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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 - by marshmellow, holiman, iceman and
// many others who came before
//
// NOTES:
// LF Demod functions are placed here to allow the flexability to use client or
// device side. Most BUT NOT ALL of these functions are currenlty safe for
// device side use currently. (DetectST for example...)
//
// There are likely many improvements to the code that could be made, please
// make suggestions...
//
// we tried to include author comments so any questions could be directed to
// the source.
//
// There are 4 main sections of code below:
//
// Utilities Section:
// for general utilities used by multiple other functions
//
// Clock / Bitrate Detection Section:
// for clock detection functions for each modulation
//
// Modulation Demods &/or Decoding Section:
// for main general modulation demodulating and encoding decoding code.
//
// Tag format detection section:
// for detection of specific tag formats within demodulated data
//
// marshmellow
//-----------------------------------------------------------------------------
#include <string.h> // for memset, memcmp and size_t
#include "lfdemod.h"
#include <stdint.h> // for uint_32+
#include <stdbool.h> // for bool
#include "parity.h" // for parity test
//**********************************************************************************************
//---------------------------------Utilities Section--------------------------------------------
//**********************************************************************************************
#define LOWEST_DEFAULT_CLOCK 32
#define FSK_PSK_THRESHOLD 123
//might not be high enough for noisy environments
#define NOICE_AMPLITUDE_THRESHOLD 10
//to allow debug print calls when used not on dev
//void dummy(char *fmt, ...){}
extern void Dbprintf(const 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 Dbprintf
#endif
signal_t signalprop = { 255, -255, 0, 0, true };
signal_t* getSignalProperties(void) {
return &signalprop;
}
static void resetSignal(void) {
signalprop.low = 255;
signalprop.high = -255;
signalprop.mean = 0;
signalprop.amplitude = 0;
signalprop.isnoise = true;
}
static void printSignal(void) {
prnt("LF Signal properties:");
prnt(" high..........%d", signalprop.high);
prnt(" low...........%d", signalprop.low);
prnt(" mean..........%d", signalprop.mean);
prnt(" amplitude.....%d", signalprop.amplitude);
prnt(" is Noise......%s", (signalprop.isnoise) ? "Yes" : "No");
prnt(" THRESHOLD noice amplitude......%d" , NOICE_AMPLITUDE_THRESHOLD);
}
// Function to compute mean for a series
// rounded to integer..
uint32_t compute_mean_uint(uint8_t *in, size_t N) {
uint32_t mean = 0;
for (size_t i = 0; i < N; i++)
mean += in[i];
return mean / N;
}
// Function to compute mean for a series
// rounded to integer..
int32_t compute_mean_int(int *in, size_t N) {
int32_t mean = 0;
for (size_t i = 0; i < N; i++)
mean += in[i];
return mean / (int)N;
}
void zeromean(uint8_t* data, size_t size) {
// zero mean data
int i, accum = 0;
for (i = 10; i < size; ++i)
accum += data[i];
accum /= (size - 10);
for (i = 0; i < size; ++i)
data[i] -= accum;
}
//test samples are not just noise
// By measuring mean and look at amplitude of signal from HIGH / LOW, we can detect noise
bool isNoise_int(int *bits, uint32_t size) {
resetSignal();
if ( bits == NULL || size < 100 ) return true;
int32_t sum = 0;
for ( size_t i = 0; i < size; i++) {
if ( bits[i] < signalprop.low ) signalprop.low = bits[i];
if ( bits[i] > signalprop.high ) signalprop.high = bits[i];
sum += bits[i];
}
// measure amplitude of signal
signalprop.mean = sum / (int)size;
signalprop.amplitude = ABS(signalprop.high - signalprop.mean);
signalprop.isnoise = signalprop.amplitude < NOICE_AMPLITUDE_THRESHOLD;
if (g_debugMode)
printSignal();
return signalprop.isnoise;
}
//test samples are not just noise
// By measuring mean and look at amplitude of signal from HIGH / LOW,
// we can detect noise
bool isNoise(uint8_t *bits, uint32_t size) {
resetSignal();
if ( bits == NULL || size < 100 ) return true;
uint32_t sum = 0;
for ( uint32_t i = 0; i < size; i++) {
if ( bits[i] < signalprop.low ) signalprop.low = bits[i];
if ( bits[i] > signalprop.high ) signalprop.high = bits[i];
sum += bits[i];
}
// measure amplitude of signal
signalprop.mean = sum / size;
signalprop.amplitude = signalprop.high - signalprop.mean;
signalprop.isnoise = signalprop.amplitude < NOICE_AMPLITUDE_THRESHOLD;
if (g_debugMode)
printSignal();
return signalprop.isnoise;
}
//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
//void getHiLo(uint8_t *bits, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo) {
void getHiLo(int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo) {
// add fuzz.
*high = (signalprop.high * fuzzHi) / 100;
if ( signalprop.low < 0 ) {
*low = (signalprop.low * fuzzLo) / 100;
} else {
uint8_t range = signalprop.high - signalprop.low;
*low = signalprop.low + ((range * (100-fuzzLo))/100);
}
// if fuzzing to great and overlap
if ( *high < *low ) {
*high = signalprop.high;
*low = signalprop.low;
}
if (g_debugMode)
prnt("getHiLo fuzzed: High %d | Low %d", *high, *low);
}
// 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
bool parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType) {
return oddparity32(bits) ^ pType;
}
//by marshmellow
// takes a array of binary values, start position, length of bits per parity (includes parity bit - MAX 32),
// 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 *bits, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen) {
uint32_t parityWd = 0;
size_t bitCnt = 0;
for (int word = 0; word < (bLen); word += pLen){
for (int bit=0; bit < pLen; bit++){
if (word+bit >= bLen) break;
parityWd = (parityWd << 1) | bits[startIdx+word+bit];
bits[bitCnt++] = (bits[startIdx+word+bit]);
}
if (word+pLen > bLen) break;
bitCnt--; // overwrite parity with next data
// if parity fails then return 0
switch (pType) {
case 3: if (bits[bitCnt]==1) {return 0;} break; //should be 0 spacer bit
case 2: if (bits[bitCnt]==0) {return 0;} break; //should be 1 spacer bit
default: if (parityTest(parityWd, pLen, pType) == 0) { return 0; } break; //test parity
}
parityWd = 0;
}
// if we got here then all the parities passed
//return 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 *src, 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) | src[word+bit];
dest[j++] = (src[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;
}
// array must be size dividable with 8
uint8_t bits_to_array(const uint8_t *bits, size_t size, uint8_t *dest) {
if ( (size == 0) || (size % 8) != 0) return 0;
for(uint32_t i = 0; i < (size / 8); i++)
dest[i] = bytebits_to_byte((uint8_t *) bits + (i * 8), 8);
return 0;
}
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 = TRUE or fail = FALSE and startIndex and length
bool preambleSearch(uint8_t *bits, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx){
return preambleSearchEx(bits, preamble, pLen, size, startIdx, false);
}
//by marshmellow
// search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found) and length if not fineone
// fineone does not look for a repeating preamble for em4x05/4x69 sends preamble once, so look for it once in the first pLen bits
//(iceman) FINDONE, only finds start index. NOT SIZE!. I see Em410xDecode (lfdemod.c) uses SIZE to determine success
bool preambleSearchEx(uint8_t *bits, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx, bool findone)
{
// Sanity check. If preamble length is bigger than bits length.
