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proxmark3/common/lfdemod.c
iceman1001 0df669a298 ADD: next step ISO11784/85
2015-06-03 21:35:03 +02:00

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//-----------------------------------------------------------------------------
// 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 demod/decode commands
//-----------------------------------------------------------------------------
#include <stdlib.h>
#include <string.h>
#include "lfdemod.h"
uint8_t justNoise(uint8_t *BitStream, size_t size)
{
static const uint8_t THRESHOLD = 123;
//test samples are not just noise
uint8_t justNoise1 = 1;
for(size_t idx=0; idx < size && justNoise1 ;idx++){
justNoise1 = BitStream[idx] < THRESHOLD;
}
return justNoise1;
}
//by marshmellow
//get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
{
*high=0;
*low=255;
// get high and low thresholds
for (size_t i=0; i < size; i++){
if (BitStream[i] > *high) *high = BitStream[i];
if (BitStream[i] < *low) *low = BitStream[i];
}
if (*high < 123) return -1; // just noise
*high = ((*high-128)*fuzzHi + 12800)/100;
*low = ((*low-128)*fuzzLo + 12800)/100;
return 1;
}
// by marshmellow
// pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
// returns 1 if passed
uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
{
uint8_t ans = 0;
for (uint8_t i = 0; i < bitLen; i++){
ans ^= ((bits >> i) & 1);
}
//PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
return (ans == pType);
}
//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)
{
uint8_t foundCnt=0;
for (int idx=0; idx < *size - pLen; idx++){
if (memcmp(BitStream+idx, preamble, pLen) == 0){
//first index found
foundCnt++;
if (foundCnt == 1){
*startIdx = idx;
}
if (foundCnt == 2){
*size = idx - *startIdx;
return 1;
}
}
}
return 0;
}
//by marshmellow
//takes 1s and 0s and searches for EM410x format - output EM ID
uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
{
//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
uint32_t i = 0;
if (BitStream[1]>1) return 0; //allow only 1s and 0s
// 111111111 bit pattern represent start of frame
// include 0 in front to help get start pos
uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
uint32_t idx = 0;
uint32_t parityBits = 0;
uint8_t errChk = 0;
uint8_t FmtLen = 10;
*startIdx = 0;
errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
if (errChk == 0 || *size < 64) return 0;
if (*size > 64) FmtLen = 22;
*startIdx += 1; //get rid of 0 from preamble
idx = *startIdx + 9;
for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
//check even parity - quit if failed
if (parityTest(parityBits, 5, 0) == 0) return 0;
//set uint64 with ID from BitStream
for (uint8_t ii=0; ii<4; ii++){
*hi = (*hi << 1) | (*lo >> 63);
*lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
}
}
if (errChk != 0) return 1;
//skip last 5 bit parity test for simplicity.
