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1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014
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 //-----------------------------------------------------------------------------
8 // Low frequency demod/decode commands
9 //-----------------------------------------------------------------------------
10
11 #include <stdlib.h>
12 #include <string.h>
13 #include "lfdemod.h"
14 uint8_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
25 //by marshmellow
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
27 int 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
32 for (size_t i=0; i < size; i++){
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
37 *high = ((*high-128)*fuzzHi + 12800)/100;
38 *low = ((*low-128)*fuzzLo + 12800)/100;
39 return 1;
40 }
41
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
45 uint8_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 }
51 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
52 return (ans == pType);
53 }
54
55 //by marshmellow
56 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
57 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
58 {
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;
74 }
75
76 //by marshmellow
77 //takes 1s and 0s and searches for EM410x format - output EM ID
78 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
79 {
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;
84 if (BitStream[1]>1){ //allow only 1s and 0s
85 // PrintAndLog("no data found");
86 return 0;
87 }
88 // 111111111 bit pattern represent start of frame
89 // include 0 in front to help get start pos
90 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
91 uint32_t idx = 0;
92 uint32_t parityBits = 0;
93 uint8_t errChk = 0;
94 uint8_t FmtLen = 10;
95 *startIdx = 0;
96 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
97 if (errChk == 0 || *size < 64) return 0;
98 if (*size > 64) FmtLen = 22;
99 *startIdx += 1; //get rid of 0 from preamble
100 idx = *startIdx + 9;
101 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
102 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
103 //check even parity - quit if failed
104 if (parityTest(parityBits, 5, 0) == 0) return 0;
105 //set uint64 with ID from BitStream
106 for (uint8_t ii=0; ii<4; ii++){
107 *hi = (*hi << 1) | (*lo >> 63);
108 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
109 }
110 }
111 if (errChk != 0) return 1;
112 //skip last 5 bit parity test for simplicity.
113 // *size = 64 | 128;
114 return 0;
115 }
116
117 // demodulates strong heavily clipped samples
118 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
119 {
120 size_t bitCnt=0, smplCnt=0, errCnt=0;
121 uint8_t waveHigh = 0;
122 //PrintAndLog("clk: %d", clk);
123 for (size_t i=0; i < *size; i++){
124 if (BinStream[i] >= high && waveHigh){
125 smplCnt++;
126 } else if (BinStream[i] <= low && !waveHigh){
127 smplCnt++;
128 } else { //transition
129 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
130 if (smplCnt > clk-(clk/4)-1) { //full clock
131 if (smplCnt > clk + (clk/4)+1) { //too many samples
132 errCnt++;
133 BinStream[bitCnt++]=77;
134 } else if (waveHigh) {
135 BinStream[bitCnt++] = invert;
136 BinStream[bitCnt++] = invert;
137 } else if (!waveHigh) {
138 BinStream[bitCnt++] = invert ^ 1;
139 BinStream[bitCnt++] = invert ^ 1;
140 }
141 waveHigh ^= 1;
142 smplCnt = 0;
143 } else if (smplCnt > (clk/2) - (clk/4)-1) {
144 if (waveHigh) {
145 BinStream[bitCnt++] = invert;
146 } else if (!waveHigh) {
147 BinStream[bitCnt++] = invert ^ 1;
148 }
149 waveHigh ^= 1;
150 smplCnt = 0;
151 } else if (!bitCnt) {
152 //first bit
153 waveHigh = (BinStream[i] >= high);
154 smplCnt = 1;
155 } else {
156 smplCnt++;
157 //transition bit oops
158 }
159 } else { //haven't hit new high or new low yet
160 smplCnt++;
161 }
162 }
163 }
164 *size = bitCnt;
165 return errCnt;
166 }
167
168 //by marshmellow
169 //takes 3 arguments - clock, invert, maxErr as integers
170 //attempts to demodulate ask while decoding manchester
171 //prints binary found and saves in graphbuffer for further commands
172 int askmandemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr)
173 {
174 size_t i;
175 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
176 if (*clk==0 || start < 0) return -3;
177 if (*invert != 1) *invert=0;
178 uint8_t initLoopMax = 255;
179 if (initLoopMax > *size) initLoopMax = *size;
180 // Detect high and lows
181 // 25% fuzz in case highs and lows aren't clipped [marshmellow]
182 int high, low;
183 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1) return -2; //just noise
184
185 // if clean clipped waves detected run alternate demod
186 if (DetectCleanAskWave(BinStream, *size, high, low)) {
187 cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
188 return manrawdecode(BinStream, size);
189 }
190
191 // PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
192 int lastBit; //set first clock check
193 uint16_t bitnum = 0; //output counter
194 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
195 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
196 uint16_t errCnt = 0, MaxBits = 512;
197 lastBit = start - *clk;
198 for (i = start; i < *size; ++i) {
199 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
200 //high found and we are expecting a bar
201 lastBit += *clk;
202 BinStream[bitnum++] = *invert;
203 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
204 //low found and we are expecting a bar
205 lastBit += *clk;
206 BinStream[bitnum++] = *invert ^ 1;
207 } else if ((i-lastBit)>(*clk+tol)){
208 //should have hit a high or low based on clock!!
