lf search use new psk, small demod adjustments

[proxmark3-svn] / common / lfdemod.c

//-----------------------------------------------------------------------------
// Copyright (C) 2014
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Low frequency commands
//-----------------------------------------------------------------------------

#include <stdlib.h>
#include <string.h>
#include "lfdemod.h"

//by marshmellow
//takes 1s and 0s and searches for EM410x format - output EM ID
uint64_t Em410xDecode(uint8_t *BitStream, size_t size)
{
        //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
        //  otherwise could be a void with no arguments
        //set defaults
        int high=0, low=128;
        uint64_t lo=0;

        uint32_t i = 0;
        uint32_t initLoopMax = 65;
        if (initLoopMax>size) initLoopMax=size;

        for (;i < initLoopMax; ++i) //65 samples should be plenty to find high and low values
        {
                if (BitStream[i] > high)
                        high = BitStream[i];
                else if (BitStream[i] < low)
                        low = BitStream[i];
        }
        if (((high !=1)||(low !=0))){  //allow only 1s and 0s
                // PrintAndLog("no data found");
                return 0;
        }
        uint8_t parityTest=0;
        // 111111111 bit pattern represent start of frame
        uint8_t frame_marker_mask[] = {1,1,1,1,1,1,1,1,1};
        uint32_t idx = 0;
        uint32_t ii=0;
        uint8_t resetCnt = 0;
        while( (idx + 64) < size) {
 restart:
                // search for a start of frame marker
                if ( memcmp(BitStream+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
                { // frame marker found
                        idx+=9;
                        for (i=0; i<10;i++){
                                for(ii=0; ii<5; ++ii){
                                        parityTest += BitStream[(i*5)+ii+idx];
                                }
                                if (parityTest== ((parityTest>>1)<<1)){
                                        parityTest=0;
                                        for (ii=0; ii<4;++ii){
                                                lo=(lo<<1LL)|(BitStream[(i*5)+ii+idx]);
                                        }
                                        //PrintAndLog("DEBUG: EM parity passed parity val: %d, i:%d, ii:%d,idx:%d, Buffer: %d%d%d%d%d,lo: %d",parityTest,i,ii,idx,BitStream[idx+ii+(i*5)-5],BitStream[idx+ii+(i*5)-4],BitStream[idx+ii+(i*5)-3],BitStream[idx+ii+(i*5)-2],BitStream[idx+ii+(i*5)-1],lo);
                                }else {//parity failed
                                        //PrintAndLog("DEBUG: EM parity failed parity val: %d, i:%d, ii:%d,idx:%d, Buffer: %d%d%d%d%d",parityTest,i,ii,idx,BitStream[idx+ii+(i*5)-5],BitStream[idx+ii+(i*5)-4],BitStream[idx+ii+(i*5)-3],BitStream[idx+ii+(i*5)-2],BitStream[idx+ii+(i*5)-1]);
                                        parityTest=0;
                                        idx-=8;
                                        if (resetCnt>5)return 0;
                                        resetCnt++;
                                        goto restart;//continue;
                                }
                        }
                        //skip last 5 bit parity test for simplicity.
                        return lo;
                }else{
                        idx++;
                }
        }
        return 0;
}

//by marshmellow
//takes 2 arguments - clock and invert both as integers
//attempts to demodulate ask while decoding manchester
//prints binary found and saves in graphbuffer for further commands
int askmandemod(uint8_t *BinStream, size_t *size, int *clk, int *invert)
{
        int i;
        int high = 0, low = 128;
        *clk=DetectASKClock(BinStream, *size, *clk); //clock default

        if (*clk<8) *clk =64;
        if (*clk<32) *clk=32;
        if (*invert != 0 && *invert != 1) *invert=0;
        uint32_t initLoopMax = 200;
        if (initLoopMax > *size) initLoopMax=*size;
        // Detect high and lows
        for (i = 0; i < initLoopMax; ++i) //200 samples should be enough to find high and low values
        {
                if (BinStream[i] > high)
                        high = BinStream[i];
                else if (BinStream[i] < low)
                        low = BinStream[i];
        }
        if ((high < 158) ){  //throw away static
                //PrintAndLog("no data found");
                return -2;
        }
        //25% fuzz in case highs and lows aren't clipped [marshmellow]
        high=(int)(((high-128)*.75)+128);
        low= (int)(((low-128)*.75)+128);