// *size = 64 | 128;
return 0;
}
//by marshmellow
//demodulates strong heavily clipped samples
int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
{
size_t bitCnt=0, smplCnt=0, errCnt=0;
uint8_t waveHigh = 0;
for (size_t i=0; i < *size; i++){
if (BinStream[i] >= high && waveHigh){
smplCnt++;
} else if (BinStream[i] <= low && !waveHigh){
smplCnt++;
} else { //transition
if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
if (smplCnt > clk-(clk/4)-1) { //full clock
if (smplCnt > clk + (clk/4)+1) { //too many samples
errCnt++;
BinStream[bitCnt++]=7;
} else if (waveHigh) {
BinStream[bitCnt++] = invert;
BinStream[bitCnt++] = invert;
} else if (!waveHigh) {
BinStream[bitCnt++] = invert ^ 1;
BinStream[bitCnt++] = invert ^ 1;
}
waveHigh ^= 1;
smplCnt = 0;
} else if (smplCnt > (clk/2) - (clk/4)-1) {
if (waveHigh) {
BinStream[bitCnt++] = invert;
} else if (!waveHigh) {
BinStream[bitCnt++] = invert ^ 1;
}
waveHigh ^= 1;
smplCnt = 0;
} else if (!bitCnt) {
//first bit
waveHigh = (BinStream[i] >= high);
smplCnt = 1;
} else {
smplCnt++;
//transition bit oops
}
} else { //haven't hit new high or new low yet
smplCnt++;
}
}
}
*size = bitCnt;
return errCnt;
}
//by marshmellow
void askAmp(uint8_t *BitStream, size_t size)
{
for(size_t i = 1; i<size; i++){
if (BitStream[i]-BitStream[i-1]>=30) //large jump up
BitStream[i]=127;
else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
BitStream[i]=-127;
}
return;
}
//by marshmellow
//attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
{
if (*size==0) return -1;
int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
if (*clk==0 || start < 0) return -3;
if (*invert != 1) *invert = 0;
if (amp==1) askAmp(BinStream, *size);
uint8_t initLoopMax = 255;
if (initLoopMax > *size) initLoopMax = *size;
// Detect high and lows
//25% clip in case highs and lows aren't clipped [marshmellow]
int high, low;
if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
return -2; //just noise
size_t errCnt = 0;
// if clean clipped waves detected run alternate demod
if (DetectCleanAskWave(BinStream, *size, high, low)) {
errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
if (askType) //askman
return manrawdecode(BinStream, size, 0);
else //askraw
return errCnt;
}
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;
lastBit = start - *clk;
for (i = start; i < *size; ++i) {
if (i-lastBit >= *clk-tol){
if (BinStream[i] >= high) {
BinStream[bitnum++] = *invert;
} else if (BinStream[i] <= low) {
BinStream[bitnum++] = *invert ^ 1;
} else if (i-lastBit >= *clk+tol) {
if (bitnum > 0) {
BinStream[bitnum++]=7;
errCnt++;
}
} else { //in tolerance - looking for peak
continue;
}
midBit = 0;
lastBit += *clk;
} else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
if (BinStream[i] >= high) {
BinStream[bitnum++] = *invert;
} else if (BinStream[i] <= low) {
BinStream[bitnum++] = *invert ^ 1;
} else if (i-lastBit >= *clk/2+tol) {
BinStream[bitnum] = BinStream[bitnum-1];
bitnum++;
} else { //in tolerance - looking for peak
continue;
}
midBit = 1;
}
if (bitnum >= MaxBits) break;
}
*size = bitnum;
return errCnt;
}
//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, uint8_t invert)
{
uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
size_t i, ii;
uint16_t bestErr = 1000, bestRun = 0;
if (*size < 16) return -1;
//find correct start position [alignment]
for (ii=0;ii<2;++ii){
for (i=ii; i<*size-3; i+=2)
if (BitStream[i]==BitStream[i+1])
errCnt++;
if (bestErr>errCnt){
bestErr=errCnt;
bestRun=ii;
}
errCnt=0;
}
//decode
for (i=bestRun; i < *size-3; i+=2){
if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
BitStream[bitnum++]=invert;
} else if((BitStream[i] == 0) && BitStream[i+1] == 1){
BitStream[bitnum++]=invert^1;
} else {
BitStream[bitnum++]=7;
}
if(bitnum>MaxBits) break;
}
*size=bitnum;
return bestErr;
}
//by marshmellow
//encode binary data into binary manchester
int ManchesterEncode(uint8_t *BitStream, size_t size)
{
size_t modIdx=20000, i=0;
if (size>modIdx) return -1;
for (size_t idx=0; idx < size; idx++){
BitStream[idx+modIdx++] = BitStream[idx];
BitStream[idx+modIdx++] = BitStream[idx]^1;
}
for (; i<(size*2); i++){
BitStream[i] = BitStream[i+20000];
}
return i;
}
//by marshmellow
//take 01 or 10 = 1 and 11 or 00 = 0
//check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
//decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
{
uint16_t bitnum = 0;
