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proxmark3/common/lfdemod.c

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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 "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
//test samples are not just noise
uint8_t justNoise(uint8_t *bits, size_t size) {
#define THRESHOLD 123
uint8_t val = 1;
for(size_t idx=0; idx < size && val ;idx++)
val = bits[idx] < THRESHOLD;
return val;
}
//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
// 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 for Always 1's; 3 for Always 0'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
switch (pType) {
case 3: if (BitStream[j]==1) { return 0; } break; //should be 0 spacer bit
case 2: if (BitStream[j]==0) { return 0; } break; //should be 1 spacer bit
default: if (parityTest(parityWd, pLen, pType) == 0) { return 0; } break; //test parity
}
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; 3 Always 0's), and binary Length (length to run)
// Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
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
switch (pType) {
case 3: dest[j++]=0; break; // marker bit which should be a 0
case 2: dest[j++]=1; break; // marker bit which should be a 1
default:
dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
break;
}
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)
{
// Sanity check. If preamble length is bigger than bitstream length.
if ( *size <= pLen ) return 0;
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
int 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 -1; //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 ) return -4;
if (*size < 64) return -3;
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 -5;
//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++;
if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
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)
{
uint8_t last = 128;
for(size_t i = 1; i < size; ++i){
if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
last = 255;
else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
last = 0;
BitStream[i] = last;
}
}
//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);
if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
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)) {
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 = 3072; //max bits to collect
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) {
if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
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;
}
uint32_t manchesterEncode2Bytes(uint16_t datain) {
uint32_t output = 0;
uint8_t curBit = 0;
for (uint8_t i=0; i<16; i++) {
curBit = (datain >> (15-i) & 1);
output |= (1<<(((15-i)*2)+curBit));
}
return output;
}
//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; //spacer bits not found - not a valid gproxII
}
//translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
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;
size_t preLastSample = 0;
size_t LastSample = 0;
size_t currSample = 0;
// sync to first lo-hi transition, and threshold
// Need to threshold first sample
// 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 anywhere
// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
// (could also be fc/5 && fc/7 for fsk1 = 4-9)
for(idx = 161; idx < size-20; idx++) {
// 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]) {
preLastSample = LastSample;
LastSample = currSample;
currSample = idx-last_transition;
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 (or 3-6 = 5)
//correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
dest[numBits-1]=1;
}
dest[numBits++]=1;
} else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
//do nothing with beginning garbage
} else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
dest[numBits++]=1;
} else { //9+ = 10 sample waves (or 6+ = 7)
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
//rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
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;
//find out how many bits (n) we collected
//if lastval was 1, we have a 1->0 crossing
if (dest[idx-1]==1) {
n = (n * fclow + rfLen/2) / rfLen;
} else {// 0->1 crossing
n = (n * fchigh + rfLen/2) / rfLen;
}
if (n == 0) n = 1;
//add to our destination the bits we collected
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;
}
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
// find viking preamble 0xF200 in already demoded data
int VikingDemod_AM(uint8_t *dest, size_t *size) {
//make sure buffer has data
if (*size < 64*2) return -2;
size_t startIdx = 0;
uint8_t preamble[] = {1,1,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -4; //preamble not found
uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^
bytebits_to_byte(dest+startIdx+8,8) ^
bytebits_to_byte(dest+startIdx+16,8) ^
bytebits_to_byte(dest+startIdx+24,8) ^
bytebits_to_byte(dest+startIdx+32,8) ^
bytebits_to_byte(dest+startIdx+40,8) ^
bytebits_to_byte(dest+startIdx+48,8) ^
bytebits_to_byte(dest+startIdx+56,8);
if ( checkCalc != 0xA8 ) return -5;