        //PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
        int lastBit = 0;  //set first clock check
        uint32_t bitnum = 0;     //output counter
        int 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
        int iii = 0;
        uint32_t gLen = *size;
        if (gLen > 3000) gLen=3000;
        uint8_t errCnt =0;
        uint32_t bestStart = *size;
        uint32_t bestErrCnt = (*size/1000);
        uint32_t maxErr = (*size/1000);
        //PrintAndLog("DEBUG - lastbit - %d",lastBit);
        //loop to find first wave that works
        for (iii=0; iii < gLen; ++iii){
                if ((BinStream[iii] >= high) || (BinStream[iii] <= low)){
                        lastBit=iii-*clk;
                        errCnt=0;
                        //loop through to see if this start location works
                        for (i = iii; i < *size; ++i) {
                                if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
                                        lastBit+=*clk;
                                } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
                                        //low found and we are expecting a bar
                                        lastBit+=*clk;
                                } else {
                                        //mid value found or no bar supposed to be here
                                        if ((i-lastBit)>(*clk+tol)){
                                                //should have hit a high or low based on clock!!

                                                //debug
                                                //PrintAndLog("DEBUG - no wave in expected area - location: %d, expected: %d-%d, lastBit: %d - resetting search",i,(lastBit+(clk-((int)(tol)))),(lastBit+(clk+((int)(tol)))),lastBit);

                                                errCnt++;
                                                lastBit+=*clk;//skip over until hit too many errors
                                                if (errCnt>(maxErr)) break;  //allow 1 error for every 1000 samples else start over
                                        }
                                }
                                if ((i-iii) >(400 * *clk)) break; //got plenty of bits
                        }
                        //we got more than 64 good bits and not all errors
                        if ((((i-iii)/ *clk) > (64+errCnt)) && (errCnt<maxErr)) {
                                //possible good read
                                if (errCnt==0){
                                        bestStart=iii;
                                        bestErrCnt=errCnt;
                                        break;  //great read - finish
                                }
                                if (errCnt<bestErrCnt){  //set this as new best run
                                        bestErrCnt=errCnt;
                                        bestStart = iii;
                                }
                        }
                }
        }
        if (bestErrCnt<maxErr){
                //best run is good enough set to best run and set overwrite BinStream
                iii=bestStart;
                lastBit = bestStart - *clk;
                bitnum=0;
                for (i = iii; i < *size; ++i) {
                        if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
                                lastBit += *clk;
                                BinStream[bitnum] = *invert;
                                bitnum++;
                        } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
                                //low found and we are expecting a bar
                                lastBit+=*clk;
                                BinStream[bitnum] = 1-*invert;
                                bitnum++;
                        } else {
                                //mid value found or no bar supposed to be here
                                if ((i-lastBit)>(*clk+tol)){
                                        //should have hit a high or low based on clock!!

                                        //debug
                                        //PrintAndLog("DEBUG - no wave in expected area - location: %d, expected: %d-%d, lastBit: %d - resetting search",i,(lastBit+(clk-((int)(tol)))),(lastBit+(clk+((int)(tol)))),lastBit);
                                        if (bitnum > 0){
                                                BinStream[bitnum]=77;
                                                bitnum++;
                                        }

                                        lastBit+=*clk;//skip over error
                                }
                        }
                        if (bitnum >=400) break;
                }
                *size=bitnum;
        } else{
                *invert=bestStart;
                *clk=iii;
                return -1;
        }
        return bestErrCnt;
}

//by marshmellow
//take 10 and 01 and manchester decode
//run through 2 times and take least errCnt
int manrawdecode(uint8_t * BitStream, size_t *size)
{
        int bitnum=0;
        int errCnt =0;
        int i=1;
        int bestErr = 1000;
        int bestRun = 0;
        int ii=1;
        for (ii=1;ii<3;++ii){
                i=1;
                for (i=i+ii;i<*size-2;i+=2){
                        if(BitStream[i]==1 && (BitStream[i+1]==0)){
                        } else if((BitStream[i]==0)&& BitStream[i+1]==1){
                        } else {
                                errCnt++;
                        }
                        if(bitnum>300) break;
                }
                if (bestErr>errCnt){
                        bestErr=errCnt;
                        bestRun=ii;
                }
                errCnt=0;
        }
        errCnt=bestErr;
        if (errCnt<20){
                ii=bestRun;
                i=1;
                for (i=i+ii;i < *size-2;i+=2){
                        if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
                                BitStream[bitnum++]=0;
                        } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
                                BitStream[bitnum++]=1;
                        } else {
                                BitStream[bitnum++]=77;
                                //errCnt++;
                        }
                        if(bitnum>300) break;
                }
                *size=bitnum;
        }
        return errCnt;
}