if ( *size <= pLen ) return false;
uint8_t foundCnt = 0;
for (size_t idx = 0; idx < *size - pLen; idx++) {
if (memcmp(bits+idx, preamble, pLen) == 0){
//first index found
foundCnt++;
if (foundCnt == 1){
if (g_debugMode) prnt("DEBUG: (preambleSearchEx) preamble found at %i", idx);
*startIdx = idx;
if (findone) return true;
}
if (foundCnt == 2){
if (g_debugMode) prnt("DEBUG: (preambleSearchEx) preamble 2 found at %i", idx);
*size = idx - *startIdx;
return true;
}
}
}
return (foundCnt > 0);
}
// find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
size_t findModStart(uint8_t *src, size_t size, uint8_t expWaveSize) {
size_t i = 0;
size_t waveSizeCnt = 0;
uint8_t thresholdCnt = 0;
bool isAboveThreshold = src[i++] >= signalprop.mean; //FSK_PSK_THRESHOLD;
for (; i < size-20; i++ ) {
if (src[i] < signalprop.mean && isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
isAboveThreshold = false;
waveSizeCnt = 0;
} else if (src[i] >= signalprop.mean && !isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
isAboveThreshold = true;
waveSizeCnt = 0;
} else {
waveSizeCnt++;
}
if (thresholdCnt > 10) break;
}
if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at index %u, count: %u", i, thresholdCnt);
return i;
}
int getClosestClock(int testclk) {
uint16_t clocks[] = {8, 16, 32, 40, 50, 64, 128, 256, 384};
uint8_t limit[] = {1, 2, 4, 4, 5, 8, 8, 8, 8};
for (uint8_t i = 0; i < 9; i++)
if ( testclk >= clocks[i]-limit[i] && testclk <= clocks[i]+limit[i] )
return clocks[i];
return 0;
}
void getNextLow(uint8_t *samples, size_t size, int low, size_t *i) {
while ((samples[*i] > low) && (*i < size))
*i += 1;
}
void getNextHigh(uint8_t *samples, size_t size, int high, size_t *i) {
while ((samples[*i] < high) && (*i < size))
*i += 1;
}
// load wave counters
bool loadWaveCounters(uint8_t *samples, size_t size, int lowToLowWaveLen[], int highToLowWaveLen[], int *waveCnt, int *skip, int *minClk, int *high, int *low) {
size_t i = 0, firstLow, firstHigh;
//size_t testsize = (size < 512) ? size : 512;
// just noise - no super good detection. good enough
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG STT: just noise detected - quitting");
return false;
}
getHiLo(high, low, 80, 80);
// get to first full low to prime loop and skip incomplete first pulse
getNextHigh(samples, size, *high, &i);
getNextLow(samples, size, *low, &i);
*skip = i;
// populate tmpbuff buffer with pulse lengths
while (i < size) {
// measure from low to low
firstLow = i;
//find first high point for this wave
getNextHigh(samples, size, *high, &i);
firstHigh = i;
getNextLow(samples, size, *low, &i);
if (*waveCnt >= (size/LOWEST_DEFAULT_CLOCK))
break;
highToLowWaveLen[*waveCnt] = i - firstHigh; //first high to first low
lowToLowWaveLen[*waveCnt] = i - firstLow;
*waveCnt += 1;
if (i-firstLow < *minClk && i < size) {
*minClk = i - firstLow;
}
}
return true;
}
size_t pskFindFirstPhaseShift(uint8_t *samples, size_t size, uint8_t *curPhase, size_t waveStart, uint16_t fc, uint16_t *fullWaveLen) {
uint16_t loopCnt = (size+3 < 4096) ? size : 4096; //don't need to loop through entire array...
uint16_t avgWaveVal=0, lastAvgWaveVal=0;
size_t i = waveStart, waveEnd, waveLenCnt, firstFullWave;
for (; i<loopCnt; i++) {
// find peak // was "samples[i] + fc" but why? must have been used to weed out some wave error... removed..
if (samples[i] < samples[i+1] && samples[i+1] >= samples[i+2]){
waveEnd = i+1;
if (g_debugMode == 2) prnt("DEBUG PSK: waveEnd: %u, waveStart: %u", waveEnd, waveStart);
waveLenCnt = waveEnd-waveStart;
if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+8)){ //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 (could cause inverting)
if (lastAvgWaveVal > FSK_PSK_THRESHOLD) *curPhase ^= 1;
return firstFullWave;
}
waveStart = i+1;
avgWaveVal = 0;
}
avgWaveVal += samples[i+2];
}
return 0;
}
//by marshmellow
//amplify based on ask edge detection - not accurate enough to use all the time
void askAmp(uint8_t *bits, size_t size) {
uint8_t last = 128;
for(size_t i = 1; i < size; ++i){
if ( bits[i] - bits[i-1] >= 30) //large jump up
last = 255;
else if ( bits[i-1] - bits[i] >= 20) //large jump down
last = 0;
bits[i] = last;
}
}
// iceman, simplify this
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
//NOTE: bitstream must have triple the size of "size" available in memory to do the swap
int ManchesterEncode(uint8_t *bits, size_t size) {
//allow up to 4096b out (means bits must be at least 2048+4096 to handle the swap)
size = (size > 2048) ? 2048 : size;
size_t modIdx = size;
size_t i;
for (size_t idx=0; idx < size; idx++){
bits[idx+modIdx++] = bits[idx];
bits[idx+modIdx++] = bits[idx]^1;
}
for (i=0; i < (size*2); i++){
bits[i] = bits[i+size];
}
return i;
}
// by marshmellow
// to detect a wave that has heavily clipped (clean) samples
// loop 512 samples, if 250 of them is deemed maxed out, we assume the wave is clipped.
