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proxmark3/common/lfdemod.c
Philippe Teuwen 3aeb5c493f fix a few cppcheck warnings
2023-09-07 22:28:37 +02:00

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//-----------------------------------------------------------------------------
// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// See LICENSE.txt for the text of the license.
//-----------------------------------------------------------------------------
// Low frequency demod/decode commands
//
// NOTES:
// LF Demod functions are placed here to allow the flexibility 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 "lfdemod.h"
#include <string.h> // for memset, memcmp and size_t
#include <stdlib.h> // qsort
#include "parity.h" // for parity test
#include "pm3_cmd.h" // error codes
#include "commonutil.h" // Arraylen
// **********************************************************************************************
// ---------------------------------Utilities Section--------------------------------------------
// **********************************************************************************************
#define LOWEST_DEFAULT_CLOCK 32
#define FSK_PSK_THRESHOLD 123
//to allow debug print calls when used not on dev
#ifndef ON_DEVICE
#include "ui.h"
#include "util.h"
# include "cmddata.h"
# define prnt(args...) PrintAndLogEx(DEBUG, ## args );
#else
# include "dbprint.h"
uint8_t g_debugMode = 0;
# define prnt Dbprintf
#endif
static 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) ? _RED_("Yes") : _GREEN_("No"));
prnt(" THRESHOLD noise amplitude......%d", NOISE_AMPLITUDE_THRESHOLD);
}
#ifndef ON_DEVICE
static int cmp_uint8(const void *a, const void *b) {
if (*(const uint8_t *)a < * (const uint8_t *)b)
return -1;
else
return *(const uint8_t *)a > *(const uint8_t *)b;
}
#endif
void computeSignalProperties(const uint8_t *samples, uint32_t size) {
resetSignal();
if (samples == NULL || size < SIGNAL_MIN_SAMPLES) return;
uint32_t sum = 0;
uint32_t offset_size = size - SIGNAL_IGNORE_FIRST_SAMPLES;
#ifndef ON_DEVICE
uint8_t tmp[offset_size];
memcpy(tmp, samples + SIGNAL_IGNORE_FIRST_SAMPLES, sizeof(tmp));
qsort(tmp, sizeof(tmp), sizeof(uint8_t), cmp_uint8);
uint8_t low10 = 0.5 * (tmp[(int)(offset_size * 0.1)] + tmp[(int)((offset_size - 1) * 0.1)]);
uint8_t hi90 = 0.5 * (tmp[(int)(offset_size * 0.9)] + tmp[(int)((offset_size - 1) * 0.9)]);
uint32_t cnt = 0;
for (uint32_t i = SIGNAL_IGNORE_FIRST_SAMPLES; i < size; i++) {
if (samples[i] < signalprop.low) signalprop.low = samples[i];
if (samples[i] > signalprop.high) signalprop.high = samples[i];
if (samples[i] < low10 || samples[i] > hi90)
continue;
sum += samples[i];
cnt++;
}
if (cnt > 0)
signalprop.mean = sum / cnt;
else
signalprop.mean = 0;
#else
for (uint32_t i = SIGNAL_IGNORE_FIRST_SAMPLES; i < size; i++) {
if (samples[i] < signalprop.low) signalprop.low = samples[i];
if (samples[i] > signalprop.high) signalprop.high = samples[i];
sum += samples[i];
}
signalprop.mean = sum / offset_size;
#endif
// measure amplitude of signal
signalprop.amplitude = signalprop.high - signalprop.mean;
// By measuring mean and look at amplitude of signal from HIGH / LOW,
// we can detect noise
signalprop.isnoise = signalprop.amplitude < NOISE_AMPLITUDE_THRESHOLD;
if (g_debugMode)
printSignal();
}
void removeSignalOffset(uint8_t *samples, uint32_t size) {
if (samples == NULL || size < SIGNAL_MIN_SAMPLES) return;
int acc_off = 0;
uint32_t offset_size = size - SIGNAL_IGNORE_FIRST_SAMPLES;
#ifndef ON_DEVICE
uint8_t tmp[offset_size];