uint16_t errCnt = 0;
size_t i = offset;
uint16_t MaxBits=512;
//if not enough samples - error
if (*size < 51) return -1;
//check for phase change faults - skip one sample if faulty
uint8_t offsetA = 1, offsetB = 1;
for (; i<48; i+=2){
if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
}
if (!offsetA && offsetB) offset++;
for (i=offset; i<*size-3; i+=2){
//check for phase error
if (BitStream[i+1]==BitStream[i+2]) {
BitStream[bitnum++]=7;
errCnt++;
}
if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
BitStream[bitnum++]=1^invert;
} else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
BitStream[bitnum++]=invert;
} else {
BitStream[bitnum++]=7;
errCnt++;
}
if(bitnum>MaxBits) break;
}
*size=bitnum;
return errCnt;
}
// by marshmellow
// demod gProxIIDemod
// error returns as -x
// success returns start position in BitStream
// BitStream must contain previously askrawdemod and biphasedemoded data
int gProxII_Demod(uint8_t BitStream[], size_t *size)
{
size_t startIdx=0;
uint8_t preamble[] = {1,1,1,1,1,0};
uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -3; //preamble not found
if (*size != 96) return -2; //should have found 96 bits
//check first 6 spacer bits to verify format
if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
//confirmed proper separator bits found
//return start position
return (int) startIdx;
}
return -5;
}
//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)
{
size_t last_transition = 0;
size_t idx = 1;
//uint32_t maxVal=0;
if (fchigh==0) fchigh=10;
if (fclow==0) fclow=8;
//set the threshold close to 0 (graph) or 128 std to avoid static
uint8_t threshold_value = 123;
// 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 if ((idx-last_transition) > (fchigh+1) && !numBits) { //12 + and first bit = garbage
//do nothing with beginning garbage
} else { //9+ = 10 waves
dest[numBits++]=0;
}
last_transition = idx;
}
}
return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
}
//translate 11111100000 to 10
size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
uint8_t invert, uint8_t fchigh, uint8_t fclow)
{
uint8_t lastval=dest[0];
size_t idx=0;
size_t numBits=0;
uint32_t n=1;
for( idx=1; idx < size; idx++) {
n++;
if (dest[idx]==lastval) continue;
//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;
memset(dest+numBits, dest[idx-1]^invert , n);
numBits += n;
n=0;
lastval=dest[idx];
}//end for
// if valid extra bits at the end were all the same frequency - add them in
if (n > rfLen/fchigh) {
if (dest[idx-2]==1) {
n = (n * fclow + rfLen/2) / rfLen;
} else {
n = (n * fchigh + rfLen/2) / rfLen;
}
memset(dest+numBits, dest[idx-1]^invert , n);
numBits += n;
}
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, 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)
{
if (justNoise(dest, *size)) return -1;
size_t numStart=0, size2=*size, startIdx=0;
// FSK demodulator
*size = fskdemod(dest, size2,50,1,10,8); //fsk2a
if (*size < 96*2) return -2;
// 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
uint8_t preamble[] = {0,0,0,1,1,1,0,1};
// find bitstring in array
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -3; //preamble not found
numStart = startIdx + sizeof(preamble);
// final loop, go over previously decoded FSK data and manchester decode into usable tag ID
for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
if (dest[idx] == dest[idx+1]){
return -4; //not manchester data
}
*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)|1;
else // 0 1
*lo=(*lo<<1)|0;
}
return (int)startIdx;
}
// loop to get raw paradox waveform then FSK demodulate the TAG ID from it
int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
{
if (justNoise(dest, *size)) return -1;
size_t numStart=0, size2=*size, startIdx=0;
// FSK demodulator
*size = fskdemod(dest, size2,50,1,10,8); //fsk2a
if (*size < 96) return -2;
// 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
uint8_t preamble[] = {0,0,0,0,1,1,1,1};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -3; //preamble not found
numStart = startIdx + sizeof(preamble);
// final loop, go over previously decoded FSK data and manchester decode into usable tag ID
for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
if (dest[idx] == dest[idx+1])
return -4; //not manchester data
*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)|1;
else // 0 1
*lo=(*lo<<1)|0;
}