bool 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;
// sanity check
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 > 250) return true;
}
return allArePeaks;
}
//**********************************************************************************************
//-------------------Clock / Bitrate Detection Section------------------------------------------
//**********************************************************************************************
// 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, int high, int low, int *clock) {
size_t startwave;
size_t i = 100;
size_t minClk = 512;
int shortestWaveIdx = 0;
// get to first full low to prime loop and skip incomplete first pulse
getNextHigh(dest, size, high, &i);
getNextLow(dest, size, low, &i);
// loop through all samples (well, we don't want to go out-of-bounds)
while (i < size-512) {
// measure from low to low
startwave = i;
getNextHigh(dest, size, high, &i);
getNextLow(dest, size, low, &i);
//get minimum measured distance
if (i-startwave < minClk && i < size) {
minClk = i - startwave;
shortestWaveIdx = startwave;
}
}
// set clock
if (g_debugMode == 2) prnt("DEBUG ASK: DetectStrongAskClock smallest wave: %d", minClk);
*clock = getClosestClock(minClk);
if (*clock == 0)
return -1;
return shortestWaveIdx;
}
// 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) {
//don't need to loop through entire array. (cotag has clock of 384)
uint16_t loopCnt = 1500;
// not enough samples
if (size <= loopCnt + 60){
if (g_debugMode == 2) prnt("DEBUG DetectASKClock: not enough samples - aborting");
return -1;
}
// just noise - no super good detection. good enough
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG DetectASKClock: just noise detected - aborting");
return -2;
}
size_t i = 1;
uint16_t num_clks = 9;
// first 255 value pos0 is placeholder for user inputed clock.
uint16_t clk[] = {255, 8, 16, 32, 40, 50, 64, 100, 128, 255};
// sometimes there is a strange end wave - filter out this
size -= 60;
// What is purpose?
// already have a valid clock?
uint8_t found_clk = 0;
for (; i < num_clks; ++i) {
if (clk[i] == *clock) {
found_clk = i;
}
}
// threshold 75% of high, low peak
int peak_hi, peak_low;
getHiLo(&peak_hi, &peak_low, 75, 75);
// test for large clean, STRONG, CLIPPED peaks
if (!found_clk) {
if (DetectCleanAskWave(dest, size, peak_hi, peak_low)){
int idx = DetectStrongAskClock(dest, size, peak_hi, peak_low, clock);
if (g_debugMode == 2)
prnt("DEBUG ASK: DetectASKClock Clean ASK Wave detected: clk %i, Best Starting Position: %i", *clock, idx);
// return shortest wave start position
if (idx > -1)
return idx;
}
}
// test for weak peaks
// test clock if given as cmd parameter
if ( *clock > 0 )
clk[0] = *clock;
uint8_t clkCnt, tol = 0;
size_t j = 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, arrLoc, loopEnd;
if (found_clk) {
clkCnt = found_clk;
num_clks = found_clk + 1;
} else {
clkCnt = 1;
}
//test each valid clock from smallest to greatest to see which lines up
for (; clkCnt < num_clks; 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)
// get to first full low to prime loop and skip incomplete first pulse
getNextHigh(dest, size, peak_hi, &j);
getNextLow(dest, size, peak_low, &j);
for (; j < loopCnt; j++){
errCnt = 0;
// now that we have the first one lined up test rest of wave array
loopEnd = ((size-j-tol) / clk[clkCnt]) - 1;
for (i=0; i < loopEnd; ++i){
arrLoc = j + (i * clk[clkCnt]);
if (dest[arrLoc] >= peak_hi || dest[arrLoc] <= peak_low){
} else if (dest[arrLoc-tol] >= peak_hi || dest[arrLoc-tol] <= peak_low){
} else if (dest[arrLoc+tol] >= peak_hi || dest[arrLoc+tol] <= peak_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, j, i);
if (errCnt == 0 && clkCnt < 7) {
if (!found_clk)
*clock = clk[clkCnt];
return j;
}
// 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] = j;
}
}
}
uint8_t k, best = 0;
for (k=1; k < num_clks; ++k){
if (bestErr[k] < bestErr[best]){
if (bestErr[k] == 0) bestErr[k] = 1;
// current best bit to error ratio vs new bit to error ratio
if ( (size/clk[best])/bestErr[best] < (size/clk[k])/bestErr[k] ){
best = k;
}
}
//if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d", clk[k], bestErr[k], clk[best], bestStart[best]);
}
if (!found_clk)
*clock = clk[best];
return bestStart[best];
}
int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low, bool *strong) {
//find shortest transition from high to low
*strong = false;
size_t i = 0;
size_t transition1 = 0;
int lowestTransition = 255;
bool lastWasHigh = false;
size_t transitionSampleCount = 0;
//find first valid beginning of a high or low wave
while ((dest[i] >= peak || dest[i] <= low) && (i < size))
++i;
while ((dest[i] < peak && dest[i] > low) && (i < size))
++i;
lastWasHigh = (dest[i] >= peak);
if (i == size)
return 0;
transition1 = i;
for (;i < size; i++) {
if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
lastWasHigh = (dest[i] >= peak);
if (i-transition1 < lowestTransition)
lowestTransition = i-transition1;
transition1 = i;
} else if (dest[i] < peak && dest[i] > low) {
transitionSampleCount++;
}
}
if (lowestTransition == 255)
lowestTransition = 0;
if (g_debugMode == 2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d", lowestTransition);
// if less than 10% of the samples were not peaks (or 90% were peaks) then we have a strong wave
if (transitionSampleCount / size < 10) {
*strong = true;
lowestTransition = getClosestClock(lowestTransition);
}
return lowestTransition;
}
//by marshmellow
//detect nrz clock by reading #peaks vs no peaks(or errors)
int DetectNRZClock(uint8_t *dest, size_t size, int clock, size_t *clockStartIdx) {
size_t i = 0;
uint8_t clk[] = {8,16,32,40,50,64,100,128,255};
size_t loopCnt = 4096; //don't need to loop through entire array...
