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eb191de6 1//-----------------------------------------------------------------------------
ba1a299c 2// Copyright (C) 2014
eb191de6 3//
4// This code is licensed to you under the terms of the GNU GPL, version 2 or,
5// at your option, any later version. See the LICENSE.txt file for the text of
6// the license.
7//-----------------------------------------------------------------------------
1e090a61 8// Low frequency demod/decode commands
eb191de6 9//-----------------------------------------------------------------------------
10
eb191de6 11#include <stdlib.h>
12#include <string.h>
eb191de6 13#include "lfdemod.h"
a1d17964 14uint8_t justNoise(uint8_t *BitStream, size_t size)
15{
16 static const uint8_t THRESHOLD = 123;
17 //test samples are not just noise
18 uint8_t justNoise1 = 1;
19 for(size_t idx=0; idx < size && justNoise1 ;idx++){
20 justNoise1 = BitStream[idx] < THRESHOLD;
21 }
22 return justNoise1;
23}
24
1e090a61 25//by marshmellow
872e3d4d 26//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
1e090a61 27int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
28{
29 *high=0;
30 *low=255;
31 // get high and low thresholds
2eec55c8 32 for (size_t i=0; i < size; i++){
1e090a61 33 if (BitStream[i] > *high) *high = BitStream[i];
34 if (BitStream[i] < *low) *low = BitStream[i];
35 }
36 if (*high < 123) return -1; // just noise
75cbbe9a 37 *high = ((*high-128)*fuzzHi + 12800)/100;
38 *low = ((*low-128)*fuzzLo + 12800)/100;
1e090a61 39 return 1;
40}
41
a1d17964 42// by marshmellow
43// pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
44// returns 1 if passed
45uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
46{
47 uint8_t ans = 0;
48 for (uint8_t i = 0; i < bitLen; i++){
49 ans ^= ((bits >> i) & 1);
50 }
f3bf15e4 51 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
a1d17964 52 return (ans == pType);
53}
54
55//by marshmellow
2147c307 56//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
a1d17964 57uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
58{
e0165dcf 59 uint8_t foundCnt=0;
60 for (int idx=0; idx < *size - pLen; idx++){
61 if (memcmp(BitStream+idx, preamble, pLen) == 0){
62 //first index found
63 foundCnt++;
64 if (foundCnt == 1){
65 *startIdx = idx;
66 }
67 if (foundCnt == 2){
68 *size = idx - *startIdx;
69 return 1;
70 }
71 }
72 }
73 return 0;
a1d17964 74}
75
2147c307 76//by marshmellow
77//takes 1s and 0s and searches for EM410x format - output EM ID
78uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
79{
e0165dcf 80 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
81 // otherwise could be a void with no arguments
82 //set defaults
83 uint32_t i = 0;
2767fc02 84 if (BitStream[1]>1) return 0; //allow only 1s and 0s
85
e0165dcf 86 // 111111111 bit pattern represent start of frame
87 // include 0 in front to help get start pos
88 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
89 uint32_t idx = 0;
90 uint32_t parityBits = 0;
91 uint8_t errChk = 0;
92 uint8_t FmtLen = 10;
93 *startIdx = 0;
94 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
95 if (errChk == 0 || *size < 64) return 0;
96 if (*size > 64) FmtLen = 22;
97 *startIdx += 1; //get rid of 0 from preamble
98 idx = *startIdx + 9;
99 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
100 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
2eec55c8 101 //check even parity - quit if failed
102 if (parityTest(parityBits, 5, 0) == 0) return 0;
e0165dcf 103 //set uint64 with ID from BitStream
104 for (uint8_t ii=0; ii<4; ii++){
105 *hi = (*hi << 1) | (*lo >> 63);
106 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
107 }
108 }
109 if (errChk != 0) return 1;
110 //skip last 5 bit parity test for simplicity.
111 // *size = 64 | 128;
112 return 0;
2147c307 113}
114
fef74fdc 115//by marshmellow
116//demodulates strong heavily clipped samples
23f0a7d8 117int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
118{
119 size_t bitCnt=0, smplCnt=0, errCnt=0;
120 uint8_t waveHigh = 0;
23f0a7d8 121 for (size_t i=0; i < *size; i++){
122 if (BinStream[i] >= high && waveHigh){
123 smplCnt++;
124 } else if (BinStream[i] <= low && !waveHigh){
125 smplCnt++;
126 } else { //transition
127 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
128 if (smplCnt > clk-(clk/4)-1) { //full clock
129 if (smplCnt > clk + (clk/4)+1) { //too many samples
130 errCnt++;
2767fc02 131 BinStream[bitCnt++]=7;
23f0a7d8 132 } else if (waveHigh) {
133 BinStream[bitCnt++] = invert;
134 BinStream[bitCnt++] = invert;
135 } else if (!waveHigh) {
136 BinStream[bitCnt++] = invert ^ 1;
137 BinStream[bitCnt++] = invert ^ 1;
138 }
139 waveHigh ^= 1;
140 smplCnt = 0;
141 } else if (smplCnt > (clk/2) - (clk/4)-1) {
142 if (waveHigh) {
143 BinStream[bitCnt++] = invert;
144 } else if (!waveHigh) {
145 BinStream[bitCnt++] = invert ^ 1;
146 }
147 waveHigh ^= 1;
148 smplCnt = 0;
149 } else if (!bitCnt) {
150 //first bit
151 waveHigh = (BinStream[i] >= high);
152 smplCnt = 1;
153 } else {
154 smplCnt++;
155 //transition bit oops
156 }
157 } else { //haven't hit new high or new low yet
158 smplCnt++;
159 }
160 }
161 }
162 *size = bitCnt;
163 return errCnt;
164}
165
eb191de6 166//by marshmellow
fef74fdc 167void askAmp(uint8_t *BitStream, size_t size)
168{
169 for(size_t i = 1; i<size; i++){
170 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
171 BitStream[i]=127;
172 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
173 BitStream[i]=-127;
174 }
175 return;
176}
177
178//by marshmellow
179//attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
180int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
eb191de6 181{
fef74fdc 182 if (*size==0) return -1;
6e984446 183 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
2eec55c8 184 if (*clk==0 || start < 0) return -3;
fef74fdc 185 if (*invert != 1) *invert = 0;
186 if (amp==1) askAmp(BinStream, *size);
187
2eec55c8 188 uint8_t initLoopMax = 255;
189 if (initLoopMax > *size) initLoopMax = *size;
ba1a299c 190 // Detect high and lows