209 //PrintAndLog("DEBUG - no wave in expected area - location: %d, expected: %d-%d, lastBit: %d - resetting search",i,(lastBit+(clk-((int)(tol)))),(lastBit+(clk+((int)(tol)))),lastBit);
210 if (bitnum > 0) {
211 BinStream[bitnum++] = 77;
212 errCnt++;
213 }
214 lastBit += *clk;//skip over error
215 }
216 if (bitnum >= MaxBits) break;
217 }
218 *size = bitnum;
219 return errCnt;
220 }
221
222 //by marshmellow
223 //encode binary data into binary manchester
224 int ManchesterEncode(uint8_t *BitStream, size_t size)
225 {
226 size_t modIdx=20000, i=0;
227 if (size>modIdx) return -1;
228 for (size_t idx=0; idx < size; idx++){
229 BitStream[idx+modIdx++] = BitStream[idx];
230 BitStream[idx+modIdx++] = BitStream[idx]^1;
231 }
232 for (; i<(size*2); i++){
233 BitStream[i] = BitStream[i+20000];
234 }
235 return i;
236 }
237
238 //by marshmellow
239 //take 10 and 01 and manchester decode
240 //run through 2 times and take least errCnt
241 int manrawdecode(uint8_t * BitStream, size_t *size)
242 {
243 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
244 size_t i, ii;
245 uint16_t bestErr = 1000, bestRun = 0;
246 if (size == 0) return -1;
247 for (ii=0;ii<2;++ii){
248 for (i=ii; i<*size-2; i+=2)
249 if (BitStream[i]==BitStream[i+1])
250 errCnt++;
251
252 if (bestErr>errCnt){
253 bestErr=errCnt;
254 bestRun=ii;
255 }
256 errCnt=0;
257 }
258 for (i=bestRun; i < *size-2; i+=2){
259 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
260 BitStream[bitnum++]=0;
261 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
262 BitStream[bitnum++]=1;
263 } else {
264 BitStream[bitnum++]=77;
265 }
266 if(bitnum>MaxBits) break;
267 }
268 *size=bitnum;
269 return bestErr;
270 }
271
272 //by marshmellow
273 //take 01 or 10 = 1 and 11 or 00 = 0
274 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
275 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
276 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
277 {
278 uint16_t bitnum = 0;
279 uint16_t errCnt = 0;
280 size_t i = offset;
281 uint16_t MaxBits=512;
282 //if not enough samples - error
283 if (*size < 51) return -1;
284 //check for phase change faults - skip one sample if faulty
285 uint8_t offsetA = 1, offsetB = 1;
286 for (; i<48; i+=2){
287 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
288 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
289 }
290 if (!offsetA && offsetB) offset++;
291 for (i=offset; i<*size-3; i+=2){
292 //check for phase error
293 if (BitStream[i+1]==BitStream[i+2]) {
294 BitStream[bitnum++]=77;
295 errCnt++;
296 }
297 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
298 BitStream[bitnum++]=1^invert;
299 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
300 BitStream[bitnum++]=invert;
301 } else {
302 BitStream[bitnum++]=77;
303 errCnt++;
304 }
305 if(bitnum>MaxBits) break;
306 }
307 *size=bitnum;
308 return errCnt;
309 }
310
311 //by marshmellow
312 void askAmp(uint8_t *BitStream, size_t size)
313 {
314 int shift = 127;
315 int shiftedVal=0;
316 for(size_t i = 1; i<size; i++){
317 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
318 shift=127;
319 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
320 shift=-127;
321
322 shiftedVal=BitStream[i]+shift;
323
324 if (shiftedVal>255)
325 shiftedVal=255;
326 else if (shiftedVal<0)
327 shiftedVal=0;
328 BitStream[i-1] = shiftedVal;
329 }
330 return;
331 }
332
333 //by marshmellow
334 //takes 3 arguments - clock, invert and maxErr as integers
335 //attempts to demodulate ask only
336 int askrawdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp)
337 {
338 if (*size==0) return -1;
339 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
340 if (*clk==0 || start < 0) return -1;
341 if (*invert != 1) *invert = 0;
342 if (amp==1) askAmp(BinStream, *size);
343
344 uint8_t initLoopMax = 255;
345 if (initLoopMax > *size) initLoopMax = *size;