if (*size != 64) return -6;
//return start position
return (int) startIdx;
}
// by iceman
// find Visa2000 preamble in already demoded data
int Visa2kDemod_AM(uint8_t *dest, size_t *size) {
if (*size < 96*2) return -1; //make sure buffer has data
size_t startIdx = 0;
uint8_t preamble[] = {0,1,0,1,0,1,1,0,0,1,0,0,1,0,0,1,0,1,0,1,0,0,1,1,0,0,1,1,0,0,1,0};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -2; //preamble not found
if (*size != 96) return -3; //wrong demoded size
//return start position
return (int) startIdx;
}
// by iceman
// find Noralsy preamble in already demoded data
int NoralsyDemod_AM(uint8_t *dest, size_t *size) {
if (*size < 96*2) return -1; //make sure buffer has data
size_t startIdx = 0;
uint8_t preamble[] = {1,0,1,1,1,0,1,1,0,0,0,0};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -2; //preamble not found
if (*size != 96) return -3; //wrong demoded size
//return start position
return (int) startIdx;
}
// find presco preamble 0x10D in already demoded data
int PrescoDemod(uint8_t *dest, size_t *size) {
if (*size < 128*2) return -1; //make sure buffer has data
size_t startIdx = 0;
uint8_t preamble[] = {0,0,0,1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -2; //preamble not found
if (*size != 128) return -3; //wrong demoded size
//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)
{
//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;
}
// ASK/Diphase fc/64 (inverted Biphase)
// Note: this i s not a demod, this is only a detection
// the parameter *dest needs to be demoded before call
int JablotronDemod(uint8_t *dest, size_t *size){
//make sure buffer has enough data
if (*size < 64) return -1;
size_t startIdx = 0;
// 0xFFFF preamble, 64bits
uint8_t preamble[] = {
1,1,1,1,
1,1,1,1,
1,1,1,1,
1,1,1,1,
0
};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -4; //preamble not found
if (*size != 64) return -3;
uint8_t checkchksum = 0;
for (int i=16; i < 56; i += 8) {
checkchksum += bytebits_to_byte(dest+startIdx+i,8);
}
checkchksum ^= 0x3A;
uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
if ( checkchksum != crc ) return -5;
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 a 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;
}
// find nedap preamble in already demoded data
int NedapDemod(uint8_t *dest, size_t *size) {
//make sure buffer has data
if (*size < 128) return -3;
size_t startIdx = 0;
//uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -4; //preamble not found
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)
{
bool allArePeaks = true;
uint16_t cntPeaks=0;
size_t loopEnd = 512+160;
if (loopEnd > size) loopEnd = size;
for (size_t i=160; i<loopEnd; i++){
if (dest[i]>low && dest[i]<high)
allArePeaks = false;
else
cntPeaks++;
}
if (!allArePeaks){
if (cntPeaks > 300) return true;
}
return allArePeaks;
}
// 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 = 100;
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
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];
}
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+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)
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);
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;
//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
if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
if(errCnt==0 && clkCnt<7) {
if (!clockFnd) *clock = clk[clkCnt];
return ii;
}
//if we found errors see if it is lowest so far and save it as best run
if(errCnt<bestErr[clkCnt]){
bestErr[clkCnt]=errCnt;
bestStart[clkCnt]=ii;
}
}
}
uint8_t iii;
uint8_t best=0;
for (iii=1; iii<clkEnd; ++iii){
if (bestErr[iii] < bestErr[best]){
if (bestErr[iii] == 0) bestErr[iii]=1;
// current best bit to error ratio vs new bit to error ratio
if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
best = iii;
}
}
if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d",clk[iii],bestErr[iii],clk[best],bestStart[best]);
}
if (!clockFnd) *clock = clk[best];
return bestStart[best];
}
//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-20;
//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;
if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
//find first full wave
for (i=160; i<loopCnt; i++){
if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
if (waveStart == 0) {
waveStart = i+1;
//prnt("DEBUG: waveStart: %d",waveStart);
} else {
waveEnd = i+1;
//prnt("DEBUG: waveEnd: %d",waveEnd);
waveLenCnt = waveEnd-waveStart;
if (waveLenCnt > fc){
firstFullWave = waveStart;
fullWaveLen=waveLenCnt;
break;
}
waveStart=0;
}
}
}
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--){
lastClkBit = firstFullWave; //set end of wave as clock align
waveStart = 0;
errCnt=0;
peakcnt=0;
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
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
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];
} 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;
}
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)
{
size_t i=0;
uint8_t clk[]={8,16,32,40,50,64,100,128,255};
size_t loopCnt = 4096; //don't need to loop through entire array...