fef74fdc 191 //25% clip in case highs and lows aren't clipped [marshmellow]
2eec55c8 192 int high, low;
fef74fdc 193 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
194 return -2; //just noise
ba1a299c 195
fef74fdc 196 size_t errCnt = 0;
23f0a7d8 197 // if clean clipped waves detected run alternate demod
198 if (DetectCleanAskWave(BinStream, *size, high, low)) {
fef74fdc 199 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
200 if (askType) //askman
201 return manrawdecode(BinStream, size, 0);
202 else //askraw
203 return errCnt;
23f0a7d8 204 }
205
fef74fdc 206 int lastBit; //set first clock check - can go negative
207 size_t i, bitnum = 0; //output counter
208 uint8_t midBit = 0;
2eec55c8 209 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
fef74fdc 210 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
211 size_t MaxBits = 1024;
6e984446 212 lastBit = start - *clk;
fef74fdc 213
6e984446 214 for (i = start; i < *size; ++i) {
fef74fdc 215 if (i-lastBit >= *clk-tol){
216 if (BinStream[i] >= high) {
217 BinStream[bitnum++] = *invert;
218 } else if (BinStream[i] <= low) {
219 BinStream[bitnum++] = *invert ^ 1;
220 } else if (i-lastBit >= *clk+tol) {
221 if (bitnum > 0) {
222 BinStream[bitnum++]=7;
223 errCnt++;
224 }
225 } else { //in tolerance - looking for peak
226 continue;
227 }
228 midBit = 0;
2eec55c8 229 lastBit += *clk;
fef74fdc 230 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
231 if (BinStream[i] >= high) {
232 BinStream[bitnum++] = *invert;
233 } else if (BinStream[i] <= low) {
234 BinStream[bitnum++] = *invert ^ 1;
235 } else if (i-lastBit >= *clk/2+tol) {
236 BinStream[bitnum] = BinStream[bitnum-1];
237 bitnum++;
238 } else { //in tolerance - looking for peak
239 continue;
240 }
241 midBit = 1;
2eec55c8 242 }
243 if (bitnum >= MaxBits) break;
ba1a299c 244 }
2eec55c8 245 *size = bitnum;
6e984446 246 return errCnt;
eb191de6 247}
248
249//by marshmellow
250//take 10 and 01 and manchester decode
251//run through 2 times and take least errCnt
fef74fdc 252int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
eb191de6 253{
13d77ef9 254 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
255 size_t i, ii;
256 uint16_t bestErr = 1000, bestRun = 0;
fef74fdc 257 if (*size < 16) return -1;
2767fc02 258 //find correct start position [alignment]
13d77ef9 259 for (ii=0;ii<2;++ii){
fef74fdc 260 for (i=ii; i<*size-3; i+=2)
2eec55c8 261 if (BitStream[i]==BitStream[i+1])
ba1a299c 262 errCnt++;
2eec55c8 263
ba1a299c 264 if (bestErr>errCnt){
265 bestErr=errCnt;
266 bestRun=ii;
267 }
268 errCnt=0;
269 }
2767fc02 270 //decode
fef74fdc 271 for (i=bestRun; i < *size-3; i+=2){
23f0a7d8 272 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
fef74fdc 273 BitStream[bitnum++]=invert;
23f0a7d8 274 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
fef74fdc 275 BitStream[bitnum++]=invert^1;
23f0a7d8 276 } else {
2767fc02 277 BitStream[bitnum++]=7;
ba1a299c 278 }
23f0a7d8 279 if(bitnum>MaxBits) break;
ba1a299c 280 }
23f0a7d8 281 *size=bitnum;
2eec55c8 282 return bestErr;
f822a063 283}
284
fef74fdc 285//by marshmellow
286//encode binary data into binary manchester
287int ManchesterEncode(uint8_t *BitStream, size_t size)
288{
289 size_t modIdx=20000, i=0;
290 if (size>modIdx) return -1;
291 for (size_t idx=0; idx < size; idx++){
292 BitStream[idx+modIdx++] = BitStream[idx];
293 BitStream[idx+modIdx++] = BitStream[idx]^1;
294 }
295 for (; i<(size*2); i++){
296 BitStream[i] = BitStream[i+20000];
297 }
298 return i;
299}
300
f822a063 301//by marshmellow
2147c307 302//take 01 or 10 = 1 and 11 or 00 = 0
303//check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
13d77ef9 304//decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
1e090a61 305int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
f822a063 306{
2eec55c8 307 uint16_t bitnum = 0;
308 uint16_t errCnt = 0;
309 size_t i = offset;
2147c307 310 uint16_t MaxBits=512;
311 //if not enough samples - error
312 if (*size < 51) return -1;
313 //check for phase change faults - skip one sample if faulty
314 uint8_t offsetA = 1, offsetB = 1;
315 for (; i<48; i+=2){
316 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
317 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
318 }
319 if (!offsetA && offsetB) offset++;
320 for (i=offset; i<*size-3; i+=2){
321 //check for phase error
13d77ef9 322 if (BitStream[i+1]==BitStream[i+2]) {
2767fc02 323 BitStream[bitnum++]=7;
2147c307 324 errCnt++;
325 }
ba1a299c 326 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
1e090a61 327 BitStream[bitnum++]=1^invert;
ba1a299c 328 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
1e090a61 329 BitStream[bitnum++]=invert;
ba1a299c 330 } else {
2767fc02 331 BitStream[bitnum++]=7;
ba1a299c 332 errCnt++;
333 }
6de43508 334 if(bitnum>MaxBits) break;
ba1a299c 335 }
336 *size=bitnum;
337 return errCnt;
eb191de6 338}
339
fef74fdc 340// by marshmellow
11081e04 341// demod gProxIIDemod
342// error returns as -x
343// success returns start position in BitStream
344// BitStream must contain previously askrawdemod and biphasedemoded data
345int gProxII_Demod(uint8_t BitStream[], size_t *size)
346{
347 size_t startIdx=0;
348 uint8_t preamble[] = {1,1,1,1,1,0};
349
350 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
351 if (errChk == 0) return -3; //preamble not found
352 if (*size != 96) return -2; //should have found 96 bits
353 //check first 6 spacer bits to verify format
354 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
355 //confirmed proper separator bits found
356 //return start position
357 return (int) startIdx;
358 }
359 return -5;
360}
361
ba1a299c 362//translate wave to 11111100000 (1 for each short wave 0 for each long wave)
f822a063 363size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
eb191de6 364{
2eec55c8 365 size_t last_transition = 0;
366 size_t idx = 1;
ac3ba7ee 367 //uint32_t maxVal=0;
ba1a299c 368 if (fchigh==0) fchigh=10;
369 if (fclow==0) fclow=8;
84871873 370 //set the threshold close to 0 (graph) or 128 std to avoid static