//if we already have a valid clock quit
for (; i < 8; ++i)
if (clk[i] == clock) return clock;
if (size < 20) return 0;
// size must be larger than 20 here
if (size < loopCnt) loopCnt = size-20;
// just noise - no super good detection. good enough
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG DetectNZRClock: just noise detected - quitting");
return 0;
}
//get high and low peak
int peak, low;
//getHiLo(dest, loopCnt, &peak, &low, 90, 90);
getHiLo(&peak, &low, 90, 90);
bool strong = false;
int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low, &strong);
if (strong) return lowestTransition;
size_t ii;
uint8_t clkCnt;
uint8_t tol = 0;
uint16_t smplCnt = 0;
int16_t peakcnt = 0;
int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
uint16_t minPeak = 255;
bool firstpeak = true;
//test for large clipped waves - ignore first peak
for (i=0; i<loopCnt; i++){
if (dest[i] >= peak || dest[i] <= low){
if (firstpeak) continue;
smplCnt++;
} else {
firstpeak = false;
if (smplCnt > 0) {
if (minPeak > smplCnt && smplCnt > 7) minPeak = smplCnt;
peakcnt++;
if (g_debugMode == 2) prnt("DEBUG NRZ: minPeak: %d, smplCnt: %d, peakcnt: %d",minPeak,smplCnt,peakcnt);
smplCnt = 0;
}
}
}
if (minPeak < 8) return 0;
bool errBitHigh = 0, bitHigh = 0, lastPeakHigh = 0;
uint8_t ignoreCnt = 0, ignoreWindow = 4;
int lastBit = 0;
size_t bestStart[] = {0,0,0,0,0,0,0,0,0};
peakcnt = 0;
//test each valid clock from smallest to greatest to see which lines up
for (clkCnt=0; clkCnt < 8; ++clkCnt){
//ignore clocks smaller than smallest peak
if (clk[clkCnt] < minPeak - (clk[clkCnt]/4)) continue;
//try lining up the peaks by moving starting point (try first 256)
for (ii=20; ii < loopCnt; ++ii){
if ((dest[ii] >= peak) || (dest[ii] <= low)){
peakcnt=0;
bitHigh = false;
ignoreCnt = 0;
lastBit = ii-clk[clkCnt];
//loop through to see if this start location works
for (i = ii; i < size-20; ++i) {
//if we are at a clock bit
if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
//test high/low
if (dest[i] >= peak || dest[i] <= low) {
//if same peak don't count it
if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
peakcnt++;
}
lastPeakHigh = (dest[i] >= peak);
bitHigh = true;
errBitHigh = false;
ignoreCnt = ignoreWindow;
lastBit += clk[clkCnt];
} else if (i == lastBit + clk[clkCnt] + tol) {
lastBit += clk[clkCnt];
}
//else if not a clock bit and no peaks
} else if (dest[i] < peak && dest[i] > low){
if (ignoreCnt == 0){
bitHigh = false;
if (errBitHigh == true)
peakcnt--;
errBitHigh = false;
} else {
ignoreCnt--;
}
// else if not a clock bit but we have a peak
} else if ((dest[i] >= peak || dest[i] <= low) && (!bitHigh)) {
//error bar found no clock...
errBitHigh = true;
}
}
if (peakcnt > peaksdet[clkCnt]) {
bestStart[clkCnt] = ii;
peaksdet[clkCnt] = peakcnt;
}
}
}
}
uint8_t best = 0;
for (int m = 7; m > 0; m--){
if ((peaksdet[m] >= (peaksdet[best]-1)) && (peaksdet[m] <= peaksdet[best]+1) && lowestTransition) {
if (clk[m] > (lowestTransition - (clk[m]/8)) && clk[m] < (lowestTransition + (clk[m]/8))) {
best = m;
}
} else if (peaksdet[m] > peaksdet[best]){
best = m;
}
if (g_debugMode == 2) prnt("DEBUG NRZ: Clk: %d, peaks: %d, minPeak: %d, bestClk: %d, lowestTrs: %d", clk[m], peaksdet[m], minPeak, clk[best], lowestTransition);
}
*clockStartIdx = bestStart[best];
return clk[best];
}
//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 *bits, size_t size, bool 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 < 180) return 0;
// prime i to first up transition
for (i = 160; i < size-20; i++)
if (bits[i] > bits[i-1] && bits[i] >= bits[i+1])
break;
for (; i < size-20; i++){
if (bits[i] > bits[i-1] && bits[i] >= bits[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 m=0; m<15; m++){
if (fcLens[m] == fcCounter){
fcCnts[m]++;
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[i] == 0) break;
}
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 (uint16_t)fcLens[best2] << 8 | fcLens[best1];
}
//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, size_t *firstPhaseShift, uint8_t *curPhase, uint8_t *fc) {
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 we already have a valid clock quit
size_t i = 1;
for (; i < 8; ++i)
if (clk[i] == clock) return clock;
if (size < 160+20) return 0;
// size must be larger than 20 here, and 160 later on.
if (size < loopCnt) loopCnt = size-20;
uint16_t fcs = countFC(dest, size, 0);
*fc = fcs & 0xFF;
if (g_debugMode == 2) prnt("DEBUG PSK: FC: %d, FC2: %d",*fc, fcs>>8);
if ((fcs >> 8) == 10 && *fc == 8) return 0;
if (*fc != 2 && *fc != 4 && *fc != 8) return 0;
size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
uint8_t clkCnt, tol=1;
uint16_t peakcnt=0, errCnt=0, waveLenCnt=0, fullWaveLen=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};
//find start of modulating data in trace
i = findModStart(dest, size, *fc);
firstFullWave = pskFindFirstPhaseShift(dest, size, curPhase, i, *fc, &fullWaveLen);
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;
fullWaveLen = 0;
}
*firstPhaseShift = firstFullWave;
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--){
tol = *fc/2;
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];
}
//by marshmellow
//detects the bit clock for FSK given the high and low Field Clocks
uint8_t detectFSKClk(uint8_t *bits, size_t size, uint8_t fcHigh, uint8_t fcLow, int *firstClockEdge) {
if (size == 0)
return 0;
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;
uint8_t fcTol = ((fcHigh * 100 - fcLow * 100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
// prime i to first peak / up transition
for (i = 160; i < size-20; i++)
if (bits[i] > bits[i-1] && bits[i] >= bits[i+1])
break;
for (; i < size-20; i++){
fcCounter++;
rfCounter++;
if (bits[i] <= bits[i-1] || bits[i] < bits[i+1])
continue;
// else new peak
// if we got less than the small fc + tolerance then set it to the small fc
// if it is inbetween set it to the last counter
if (fcCounter < fcHigh && fcCounter > fcLow)
fcCounter = lastFCcnt;
else 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){
//prnt("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
rfCnts[rfLensFnd]++;
rfLens[rfLensFnd++] = rfCounter;
}
} else {
*firstClockEdge = i;
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 m = 7;
for (; m >= 2; m--){
if (rfLens[rfHighest] % clk[m] < tol1 || rfLens[rfHighest] % clk[m] > clk[m]-tol1){
if (rfLens[rfHighest2] % clk[m] < tol1 || rfLens[rfHighest2] % clk[m] > clk[m]-tol1){
if (rfLens[rfHighest3] % clk[m] < tol1 || rfLens[rfHighest3] % clk[m] > clk[m]-tol1){
if (g_debugMode == 2)
prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance", clk[m]);
break;
}
}
}
}
if (m < 2) return 0; // oops we went too far
return clk[m];
}
//**********************************************************************************************
//--------------------Modulation Demods &/or Decoding Section-----------------------------------
//**********************************************************************************************
// look for Sequence Terminator - should be pulses of clk*(1 or 2), clk*2, clk*(1.5 or 2), by idx we mean graph position index...
bool findST(int *stStopLoc, int *stStartIdx, int lowToLowWaveLen[], int highToLowWaveLen[], int clk, int tol, int buffSize, size_t *i) {
if (buffSize < *i+4) return false;
for (; *i < buffSize - 4; *i+=1) {
*stStartIdx += lowToLowWaveLen[*i]; //caution part of this wave may be data and part may be ST.... to be accounted for in main function for now...