//by marshmellow
//take 01 or 10 = 0 and 11 or 00 = 1
int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset)
{
        uint8_t bitnum=0;
        uint32_t errCnt =0;
        uint32_t i=1;
        i=offset;
        for (;i<*size-2;i+=2){
                if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
                        BitStream[bitnum++]=1;
                } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
                        BitStream[bitnum++]=0;
                } else {
                        BitStream[bitnum++]=77;
                        errCnt++;
                }
                if(bitnum>250) break;
        }
        *size=bitnum;
        return errCnt;
}

//by marshmellow
//takes 2 arguments - clock and invert both as integers
//attempts to demodulate ask only
//prints binary found and saves in graphbuffer for further commands
int askrawdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert)
{
        uint32_t i;
        // int invert=0;  //invert default
        int high = 0, low = 128;
        *clk=DetectASKClock(BinStream, *size, *clk); //clock default
        uint8_t BitStream[502] = {0};

        if (*clk<8) *clk =64;
        if (*clk<32) *clk=32;
        if (*invert != 0 && *invert != 1) *invert =0;
        uint32_t initLoopMax = 200;
        if (initLoopMax > *size) initLoopMax=*size;
        // Detect high and lows
        for (i = 0; i < initLoopMax; ++i) //200 samples should be plenty to find high and low values
        {
                if (BinStream[i] > high)
                        high = BinStream[i];
                else if (BinStream[i] < low)
                        low = BinStream[i];
        }
        if ((high < 134)){  //throw away static  high has to be more than 6 on graph. noise <= -10 here
                //   PrintAndLog("no data found");
                return -2;
        }
        //25% fuzz in case highs and lows aren't clipped [marshmellow]
        high=(int)(((high-128)*.75)+128);
        low= (int)(((low-128)*.75)+128);

        //PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
        int lastBit = 0;  //set first clock check
        uint32_t bitnum = 0;     //output counter
        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
        uint32_t iii = 0;
        uint32_t gLen = *size;
        if (gLen > 500) gLen=500;
        uint8_t errCnt =0;
        uint32_t bestStart = *size;
        uint32_t bestErrCnt = (*size/1000);
        uint8_t midBit=0;
        //PrintAndLog("DEBUG - lastbit - %d",lastBit);
        //loop to find first wave that works
        for (iii=0; iii < gLen; ++iii){
                if ((BinStream[iii]>=high) || (BinStream[iii]<=low)){
                        lastBit=iii-*clk;
                        //loop through to see if this start location works
                        for (i = iii; i < *size; ++i) {
                                if ((BinStream[i] >= high) && ((i-lastBit)>(*clk-tol))){
                                        lastBit+=*clk;
                                        BitStream[bitnum] = *invert;
                                        bitnum++;
                                        midBit=0;
                                } else if ((BinStream[i] <= low) && ((i-lastBit)>(*clk-tol))){
                                        //low found and we are expecting a bar
                                        lastBit+=*clk;
                                        BitStream[bitnum] = 1- *invert;
                                        bitnum++;
                                        midBit=0;
                                } else if ((BinStream[i]<=low) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
                                        //mid bar?
                                        midBit=1;
                                        BitStream[bitnum]= 1- *invert;
                                        bitnum++;
                                } else if ((BinStream[i]>=high) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
                                        //mid bar?
                                        midBit=1;
                                        BitStream[bitnum]= *invert;
                                        bitnum++;
                                } else if ((i-lastBit)>((*clk/2)+tol) && (midBit==0)){
                                        //no mid bar found
                                        midBit=1;
                                        BitStream[bitnum]= BitStream[bitnum-1];
                                        bitnum++;
                                } else {
                                        //mid value found or no bar supposed to be here