371 uint8_t threshold_value = 123;
ba1a299c 372
373 // sync to first lo-hi transition, and threshold
374
375 // Need to threshold first sample
376
377 if(dest[0] < threshold_value) dest[0] = 0;
378 else dest[0] = 1;
379
380 size_t numBits = 0;
381 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
382 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
383 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
384 for(idx = 1; idx < size; idx++) {
385 // threshold current value
386
387 if (dest[idx] < threshold_value) dest[idx] = 0;
388 else dest[idx] = 1;
389
390 // Check for 0->1 transition
391 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
392 if ((idx-last_transition)<(fclow-2)){ //0-5 = garbage noise
393 //do nothing with extra garbage
394 } else if ((idx-last_transition) < (fchigh-1)) { //6-8 = 8 waves
2eec55c8 395 dest[numBits++]=1;
13d77ef9 396 } else if ((idx-last_transition) > (fchigh+1) && !numBits) { //12 + and first bit = garbage
397 //do nothing with beginning garbage
398 } else { //9+ = 10 waves
2eec55c8 399 dest[numBits++]=0;
ba1a299c 400 }
401 last_transition = idx;
ba1a299c 402 }
403 }
404 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
eb191de6 405}
406
ba1a299c 407//translate 11111100000 to 10
2eec55c8 408size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
e0165dcf 409 uint8_t invert, uint8_t fchigh, uint8_t fclow)
eb191de6 410{
ba1a299c 411 uint8_t lastval=dest[0];
2eec55c8 412 size_t idx=0;
ba1a299c 413 size_t numBits=0;
414 uint32_t n=1;
ba1a299c 415 for( idx=1; idx < size; idx++) {
13d77ef9 416 n++;
2eec55c8 417 if (dest[idx]==lastval) continue;
418
ba1a299c 419 //if lastval was 1, we have a 1->0 crossing
13d77ef9 420 if (dest[idx-1]==1) {
75cbbe9a 421 if (!numBits && n < rfLen/fclow) {
13d77ef9 422 n=0;
423 lastval = dest[idx];
424 continue;
425 }
75cbbe9a 426 n = (n * fclow + rfLen/2) / rfLen;
13d77ef9 427 } else {// 0->1 crossing
428 //test first bitsample too small
75cbbe9a 429 if (!numBits && n < rfLen/fchigh) {
13d77ef9 430 n=0;
431 lastval = dest[idx];
432 continue;
433 }
75cbbe9a 434 n = (n * fchigh + rfLen/2) / rfLen;
ba1a299c 435 }
436 if (n == 0) n = 1;
437
2eec55c8 438 memset(dest+numBits, dest[idx-1]^invert , n);
439 numBits += n;
ba1a299c 440 n=0;
441 lastval=dest[idx];
442 }//end for
13d77ef9 443 // if valid extra bits at the end were all the same frequency - add them in
75cbbe9a 444 if (n > rfLen/fchigh) {
13d77ef9 445 if (dest[idx-2]==1) {
75cbbe9a 446 n = (n * fclow + rfLen/2) / rfLen;
13d77ef9 447 } else {
75cbbe9a 448 n = (n * fchigh + rfLen/2) / rfLen;
13d77ef9 449 }
2eec55c8 450 memset(dest+numBits, dest[idx-1]^invert , n);
13d77ef9 451 numBits += n;
452 }
ba1a299c 453 return numBits;
eb191de6 454}
455//by marshmellow (from holiman's base)
456// full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
f822a063 457int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
eb191de6 458{
ba1a299c 459 // FSK demodulator
460 size = fsk_wave_demod(dest, size, fchigh, fclow);
2eec55c8 461 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
ba1a299c 462 return size;
eb191de6 463}
a1d17964 464
eb191de6 465// loop to get raw HID waveform then FSK demodulate the TAG ID from it
ec75f5c1 466int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
eb191de6 467{
e0165dcf 468 if (justNoise(dest, *size)) return -1;
469
470 size_t numStart=0, size2=*size, startIdx=0;
471 // FSK demodulator
472 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
2eec55c8 473 if (*size < 96*2) return -2;
e0165dcf 474 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
475 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
476 // find bitstring in array
477 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
478 if (errChk == 0) return -3; //preamble not found
479
480 numStart = startIdx + sizeof(preamble);
481 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
482 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
483 if (dest[idx] == dest[idx+1]){
484 return -4; //not manchester data
485 }
486 *hi2 = (*hi2<<1)|(*hi>>31);
487 *hi = (*hi<<1)|(*lo>>31);
488 //Then, shift in a 0 or one into low
489 if (dest[idx] && !dest[idx+1]) // 1 0
490 *lo=(*lo<<1)|1;
491 else // 0 1
492 *lo=(*lo<<1)|0;
493 }
494 return (int)startIdx;
eb191de6 495}
496
ec75f5c1 497// loop to get raw paradox waveform then FSK demodulate the TAG ID from it
a1d17964 498int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
ec75f5c1 499{
a1d17964 500 if (justNoise(dest, *size)) return -1;
501
502 size_t numStart=0, size2=*size, startIdx=0;
ec75f5c1 503 // FSK demodulator
a1d17964 504 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
505 if (*size < 96) return -2;
ec75f5c1 506
a1d17964 507 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
508 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
509
510 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
511 if (errChk == 0) return -3; //preamble not found
512
513 numStart = startIdx + sizeof(preamble);
514 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
515 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
516 if (dest[idx] == dest[idx+1])
517 return -4; //not manchester data
518 *hi2 = (*hi2<<1)|(*hi>>31);
519 *hi = (*hi<<1)|(*lo>>31);
520 //Then, shift in a 0 or one into low
521 if (dest[idx] && !dest[idx+1]) // 1 0
522 *lo=(*lo<<1)|1;
523 else // 0 1
524 *lo=(*lo<<1)|0;
ec75f5c1 525 }
a1d17964 526 return (int)startIdx;
ec75f5c1 527}
528
ba1a299c 529uint32_t bytebits_to_byte(uint8_t* src, size_t numbits)
eb191de6 530{
ba1a299c 531 uint32_t num = 0;
532 for(int i = 0 ; i < numbits ; i++)
533 {
534 num = (num << 1) | (*src);
535 src++;
536 }
537 return num;
eb191de6 538}
539
540int IOdemodFSK(uint8_t *dest, size_t size)
541{
a1d17964 542 if (justNoise(dest, size)) return -1;
ba1a299c 543 //make sure buffer has data
a1d17964 544 if (size < 66*64) return -2;
ba1a299c 545 // FSK demodulator
a1d17964 546 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
547 if (size < 65) return -3; //did we get a good demod?