346 // Detect high and lows
347 //25% clip in case highs and lows aren't clipped [marshmellow]
348 int high, low;
349 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
350 return -1; //just noise
351
352 // if clean clipped waves detected run alternate demod
353 if (DetectCleanAskWave(BinStream, *size, high, low))
354 return cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
355
356 int lastBit; //set first clock check - can go negative
357 size_t i, errCnt = 0, bitnum = 0; //output counter
358 uint8_t midBit = 0;
359 size_t MaxBits = 1024;
360 lastBit = start - *clk;
361
362 for (i = start; i < *size; ++i) {
363 if (i - lastBit > *clk){
364 if (BinStream[i] >= high) {
365 BinStream[bitnum++] = *invert;
366 } else if (BinStream[i] <= low) {
367 BinStream[bitnum++] = *invert ^ 1;
368 } else {
369 if (bitnum > 0) {
370 BinStream[bitnum++]=77;
371 errCnt++;
372 }
373 }
374 midBit = 0;
375 lastBit += *clk;
376 } else if (i-lastBit > (*clk/2) && midBit == 0){
377 if (BinStream[i] >= high) {
378 BinStream[bitnum++] = *invert;
379 } else if (BinStream[i] <= low) {
380 BinStream[bitnum++] = *invert ^ 1;
381 } else {
382
383 BinStream[bitnum] = BinStream[bitnum-1];
384 bitnum++;
385 }
386 midBit = 1;
387 }
388 if (bitnum >= MaxBits) break;
389 }
390 *size = bitnum;
391 return errCnt;
392 }
393
394 // demod gProxIIDemod
395 // error returns as -x
396 // success returns start position in BitStream
397 // BitStream must contain previously askrawdemod and biphasedemoded data
398 int gProxII_Demod(uint8_t BitStream[], size_t *size)
399 {
400 size_t startIdx=0;
401 uint8_t preamble[] = {1,1,1,1,1,0};
402
403 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
404 if (errChk == 0) return -3; //preamble not found
405 if (*size != 96) return -2; //should have found 96 bits
406 //check first 6 spacer bits to verify format
407 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
408 //confirmed proper separator bits found
409 //return start position
410 return (int) startIdx;
411 }
412 return -5;
413 }
414
415 //translate wave to 11111100000 (1 for each short wave 0 for each long wave)
416 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
417 {
418 size_t last_transition = 0;
419 size_t idx = 1;
420 //uint32_t maxVal=0;
421 if (fchigh==0) fchigh=10;
422 if (fclow==0) fclow=8;
423 //set the threshold close to 0 (graph) or 128 std to avoid static
424 uint8_t threshold_value = 123;
425
426 // sync to first lo-hi transition, and threshold
427
428 // Need to threshold first sample
429
430 if(dest[0] < threshold_value) dest[0] = 0;
431 else dest[0] = 1;
432
433 size_t numBits = 0;
434 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
435 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
436 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
437 for(idx = 1; idx < size; idx++) {
438 // threshold current value
439
440 if (dest[idx] < threshold_value) dest[idx] = 0;
441 else dest[idx] = 1;
442
443 // Check for 0->1 transition
444 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
445 if ((idx-last_transition)<(fclow-2)){ //0-5 = garbage noise
446 //do nothing with extra garbage
447 } else if ((idx-last_transition) < (fchigh-1)) { //6-8 = 8 waves
448 dest[numBits++]=1;
449 } else if ((idx-last_transition) > (fchigh+1) && !numBits) { //12 + and first bit = garbage
450 //do nothing with beginning garbage
451 } else { //9+ = 10 waves
452 dest[numBits++]=0;
453 }
454 last_transition = idx;
455 }
456 }
457 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
458 }
459
460 //translate 11111100000 to 10
461 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
462 uint8_t invert, uint8_t fchigh, uint8_t fclow)
463 {
464 uint8_t lastval=dest[0];
465 size_t idx=0;
466 size_t numBits=0;
467 uint32_t n=1;
468 for( idx=1; idx < size; idx++) {
469 n++;
470 if (dest[idx]==lastval) continue;