                                        if ((i-lastBit)>(*clk+tol)){
                                                //should have hit a high or low based on clock!!
                                                //debug
                                                //PrintAndLog("DEBUG - no wave in expected area - location: %d, expected: %d-%d, lastBit: %d - resetting search",i,(lastBit+(clk-((int)(tol)))),(lastBit+(clk+((int)(tol)))),lastBit);
                                                if (bitnum > 0){
                                                        BitStream[bitnum]=77;
                                                        bitnum++;
                                                }

                                                errCnt++;
                                                lastBit+=*clk;//skip over until hit too many errors
                                                if (errCnt > ((*size/1000))){  //allow 1 error for every 1000 samples else start over
                                                        errCnt=0;
                                                        bitnum=0;//start over
                                                        break;
                                                }
                                        }
                                }
                                if (bitnum>500) break;
                        }
                        //we got more than 64 good bits and not all errors
                        if ((bitnum > (64+errCnt)) && (errCnt<(*size/1000))) {
                                //possible good read
                                if (errCnt==0) break;  //great read - finish
                                if (bestStart == iii) break;  //if current run == bestErrCnt run (after exhausted testing) then finish
                                if (errCnt<bestErrCnt){  //set this as new best run
                                        bestErrCnt=errCnt;
                                        bestStart = iii;
                                }
                        }
                }
                if (iii>=gLen){ //exhausted test
                        //if there was a ok test go back to that one and re-run the best run (then dump after that run)
                        if (bestErrCnt < (*size/1000)) iii=bestStart;
                }
        }
        if (bitnum>16){
                for (i=0; i < bitnum; ++i){
                        BinStream[i]=BitStream[i];
                }
                *size=bitnum;
        } else return -1;
        return errCnt;
}
//translate wave to 11111100000 (1 for each short wave 0 for each long wave)
size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
{
        uint32_t last_transition = 0;
        uint32_t idx = 1;
        //uint32_t maxVal=0;
        if (fchigh==0) fchigh=10;
        if (fclow==0) fclow=8;
        //set the threshold close to 0 (graph) to avoid static
        uint8_t threshold_value = 134; //(uint8_t)(((maxVal-128)*.75)+128);

        // sync to first lo-hi transition, and threshold

        // Need to threshold first sample

        if(dest[0] < 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++) {
                // threshold current value

                if (dest[idx] < threshold_value) dest[idx] = 0;
                else dest[idx] = 1;

                // Check for 0->1 transition
                if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
                        if ((idx-last_transition)<(fclow-2)){            //0-5 = garbage noise
                                //do nothing with extra garbage
                        } else if ((idx-last_transition) < (fchigh-1)) { //6-8 = 8 waves
                                dest[numBits]=1;
                        } else {                                                        //9+ = 10 waves
                                dest[numBits]=0;
                        }
                        last_transition = idx;
                        numBits++;
                }
        }
        return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
}

uint32_t myround2(float f)
{
        if (f >= 2000) return 2000;//something bad happened
        return (uint32_t) (f + (float)0.5);
}

//translate 11111100000 to 10
size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t maxConsequtiveBits,
    uint8_t invert, uint8_t fchigh, uint8_t fclow)
{
        uint8_t lastval=dest[0];
        uint32_t idx=0;
        size_t numBits=0;
        uint32_t n=1;

        for( idx=1; idx < size; idx++) {

                if (dest[idx]==lastval) {
                        n++;
                        continue;
                }
                //if lastval was 1, we have a 1->0 crossing
                if ( dest[idx-1]==1 ) {
                        n=myround2((float)(n+1)/((float)(rfLen)/(float)fclow));
                } else {// 0->1 crossing
                        n=myround2((float)(n+1)/((float)(rfLen-2)/(float)fchigh));  //-2 for fudge factor
                }
                if (n == 0) n = 1;

                if(n < maxConsequtiveBits) //Consecutive
                {
                        if(invert==0){ //invert bits
                                memset(dest+numBits, dest[idx-1] , n);
                        }else{
                                memset(dest+numBits, dest[idx-1]^1 , n);
                        }
                        numBits += n;
                }
                n=0;
                lastval=dest[idx];
        }//end for
        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)
{
        // FSK demodulator
        size = fsk_wave_demod(dest, size, fchigh, fclow);
        size = aggregate_bits(dest, size, rfLen, 192, invert, fchigh, fclow);
        return size;
}
// loop to get raw HID waveform then FSK demodulate the TAG ID from it
int HIDdemodFSK(uint8_t *dest, size_t size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
{

        size_t idx=0; //, found=0; //size=0,
        // FSK demodulator
        size = fskdemod(dest, size,50,0,10,8);