ba1a299c 548 //Index map
549 //0 10 20 30 40 50 60
550 //| | | | | | |
551 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
552 //-----------------------------------------------------------------------------
553 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
554 //
555 //XSF(version)facility:codeone+codetwo
556 //Handle the data
a1d17964 557 size_t startIdx = 0;
558 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
559 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
560 if (errChk == 0) return -4; //preamble not found
eb191de6 561
a1d17964 562 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
563 //confirmed proper separator bits found
564 //return start position
565 return (int) startIdx;
1e090a61 566 }
a1d17964 567 return -5;
1e090a61 568}
569
570// by marshmellow
571// takes a array of binary values, start position, length of bits per parity (includes parity bit),
572// Parity Type (1 for odd 0 for even), and binary Length (length to run)
573size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
574{
575 uint32_t parityWd = 0;
576 size_t j = 0, bitCnt = 0;
577 for (int word = 0; word < (bLen); word+=pLen){
578 for (int bit=0; bit < pLen; bit++){
579 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
f3bf15e4 580 BitStream[j++] = (BitStream[startIdx+word+bit]);
1e090a61 581 }
582 j--;
583 // if parity fails then return 0
584 if (parityTest(parityWd, pLen, pType) == 0) return -1;
585 bitCnt+=(pLen-1);
586 parityWd = 0;
587 }
588 // if we got here then all the parities passed
589 //return ID start index and size
590 return bitCnt;
591}
592
593// by marshmellow
594// FSK Demod then try to locate an AWID ID
a1d17964 595int AWIDdemodFSK(uint8_t *dest, size_t *size)
1e090a61 596{
a1d17964 597 //make sure buffer has enough data
598 if (*size < 96*50) return -1;
599
600 if (justNoise(dest, *size)) return -2;
1e090a61 601
602 // FSK demodulator
a1d17964 603 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
604 if (*size < 96) return -3; //did we get a good demod?
605
606 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
607 size_t startIdx = 0;
608 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
609 if (errChk == 0) return -4; //preamble not found
610 if (*size != 96) return -5;
611 return (int)startIdx;
1e090a61 612}
613
614// by marshmellow
615// FSK Demod then try to locate an Farpointe Data (pyramid) ID
a1d17964 616int PyramiddemodFSK(uint8_t *dest, size_t *size)
1e090a61 617{
f3bf15e4 618 //make sure buffer has data
619 if (*size < 128*50) return -5;
a1d17964 620
f3bf15e4 621 //test samples are not just noise
622 if (justNoise(dest, *size)) return -1;
1e090a61 623
f3bf15e4 624 // FSK demodulator
625 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
626 if (*size < 128) return -2; //did we get a good demod?
a1d17964 627
f3bf15e4 628 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
a1d17964 629 size_t startIdx = 0;
630 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
631 if (errChk == 0) return -4; //preamble not found
632 if (*size != 128) return -3;
633 return (int)startIdx;
1e090a61 634}
635
fef74fdc 636// by marshmellow
637// to detect a wave that has heavily clipped (clean) samples
cc15a118 638uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
6de43508 639{
1fbf8956 640 uint16_t allPeaks=1;
6de43508 641 uint16_t cntPeaks=0;
cc15a118 642 size_t loopEnd = 512+60;
1fbf8956 643 if (loopEnd > size) loopEnd = size;
644 for (size_t i=60; i<loopEnd; i++){
6de43508 645 if (dest[i]>low && dest[i]<high)
646 allPeaks=0;
647 else
648 cntPeaks++;
649 }
1fbf8956 650 if (allPeaks == 0){
651 if (cntPeaks > 300) return 1;
6de43508 652 }
653 return allPeaks;
654}
655
2eec55c8 656// by marshmellow
657// to help detect clocks on heavily clipped samples
cc15a118 658// based on count of low to low
659int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
13d77ef9 660{
cc15a118 661 uint8_t fndClk[] = {8,16,32,40,50,64,128};
662 size_t startwave;
663 size_t i = 0;
664 size_t minClk = 255;
665 // get to first full low to prime loop and skip incomplete first pulse
666 while ((dest[i] < high) && (i < size))
667 ++i;
668 while ((dest[i] > low) && (i < size))
669 ++i;
670
671 // loop through all samples
672 while (i < size) {
673 // measure from low to low
674 while ((dest[i] > low) && (i < size))
675 ++i;
676 startwave= i;
677 while ((dest[i] < high) && (i < size))
678 ++i;
679 while ((dest[i] > low) && (i < size))
680 ++i;
681 //get minimum measured distance
682 if (i-startwave < minClk && i < size)
683 minClk = i - startwave;
13d77ef9 684 }
cc15a118 685 // set clock
686 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
687 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
688 return fndClk[clkCnt];
13d77ef9 689 }
cc15a118 690 return 0;
13d77ef9 691}
692
eb191de6 693// by marshmellow
694// not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
695// maybe somehow adjust peak trimming value based on samples to fix?
6de43508 696// return start index of best starting position for that clock and return clock (by reference)
697int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
eb191de6 698{
6e984446 699 size_t i=1;
cc15a118 700 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
701 uint8_t clkEnd = 9;
2eec55c8 702 uint8_t loopCnt = 255; //don't need to loop through entire array...
cc15a118 703 if (size <= loopCnt) return -1; //not enough samples
6e984446 704
705 //if we already have a valid clock
706 uint8_t clockFnd=0;
cc15a118 707 for (;i<clkEnd;++i)
708 if (clk[i] == *clock) clockFnd = i;
6e984446 709 //clock found but continue to find best startpos
e0165dcf 710
711 //get high and low peak
712 int peak, low;
2eec55c8 713 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
e0165dcf 714
715 //test for large clean peaks
cc15a118 716 if (!clockFnd){
717 if (DetectCleanAskWave(dest, size, peak, low)==1){
718 int ans = DetectStrongAskClock(dest, size, peak, low);
719 for (i=clkEnd-1; i>0; i--){
720 if (clk[i] == ans) {
721 *clock = ans;
722 //clockFnd = i;
723 return 0; // for strong waves i don't use the 'best start position' yet...