memcpy(tmp, samples + SIGNAL_IGNORE_FIRST_SAMPLES, sizeof(tmp));
qsort(tmp, sizeof(tmp), sizeof(uint8_t), cmp_uint8);
uint8_t low10 = 0.5 * (tmp[(int)(offset_size * 0.05)] + tmp[(int)((offset_size - 1) * 0.05)]);
uint8_t hi90 = 0.5 * (tmp[(int)(offset_size * 0.95)] + tmp[(int)((offset_size - 1) * 0.95)]);
int32_t cnt = 0;
for (uint32_t i = SIGNAL_IGNORE_FIRST_SAMPLES; i < size; i++) {
if (samples[i] < low10 || samples[i] > hi90)
continue;
acc_off += samples[i] - 128;
cnt++;
}
if (cnt > 0)
acc_off /= cnt;
else
acc_off = 0;
#else
for (uint32_t i = SIGNAL_IGNORE_FIRST_SAMPLES; i < size; i++)
acc_off += samples[i] - 128;
acc_off /= (int)offset_size;
#endif
// shift and saturate samples to center the mean
for (uint32_t i = 0; i < size; i++) {
if (acc_off > 0) {
samples[i] = (samples[i] >= acc_off) ? samples[i] - acc_off : 0;
}
if (acc_off < 0) {
samples[i] = (255 - samples[i] >= -acc_off) ? samples[i] - acc_off : 255;
}
}
}
// 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;
}
// prnt("getHiLo fuzzed: High %d | Low %d", *high, *low);
}
// 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;
}
// 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;
}
static size_t removeEm410xParity(uint8_t *bits, size_t startIdx, bool isLong, bool *validShort, bool *validShortExtended, bool *validLong) {
uint32_t parityWd = 0;
size_t bitCnt = 0;
bool validColParity = false;
bool validRowParity = true;
bool validRowParitySkipColP = true;
*validShort = false;
*validShortExtended = false;
*validLong = false;
uint8_t bLen = isLong ? 110 : 55;
uint16_t parityCol[4] = { 0, 0, 0, 0 };
for (int word = 0; word < bLen; word += 5) {
for (int bit = 0; bit < 5; bit++) {
if (word + bit >= bLen) {
break;
}
parityWd = (parityWd << 1) | bits[startIdx + word + bit];
if ((word <= 50) && (bit < 4)) {
parityCol[bit] = (parityCol[bit] << 1) | bits[startIdx + word + bit];
}
bits[bitCnt++] = (bits[startIdx + word + bit]);
}
if (word + 5 > bLen) break;
bitCnt--; // overwrite parity with next data
validRowParity &= parityTest(parityWd, 5, 0) != 0;
if (word == 50) { // column parity nibble on short EM and on Electra
validColParity = parityTest(parityCol[0], 11, 0) != 0;
validColParity &= parityTest(parityCol[1], 11, 0) != 0;
validColParity &= parityTest(parityCol[2], 11, 0) != 0;
validColParity &= parityTest(parityCol[3], 11, 0) != 0;
} else {
validRowParitySkipColP &= parityTest(parityWd, 5, 0) != 0;
}
parityWd = 0;
}
if (!isLong && validRowParitySkipColP && validColParity) {
*validShort = true;
}
if (isLong && validRowParity) {
*validLong = true;
}
if (isLong && validRowParitySkipColP && validColParity) {
*validShortExtended = true;
}
if (*validShort || *validShortExtended || *validLong) {
return bitCnt;
} else {
return 0;
}
}
// 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(const 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
int bits_to_array(const uint8_t *bits, size_t size, uint8_t *dest) {
if ((size == 0) || (size % 8) != 0) return PM3_EINVARG;
for (uint32_t i = 0; i < (size / 8); i++)
dest[i] = bytebits_to_byte((uint8_t *) bits + (i * 8), 8);
return PM3_SUCCESS;
}
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;
}
// 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);
}
// 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 >= 1) prnt("DEBUG: (preambleSearchEx) preamble found at %zu", idx);
*startIdx = idx;
if (findone)
return true;
}
if (foundCnt == 2) {
if (g_debugMode >= 1) prnt("DEBUG: (preambleSearchEx) preamble 2 found at %zu", 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.