471
472 //if lastval was 1, we have a 1->0 crossing
473 if (dest[idx-1]==1) {
474 if (!numBits && n < rfLen/fclow) {
475 n=0;
476 lastval = dest[idx];
477 continue;
478 }
479 n = (n * fclow + rfLen/2) / rfLen;
480 } else {// 0->1 crossing
481 //test first bitsample too small
482 if (!numBits && n < rfLen/fchigh) {
483 n=0;
484 lastval = dest[idx];
485 continue;
486 }
487 n = (n * fchigh + rfLen/2) / rfLen;
488 }
489 if (n == 0) n = 1;
490
491 memset(dest+numBits, dest[idx-1]^invert , n);
492 numBits += n;
493 n=0;
494 lastval=dest[idx];
495 }//end for
496 // if valid extra bits at the end were all the same frequency - add them in
497 if (n > rfLen/fchigh) {
498 if (dest[idx-2]==1) {
499 n = (n * fclow + rfLen/2) / rfLen;
500 } else {
501 n = (n * fchigh + rfLen/2) / rfLen;
502 }
503 memset(dest+numBits, dest[idx-1]^invert , n);
504 numBits += n;
505 }
506 return numBits;
507 }
508 //by marshmellow (from holiman's base)
509 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
510 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
511 {
512 // FSK demodulator
513 size = fsk_wave_demod(dest, size, fchigh, fclow);
514 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
515 return size;
516 }
517
518 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
519 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
520 {
521 if (justNoise(dest, *size)) return -1;
522
523 size_t numStart=0, size2=*size, startIdx=0;
524 // FSK demodulator
525 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
526 if (*size < 96*2) return -2;
527 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
528 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
529 // find bitstring in array
530 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
531 if (errChk == 0) return -3; //preamble not found
532
533 numStart = startIdx + sizeof(preamble);
534 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
535 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
536 if (dest[idx] == dest[idx+1]){
537 return -4; //not manchester data
538 }
539 *hi2 = (*hi2<<1)|(*hi>>31);
540 *hi = (*hi<<1)|(*lo>>31);
541 //Then, shift in a 0 or one into low
542 if (dest[idx] && !dest[idx+1]) // 1 0
543 *lo=(*lo<<1)|1;
544 else // 0 1
545 *lo=(*lo<<1)|0;
546 }
547 return (int)startIdx;
548 }
549
550 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
551 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
552 {
553 if (justNoise(dest, *size)) return -1;
554
555 size_t numStart=0, size2=*size, startIdx=0;
556 // FSK demodulator
557 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
558 if (*size < 96) return -2;
559
560 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
561 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
562
563 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
564 if (errChk == 0) return -3; //preamble not found
565
566 numStart = startIdx + sizeof(preamble);
567 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
568 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
569 if (dest[idx] == dest[idx+1])
570 return -4; //not manchester data
571 *hi2 = (*hi2<<1)|(*hi>>31);
572 *hi = (*hi<<1)|(*lo>>31);
573 //Then, shift in a 0 or one into low
574 if (dest[idx] && !dest[idx+1]) // 1 0
575 *lo=(*lo<<1)|1;
576 else // 0 1
577 *lo=(*lo<<1)|0;
578 }
579 return (int)startIdx;
580 }
581
582 uint32_t bytebits_to_byte(uint8_t* src, size_t numbits)
583 {
584 uint32_t num = 0;
585 for(int i = 0 ; i < numbits ; i++)
586 {
587 num = (num << 1) | (*src);
588 src++;
589 }
590 return num;
591 }
592
593 int IOdemodFSK(uint8_t *dest, size_t size)
594 {
595 if (justNoise(dest, size)) return -1;
596 //make sure buffer has data
597 if (size < 66*64) return -2;
598 // FSK demodulator
599 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
600 if (size < 65) return -3; //did we get a good demod?