724 //break; //clock found but continue to find best startpos [not yet]
725 }
e0165dcf 726 }
727 }
728 }
cc15a118 729
2eec55c8 730 uint8_t ii;
731 uint8_t clkCnt, tol = 0;
732 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
733 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
734 size_t errCnt = 0;
735 size_t arrLoc, loopEnd;
6e984446 736
cc15a118 737 if (clockFnd>0) {
738 clkCnt = clockFnd;
739 clkEnd = clockFnd+1;
740 }
741 else clkCnt=1;
742
743 //test each valid clock from smallest to greatest to see which lines up
744 for(; clkCnt < clkEnd; clkCnt++){
fef74fdc 745 if (clk[clkCnt] <= 32){
e0165dcf 746 tol=1;
747 }else{
748 tol=0;
749 }
2767fc02 750 //if no errors allowed - keep start within the first clock
cc15a118 751 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
e0165dcf 752 bestErr[clkCnt]=1000;
6e984446 753 //try lining up the peaks by moving starting point (try first few clocks)
cc15a118 754 for (ii=0; ii < loopCnt; ii++){
2eec55c8 755 if (dest[ii] < peak && dest[ii] > low) continue;
756
757 errCnt=0;
758 // now that we have the first one lined up test rest of wave array
759 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
760 for (i=0; i < loopEnd; ++i){
761 arrLoc = ii + (i * clk[clkCnt]);
762 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
763 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
764 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
765 }else{ //error no peak detected
766 errCnt++;
e0165dcf 767 }
768 }
cc15a118 769 //if we found no errors then we can stop here and a low clock (common clocks)
2eec55c8 770 // this is correct one - return this clock
771 //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
cc15a118 772 if(errCnt==0 && clkCnt<7) {
773 if (!clockFnd) *clock = clk[clkCnt];
2eec55c8 774 return ii;
775 }
776 //if we found errors see if it is lowest so far and save it as best run
777 if(errCnt<bestErr[clkCnt]){
778 bestErr[clkCnt]=errCnt;
779 bestStart[clkCnt]=ii;
780 }
e0165dcf 781 }
782 }
cc15a118 783 uint8_t iii;
e0165dcf 784 uint8_t best=0;
cc15a118 785 for (iii=1; iii<clkEnd; ++iii){
2eec55c8 786 if (bestErr[iii] < bestErr[best]){
787 if (bestErr[iii] == 0) bestErr[iii]=1;
e0165dcf 788 // current best bit to error ratio vs new bit to error ratio
2eec55c8 789 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
e0165dcf 790 best = iii;
791 }
792 }
793 }
2767fc02 794 //if (bestErr[best] > maxErr) return -1;
cc15a118 795 if (!clockFnd) *clock = clk[best];
e0165dcf 796 return bestStart[best];
eb191de6 797}
ba1a299c 798
799//by marshmellow
6de43508 800//detect psk clock by reading each phase shift
801// a phase shift is determined by measuring the sample length of each wave
802int DetectPSKClock(uint8_t dest[], size_t size, int clock)
ba1a299c 803{
e0165dcf 804 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
805 uint16_t loopCnt = 4096; //don't need to loop through entire array...
806 if (size == 0) return 0;
807 if (size<loopCnt) loopCnt = size;
808
809 //if we already have a valid clock quit
810 size_t i=1;
811 for (; i < 8; ++i)
812 if (clk[i] == clock) return clock;
813
814 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
815 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
816 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
817 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
818 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
2eec55c8 819 fc = countFC(dest, size, 0);
820 if (fc!=2 && fc!=4 && fc!=8) return -1;
e0165dcf 821 //PrintAndLog("DEBUG: FC: %d",fc);
822
823 //find first full wave
824 for (i=0; i<loopCnt; i++){
825 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
826 if (waveStart == 0) {
827 waveStart = i+1;
828 //PrintAndLog("DEBUG: waveStart: %d",waveStart);
829 } else {
830 waveEnd = i+1;
831 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
832 waveLenCnt = waveEnd-waveStart;
833 if (waveLenCnt > fc){
834 firstFullWave = waveStart;
835 fullWaveLen=waveLenCnt;
836 break;
837 }
838 waveStart=0;
839 }
840 }
841 }
842 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
843
844 //test each valid clock from greatest to smallest to see which lines up
845 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
846 lastClkBit = firstFullWave; //set end of wave as clock align
847 waveStart = 0;
848 errCnt=0;
849 peakcnt=0;
850 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
851
852 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
853 //top edge of wave = start of new wave
854 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
855 if (waveStart == 0) {
856 waveStart = i+1;
857 waveLenCnt=0;
858 } else { //waveEnd
859 waveEnd = i+1;
860 waveLenCnt = waveEnd-waveStart;
861 if (waveLenCnt > fc){
862 //if this wave is a phase shift
863 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
864 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
865 peakcnt++;
866 lastClkBit+=clk[clkCnt];
867 } else if (i<lastClkBit+8){
868 //noise after a phase shift - ignore
869 } else { //phase shift before supposed to based on clock
870 errCnt++;
871 }
872 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
873 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
874 }
875 waveStart=i+1;
876 }
877 }
878 }
879 if (errCnt == 0){
880 return clk[clkCnt];
881 }
882 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
883 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
884 }
885 //all tested with errors
886 //return the highest clk with the most peaks found
887 uint8_t best=7;
888 for (i=7; i>=1; i--){
889 if (peaksdet[i] > peaksdet[best]) {
890 best = i;
891 }
892 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
893 }
894 return clk[best];
ba1a299c 895}
896
6de43508 897//by marshmellow
898//detect nrz clock by reading #peaks vs no peaks(or errors)
899int DetectNRZClock(uint8_t dest[], size_t size, int clock)
ba1a299c 900{
2eec55c8 901 size_t i=0;
902 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
903 size_t loopCnt = 4096; //don't need to loop through entire array...