        // final loop, go over previously decoded manchester data and decode into usable tag ID
        // 111000 bit pattern represent start of frame, 01 pattern represents a 1 and 10 represents a 0
        uint8_t frame_marker_mask[] = {1,1,1,0,0,0};
        int numshifts = 0;
        idx = 0;
        //one scan
        while( idx + sizeof(frame_marker_mask) < size) {
                // search for a start of frame marker
                if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
                { // frame marker found
                        idx+=sizeof(frame_marker_mask);
                        while(dest[idx] != dest[idx+1] && idx < size-2)
                        {
                                // Keep going until next frame marker (or error)
                                // Shift in a bit. Start by shifting high registers
                                *hi2 = (*hi2<<1)|(*hi>>31);
                                *hi = (*hi<<1)|(*lo>>31);
                                //Then, shift in a 0 or one into low
                                if (dest[idx] && !dest[idx+1])  // 1 0
                                        *lo=(*lo<<1)|0;
                                else // 0 1
                                        *lo=(*lo<<1)|1;
                                numshifts++;
                                idx += 2;
                        }
                        // Hopefully, we read a tag and  hit upon the next frame marker
                        if(idx + sizeof(frame_marker_mask) < size)
                        {
                                if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
                                {
                                        //good return
                                        return idx;
                                }
                        }
                        // reset
                        *hi2 = *hi = *lo = 0;
                        numshifts = 0;
                }else   {
                        idx++;
                }
        }
        return -1;
}

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;
}

int IOdemodFSK(uint8_t *dest, size_t size)
{
        static const uint8_t THRESHOLD = 134;
        uint32_t idx=0;
        //make sure buffer has data
        if (size < 66) return -1;
        //test samples are not just noise
        uint8_t justNoise = 1;
        for(idx=0;idx< size && justNoise ;idx++){
                justNoise = dest[idx] < THRESHOLD;
        }
        if(justNoise) return 0;

        // FSK demodulator
        size = fskdemod(dest, size, 64, 1, 10, 8);  //  RF/64 and invert
        if (size < 65) return -1;  //did we get a good demod?
        //Index map
        //0           10          20          30          40          50          60
        //|           |           |           |           |           |           |
        //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
        //-----------------------------------------------------------------------------
        //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
        //
        //XSF(version)facility:codeone+codetwo
        //Handle the data
        uint8_t mask[] = {0,0,0,0,0,0,0,0,0,1};
        for( idx=0; idx < (size - 65); idx++) {
                if ( memcmp(dest + idx, mask, sizeof(mask))==0) {
                        //frame marker found
                        if (!dest[idx+8] && dest[idx+17]==1 && dest[idx+26]==1 && dest[idx+35]==1 && dest[idx+44]==1 && dest[idx+53]==1){
                                //confirmed proper separator bits found
                                //return start position
                                return (int) idx;
                        }
                }
        }
        return 0;
}

// by marshmellow
// not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
// maybe somehow adjust peak trimming value based on samples to fix?
int DetectASKClock(uint8_t dest[], size_t size, int clock)
{
        int i=0;
        int peak=0;
        int low=128;
        int clk[]={16,32,40,50,64,100,128,256};
        int loopCnt = 256;  //don't need to loop through entire array...
        if (size<loopCnt) loopCnt = size;

        //if we already have a valid clock quit
        for (;i<8;++i)
                if (clk[i] == clock) return clock;