if (lowToLowWaveLen[*i] >= clk*1-tol && lowToLowWaveLen[*i] <= (clk*2)+tol && highToLowWaveLen[*i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
if (lowToLowWaveLen[*i+1] >= clk*2-tol && lowToLowWaveLen[*i+1] <= clk*2+tol && highToLowWaveLen[*i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
if (lowToLowWaveLen[*i+2] >= (clk*3)/2-tol && lowToLowWaveLen[*i+2] <= clk*2+tol && highToLowWaveLen[*i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
if (lowToLowWaveLen[*i+3] >= clk*1-tol && lowToLowWaveLen[*i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
*stStopLoc = *i + 3;
return true;
}
}
}
}
}
return false;
}
//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 *ststart, size_t *stend) {
size_t bufsize = *size;
//need to loop through all samples and identify our clock, look for the ST pattern
int clk = 0;
int tol = 0;
int j=0, high, low, skip=0, start=0, end=0, minClk=255;
size_t i = 0;
//probably should malloc... || test if memory is available ... handle device side? memory danger!!! [marshmellow]
int tmpbuff[bufsize / LOWEST_DEFAULT_CLOCK]; // low to low wave count //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
int waveLen[bufsize / LOWEST_DEFAULT_CLOCK]; // high to low wave count //if clock is larger then we waste memory in array size that is not needed...
//size_t testsize = (bufsize < 512) ? bufsize : 512;
int phaseoff = 0;
high = low = 128;
memset(tmpbuff, 0, sizeof(tmpbuff));
memset(waveLen, 0, sizeof(waveLen));
if (!loadWaveCounters(buffer, bufsize, tmpbuff, waveLen, &j, &skip, &minClk, &high, &low)) return false;
// set clock - might be able to get this externally and remove this work...
clk = getClosestClock(minClk);
// clock not found - ERROR
if (!clk) {
if (g_debugMode == 2) prnt("DEBUG STT: clock not found - quitting");
return false;
}
*foundclock = clk;
tol = clk/8;
if (!findST(&start, &skip, tmpbuff, waveLen, clk, tol, j, &i)) {
// first ST not found - ERROR
if (g_debugMode == 2) prnt("DEBUG STT: first STT not found - quitting");
return false;
} else {
if (g_debugMode == 2) prnt("DEBUG STT: first STT found at wave: %i, skip: %i, j=%i", start, skip, j);
}
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
int dummy1 = 0;
end = skip;
i += 3;
if (!findST(&dummy1, &end, tmpbuff, waveLen, clk, tol, j, &i)) {
//didn't find second ST - ERROR
if (g_debugMode == 2) prnt("DEBUG STT: second STT not found - quitting");
return false;
}
end -= phaseoff;
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 ( clk - (datalen % clk) <= clk/8) {
// padd the amount off - could be problematic... but shouldn't happen often
datalen += clk - (datalen % clk);
} else if ( (datalen % clk) <= clk/8 ) {
// padd the amount off - could be problematic... but shouldn't happen often
datalen -= datalen % clk;
} else {
if (g_debugMode == 2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
return false;
}
// 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;
if (buffer[dataloc-(clk*4)-(clk/4)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
//we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start
for ( i=0; i <= (clk/4); ++i ) {
if ( buffer[dataloc - (clk*4) - i] <= low ) {
dataloc -= i;
break;
}
}
}
size_t newloc = 0;
i=0;
if (g_debugMode == 2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);
bool firstrun = true;
// 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+clk/4]<high && buffer[dataloc+clk/4]>low) {
for(i=0; i < clk/2-tol; ++i) {
buffer[dataloc+i] = high+5;
}
} //test for small spike outlier (high between two lows) in the case of very strong waves
if (buffer[dataloc] > low && buffer[dataloc+clk/4] <= low) {
for(i=0; i < clk/4; ++i) {
buffer[dataloc+i] = buffer[dataloc+clk/4];
}
}
if (firstrun) {
*stend = dataloc;
*ststart = dataloc-(clk*4);
firstrun=false;
}
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...
if (g_debugMode == 2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
dataloc += clk*4;
}
*size = newloc;
return true;
}
//by marshmellow
//take 11 10 01 11 00 and make 01100 ... miller decoding
//check for phase errors - should never have half a 1 or 0 by itself and should never exceed 1111 or 0000 in a row
//decodes miller encoded binary
//NOTE askrawdemod will NOT demod miller encoded ask unless the clock is manually set to 1/2 what it is detected as!
int millerRawDecode(uint8_t *bits, size_t *size, int invert) {
if (*size < 16) return -1;
uint16_t MaxBits = 512, errCnt = 0;
size_t i, bitCnt = 0;
uint8_t alignCnt = 0, curBit = bits[0], alignedIdx = 0, halfClkErr = 0;
//find alignment, needs 4 1s or 0s to properly align
for (i=1; i < *size-1; i++) {
alignCnt = (bits[i] == curBit) ? alignCnt+1 : 0;
curBit = bits[i];
if (alignCnt == 4) break;
}
// for now error if alignment not found. later add option to run it with multiple offsets...
if (alignCnt != 4) {
if (g_debugMode) prnt("ERROR MillerDecode: alignment not found so either your bits is not miller or your data does not have a 101 in it");
return -1;
}
alignedIdx = (i-1) % 2;
for (i = alignedIdx; i < *size-3; i += 2) {
halfClkErr = (uint8_t)((halfClkErr << 1 | bits[i]) & 0xFF);
if ( (halfClkErr & 0x7) == 5 || (halfClkErr & 0x7) == 2 || (i > 2 && (halfClkErr & 0x7) == 0) || (halfClkErr & 0x1F) == 0x1F) {
errCnt++;
bits[bitCnt++] = 7;
continue;
}
bits[bitCnt++] = bits[i] ^ bits[i+1] ^ invert;
if (bitCnt > MaxBits) break;
}
*size = bitCnt;
return errCnt;
}
//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 *bits, size_t *size, int *offset, int invert) {
//sanity check
if (*size < 51) return -1;
uint16_t bitnum = 0;
uint16_t errCnt = 0;
size_t i = *offset;
uint16_t maxbits = 512;
//check for phase change faults - skip one sample if faulty
bool offsetA = true, offsetB = true;
for (; i < *offset+48; i += 2){
if (bits[i+1] == bits[i+2]) offsetA = false;
if (bits[i+2] == bits[i+3]) offsetB = false;
}
if (!offsetA && offsetB) ++*offset;
for (i = *offset; i < *size-3; i += 2){
//check for phase error
if (bits[i+1] == bits[i+2]) {
bits[bitnum++] = 7;
errCnt++;
}
if((bits[i]==1 && bits[i+1]==0) || (bits[i]==0 && bits[i+1]==1)){
bits[bitnum++] = 1 ^ invert;
} else if((bits[i]==0 && bits[i+1]==0) || (bits[i]==1 && bits[i+1]==1)){
bits[bitnum++] = invert;
} else {
bits[bitnum++] = 7;
errCnt++;
}
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 *bits, size_t *size, uint8_t invert, uint8_t *alignPos){
// sanity check
if (*size < 16) return -1;
int errCnt = 0, bestErr = 1000;
uint16_t bitnum = 0, maxBits = 512, bestRun = 0;
size_t i, k;
//find correct start position [alignment]
for (k = 0; k < 2; ++k){
for (i = k; i < *size-3; i += 2) {
if (bits[i] == bits[i+1])
errCnt++;
}
if (bestErr > errCnt){
bestErr = errCnt;
bestRun = k;
}
errCnt = 0;
}
*alignPos = bestRun;
//decode
for (i = bestRun; i < *size-3; i += 2){
if (bits[i] == 1 && (bits[i+1] == 0)){
bits[bitnum++] = invert;
} else if ((bits[i] == 0) && bits[i+1] == 1){
bits[bitnum++] = invert^1;
} else {
bits[bitnum++] = 7;
}
if (bitnum > maxBits) break;
}
*size = bitnum;
return bestErr;
}
//by marshmellow
//demodulates strong heavily clipped samples
//RETURN: num of errors. if 0, is ok.