e0165dcf 904 if (size == 0) return 0;
905 if (size<loopCnt) loopCnt = size;
906
907 //if we already have a valid clock quit
908 for (; i < 8; ++i)
909 if (clk[i] == clock) return clock;
910
911 //get high and low peak
912 int peak, low;
2eec55c8 913 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
e0165dcf 914
915 //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
2eec55c8 916 size_t ii;
e0165dcf 917 uint8_t clkCnt;
918 uint8_t tol = 0;
2eec55c8 919 uint16_t peakcnt=0;
920 uint16_t peaksdet[]={0,0,0,0,0,0,0,0};
921 uint16_t maxPeak=0;
e0165dcf 922 //test for large clipped waves
923 for (i=0; i<loopCnt; i++){
924 if (dest[i] >= peak || dest[i] <= low){
925 peakcnt++;
926 } else {
927 if (peakcnt>0 && maxPeak < peakcnt){
928 maxPeak = peakcnt;
929 }
930 peakcnt=0;
931 }
932 }
933 peakcnt=0;
934 //test each valid clock from smallest to greatest to see which lines up
935 for(clkCnt=0; clkCnt < 8; ++clkCnt){
936 //ignore clocks smaller than largest peak
937 if (clk[clkCnt]<maxPeak) continue;
938
939 //try lining up the peaks by moving starting point (try first 256)
940 for (ii=0; ii< loopCnt; ++ii){
941 if ((dest[ii] >= peak) || (dest[ii] <= low)){
942 peakcnt=0;
943 // now that we have the first one lined up test rest of wave array
944 for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
945 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
946 peakcnt++;
947 }
948 }
949 if(peakcnt>peaksdet[clkCnt]) {
950 peaksdet[clkCnt]=peakcnt;
951 }
952 }
953 }
954 }
955 int iii=7;
2eec55c8 956 uint8_t best=0;
e0165dcf 957 for (iii=7; iii > 0; iii--){
958 if (peaksdet[iii] > peaksdet[best]){
959 best = iii;
960 }
961 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
962 }
963 return clk[best];
ba1a299c 964}
965
04d2721b 966// by marshmellow
967// convert psk1 demod to psk2 demod
968// only transition waves are 1s
969void psk1TOpsk2(uint8_t *BitStream, size_t size)
970{
971 size_t i=1;
972 uint8_t lastBit=BitStream[0];
973 for (; i<size; i++){
2767fc02 974 if (BitStream[i]==7){
7a8a982b 975 //ignore errors
976 } else if (lastBit!=BitStream[i]){
04d2721b 977 lastBit=BitStream[i];
978 BitStream[i]=1;
979 } else {
980 BitStream[i]=0;
981 }
982 }
983 return;
984}
ba1a299c 985
3bc66a96 986// by marshmellow
987// convert psk2 demod to psk1 demod
988// from only transition waves are 1s to phase shifts change bit
989void psk2TOpsk1(uint8_t *BitStream, size_t size)
990{
712ebfa6 991 uint8_t phase=0;
992 for (size_t i=0; i<size; i++){
993 if (BitStream[i]==1){
3bc66a96 994 phase ^=1;
995 }
996 BitStream[i]=phase;
997 }
998 return;
999}
1000
04d2721b 1001// redesigned by marshmellow adjusted from existing decode functions
1002// indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
ba1a299c 1003int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1004{
1005 //26 bit 40134 format (don't know other formats)
1006 int i;
84871873 1007 int long_wait=29;//29 leading zeros in format
ba1a299c 1008 int start;
1009 int first = 0;
1010 int first2 = 0;
1011 int bitCnt = 0;
1012 int ii;
1013 // Finding the start of a UID
1014 for (start = 0; start <= *size - 250; start++) {
1015 first = bitStream[start];
1016 for (i = start; i < start + long_wait; i++) {
1017 if (bitStream[i] != first) {
1018 break;
1019 }
1020 }
1021 if (i == (start + long_wait)) {
1022 break;
1023 }
1024 }
1025 if (start == *size - 250 + 1) {
1026 // did not find start sequence
1027 return -1;
1028 }
ba1a299c 1029 // Inverting signal if needed
1030 if (first == 1) {
1031 for (i = start; i < *size; i++) {
1032 bitStream[i] = !bitStream[i];
1033 }
1034 *invert = 1;
1035 }else *invert=0;
1036
1037 int iii;
84871873 1038 //found start once now test length by finding next one
ba1a299c 1039 for (ii=start+29; ii <= *size - 250; ii++) {
1040 first2 = bitStream[ii];
1041 for (iii = ii; iii < ii + long_wait; iii++) {
1042 if (bitStream[iii] != first2) {
1043 break;
1044 }
1045 }
1046 if (iii == (ii + long_wait)) {
1047 break;
1048 }
1049 }
1050 if (ii== *size - 250 + 1){
1051 // did not find second start sequence
1052 return -2;
1053 }
1054 bitCnt=ii-start;
1055
1056 // Dumping UID
1057 i = start;
1058 for (ii = 0; ii < bitCnt; ii++) {
1059 bitStream[ii] = bitStream[i++];
1060 }
1061 *size=bitCnt;
1062 return 1;
1063}
1064
6de43508 1065// by marshmellow - demodulate NRZ wave (both similar enough)
04d2721b 1066// peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
6de43508 1067// there probably is a much simpler way to do this....
1068int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert, int maxErr)
ba1a299c 1069{
e0165dcf 1070 if (justNoise(dest, *size)) return -1;
1071 *clk = DetectNRZClock(dest, *size, *clk);
1072 if (*clk==0) return -2;
2eec55c8 1073 size_t i, gLen = 4096;
e0165dcf 1074 if (gLen>*size) gLen = *size;
1075 int high, low;
1076 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1077 int lastBit = 0; //set first clock check
2eec55c8 1078 size_t iii = 0, bitnum = 0; //bitnum counter
1079 uint16_t errCnt = 0, MaxBits = 1000;
1080 size_t bestErrCnt = maxErr+1;
1081 size_t bestPeakCnt = 0, bestPeakStart = 0;
1082 uint8_t bestFirstPeakHigh=0, firstPeakHigh=0, curBit=0, bitHigh=0, errBitHigh=0;
e0165dcf 1083 uint8_t tol = 1; //clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave
e0165dcf 1084 uint16_t peakCnt=0;
1085 uint8_t ignoreWindow=4;
2eec55c8 1086 uint8_t ignoreCnt=ignoreWindow; //in case of noise near peak
e0165dcf 1087 //loop to find first wave that works - align to clock
1088 for (iii=0; iii < gLen; ++iii){
1089 if ((dest[iii]>=high) || (dest[iii]<=low)){
1090 if (dest[iii]>=high) firstPeakHigh=1;
1091 else firstPeakHigh=0;
1092 lastBit=iii-*clk;
1093 peakCnt=0;
1094 errCnt=0;
e0165dcf 1095 //loop through to see if this start location works
1096 for (i = iii; i < *size; ++i) {
2eec55c8 1097 // if we are at a clock bit
1098 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1099 //test high/low
1100 if (dest[i] >= high || dest[i] <= low) {
1101 bitHigh = 1;
1102 peakCnt++;
1103 errBitHigh = 0;
1104 ignoreCnt = ignoreWindow;
1105 lastBit += *clk;
1106 } else if (i == lastBit + *clk + tol) {
1107 lastBit += *clk;
1108 }
e0165dcf 1109 //else if no bars found
2eec55c8 1110 } else if (dest[i] < high && dest[i] > low){
e0165dcf 1111 if (ignoreCnt==0){
1112 bitHigh=0;
2eec55c8 1113 if (errBitHigh==1) errCnt++;
e0165dcf 1114 errBitHigh=0;
1115 } else {
1116 ignoreCnt--;
1117 }
2eec55c8 1118 } else if ((dest[i]>=high || dest[i]<=low) && (bitHigh==0)) {
e0165dcf 1119 //error bar found no clock...