        //get high and low peak
        for (i=0; i < loopCnt; ++i){
                if(dest[i] > peak){
                        peak = dest[i];
                }
                if(dest[i] < low){
                        low = dest[i];
                }
        }
        peak=(int)(((peak-128)*.75)+128);
        low= (int)(((low-128)*.75)+128);
        int ii;
        int clkCnt;
        int tol = 0;
        int bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000};
        int errCnt=0;
        //test each valid clock from smallest to greatest to see which lines up
        for(clkCnt=0; clkCnt < 6; ++clkCnt){
                if (clk[clkCnt] == 32){
                        tol=1;
                }else{
                        tol=0;
                }
                bestErr[clkCnt]=1000;
                //try lining up the peaks by moving starting point (try first 256)
                for (ii=0; ii< loopCnt; ++ii){
                        if ((dest[ii] >= peak) || (dest[ii] <= low)){
                                errCnt=0;
                                // now that we have the first one lined up test rest of wave array
                                for (i=0; i<((int)(size/clk[clkCnt])-1); ++i){
                                        if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
                                        }else if(dest[ii+(i*clk[clkCnt])-tol]>=peak || dest[ii+(i*clk[clkCnt])-tol]<=low){
                                        }else if(dest[ii+(i*clk[clkCnt])+tol]>=peak || dest[ii+(i*clk[clkCnt])+tol]<=low){
                                        }else{  //error no peak detected
                                                errCnt++;
                                        }
                                }
                                //if we found no errors this is correct one - return this clock
                                if(errCnt==0) return clk[clkCnt];
                                //if we found errors see if it is lowest so far and save it as best run
                                if(errCnt<bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
                        }
                }
        }
        int iii=0;
        int best=0;
        for (iii=0; iii<7;++iii){
                if (bestErr[iii]<bestErr[best]){
                        //                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;
                        }
                }
        }
        return clk[best];
}

//by marshmellow
//detect psk clock by reading #peaks vs no peaks(or errors)
int DetectpskNRZClock(uint8_t dest[], size_t size, int clock)
{
        int i=0;
        int peak=0;
        int low=128;
        int clk[]={16,32,40,50,64,100,128,256};
        int loopCnt = 2048;  //don't need to loop through entire array...
        if (size<loopCnt) loopCnt = size;

        //if we already have a valid clock quit
        for (; i < 8; ++i)
                if (clk[i] == clock) return clock;

        //get high and low peak
        for (i=0; i < loopCnt; ++i){
                if(dest[i] > peak){
                        peak = dest[i];
                }
                if(dest[i] < low){
                        low = dest[i];
                }
        }
        peak=(int)(((peak-128)*.75)+128);
        low= (int)(((low-128)*.75)+128);
        //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
        int ii;
        uint8_t clkCnt;
        uint8_t tol = 0;
        int peakcnt=0;
        int errCnt=0;
        int bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
        int peaksdet[]={0,0,0,0,0,0,0,0,0};
        //test each valid clock from smallest to greatest to see which lines up
        for(clkCnt=0; clkCnt < 6; ++clkCnt){
                if (clk[clkCnt] == 32){
                        tol=1;
                }else{
                        tol=0;
                }
                //try lining up the peaks by moving starting point (try first 256)
                for (ii=0; ii< loopCnt; ++ii){
                        if ((dest[ii] >= peak) || (dest[ii] <= low)){
                                errCnt=0;
                                peakcnt=0;
                                // now that we have the first one lined up test rest of wave array
                                for (i=0; i < ((int)(size/clk[clkCnt])-1); ++i){
                                        if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
                                                peakcnt++;
                                        }else if(dest[ii+(i*clk[clkCnt])-tol]>=peak || dest[ii+(i*clk[clkCnt])-tol]<=low){
                                                peakcnt++;
                                        }else if(dest[ii+(i*clk[clkCnt])+tol]>=peak || dest[ii+(i*clk[clkCnt])+tol]<=low){
                                                peakcnt++;
                                        }else{  //error no peak detected
                                                errCnt++;
                                        }
                                }
                                if(peakcnt>peaksdet[clkCnt]) {
                                        peaksdet[clkCnt]=peakcnt;
                                        bestErr[clkCnt]=errCnt;
                                }
                        }
                }
        }
        int iii=0;
        int best=0;
        //int ratio2;  //debug
        int ratio;
        //int bits;
        for (iii=0; iii < 7; ++iii){
                ratio=1000;
                //ratio2=1000;  //debug
                //bits=size/clk[iii];  //debug
                if (peaksdet[iii] > 0){
                        ratio=bestErr[iii]/peaksdet[iii];
                        if (((bestErr[best]/peaksdet[best]) > (ratio)+1)){
                                best = iii;
                        }
                        //ratio2=bits/peaksdet[iii]; //debug
                }
                //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d, ratio: %d, bits: %d, peakbitr: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best],ratio, bits,ratio2);
        }
        return clk[best];
}