int cleanAskRawDemod(uint8_t *bits, size_t *size, int clk, int invert, int high, int low, int *startIdx) {
*startIdx = 0;
size_t bitCnt = 0, smplCnt = 1, errCnt = 0, pos = 0;
uint8_t cl_4 = clk / 4;
uint8_t cl_2 = clk / 2;
bool waveHigh = true;
getNextHigh(bits, *size, high, &pos);
// sample counts, like clock = 32.. it tries to find 32/4 = 8, 32/2 = 16
for (size_t i = pos; i < *size; i++){
if (bits[i] >= high && waveHigh){
smplCnt++;
} else if (bits[i] <= low && !waveHigh){
smplCnt++;
} else { //transition
if ((bits[i] >= high && !waveHigh) || (bits[i] <= low && waveHigh)){
// 32-8-1 = 23
// 32+8+1 = 41
if (smplCnt > clk - cl_4 - 1) { //full clock
if (smplCnt > clk + cl_4 + 1) { //too many samples
errCnt++;
if (g_debugMode == 2) prnt("DEBUG ASK: cleanAskRawDemod ASK Modulation Error FULL at: %u [%u]", i, smplCnt);
bits[bitCnt++] = 7;
} else if (waveHigh) {
bits[bitCnt++] = invert;
bits[bitCnt++] = invert;
} else if (!waveHigh) {
bits[bitCnt++] = invert ^ 1;
bits[bitCnt++] = invert ^ 1;
}
if (*startIdx == 0)
*startIdx = i - clk;
waveHigh = !waveHigh;
smplCnt = 0;
// 16-8-1 = 7
} else if (smplCnt > cl_2 - cl_4 - 1) { //half clock
if (smplCnt > cl_2 + cl_4 + 1) { //too many samples
errCnt++;
if (g_debugMode == 2) prnt("DEBUG ASK: cleanAskRawDemod ASK Modulation Error HALF at: %u [%u]", i, smplCnt);
bits[bitCnt++] = 7;
}
if (waveHigh) {
bits[bitCnt++] = invert;
} else if (!waveHigh) {
bits[bitCnt++] = invert ^ 1;
}
if (*startIdx == 0)
*startIdx = i - cl_2;
waveHigh = !waveHigh;
smplCnt = 0;
} else {
smplCnt++;
//transition bit oops
}
} else { //haven't hit new high or new low yet
smplCnt++;
}
}
}
*size = bitCnt;
return errCnt;
}
//by marshmellow
//attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
int askdemod_ext(uint8_t *bits, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType, int *startIdx) {
if (*size == 0) return -1;
int start = DetectASKClock(bits, *size, clk, maxErr);
if (*clk == 0 || start < 0) return -3;
if (*invert != 1) *invert = 0;
// amplify signal data.
// ICEMAN todo,
if (amp == 1) askAmp(bits, *size);
if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, beststart %d, amp %d", *clk, start, amp);
//start pos from detect ask clock is 1/2 clock offset
// NOTE: can be negative (demod assumes rest of wave was there)
*startIdx = start - (*clk/2);
uint16_t initLoopMax = 1024;
if (initLoopMax > *size) initLoopMax = *size;
// just noise - no super good detection. good enough
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG askdemod_ext: just noise detected - aborting");
return -2;
}
// Detect high and lows
//25% clip in case highs and lows aren't clipped [marshmellow]
int high, low;
//getHiLo(bits, initLoopMax, &high, &low, 75, 75);
getHiLo(&high, &low, 75, 75);
size_t errCnt = 0;
// if clean clipped waves detected run alternate demod
if (DetectCleanAskWave(bits, *size, high, low)) {
if (g_debugMode == 2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
errCnt = cleanAskRawDemod(bits, size, *clk, *invert, high, low, startIdx);
if (askType) { //ask/manchester
uint8_t alignPos = 0;
errCnt = manrawdecode(bits, size, 0, &alignPos);
*startIdx += *clk/2 * alignPos;
if (g_debugMode)
prnt("DEBUG: (askdemod_ext) CLEAN: startIdx %i, alignPos %u", *startIdx, alignPos);
}
return errCnt;
}
if (g_debugMode) prnt("DEBUG: (askdemod_ext) Weak wave detected: startIdx %i", *startIdx);
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 (bits[i] >= high) {
bits[bitnum++] = *invert;
} else if (bits[i] <= low) {
bits[bitnum++] = *invert ^ 1;
} else if (i-lastBit >= *clk + tol) {
if (bitnum > 0) {
if (g_debugMode == 2) prnt("DEBUG: (askdemod_ext) Modulation Error at: %u", i);
bits[bitnum++] = 7;
errCnt++;
}
} else { //in tolerance - looking for peak
continue;
}
midBit = 0;
lastBit += *clk;
} else if (i-lastBit >= (*clk/2 - tol) && !midBit && !askType){
if (bits[i] >= high) {
bits[bitnum++] = *invert;
} else if (bits[i] <= low) {
bits[bitnum++] = *invert ^ 1;
} else if (i-lastBit >= *clk/2 + tol) {
bits[bitnum] = bits[bitnum-1];
bitnum++;
} else { //in tolerance - looking for peak
continue;
}
midBit = 1;
}
if (bitnum >= MaxBits) break;
}
*size = bitnum;
return errCnt;
}
int askdemod(uint8_t *bits, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType) {
int start = 0;
return askdemod_ext(bits, size, clk, invert, maxErr, amp, askType, &start);
}
// 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, int *startIdx) {
if (signalprop.isnoise) return -1;
size_t clkStartIdx = 0;
*clk = DetectNRZClock(dest, *size, *clk, &clkStartIdx);
if (*clk == 0) return -2;
size_t i, gLen = 4096;
if (gLen > *size)
gLen = *size-20;
// just noise - no super good detection. good enough
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG nrzRawDemod: just noise detected - quitting");
return -3;
}
int high, low;
//getHiLo(dest, gLen, &high, &low, 75, 75);
getHiLo(&high, &low, 75, 75);
getHiLo(&high, &low, 75, 75);
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;
if (lastBit == 0) {
*startIdx = i - (numBits * *clk);
if (g_debugMode == 2) prnt("DEBUG NRZ: startIdx %i", *startIdx);
}
lastBit = i-1;
}
}
*size = numBits;
return 0;
}
//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, int *startIdx) {
if ( size < 1024 ) return 0; // not enough samples
if (fchigh == 0) fchigh = 10;
if (fclow == 0) fclow = 8;
//set the threshold close to 0 (graph) or 128 std to avoid static
size_t preLastSample = 0;
size_t LastSample = 0;
size_t currSample = 0;
size_t last_transition = 0;
size_t idx = 1;
size_t numBits = 0;
//find start of modulating data in trace
idx = findModStart(dest, size, fchigh);
// Need to threshold first sample
dest[0] = (dest[idx] < signalprop.mean) ? 0 : 1;
last_transition = idx;
idx++;
// Definition: cycles between consecutive lo-hi transitions
// Lets define some expected lengths. FSK1 is easier since it has bigger differences between.