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;
}
int IOdemodFSK(uint8_t *dest, size_t size)
{
if (justNoise(dest, size)) return -1;
//make sure buffer has data
if (size < 66*64) return -2;
// FSK demodulator
size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
if (size < 65) return -3; //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
size_t startIdx = 0;
uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
if (errChk == 0) return -4; //preamble not found
if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
//confirmed proper separator bits found
//return start position
return (int) startIdx;
}
return -5;
}
// 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), 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--;
// if parity fails then return 0
if (parityTest(parityWd, pLen, pType) == 0) return -1;
bitCnt+=(pLen-1);
parityWd = 0;
}
// if we got here then all the parities passed
//return ID start index and size
return bitCnt;
}
// Ask/Biphase Demod then try to locate an ISO 11784/85 ID
// BitStream must contain previously askrawdemod and biphasedemoded data
int ISO11784demodBI(uint8_t *dest, size_t *size)
{
//make sure buffer has enough data
if (*size < 128) return -1;
size_t startIdx = 0;
uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -2; //preamble not found
return (int)startIdx;
}
// by marshmellow
// FSK Demod then try to locate an AWID ID
int AWIDdemodFSK(uint8_t *dest, size_t *size)
{
//make sure buffer has enough data
if (*size < 96*50) return -1;
if (justNoise(dest, *size)) return -2;
// FSK demodulator
*size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
if (*size < 96) return -3; //did we get a good demod?
uint8_t preamble[] = {0,0,0,0,0,0,0,1};
size_t startIdx = 0;
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -4; //preamble not found
if (*size != 96) return -5;
return (int)startIdx;
}
// by marshmellow
// FSK Demod then try to locate an Farpointe Data (pyramid) ID
int PyramiddemodFSK(uint8_t *dest, size_t *size)
{
//make sure buffer has data
if (*size < 128*50) return -5;
//test samples are not just noise
if (justNoise(dest, *size)) return -1;
// FSK demodulator
*size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
if (*size < 128) return -2; //did we get a good demod?
uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
size_t startIdx = 0;
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -4; //preamble not found
if (*size != 128) return -3;
return (int)startIdx;
}
// by marshmellow
// 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;
uint16_t cntPeaks=0;
size_t loopEnd = 512+60;
if (loopEnd > size) loopEnd = size;
for (size_t i=60; i<loopEnd; i++){
if (dest[i]>low && dest[i]<high)
allPeaks=0;
else
cntPeaks++;
}
if (allPeaks == 0){
if (cntPeaks > 300) return 1;
}
return allPeaks;
}
// by marshmellow
// to help detect clocks on heavily clipped samples
// based on count of low to low
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 minClk = 255;
// get to first full low to prime loop and skip incomplete first pulse
while ((dest[i] < high) && (i < size))
++i;
while ((dest[i] > low) && (i < size))
++i;
// loop through all samples
while (i < size) {
// measure from low to low
while ((dest[i] > low) && (i < size))
++i;
startwave= i;
while ((dest[i] < high) && (i < size))
++i;
while ((dest[i] > low) && (i < size))
++i;
//get minimum measured distance
if (i-startwave < minClk && i < size)
minClk = i - startwave;
}
// set clock
for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
return fndClk[clkCnt];
}
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?
// return start index of best starting position for that clock and return clock (by reference)
int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
{
size_t i=1;
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 we already have a valid clock
uint8_t clockFnd=0;
for (;i<clkEnd;++i)
if (clk[i] == *clock) clockFnd = i;
//clock found but continue to find best startpos
//get high and low peak
int peak, low;
if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
//test for large clean peaks
if (!clockFnd){
if (DetectCleanAskWave(dest, size, peak, low)==1){
int ans = DetectStrongAskClock(dest, size, peak, low);
for (i=clkEnd-1; i>0; i--){
if (clk[i] == ans) {
*clock = ans;
//clockFnd = i;
return 0; // for strong waves i don't use the 'best start position' yet...