1120 errBitHigh=1;
1121 }
2eec55c8 1122 if (((i-iii) / *clk)>=MaxBits) break;
e0165dcf 1123 }
1124 //we got more than 64 good bits and not all errors
2eec55c8 1125 if (((i-iii) / *clk) > 64 && (errCnt <= (maxErr))) {
e0165dcf 1126 //possible good read
2eec55c8 1127 if (!errCnt || peakCnt > bestPeakCnt){
e0165dcf 1128 bestFirstPeakHigh=firstPeakHigh;
1129 bestErrCnt = errCnt;
1130 bestPeakCnt = peakCnt;
1131 bestPeakStart = iii;
2eec55c8 1132 if (!errCnt) break; //great read - finish
e0165dcf 1133 }
e0165dcf 1134 }
1135 }
1136 }
1137 //PrintAndLog("DEBUG: bestErrCnt: %d, maxErr: %d, bestStart: %d, bestPeakCnt: %d, bestPeakStart: %d",bestErrCnt,maxErr,bestStart,bestPeakCnt,bestPeakStart);
2eec55c8 1138 if (bestErrCnt > maxErr) return bestErrCnt;
1139
1140 //best run is good enough set to best run and set overwrite BinStream
1141 lastBit = bestPeakStart - *clk;
1142 memset(dest, bestFirstPeakHigh^1, bestPeakStart / *clk);
1143 bitnum += (bestPeakStart / *clk);
1144 for (i = bestPeakStart; i < *size; ++i) {
1145 // if expecting a clock bit
1146 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1147 // test high/low
1148 if (dest[i] >= high || dest[i] <= low) {
1149 peakCnt++;
1150 bitHigh = 1;
1151 errBitHigh = 0;
1152 ignoreCnt = ignoreWindow;
1153 curBit = *invert;
1154 if (dest[i] >= high) curBit ^= 1;
1155 dest[bitnum++] = curBit;
1156 lastBit += *clk;
1157 //else no bars found in clock area
1158 } else if (i == lastBit + *clk + tol) {
1159 dest[bitnum++] = curBit;
1160 lastBit += *clk;
1161 }
1162 //else if no bars found
1163 } else if (dest[i] < high && dest[i] > low){
1164 if (ignoreCnt == 0){
1165 bitHigh = 0;
1166 if (errBitHigh == 1){
2767fc02 1167 dest[bitnum++] = 7;
2eec55c8 1168 errCnt++;
e0165dcf 1169 }
2eec55c8 1170 errBitHigh=0;
1171 } else {
1172 ignoreCnt--;
e0165dcf 1173 }
2eec55c8 1174 } else if ((dest[i] >= high || dest[i] <= low) && (bitHigh == 0)) {
1175 //error bar found no clock...
1176 errBitHigh=1;
e0165dcf 1177 }
2eec55c8 1178 if (bitnum >= MaxBits) break;
e0165dcf 1179 }
2eec55c8 1180 *size = bitnum;
1181 return bestErrCnt;
ba1a299c 1182}
1183
1e090a61 1184//by marshmellow
03e6bb4a 1185//detects the bit clock for FSK given the high and low Field Clocks
1186uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1e090a61 1187{
e0165dcf 1188 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1189 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1190 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1191 uint8_t rfLensFnd = 0;
2eec55c8 1192 uint8_t lastFCcnt = 0;
1193 uint16_t fcCounter = 0;
e0165dcf 1194 uint16_t rfCounter = 0;
1195 uint8_t firstBitFnd = 0;
1196 size_t i;
1197 if (size == 0) return 0;
1198
1199 uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1200 rfLensFnd=0;
1201 fcCounter=0;
1202 rfCounter=0;
1203 firstBitFnd=0;
1204 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1205 // prime i to first up transition
1206 for (i = 1; i < size-1; i++)
1207 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1208 break;
1209
1210 for (; i < size-1; i++){
2eec55c8 1211 fcCounter++;
1212 rfCounter++;
1213
1214 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1215 continue;
1216 // else new peak
1217 // if we got less than the small fc + tolerance then set it to the small fc
1218 if (fcCounter < fcLow+fcTol)
1219 fcCounter = fcLow;
1220 else //set it to the large fc
1221 fcCounter = fcHigh;
1222
1223 //look for bit clock (rf/xx)
1224 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1225 //not the same size as the last wave - start of new bit sequence
1226 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1227 for (int ii=0; ii<15; ii++){
1228 if (rfLens[ii] == rfCounter){
1229 rfCnts[ii]++;
1230 rfCounter = 0;
1231 break;
e0165dcf 1232 }
e0165dcf 1233 }
2eec55c8 1234 if (rfCounter > 0 && rfLensFnd < 15){
1235 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1236 rfCnts[rfLensFnd]++;
1237 rfLens[rfLensFnd++] = rfCounter;
1238 }
1239 } else {
1240 firstBitFnd++;
e0165dcf 1241 }
2eec55c8 1242 rfCounter=0;
1243 lastFCcnt=fcCounter;
e0165dcf 1244 }
2eec55c8 1245 fcCounter=0;
e0165dcf 1246 }
1247 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1248
1249 for (i=0; i<15; i++){
1250 //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1251 //get highest 2 RF values (might need to get more values to compare or compare all?)
1252 if (rfCnts[i]>rfCnts[rfHighest]){
1253 rfHighest3=rfHighest2;
1254 rfHighest2=rfHighest;
1255 rfHighest=i;
1256 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1257 rfHighest3=rfHighest2;
1258 rfHighest2=i;
1259 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1260 rfHighest3=i;
1261 }
1262 }
1263 // set allowed clock remainder tolerance to be 1 large field clock length+1
1264 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1265 uint8_t tol1 = fcHigh+1;
1266
1267 //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1268
1269 // loop to find the highest clock that has a remainder less than the tolerance
1270 // compare samples counted divided by
1271 int ii=7;
1272 for (; ii>=0; ii--){
1273 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1274 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1275 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1276 break;
1277 }
1278 }
1279 }
1280 }
1281
1282 if (ii<0) return 0; // oops we went too far
1283
1284 return clk[ii];
03e6bb4a 1285}
1e090a61 1286
03e6bb4a 1287//by marshmellow
1288//countFC is to detect the field clock lengths.