// FSK1 8/5
// 50/8 = 6 | 40/8 = 5 | 64/8 = 8
// 50/5 = 10 | 40/5 = 8 | 64/5 = 12
// FSK2 10/8
// 50/10 = 5 | 40/10 = 4 | 64/10 = 6
// 50/8 = 6 | 40/8 = 5 | 64/8 = 8
// count cycles between consecutive lo-hi transitions,
// in practice due to noise etc we may end up with anywhere
// To allow fuzz would mean +-1 on expected cycle width.
// FSK1 8/5
// 50/8 = 6 (5-7) | 40/8 = 5 (4-6) | 64/8 = 8 (7-9)
// 50/5 = 10 (9-11) | 40/5 = 8 (7-9) | 64/5 = 12 (11-13)
// FSK2 10/8
// 50/10 = 5 (4-6) | 40/10 = 4 (3-5) | 64/10 = 6 (5-7)
// 50/8 = 6 (5-7) | 40/8 = 5 (4-6) | 64/8 = 8 (7-9)
//
// It easy to see to the overgaping, but luckily we the group value also, like 1111000001111
// to separate between which bit to demodulate to.
// process:
// count width from 0-1 transition to 1-0.
// determine the width is withing FUZZ_min and FUZZ_max tolerances
// width should be divided with exp_one. i:e 6+7+6+2=21, 21/5 = 4,
// the 1-0 to 0-1 width should be divided with exp_zero. Ie: 3+5+6+7 = 21/6 = 3
for(; idx < size-20; idx++) {
// threshold current value
dest[idx] = (dest[idx] < signalprop.mean) ? 0 : 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 (numBits > 1 && LastSample > (fchigh-2) && (preLastSample < (fchigh-1))){
dest[numBits-1]=1;
}
dest[numBits++]=1;
if (numBits > 0 && *startIdx == 0)
*startIdx = idx - fclow;
} else if (currSample > (fchigh+1) && numBits < 3) { //12 + and first two bit = unusable garbage
//do nothing with beginning garbage and reset.. should be rare..
numBits = 0;
} 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;
if (numBits > 0 && *startIdx == 0) {
*startIdx = idx - fclow;
}
} else { //9+ = 10 sample waves (or 6+ = 7)
dest[numBits++]=0;
if (numBits > 0 && *startIdx == 0) {
*startIdx = idx - fchigh;
}
}
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 clk, uint8_t invert, uint8_t fchigh, uint8_t fclow, int *startIdx) {
uint8_t lastval = dest[0];
size_t i = 0;
size_t numBits = 0;
uint32_t n = 1;
uint8_t hclk = clk/2;
for( i = 1; i < size; i++) {
n++;
if (dest[i] == lastval) continue; //skip until we hit a transition
//find out how many bits (n) we collected (use 1/2 clk tolerance)
if (dest[i-1] == 1)
//if lastval was 1, we have a 1->0 crossing
n = (n * fclow + hclk) / clk;
else
// 0->1 crossing
n = (n * fchigh + hclk) / clk;
if (n == 0)
n = 1;
//first transition - save startidx
if (numBits == 0) {
if (lastval == 1) { //high to low
*startIdx += (fclow * i) - (n*clk);
if (g_debugMode == 2) prnt("DEBUG (aggregate_bits) FSK startIdx %i, fclow*idx %i, n*clk %u", *startIdx, fclow*i, n*clk);
} else {
*startIdx += (fchigh * i) - (n*clk);
if (g_debugMode == 2) prnt("DEBUG (aggregate_bits) FSK startIdx %i, fchigh*idx %i, n*clk %u", *startIdx, fchigh*i, n*clk);
}
}
//add to our destination the bits we collected
memset(dest+numBits, dest[i-1] ^ invert , n);
numBits += n;
n = 0;
lastval = dest[i];
}//end for
// if valid extra bits at the end were all the same frequency - add them in
if (n > clk/fchigh) {
if (dest[i-2] == 1) {
n = (n * fclow + clk/2) / clk;
} else {
n = (n * fchigh + clk/2) / clk;
}
memset(dest+numBits, dest[i-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)
size_t fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow, int *start_idx) {
if (signalprop.isnoise) return 0;
// FSK demodulator
size = fsk_wave_demod(dest, size, fchigh, fclow, start_idx);
size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow, start_idx);
return size;
}
// by marshmellow
// convert psk1 demod to psk2 demod
// only transition waves are 1s
//TODO: Iceman - hard coded value 7, should be #define
void psk1TOpsk2(uint8_t *bits, size_t size) {
uint8_t lastbit = bits[0];
for (size_t i = 1; i < size; i++){
//ignore errors
if (bits[i] == 7) continue;
if (lastbit != bits[i]){
lastbit = bits[i];
bits[i] = 1;
} else {
bits[i] = 0;
}
}
}
// by marshmellow
// convert psk2 demod to psk1 demod
// from only transition waves are 1s to phase shifts change bit
void psk2TOpsk1(uint8_t *bits, size_t size) {
uint8_t phase = 0;
for (size_t i = 0; i < size; i++){
if (bits[i] == 1){
phase ^= 1;
}
bits[i] = phase;
}
}
//by marshmellow - demodulate PSK1 wave
//uses wave lengths (# Samples)
//TODO: Iceman - hard coded value 7, should be #define
int pskRawDemod_ext(uint8_t *dest, size_t *size, int *clock, int *invert, int *startIdx) {
// sanity check
if (*size < 170) return -1;
uint8_t curPhase = *invert;
uint8_t fc=0;
size_t i=0, numBits=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
uint16_t fullWaveLen=0, waveLenCnt=0, avgWaveVal=0;
uint16_t errCnt=0, errCnt2=0;
*clock = DetectPSKClock(dest, *size, *clock, &firstFullWave, &curPhase, &fc);
if (*clock <= 0) return -1;
//if clock detect found firstfullwave...