//break; //clock found but continue to find best startpos [not yet]
}
}
}
}
uint8_t ii;
uint8_t clkCnt, tol = 0;
uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
size_t errCnt = 0;
size_t arrLoc, loopEnd;
if (clockFnd>0) {
clkCnt = clockFnd;
clkEnd = clockFnd+1;
}
else clkCnt=1;
//test each valid clock from smallest to greatest to see which lines up
for(; clkCnt < clkEnd; clkCnt++){
if (clk[clkCnt] <= 32){
tol=1;
}else{
tol=0;
}
//if no errors allowed - keep start within the first clock
if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
bestErr[clkCnt]=1000;
//try lining up the peaks by moving starting point (try first few clocks)
for (ii=0; ii < loopCnt; ii++){
if (dest[ii] < peak && dest[ii] > low) continue;
errCnt=0;
// now that we have the first one lined up test rest of wave array
loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
for (i=0; i < loopEnd; ++i){
arrLoc = ii + (i * clk[clkCnt]);
if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
}else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
}else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
}else{ //error no peak detected
errCnt++;
}
}
//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(errCnt==0 && clkCnt<7) {
if (!clockFnd) *clock = clk[clkCnt];
return ii;
}
//if we found errors see if it is lowest so far and save it as best run
if(errCnt<bestErr[clkCnt]){
bestErr[clkCnt]=errCnt;
bestStart[clkCnt]=ii;
}
}
}
uint8_t iii;
uint8_t best=0;
for (iii=1; iii<clkEnd; ++iii){
if (bestErr[iii] < bestErr[best]){
if (bestErr[iii] == 0) bestErr[iii]=1;
// current best bit to error ratio vs new bit to error ratio
if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
best = iii;
}
}
}
//if (bestErr[best] > maxErr) return -1;
if (!clockFnd) *clock = clk[best];
return bestStart[best];
}
//by marshmellow
//detect psk clock by reading each phase shift
// a phase shift is determined by measuring the sample length of each wave
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 we already have a valid clock quit
size_t i=1;
for (; i < 8; ++i)
if (clk[i] == clock) return clock;
size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
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);
//find first full wave
for (i=0; 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);
} else {
waveEnd = i+1;
//PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
waveLenCnt = waveEnd-waveStart;
if (waveLenCnt > fc){
firstFullWave = waveStart;
fullWaveLen=waveLenCnt;
break;
}
waveStart=0;
}
}
}
//PrintAndLog("DEBUG: 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--){
lastClkBit = firstFullWave; //set end of wave as clock align
waveStart = 0;
errCnt=0;
peakcnt=0;
//PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
//top edge of wave = start of new wave
if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
if (waveStart == 0) {
waveStart = i+1;
waveLenCnt=0;
} else { //waveEnd
waveEnd = i+1;
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 (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
peakcnt++;
lastClkBit+=clk[clkCnt];
} else if (i<lastClkBit+8){
//noise after a phase shift - ignore
} else { //phase shift before supposed to based on clock
errCnt++;
}
} else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
}
waveStart=i+1;
}
}
}
if (errCnt == 0){
return clk[clkCnt];
}
if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
}
//all tested with errors
//return the highest clk with the most peaks found
uint8_t best=7;
for (i=7; i>=1; i--){
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]);
}
return clk[best];
}
//by marshmellow
//detect nrz clock by reading #peaks vs no peaks(or errors)
int DetectNRZClock(uint8_t dest[], size_t size, int clock)
{
size_t i=0;
uint8_t clk[]={8,16,32,40,50,64,100,128,255};
size_t loopCnt = 4096; //don't need to loop through entire array...
