        rfCounter=0;
        firstBitFnd=0;
        //PrintAndLog("DEBUG: fcTol: %d",fcTol);
-       // prime i to first up transition
-       for (i = 1; i < size-1; i++)
+       // prime i to first peak / up transition
+       for (i = 160; i < size-20; i++)
                if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
                        break;
 
-       for (; i < size-1; i++){
+       for (; i < size-20; i++){
                fcCounter++;
                rfCounter++;
 
@@ -1252,7 +1291,7 @@ uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fc
                        //not the same size as the last wave - start of new bit sequence
                        if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
                                for (int ii=0; ii<15; ii++){
-                                       if (rfLens[ii] == rfCounter){
+                                       if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
                                                rfCnts[ii]++;
                                                rfCounter = 0;
                                                break;
@@ -1274,7 +1313,6 @@ uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fc
        uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
 
        for (i=0; i<15; i++){
-               //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
                //get highest 2 RF values  (might need to get more values to compare or compare all?)
                if (rfCnts[i]>rfCnts[rfHighest]){
                        rfHighest3=rfHighest2;
@@ -1286,20 +1324,23 @@ uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fc
                } else if(rfCnts[i]>rfCnts[rfHighest3]){
                        rfHighest3=i;
                }
+               if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
        }  
        // set allowed clock remainder tolerance to be 1 large field clock length+1 
        //   we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off  
        uint8_t tol1 = fcHigh+1; 
        
-       //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
+       if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
 
        // loop to find the highest clock that has a remainder less than the tolerance
        //   compare samples counted divided by
+       // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
        int ii=7;
-       for (; ii>=0; ii--){
+       for (; ii>=2; ii--){
                if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
                        if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
                                if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
+                                       if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
                                        break;
                                }
                        }
@@ -1317,8 +1358,8 @@ uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fc
 //mainly used for FSK field clock detection
 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
 {
-       uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
-       uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
+       uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
+       uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
        uint8_t fcLensFnd = 0;
        uint8_t lastFCcnt=0;
        uint8_t fcCounter = 0;
@@ -1326,11 +1367,11 @@ uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
        if (size == 0) return 0;
 
        // prime i to first up transition
-       for (i = 1; i < size-1; i++)
+       for (i = 160; i < size-20; i++)
                if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
                        break;
 
-       for (; i < size-1; i++){
+       for (; i < size-20; i++){
                if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
                        // new up transition
                        fcCounter++;
@@ -1343,14 +1384,14 @@ uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
                        lastFCcnt = fcCounter;
                        }
                        // find which fcLens to save it to:
-                       for (int ii=0; ii<10; ii++){
+                       for (int ii=0; ii<15; ii++){
                                if (fcLens[ii]==fcCounter){
                                        fcCnts[ii]++;
                                        fcCounter=0;
                                        break;
                                }
                        }
-                       if (fcCounter>0 && fcLensFnd<10){
+                       if (fcCounter>0 && fcLensFnd<15){
                                //add new fc length 
                                fcCnts[fcLensFnd]++;
                                fcLens[fcLensFnd++]=fcCounter;
@@ -1362,11 +1403,10 @@ uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
                }
        }
        
-       uint8_t best1=9, best2=9, best3=9;
+       uint8_t best1=14, best2=14, best3=14;
        uint16_t maxCnt1=0;
        // go through fclens and find which ones are bigest 2  
-       for (i=0; i<10; i++){
-               // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);    
+       for (i=0; i<15; i++){
                // get the 3 best FC values
                if (fcCnts[i]>maxCnt1) {
                        best3=best2;
@@ -1379,7 +1419,9 @@ uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
                } else if(fcCnts[i]>fcCnts[best3]){
                        best3=i;
                }
+               if (g_debugMode==2) prnt("DEBUG countfc: FC %u, Cnt %u, best fc: %u, best2 fc: %u",fcLens[i],fcCnts[i],fcLens[best1],fcLens[best2]);
        }
+       if (fcLens[best1]==0) return 0;
        uint8_t fcH=0, fcL=0;
        if (fcLens[best1]>fcLens[best2]){
                fcH=fcLens[best1];
@@ -1388,11 +1430,13 @@ uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
                fcH=fcLens[best2];
                fcL=fcLens[best1];
        }
-
+       if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
+               if (g_debugMode==2) prnt("DEBUG countfc: fc is too large: %u > %u. Not psk or fsk",(size-180)/fcH/3,fcCnts[best1]+fcCnts[best2]);
+               return 0; //lots of waves not psk or fsk
+       }
        // TODO: take top 3 answers and compare to known Field clocks to get top 2
 
        uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
-       // PrintAndLog("DEBUG: Best %d  best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
        if (fskAdj) return fcs; 
        return fcLens[best1];
 }
@@ -1405,6 +1449,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
        uint16_t loopCnt = 4096;  //don't need to loop through entire array...
        if (*size<loopCnt) loopCnt = *size;
 