if (size == 0) return 0;
if (size<loopCnt) loopCnt = size-20;
//if we already have a valid clock quit
for (; i < 8; ++i)
if (clk[i] == clock) return clock;
//get high and low peak
int peak, low;
if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
size_t ii;
uint8_t clkCnt;
uint8_t tol = 0;
uint16_t smplCnt = 0;
int16_t peakcnt = 0;
int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
uint16_t maxPeak = 255;
bool firstpeak = false;
//test for large clipped waves
for (i=0; i<loopCnt; i++){
if (dest[i] >= peak || dest[i] <= low){
if (!firstpeak) continue;
smplCnt++;
} else {
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;
}
}
}
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 smallest peak
if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
//try lining up the peaks by moving starting point (try first 256)
for (ii=20; ii < loopCnt; ++ii){
if ((dest[ii] >= peak) || (dest[ii] <= low)){
peakcnt=0;
bitHigh = false;
ignoreCnt = 0;
lastBit = ii-clk[clkCnt];
//loop through to see if this start location works
for (i = ii; i < size-20; ++i) {
//if we are at a clock bit
if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
//test high/low
if (dest[i] >= peak || dest[i] <= low) {
//if same peak don't count it
if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
peakcnt++;
}
lastPeakHigh = (dest[i] >= peak);
bitHigh = true;
errBitHigh = false;
ignoreCnt = ignoreWindow;
lastBit += clk[clkCnt];
} else if (i == lastBit + clk[clkCnt] + tol) {
lastBit += clk[clkCnt];
}
//else if not a clock bit and no peaks
} else if (dest[i] < peak && dest[i] > low){
if (ignoreCnt==0){
bitHigh=false;
if (errBitHigh==true) peakcnt--;
errBitHigh=false;
} else {
ignoreCnt--;
}
// else if not a clock bit but we have a peak
} else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
//error bar found no clock...
errBitHigh=true;
}
}
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]-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;
}
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];
}
// 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)
uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
uint8_t preamble_i[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0};
size_t startidx = 0;
if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
// if didn't find preamble try again inverting
if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
*invert ^= 1;
}
if (*size != 64 && *size != 224) return -2;
if (*invert==1)
for (size_t i = startidx; i < *size; i++)
bitStream[i] ^= 1;
return (int) startidx;
}
// 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
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-20;
int high, low;
if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
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;
}
//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;
}
}
*size = numBits;
return 0;
}
//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 = ((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 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-20; 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-4) && rfLens[ii] <= (rfCounter+4)){
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++){
//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;
}
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;
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>=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;
}
}
}
}
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[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
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;
size_t i;
if (size == 0) return 0;
// prime i to first up transition
for (i = 160; i < size-20; i++)
if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
break;
for (; i < size-20; 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<15; ii++){
if (fcLens[ii]==fcCounter){
fcCnts[ii]++;
fcCounter=0;
break;
}
}
if (fcCounter>0 && fcLensFnd<15){
//add new fc length
fcCnts[fcLensFnd]++;
fcLens[fcLensFnd++]=fcCounter;
}
fcCounter=0;
} else {
// count sample
fcCounter++;
}
}
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<15; i++){
// 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;
}
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];
fcL=fcLens[best2];
} else{
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;
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;
size_t numBits=0;
uint8_t curPhase = *invert;
size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
uint8_t fc=0, fullWaveLen=0, tol=1;
uint16_t errCnt=0, waveLenCnt=0;
fc = countFC(dest, *size, 0);
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 && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
lastAvgWaveVal = avgWaveVal/(waveLenCnt);
firstFullWave = waveStart;
fullWaveLen=waveLenCnt;
//if average wave value is > graph 0 then it is an up wave or a 1
if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
break;
}
waveStart = i+1;
avgWaveVal = 0;
}
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;
if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
waveStart = 0;
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;
}
//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 due to signal loss... (and we cut out the start of wave 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 - we just assume it will be there from now on...
dataloc += clk*4;
}
*size = newloc;
return true;
}
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