//by marshmellow (attempt to get rid of high immediately after a low)
void pskCleanWave(uint8_t *bitStream, size_t size)
{
        int i;
        int low=128;
        int high=0;
        int gap = 4;
 // int loopMax = 2048;
        int newLow=0;
        int newHigh=0;
        for (i=0; i < size; ++i){
                if (bitStream[i] < low) low=bitStream[i];
                if (bitStream[i] > high) high=bitStream[i];
        }
        high = (int)(((high-128)*.80)+128);
        low = (int)(((low-128)*.90)+128);
        //low = (uint8_t)(((int)(low)-128)*.80)+128;
        for (i=0; i < size; ++i){
                if (newLow == 1){
                        bitStream[i]=low+8;
                        gap--;
                        if (gap == 0){
                                newLow=0;
                                gap=4;
                        }
                }else if (newHigh == 1){
                        bitStream[i]=high-8;
                        gap--;
                        if (gap == 0){
                                newHigh=0;
                                gap=4;
                        }
                }
                if (bitStream[i] <= low) newLow=1;
                if (bitStream[i] >= high) newHigh=1;
        }
        return;
}


//redesigned by marshmellow adjusted from existing decode functions
//indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
{
        //26 bit 40134 format  (don't know other formats)
        int i;
        int long_wait;
        long_wait = 29;//29 leading zeros in format
        int start;
        int first = 0;
        int first2 = 0;
        int bitCnt = 0;
        int ii;
        // Finding the start of a UID
        for (start = 0; start <= *size - 250; start++) {
                first = bitStream[start];
                for (i = start; i < start + long_wait; i++) {
                        if (bitStream[i] != first) {
                                break;
                        }
                }
                if (i == (start + long_wait)) {
                        break;
                }
        }
        if (start == *size - 250 + 1) {
                // did not find start sequence
                return -1;
        }
        //found start once now test length by finding next one
        // Inverting signal if needed
        if (first == 1) {
                for (i = start; i < *size; i++) {
                        bitStream[i] = !bitStream[i];
                }
                *invert = 1;
        }else *invert=0;

        int iii;
        for (ii=start+29; ii <= *size - 250; ii++) {
                first2 = bitStream[ii];
                for (iii = ii; iii < ii + long_wait; iii++) {
                        if (bitStream[iii] != first2) {
                                break;
                        }
                }
                if (iii == (ii + long_wait)) {
                        break;
                }
        }
        if (ii== *size - 250 + 1){
                // did not find second start sequence
                return -2;
        }
        bitCnt=ii-start;

        // Dumping UID
        i = start;
        for (ii = 0; ii < bitCnt; ii++) {
                bitStream[ii] = bitStream[i++];
        }
        *size=bitCnt;
        return 1;
}


//by marshmellow - demodulate PSK wave or NRZ wave (both similar enough)
//peaks switch bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
int pskNRZrawDemod(uint8_t *dest, size_t *size, int *clk, int *invert)
{
        pskCleanWave(dest,*size);
        int clk2 = DetectpskNRZClock(dest, *size, *clk);
        *clk=clk2;
        uint32_t i;
        uint8_t high=0, low=128;
        uint32_t gLen = *size;
        if (gLen > 1280) gLen=1280;
        // get high
        for (i=0; i < gLen; ++i){
                if (dest[i] > high) high = dest[i];
                if (dest[i] < low) low = dest[i];
        }
        //fudge high/low bars by 25%
        high = (uint8_t)((((int)(high)-128)*.75)+128);
        low = (uint8_t)((((int)(low)-128)*.80)+128);