+       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;
@@ -1421,7 +1466,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
                        waveEnd = i+1;
                        //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
                        waveLenCnt = waveEnd-waveStart;
-                       if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave 
+                       if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
                                lastAvgWaveVal = avgWaveVal/(waveLenCnt);
                                firstFullWave = waveStart;
                                fullWaveLen=waveLenCnt;
@@ -1434,14 +1479,21 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
                }
                avgWaveVal += dest[i+2];
        }
+       if (firstFullWave == 0) {
+               // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
+               // so skip a little to ensure we are past any Start Signal
+               firstFullWave = 160;
+               memset(dest, curPhase, firstFullWave / *clock);
+       } else {
+               memset(dest, curPhase^1, firstFullWave / *clock);
+       }
+       //advance bits
+       numBits += (firstFullWave / *clock);
+       //set start of wave as clock align
+       lastClkBit = firstFullWave;
        //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);  
-       lastClkBit = firstFullWave; //set start of wave as clock align
        //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
        waveStart = 0;
-       size_t numBits=0;
-       //set skipped bits
-       memset(dest, curPhase^1, firstFullWave / *clock);
-       numBits += (firstFullWave / *clock);
        dest[numBits++] = curPhase; //set first read bit
        for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
                //top edge of wave = start of new wave 
@@ -1481,3 +1533,166 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
        *size = numBits;
        return errCnt;
 }
+
+//by marshmellow
+//attempt to identify a Sequence Terminator in ASK modulated raw wave
+bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
+       size_t bufsize = *size;
+       //need to loop through all samples and identify our clock, look for the ST pattern
+       uint8_t fndClk[] = {8,16,32,40,50,64,128};
+       int clk = 0; 
+       int tol = 0;
+       int i, j, skip, start, end, low, high, minClk, waveStart;
+       bool complete = false;
+       int tmpbuff[bufsize / 64];
+       int waveLen[bufsize / 64];
+       size_t testsize = (bufsize < 512) ? bufsize : 512;
+       int phaseoff = 0;
+       high = low = 128;
+       memset(tmpbuff, 0, sizeof(tmpbuff));
+
+       if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
+               if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
+               return false; //just noise
+       }
+       i = 0;
+       j = 0;
+       minClk = 255;
+       // get to first full low to prime loop and skip incomplete first pulse
+       while ((buffer[i] < high) && (i < bufsize))
+               ++i;
+       while ((buffer[i] > low) && (i < bufsize))
+               ++i;
+       skip = i;
+
+       // populate tmpbuff buffer with pulse lengths
+       while (i < bufsize) {
+               // measure from low to low
+               while ((buffer[i] > low) && (i < bufsize))
+                       ++i;
+               start= i;
+               while ((buffer[i] < high) && (i < bufsize))
+                       ++i;
+               //first high point for this wave
+               waveStart = i;
+               while ((buffer[i] > low) && (i < bufsize))
+                       ++i;
+               if (j >= (bufsize/64)) {
+                       break;
+               }
+               waveLen[j] = i - waveStart; //first high to first low
+               tmpbuff[j++] = i - start;
+               if (i-start < minClk && i < bufsize) {
+                       minClk = i - start;
+               }
+       }
+       // set clock  - might be able to get this externally and remove this work...
+       if (!clk) {
+               for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
+                       tol = fndClk[clkCnt]/8;
+                       if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) { 
+                               clk=fndClk[clkCnt];
+                               break;
+                       }
+               }
+               // clock not found - ERROR
+               if (!clk) {
+                       if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
+                       return false;
+               }
+       } else tol = clk/8;
+
+       *foundclock = clk;
+
+       // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
+       start = -1;
+       for (i = 0; i < j - 4; ++i) {
+               skip += tmpbuff[i];
+               if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) {           //1 to 2 clocks depending on 2 bits prior
+                       if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) {       //2 clocks and wave size is 1 1/2
+                               if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
+                                       if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
+                                               start = i + 3;
+                                               break;
+                                       }
+                               }
+                       }
+               }
+       }
+       // first ST not found - ERROR
+       if (start < 0) {
+               if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
+               return false;
+       }
+       if (waveLen[i+2] > clk*1+tol)
+               phaseoff = 0;
+       else
+               phaseoff = clk/2;
+       
+       // skip over the remainder of ST
+       skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
+
+       // now do it again to find the end
+       end = skip;
+       for (i += 3; i < j - 4; ++i) {
+               end += tmpbuff[i];
+               if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) {           //1 to 2 clocks depending on 2 bits prior
+                       if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) {       //2 clocks and wave size is 1 1/2
+                               if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
+                                       if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
+                                               complete = true;
+                                               break;
+                                       }
+                               }
+                       }
+               }
+       }
+       end -= phaseoff;
+       //didn't find second ST - ERROR
+       if (!complete) {
+               if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
+               return false;
+       }
+       if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d, phaseoff: %d", skip, end, end-skip, clk, (end-skip)/clk, phaseoff);
+       //now begin to trim out ST so we can use normal demod cmds
+       start = skip;
+       size_t datalen = end - start;
+       // check validity of datalen (should be even clock increments)  - use a tolerance of up to 1/8th a clock
+       if (datalen % clk > clk/8) {
+               if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
+               return false;
+       } else {
+               // padd the amount off - could be problematic...  but shouldn't happen often
+               datalen += datalen % clk;
+       }
+       // if datalen is less than one t55xx block - ERROR
+       if (datalen/clk < 8*4) {
+               if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");              
+               return false;
+       }
+       size_t dataloc = start;
+       size_t newloc = 0;
+       i=0;
+       // warning - overwriting buffer given with raw wave data with ST removed...
+       while ( dataloc < bufsize-(clk/2) ) {
+               //compensate for long high at end of ST not being high... (we cut out the high part)
+               if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
+                       for(i=0; i < clk/2-tol; ++i) {
+                               buffer[dataloc+i] = high+5;
+                       }
+               }
+               for (i=0; i<datalen; ++i) {
+                       if (i+newloc < bufsize) {
+                               if (i+newloc < dataloc)
+                                       buffer[i+newloc] = buffer[dataloc];
+
+                               dataloc++;                              
+                       }
+               }
+               newloc += i;
+               //skip next ST
+               dataloc += clk*4;
+       }
+       *size = newloc;
+       return true;
+}
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