static size_t findModStart(const 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 %zu, count: %u", i, thresholdCnt);
return i;
}
static int getClosestClock(int testclk) {
const uint16_t clocks[] = {8, 16, 32, 40, 50, 64, 100, 128, 256, 272, 384};
const uint8_t limit[] = {1, 2, 4, 4, 5, 8, 8, 8, 8, 24, 24};
for (uint8_t i = 0; i < ARRAYLEN(clocks); i++) {
if (testclk >= clocks[i] - limit[i] && testclk <= clocks[i] + limit[i])
return clocks[i];
}
return 0;
}
void getNextLow(const uint8_t *samples, size_t size, int low, size_t *i) {
while ((samples[*i] > low) && (*i < size))
*i += 1;
}
void getNextHigh(const 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;
//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
size_t firstLow = i;
//find first high point for this wave
getNextHigh(samples, size, *high, &i);
size_t 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(const 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;
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: %zu, waveStart: %zu", 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;
}
// 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;
for (uint8_t i = 0; i < 16; i++) {
uint8_t b = (datain >> (15 - i) & 1);
output |= (1 << (((15 - i) * 2) + b));
}
return output;
}
void manchesterEncodeUint32(uint32_t data_in, uint8_t bitlen_in, uint8_t *bits_out, uint16_t *index) {
for (int i = bitlen_in - 1; i >= 0; i--) {
if ((data_in >> i) & 1) {
bits_out[(*index)++] = 1;
bits_out[(*index)++] = 0;
} else {
bits_out[(*index)++] = 0;
bits_out[(*index)++] = 1;
}
}
}
// 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;
}
// to detect a wave that has heavily clipped (clean) samples
// loop 1024 samples, if 250 of them is deemed maxed out, we assume the wave is clipped.
bool DetectCleanAskWave(const uint8_t *dest, size_t size, uint8_t high, uint8_t low) {
bool allArePeaks = true;
uint16_t cntPeaks = 0;
size_t loopEnd = 1024 + 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 (g_debugMode == 2) prnt("DEBUG DetectCleanAskWave: peaks (200) %u", cntPeaks);
if (cntPeaks > 200) return true;
}
}
if (allArePeaks == false) {
if (g_debugMode == 2) prnt("DEBUG DetectCleanAskWave: peaks (200) %u", cntPeaks);
if (cntPeaks > 200) return true;
}
return allArePeaks;
}
// **********************************************************************************************
// -------------------Clock / Bitrate Detection Section------------------------------------------
// **********************************************************************************************
// 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 i = 100;
size_t minClk = 768;
uint16_t 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);
if (i == size)
return -1;
if (size < 768)
return -2;
// clock, numoftimes, first idx
uint16_t tmpclk[11][3] = {
{8, 0, 0},
{16, 0, 0},
{32, 0, 0},
{40, 0, 0},
{50, 0, 0},
{64, 0, 0},
{100, 0, 0},
{128, 0, 0},
{256, 0, 0},
{272, 0, 0},
{384, 0, 0},
};
// loop through all samples (well, we don't want to go out-of-bounds)
while (i < (size - 768)) {
// measure from low to low
size_t 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;
}
int foo = getClosestClock(minClk);
if (foo > 0) {
for (uint8_t j = 0; j < 11; j++) {
if (tmpclk[j][0] == foo) {
tmpclk[j][1]++;
if (tmpclk[j][2] == 0) {
tmpclk[j][2] = shortestWaveIdx;
}
break;
}
}
}
}
// find the clock with most hits and it the first index it was encountered.
int possible_clks = 0;
for (uint8_t j = 0; j < 11; j++) {
if (tmpclk[j][1] > 0) {
possible_clks++;
}
}
uint16_t second_shortest = 0;
int second = 0;
int max = 0;
for (int j = 10; j > -1; j--) {
if (g_debugMode == 2) {
prnt("DEBUG, ASK, clocks %u | hits %u | idx %u"
, tmpclk[j][0]
, tmpclk[j][1]
, tmpclk[j][2]
);
}
if (max < tmpclk[j][1]) {
second = *clock;
second_shortest = shortestWaveIdx;
*clock = tmpclk[j][0];
shortestWaveIdx = tmpclk[j][2];
max = tmpclk[j][1];
}
}
// ASK clock 8 is very rare and usually gives us false positives
if (possible_clks > 1 && *clock == 8) {
*clock = second;
shortestWaveIdx = second_shortest;
}
if (*clock == 0)
return -1;
return shortestWaveIdx;
}
// 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 = 2000;
// 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;
uint8_t num_clks = 10;
// first 255 value pos0 is placeholder for user inputed clock.
uint16_t clk[] = {255, 8, 16, 32, 40, 50, 64, 100, 128, 255, 272};
// 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;
size_t j = 0;
uint16_t bestErr[] = {1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000};
uint8_t bestStart[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
size_t errCnt, 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]);
}
bool chg = false;
for (i = 0; i < ARRAYLEN(bestErr); i++) {
chg = (bestErr[i] != 1000);
if (chg)
break;
chg = (bestStart[i] != 0);
if (chg)
break;
}
// just noise - no super good detection. good enough
if (chg == false) {
if (g_debugMode == 2) prnt("DEBUG DetectASKClock: no good values detected - aborting");
return -2;
}
if (!found_clk)
*clock = clk[best];
return bestStart[best];
}
int DetectStrongNRZClk(const 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;
}
// 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;
uint16_t clk[] = {8, 16, 32, 40, 50, 64, 100, 128, 255, 272, 384};
size_t loopCnt = 4096; //don't need to loop through entire array...