        //PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
        int lastBit = 0;  //set first clock check
        uint32_t bitnum = 0;     //output counter
        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=2;    //clock tolerance may not be needed anymore currently set to + or - 1 but could be increased for poor waves or removed entirely
        uint32_t iii = 0;
        uint8_t errCnt =0;
        uint32_t bestStart = *size;
        uint32_t maxErr = (*size/1000);
        uint32_t bestErrCnt = maxErr;
        //uint8_t midBit=0;
        uint8_t curBit=0;
        uint8_t bitHigh=0;
        uint8_t ignorewin=*clk/8;
        //PrintAndLog("DEBUG - lastbit - %d",lastBit);
        //loop to find first wave that works - align to clock
        for (iii=0; iii < gLen; ++iii){
                if ((dest[iii]>=high) || (dest[iii]<=low)){
                        lastBit=iii-*clk;
                        //loop through to see if this start location works
                        for (i = iii; i < *size; ++i) {
                                //if we found a high bar and we are at a clock bit
                                if ((dest[i]>=high ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
                                        bitHigh=1;
                                        lastBit+=*clk;
                                        ignorewin=*clk/8;
                                        bitnum++;
                                //else if low bar found and we are at a clock point
                                }else if ((dest[i]<=low ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
                                        bitHigh=1;
                                        lastBit+=*clk;
                                        ignorewin=*clk/8;
                                        bitnum++;
                                //else if no bars found
                                }else if(dest[i] < high && dest[i] > low) {
                                        if (ignorewin==0){
                                                bitHigh=0;
                                        }else ignorewin--;
                                                                                //if we are past a clock point
                                        if (i >= lastBit+*clk+tol){ //clock val
                                                lastBit+=*clk;
                                                bitnum++;
                                        }
                                //else if bar found but we are not at a clock bit and we did not just have a clock bit
                                }else if ((dest[i]>=high || dest[i]<=low) && (i<lastBit+*clk-tol || i>lastBit+*clk+tol) && (bitHigh==0)){
                                        //error bar found no clock...
                                        errCnt++;
                                }
                                if (bitnum>=1000) break;
                        }
                        //we got more than 64 good bits and not all errors
                        if ((bitnum > (64+errCnt)) && (errCnt < (maxErr))) {
                                //possible good read
                                if (errCnt == 0){
                                        bestStart = iii;
                                        bestErrCnt = errCnt;
                                        break;  //great read - finish
                                }
                                if (bestStart == iii) break;  //if current run == bestErrCnt run (after exhausted testing) then finish
                                if (errCnt < bestErrCnt){  //set this as new best run
                                        bestErrCnt = errCnt;
                                        bestStart = iii;
                                }
                        }
                }
        }
        if (bestErrCnt < maxErr){
                //best run is good enough set to best run and set overwrite BinStream
                iii=bestStart;
                lastBit=bestStart-*clk;
                bitnum=0;
                for (i = iii; i < *size; ++i) {
                        //if we found a high bar and we are at a clock bit
                        if ((dest[i] >= high ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
                                bitHigh=1;
                                lastBit+=*clk;
                                curBit=1-*invert;
                                dest[bitnum]=curBit;
                                ignorewin=*clk/8;
                                bitnum++;
                        //else if low bar found and we are at a clock point
                        }else if ((dest[i]<=low ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
                                bitHigh=1;
                                lastBit+=*clk;
                                curBit=*invert;
                                dest[bitnum]=curBit;
                                ignorewin=*clk/8;
                                bitnum++;
                        //else if no bars found
                        }else if(dest[i]<high && dest[i]>low) {
                                if (ignorewin==0){
                                        bitHigh=0;
                                }else ignorewin--;
                                //if we are past a clock point
                                if (i>=lastBit+*clk+tol){ //clock val
                                        lastBit+=*clk;
                                        dest[bitnum]=curBit;
                                        bitnum++;
                                }
                        //else if bar found but we are not at a clock bit and we did not just have a clock bit
                        }else if ((dest[i]>=high || dest[i]<=low) && ((i<lastBit+*clk-tol) || (i>lastBit+*clk+tol)) && (bitHigh==0)){
                                //error bar found no clock...
                                bitHigh=1;
                                dest[bitnum]=77;
                                bitnum++;
                                errCnt++;
                        }
                        if (bitnum >=1000) break;
                }
                *size=bitnum;
        } else{
                *size=bitnum;
                *clk=bestStart;
                return -1;
        }

        if (bitnum>16){
                *size=bitnum;
        } else return -1;
        return errCnt;
}