uint16_t tol = fc/2;
if (firstFullWave == 0) {
//find start of modulating data in trace
i = findModStart(dest, *size, fc);
//find first phase shift
firstFullWave = pskFindFirstPhaseShift(dest, *size, &curPhase, i, fc, &fullWaveLen);
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);
}
} else {
memset(dest, curPhase^1, firstFullWave / *clock);
}
//advance bits
numBits += (firstFullWave / *clock);
*startIdx = firstFullWave - (*clock * numBits)+2;
//set start of wave as clock align
lastClkBit = firstFullWave;
if (g_debugMode == 2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u, startIdx %i",firstFullWave,fullWaveLen, *startIdx);
if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit, 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;
if (waveLenCnt > fc){
//this wave is a phase shift
//prnt("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;
} else if (waveLenCnt < fc - 1) { //wave is smaller than field clock (shouldn't happen often)
errCnt2++;
if(errCnt2 > 101) return errCnt2;
avgWaveVal += dest[i+1];
continue;
}
avgWaveVal = 0;
waveStart = i+1;
}
}
avgWaveVal += dest[i+1];
}
*size = numBits;
return errCnt;
}
int pskRawDemod(uint8_t *dest, size_t *size, int *clock, int *invert) {
int start_idx = 0;
return pskRawDemod_ext(dest, size, clock, invert, &start_idx);
}
//**********************************************************************************************
//-----------------Tag format detection section-------------------------------------------------
//**********************************************************************************************
// by marshmellow
// FSK Demod then try to locate an AWID ID
int detectAWID(uint8_t *dest, size_t *size, int *waveStartIdx) {
//make sure buffer has enough data (96bits * 50clock samples)
if (*size < 96*50) return -1;
if (signalprop.isnoise) return -2;
zeromean(dest, *size);
// FSK2a demodulator clock 50, invert 1, fcHigh 10, fcLow 8
*size = fskdemod(dest, *size, 50, 1, 10, 8, waveStartIdx); //awid fsk2a
//did we get a good demod?
if (*size < 96) return -3;
size_t start_idx = 0;
uint8_t preamble[] = {0,0,0,0,0,0,0,1};
if (!preambleSearch(dest, preamble, sizeof(preamble), size, &start_idx))
return -4; //preamble not found
// wrong size? (between to preambles)
if (*size != 96) return -5;
return (int)start_idx;
}
//by marshmellow
//takes 1s and 0s and searches for EM410x format - output EM ID
int Em410xDecode(uint8_t *bits, size_t *size, size_t *start_idx, uint32_t *hi, uint64_t *lo) {
// sanity check
if (bits[1] > 1) return -1;
if (*size < 64) return -2;
uint8_t fmtlen;
*start_idx = 0;
// preamble 0111111111
// include 0 in front to help get start pos
uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
if (!preambleSearch(bits, preamble, sizeof(preamble), size, start_idx))
return -4;
// (iceman) if the preamble doesn't find two occuriences, this identification fails.
fmtlen = (*size == 128) ? 22 : 10;
//skip last 4bit parity row for simplicity
*size = removeParity(bits, *start_idx + sizeof(preamble), 5, 0, fmtlen * 5);
switch (*size) {
case 40: {
// std em410x format
*hi = 0;
*lo = ((uint64_t)(bytebits_to_byte(bits, 8)) << 32) | (bytebits_to_byte(bits + 8, 32));
break;
}
case 88: {
// long em format
*hi = (bytebits_to_byte(bits, 24));
*lo = ((uint64_t)(bytebits_to_byte(bits + 24, 32)) << 32) | (bytebits_to_byte(bits + 24 + 32, 32));
break;
}
default: return -6;
}
return 1;
}
// 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, int *waveStartIdx) {
//make sure buffer has data
if (*size < 96*50) return -1;
if (signalprop.isnoise) return -2;
zeromean(dest, *size);
// FSK demodulator fsk2a so invert and fc/10/8
*size = fskdemod(dest, *size, 50, 1, 10, 8, waveStartIdx); //hid fsk2a
//did we get a good demod?
if (*size < 96*2) return -3;
// 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
size_t start_idx = 0;
uint8_t preamble[] = {0,0,0,1,1,1,0,1};
if (!preambleSearch(dest, preamble, sizeof(preamble), size, &start_idx))
return -4; //preamble not found
// wrong size? (between to preambles)
//if (*size != 96) return -5;
size_t num_start = start_idx + sizeof(preamble);
// final loop, go over previously decoded FSK data and manchester decode into usable tag ID
for (size_t idx = num_start; (idx - num_start) < *size - sizeof(preamble); idx += 2) {
if (dest[idx] == dest[idx+1]){
return -5; //not manchester data
}
*hi2 = (*hi2 << 1) | (*hi >> 31);
*hi = (*hi << 1) | (*lo >> 31);
//Then, shift in a 0 or one into low
*lo <<= 1;
if (dest[idx] && !dest[idx+1]) // 1 0
*lo |= 1;
else // 0 1
*lo |= 0;
}
return (int)start_idx;
}
// Find IDTEC PSK1, RF Preamble == 0x4944544B, Demodsize 64bits
// by iceman
int detectIdteck(uint8_t *dest, size_t *size) {
//make sure buffer has data
if (*size < 64*2) return -1;
if (signalprop.isnoise) return -2;
size_t start_idx = 0;
uint8_t preamble[] = {0,1,0,0,1,0,0,1,0,1,0,0,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,0,1,0,1,1};
//preamble not found
if (!preambleSearch(dest, preamble, sizeof(preamble), size, &start_idx))
return -3;
// wrong demoded size
if (*size != 64) return -4;
return (int)start_idx;
}
int detectIOProx(uint8_t *dest, size_t *size, int *waveStartIdx) {
//make sure buffer has data
if (*size < 66*64) return -1;
if (signalprop.isnoise) return -2;
zeromean(dest, *size);
// FSK demodulator RF/64, fsk2a so invert, and fc/10/8
*size = fskdemod(dest, *size, 64, 1, 10, 8, waveStartIdx); //io fsk2a
//did we get enough demod data?
if (*size < 64) return -3;
//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
size_t start_idx = 0;
uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
if (!preambleSearch(dest, preamble, sizeof(preamble), size, &start_idx))
return -4; //preamble not found
// wrong size? (between to preambles)
if (*size != 64) return -5;
if ( !dest[start_idx + 8]
&& dest[start_idx + 17] == 1
&& dest[start_idx + 26] == 1
&& dest[start_idx + 35] == 1
&& dest[start_idx + 44] == 1
&& dest[start_idx + 53] == 1) {
//confirmed proper separator bits found
//return start position
return (int) start_idx;
}
return -6;
}
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