//if we already have a valid clock quit
for (; i < ARRAYLEN(clk); ++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, 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, 0, 0};
peakcnt = 0;
//test each valid clock from smallest to greatest to see which lines up
for (clkCnt = 0; clkCnt < ARRAYLEN(bestStart); ++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 = ARRAYLEN(peaksdet) - 1; 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];
}
// 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(const 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: %zu > %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];
}
// 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) {
uint16_t clk[] = {255, 16, 32, 40, 50, 64, 100, 128, 256, 272, 384}; // 255 is not a valid clock
uint16_t loopCnt = 4096; // don't need to loop through entire array...
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 waveEnd, firstFullWave = 0;
uint8_t clkCnt;
uint16_t waveLenCnt, fullWaveLen = 0;
uint16_t bestErr[] = {1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000, 1000};
uint16_t peaksdet[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
//find start of modulating data in trace
size_t 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: %zu, waveLen: %d", firstFullWave, fullWaveLen);
// Avoid autodetect if user selected a clock
for (uint8_t validClk = 1; validClk < 8; validClk++) {
if (clock == clk[validClk]) return (clock);
}
//test each valid clock from greatest to smallest to see which lines up
for (clkCnt = 9; clkCnt >= 1 ; clkCnt--) {
uint8_t tol = *fc / 2;
size_t lastClkBit = firstFullWave; //set end of wave as clock align
size_t waveStart = 0;
uint16_t errCnt = 0;
uint16_t peakcnt = 0;
if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %zu", 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;
} 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: %zu, len: %d, nextClk: %zu, i: %zu, 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 = 9;
for (i = 9; 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];
}
// detects the bit clock for FSK given the high and low Field Clocks
uint8_t detectFSKClk(const 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...
static bool findST(int *stStopLoc, int *stStartIdx,
const int lowToLowWaveLen[], const 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;
}
// 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 calloc... || 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: %zu %% %d = %zu - 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: %zu, datalen: %zu ", 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 %zu to %zu", dataloc, dataloc + (clk * 4));
dataloc += clk * 4;
}
*size = newloc;
return true;
}
// 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!
/*
static 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;
}
*/
// 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;
if (*offset < 0) *offset = 0;
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;
// main loop
for (i = *offset; i < *size - 1; 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;
}
// take 10 and 01 and manchester decode
// run through 2 times and take least errCnt
// "," indicates 00 or 11 wrong bit
uint16_t manrawdecode(uint8_t *bits, size_t *size, uint8_t invert, uint8_t *alignPos) {
// sanity check
if (*size < 16) return 0xFFFF;
int errCnt = 0, bestErr = 1000;
uint16_t bitnum = 0, maxBits = 512, bestRun = 0;
size_t i;
//find correct start position [alignment]
for (uint8_t k = 0; k < 2; k++) {
for (i = k; i < *size - 1; i += 2) {
if (bits[i] == bits[i + 1])
errCnt++;
if (errCnt > 50)
break;
}
if (bestErr > errCnt) {
bestErr = errCnt;
bestRun = k;
if (g_debugMode == 2) prnt("DEBUG manrawdecode: bestErr %d | bestRun %u", bestErr, bestRun);
}
errCnt = 0;
}
*alignPos = bestRun;
//decode
for (i = bestRun; i < *size; 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;
}
// demodulates strong heavily clipped samples
// RETURN: num of errors. if 0, is ok.