if (size == 0) return 0;
if (size<loopCnt) loopCnt = size;
//if we already have a valid clock quit
for (; i < 8; ++i)
if (clk[i] == clock) return clock;
//get high and low peak
int peak, low;
if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
//PrintAndLog("DEBUG: peak: %d, low: %d",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;
//test for large clipped waves
for (i=0; i<loopCnt; i++){
if (dest[i] >= peak || dest[i] <= low){
peakcnt++;
} else {
if (peakcnt>0 && maxPeak < peakcnt){
maxPeak = peakcnt;
}
peakcnt=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;
//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)){
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){
peakcnt++;
}
}
if(peakcnt>peaksdet[clkCnt]) {
peaksdet[clkCnt]=peakcnt;
}
}
}
}
int iii=7;
uint8_t best=0;
for (iii=7; iii > 0; iii--){
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]);
}
return clk[best];
}
// by marshmellow
// convert psk1 demod to psk2 demod
// only transition waves are 1s
void psk1TOpsk2(uint8_t *BitStream, size_t size)
{
size_t i=1;
uint8_t lastBit=BitStream[0];
for (; i<size; i++){
if (BitStream[i]==7){
//ignore errors
} else if (lastBit!=BitStream[i]){
lastBit=BitStream[i];
BitStream[i]=1;
} else {
BitStream[i]=0;
}
}
return;
}
// by marshmellow
// convert psk2 demod to psk1 demod
// from only transition waves are 1s to phase shifts change bit
void psk2TOpsk1(uint8_t *BitStream, size_t size)
{
uint8_t phase=0;
for (size_t i=0; i<size; i++){
if (BitStream[i]==1){
phase ^=1;
}
BitStream[i]=phase;
}
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=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;
}
// Inverting signal if needed
if (first == 1) {
for (i = start; i < *size; i++) {
bitStream[i] = !bitStream[i];
}
*invert = 1;
}else *invert=0;
int iii;
//found start once now test length by finding next one
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 NRZ wave (both similar enough)
// 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)
{
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;
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
}
}
}
}
//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;
}
if (bitnum >= MaxBits) break;
}
*size = bitnum;
return bestErrCnt;
}
//by marshmellow
//detects the bit clock for FSK given the high and low Field Clocks
uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
{
uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
uint8_t rfLensFnd = 0;
uint8_t lastFCcnt = 0;
uint16_t fcCounter = 0;
uint16_t rfCounter = 0;
uint8_t firstBitFnd = 0;
size_t i;
if (size == 0) return 0;
uint8_t fcTol = (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++)
if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
break;
for (; i < size-1; i++){
fcCounter++;
rfCounter++;
if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
continue;
// else new peak
// if we got less than the small fc + tolerance then set it to the small fc
if (fcCounter < fcLow+fcTol)
fcCounter = fcLow;
else //set it to the large fc
fcCounter = fcHigh;
//look for bit clock (rf/xx)
if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
//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){
rfCnts[ii]++;
rfCounter = 0;
break;
}
}
if (rfCounter > 0 && rfLensFnd < 15){
//PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
rfCnts[rfLensFnd]++;
rfLens[rfLensFnd++] = rfCounter;
}
} else {
firstBitFnd++;
}
rfCounter=0;
lastFCcnt=fcCounter;
}
fcCounter=0;
}
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;
rfHighest2=rfHighest;
rfHighest=i;
} else if(rfCnts[i]>rfCnts[rfHighest2]){
rfHighest3=rfHighest2;
rfHighest2=i;
} else if(rfCnts[i]>rfCnts[rfHighest3]){
rfHighest3=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]);
// loop to find the highest clock that has a remainder less than the tolerance
// compare samples counted divided by
int ii=7;
for (; ii>=0; 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){
break;
}
}
}
}
if (ii<0) return 0; // oops we went too far
return clk[ii];
}
//by marshmellow
//countFC is to detect the field clock lengths.