1289//counts and returns the 2 most common wave lengths
6de43508 1290//mainly used for FSK field clock detection
2eec55c8 1291uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
03e6bb4a 1292{
e0165dcf 1293 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1294 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1295 uint8_t fcLensFnd = 0;
1296 uint8_t lastFCcnt=0;
2eec55c8 1297 uint8_t fcCounter = 0;
e0165dcf 1298 size_t i;
1299 if (size == 0) return 0;
1300
1301 // prime i to first up transition
1302 for (i = 1; i < size-1; i++)
1303 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1304 break;
1305
1306 for (; i < size-1; i++){
1307 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1308 // new up transition
1309 fcCounter++;
2eec55c8 1310 if (fskAdj){
1311 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1312 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1313 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1314 if ((fcCounter==9) || fcCounter==4) fcCounter++;
e0165dcf 1315 // save last field clock count (fc/xx)
2eec55c8 1316 lastFCcnt = fcCounter;
1317 }
e0165dcf 1318 // find which fcLens to save it to:
1319 for (int ii=0; ii<10; ii++){
1320 if (fcLens[ii]==fcCounter){
1321 fcCnts[ii]++;
1322 fcCounter=0;
1323 break;
1324 }
1325 }
1326 if (fcCounter>0 && fcLensFnd<10){
1327 //add new fc length
1328 fcCnts[fcLensFnd]++;
1329 fcLens[fcLensFnd++]=fcCounter;
1330 }
1331 fcCounter=0;
1332 } else {
1333 // count sample
1334 fcCounter++;
1335 }
1336 }
1337
1338 uint8_t best1=9, best2=9, best3=9;
1339 uint16_t maxCnt1=0;
1340 // go through fclens and find which ones are bigest 2
1341 for (i=0; i<10; i++){
1342 // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);
1343 // get the 3 best FC values
1344 if (fcCnts[i]>maxCnt1) {
1345 best3=best2;
1346 best2=best1;
1347 maxCnt1=fcCnts[i];
1348 best1=i;
1349 } else if(fcCnts[i]>fcCnts[best2]){
1350 best3=best2;
1351 best2=i;
1352 } else if(fcCnts[i]>fcCnts[best3]){
1353 best3=i;
1354 }
1355 }
1356 uint8_t fcH=0, fcL=0;
1357 if (fcLens[best1]>fcLens[best2]){
1358 fcH=fcLens[best1];
1359 fcL=fcLens[best2];
1360 } else{
1361 fcH=fcLens[best2];
1362 fcL=fcLens[best1];
1363 }
1364
e0165dcf 1365 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1366
1367 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1368 // PrintAndLog("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
2eec55c8 1369 if (fskAdj) return fcs;
1370 return fcLens[best1];
6de43508 1371}
1372
1373//by marshmellow - demodulate PSK1 wave
1374//uses wave lengths (# Samples)
1375int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1376{
e0165dcf 1377 if (size == 0) return -1;
2eec55c8 1378 uint16_t loopCnt = 4096; //don't need to loop through entire array...
e0165dcf 1379 if (*size<loopCnt) loopCnt = *size;
1380
1381 uint8_t curPhase = *invert;
1382 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1383 uint8_t fc=0, fullWaveLen=0, tol=1;
1384 uint16_t errCnt=0, waveLenCnt=0;
2eec55c8 1385 fc = countFC(dest, *size, 0);
e0165dcf 1386 if (fc!=2 && fc!=4 && fc!=8) return -1;
1387 //PrintAndLog("DEBUG: FC: %d",fc);
1388 *clock = DetectPSKClock(dest, *size, *clock);
2eec55c8 1389 if (*clock == 0) return -1;
e0165dcf 1390 int avgWaveVal=0, lastAvgWaveVal=0;
1391 //find first phase shift
1392 for (i=0; i<loopCnt; i++){
1393 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1394 waveEnd = i+1;
1395 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1396 waveLenCnt = waveEnd-waveStart;
1397 if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave
1398 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1399 firstFullWave = waveStart;
1400 fullWaveLen=waveLenCnt;
1401 //if average wave value is > graph 0 then it is an up wave or a 1
2eec55c8 1402 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
e0165dcf 1403 break;
1404 }
1405 waveStart = i+1;
1406 avgWaveVal = 0;
1407 }
2eec55c8 1408 avgWaveVal += dest[i+2];
e0165dcf 1409 }
1410 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1411 lastClkBit = firstFullWave; //set start of wave as clock align
1412 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1413 waveStart = 0;
e0165dcf 1414 size_t numBits=0;
1415 //set skipped bits
2eec55c8 1416 memset(dest, curPhase^1, firstFullWave / *clock);
e0165dcf 1417 numBits += (firstFullWave / *clock);
1418 dest[numBits++] = curPhase; //set first read bit
2eec55c8 1419 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
e0165dcf 1420 //top edge of wave = start of new wave
1421 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1422 if (waveStart == 0) {
1423 waveStart = i+1;
2eec55c8 1424 waveLenCnt = 0;
e0165dcf 1425 avgWaveVal = dest[i+1];
1426 } else { //waveEnd
1427 waveEnd = i+1;
1428 waveLenCnt = waveEnd-waveStart;
1429 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1430 if (waveLenCnt > fc){
1431 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
2eec55c8 1432 //this wave is a phase shift
e0165dcf 1433 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1434 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
2eec55c8 1435 curPhase ^= 1;
e0165dcf 1436 dest[numBits++] = curPhase;
1437 lastClkBit += *clock;
2eec55c8 1438 } else if (i < lastClkBit+10+fc){
e0165dcf 1439 //noise after a phase shift - ignore
1440 } else { //phase shift before supposed to based on clock
1441 errCnt++;
2767fc02 1442 dest[numBits++] = 7;
e0165dcf 1443 }
1444 } else if (i+1 > lastClkBit + *clock + tol + fc){
1445 lastClkBit += *clock; //no phase shift but clock bit
1446 dest[numBits++] = curPhase;
1447 }
2eec55c8 1448 avgWaveVal = 0;
1449 waveStart = i+1;
e0165dcf 1450 }
1451 }
2eec55c8 1452 avgWaveVal += dest[i+1];
e0165dcf 1453 }
1454 *size = numBits;
1455 return errCnt;
6de43508 1456}
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