static uint16_t 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);
// getNextLow(bits, *size, low, &pos);
// do not skip first transition
if ((pos > cl_2 - cl_4 - 1) && (pos <= clk + cl_4 + 1)) {
bits[bitCnt++] = invert ^ 1;
}
// 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)) {
// 8 :: 8-2-1 = 5 8+2+1 = 11
// 16 :: 16-4-1 = 11 16+4+1 = 21
// 32 :: 32-8-1 = 23 32+8+1 = 41
// 64 :: 64-16-1 = 47 64+16+1 = 81
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: %zu [%zu > %u]", i, smplCnt, clk + cl_4 + 1);
bits[bitCnt++] = 7;
} else if (waveHigh) {
bits[bitCnt++] = invert;
bits[bitCnt++] = invert;
} else {
bits[bitCnt++] = invert ^ 1;
bits[bitCnt++] = invert ^ 1;
}
if (*startIdx == 0) {
*startIdx = i - clk;
if (g_debugMode == 2) prnt("DEBUG ASK: cleanAskRawDemod minus clock [%d]", *startIdx);
}
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: %zu [%zu]", i, smplCnt);
bits[bitCnt++] = 7;
}
if (waveHigh) {
bits[bitCnt++] = invert;
} else {
bits[bitCnt++] = invert ^ 1;
}
if (*startIdx == 0) {
*startIdx = i - cl_2;
if (g_debugMode == 2) prnt("DEBUG ASK: cleanAskRawDemod minus half clock [%d]", *startIdx);
}
waveHigh = !waveHigh;
smplCnt = 0;
} else {
smplCnt++;
//transition bit oops
}
} else { //haven't hit new high or new low yet
smplCnt++;
}
}
}
*size = bitCnt;
if (g_debugMode == 2) prnt("DEBUG ASK: cleanAskRawDemod Startidx %d", *startIdx);
return errCnt;
}
// 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;
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG (askdemod_ext) just noise detected - aborting");
return -2;
}
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 (askdemod_ext) clk %d, beststart %d, amp %d", *clk, start, amp);
// Detect high and lows
//25% clip in case highs and lows aren't clipped [marshmellow]
int high, low;
getHiLo(&high, &low, 75, 75);
size_t errCnt = 0;
// if clean clipped waves detected run alternate demod
if (DetectCleanAskWave(bits, *size, high, low)) {
//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);
if (g_debugMode == 2) prnt("DEBUG: (askdemod_ext) Clean wave detected --- startindex %d", *startIdx);
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 == 2) prnt("DEBUG: (askdemod_ext) CLEAN: startIdx %i, alignPos %u , bestError %zu", *startIdx, alignPos, errCnt);
}
return errCnt;
}
*startIdx = start - (*clk / 2);
if (g_debugMode == 2) 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) {
if (bitnum > 0) {
bits[bitnum] = bits[bitnum - 1];
bitnum++;
} else {
bits[bitnum] = 0;
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);
}
// 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, const int *invert, int *startIdx) {
if (signalprop.isnoise) {
if (g_debugMode == 2) prnt("DEBUG nrzRawDemod: just noise detected - quitting");
return -1;
}
size_t clkStartIdx = 0;
*clk = DetectNRZClock(dest, *size, *clk, &clkStartIdx);
if (*clk == 0) return -2;
size_t i;
int high, low;
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])
static 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, LastSample = 0;
size_t currSample = 0, last_transition = 0;
size_t idx, numBits = 0;
//find start of modulating data in trace
idx = findModStart(dest, size, fchigh);
// Need to threshold first sample
dest[idx] = (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 within 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
static 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 %zu, 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 %zu, 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;
if (g_debugMode == 2) prnt("DEBUG (aggregate_bits) extra bits in the end");
}
return numBits;
}
// 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);
if (g_debugMode == 2) prnt("DEBUG (fskdemod) got %zu bits", size);
size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow, start_idx);
if (g_debugMode == 2) prnt("DEBUG (fskdemod) got %zu bits", size);
return size;
}
// 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;
}
}
}
// 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;
}
}
// 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, const 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, firstFullWave = 0, lastClkBit = 0;
uint16_t fullWaveLen = 0, waveLenCnt;
//uint16_t 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: %zu, waveLen: %u, startIdx %i", firstFullWave, fullWaveLen, *startIdx);
prnt("DEBUG PSK: clk: %d, lastClkBit: %zu, 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;
//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-------------------------------------------------
// **********************************************************************************************
// 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;
// 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;
}
// 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;
*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;
bool validShort = false;
bool validShortExtended = false;
bool validLong = false;
*size = removeEm410xParity(bits, *start_idx + sizeof(preamble), *size == 128, &validShort, &validShortExtended, &validLong);
if (validShort) {
// std em410x format
*hi = 0;
*lo = ((uint64_t)(bytebits_to_byte(bits, 8)) << 32) | (bytebits_to_byte(bits + 8, 32));
// 1 = Short
return 1;
}
if (validShortExtended || validLong) {
// store in 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));
// 2 = Long
// 4 = ShortExtended
return ((int)validShortExtended << 2) + ((int)validLong << 1);
}
return -6;
}
// 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;
// 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;
}
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;
// 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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