//counts and returns the 2 most common wave lengths
//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 fcLensFnd = 0;
uint8_t lastFCcnt=0;
uint8_t fcCounter = 0;
size_t i;
if (size == 0) return 0;
// prime i to first up transition
for (i = 1; i < size-1; i++)
if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
break;
for (; i < size-1; i++){
if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
// new up transition
fcCounter++;
if (fskAdj){
//if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
if (lastFCcnt==5 && fcCounter==9) fcCounter--;
//if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
if ((fcCounter==9) || fcCounter==4) fcCounter++;
// save last field clock count (fc/xx)
lastFCcnt = fcCounter;
}
// find which fcLens to save it to:
for (int ii=0; ii<10; ii++){
if (fcLens[ii]==fcCounter){
fcCnts[ii]++;
fcCounter=0;
break;
}
}
if (fcCounter>0 && fcLensFnd<10){
//add new fc length
fcCnts[fcLensFnd]++;
fcLens[fcLensFnd++]=fcCounter;
}
fcCounter=0;
} else {
// count sample
fcCounter++;
}
}
uint8_t best1=9, best2=9, best3=9;
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);
// get the 3 best FC values
if (fcCnts[i]>maxCnt1) {
best3=best2;
best2=best1;
maxCnt1=fcCnts[i];
best1=i;
} else if(fcCnts[i]>fcCnts[best2]){
best3=best2;
best2=i;
} else if(fcCnts[i]>fcCnts[best3]){
best3=i;
}
}
uint8_t fcH=0, fcL=0;
if (fcLens[best1]>fcLens[best2]){
fcH=fcLens[best1];
fcL=fcLens[best2];
} else{
fcH=fcLens[best2];
fcL=fcLens[best1];
}
// 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];
}
//by marshmellow - demodulate PSK1 wave
//uses wave lengths (# Samples)
int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
{
if (size == 0) return -1;
uint16_t loopCnt = 4096; //don't need to loop through entire array...
if (*size<loopCnt) loopCnt = *size;
uint8_t curPhase = *invert;
size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
uint8_t fc=0, fullWaveLen=0, tol=1;
uint16_t errCnt=0, waveLenCnt=0;
fc = countFC(dest, *size, 0);
if (fc!=2 && fc!=4 && fc!=8) return -1;
//PrintAndLog("DEBUG: FC: %d",fc);
*clock = DetectPSKClock(dest, *size, *clock);
if (*clock == 0) return -1;
int avgWaveVal=0, lastAvgWaveVal=0;
//find first phase shift
for (i=0; i<loopCnt; i++){
if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
waveEnd = i+1;
//PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
waveLenCnt = waveEnd-waveStart;
if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave
lastAvgWaveVal = avgWaveVal/(waveLenCnt);
firstFullWave = waveStart;
fullWaveLen=waveLenCnt;
//if average wave value is > graph 0 then it is an up wave or a 1
if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
break;
}
waveStart = i+1;
avgWaveVal = 0;
}
avgWaveVal += dest[i+2];
}
//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
if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
if (waveStart == 0) {
waveStart = i+1;
waveLenCnt = 0;
avgWaveVal = dest[i+1];
} else { //waveEnd
waveEnd = i+1;
waveLenCnt = waveEnd-waveStart;
lastAvgWaveVal = avgWaveVal/waveLenCnt;
if (waveLenCnt > fc){
//PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
//this wave is a phase shift
//PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
curPhase ^= 1;
dest[numBits++] = curPhase;
lastClkBit += *clock;
} else if (i < lastClkBit+10+fc){
//noise after a phase shift - ignore
} else { //phase shift before supposed to based on clock
errCnt++;
dest[numBits++] = 7;
}
} else if (i+1 > lastClkBit + *clock + tol + fc){
lastClkBit += *clock; //no phase shift but clock bit
dest[numBits++] = curPhase;
}
avgWaveVal = 0;
waveStart = i+1;
}
}
avgWaveVal += dest[i+1];
}
*size = numBits;
return errCnt;
}
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