601 //Index map
602 //0 10 20 30 40 50 60
603 //| | | | | | |
604 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
605 //-----------------------------------------------------------------------------
606 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
607 //
608 //XSF(version)facility:codeone+codetwo
609 //Handle the data
610 size_t startIdx = 0;
611 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
612 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
613 if (errChk == 0) return -4; //preamble not found
614
615 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
616 //confirmed proper separator bits found
617 //return start position
618 return (int) startIdx;
619 }
620 return -5;
621 }
622
623 // by marshmellow
624 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
625 // Parity Type (1 for odd 0 for even), and binary Length (length to run)
626 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
627 {
628 uint32_t parityWd = 0;
629 size_t j = 0, bitCnt = 0;
630 for (int word = 0; word < (bLen); word+=pLen){
631 for (int bit=0; bit < pLen; bit++){
632 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
633 BitStream[j++] = (BitStream[startIdx+word+bit]);
634 }
635 j--;
636 // if parity fails then return 0
637 if (parityTest(parityWd, pLen, pType) == 0) return -1;
638 bitCnt+=(pLen-1);
639 parityWd = 0;
640 }
641 // if we got here then all the parities passed
642 //return ID start index and size
643 return bitCnt;
644 }
645
646 // by marshmellow
647 // FSK Demod then try to locate an AWID ID
648 int AWIDdemodFSK(uint8_t *dest, size_t *size)
649 {
650 //make sure buffer has enough data
651 if (*size < 96*50) return -1;
652
653 if (justNoise(dest, *size)) return -2;
654
655 // FSK demodulator
656 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
657 if (*size < 96) return -3; //did we get a good demod?
658
659 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
660 size_t startIdx = 0;
661 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
662 if (errChk == 0) return -4; //preamble not found
663 if (*size != 96) return -5;
664 return (int)startIdx;
665 }
666
667 // by marshmellow
668 // FSK Demod then try to locate an Farpointe Data (pyramid) ID
669 int PyramiddemodFSK(uint8_t *dest, size_t *size)
670 {
671 //make sure buffer has data
672 if (*size < 128*50) return -5;
673
674 //test samples are not just noise
675 if (justNoise(dest, *size)) return -1;
676
677 // FSK demodulator
678 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
679 if (*size < 128) return -2; //did we get a good demod?
680
681 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
682 size_t startIdx = 0;
683 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
684 if (errChk == 0) return -4; //preamble not found
685 if (*size != 128) return -3;
686 return (int)startIdx;
687 }
688
689
690 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, int high, int low)
691 {
692 uint16_t allPeaks=1;
693 uint16_t cntPeaks=0;
694 size_t loopEnd = 572;
695 if (loopEnd > size) loopEnd = size;
696 for (size_t i=60; i<loopEnd; i++){
697 if (dest[i]>low && dest[i]<high)
698 allPeaks=0;
699 else
700 cntPeaks++;
701 }
702 if (allPeaks == 0){
703 if (cntPeaks > 300) return 1;
704 }
705 return allPeaks;
706 }
707
708 // by marshmellow
709 // to help detect clocks on heavily clipped samples
710 // based on counts between zero crossings
711 int DetectStrongAskClock(uint8_t dest[], size_t size)
712 {
713 int clk[]={0,8,16,32,40,50,64,100,128};
714 size_t idx = 40;
715 uint8_t high=0;
716 size_t cnt = 0;
717 size_t highCnt = 0;
718 size_t highCnt2 = 0;
719 for (;idx < size; idx++){
720 if (dest[idx]>128) {
721 if (!high){
722 high=1;
723 if (cnt > highCnt){
724 if (highCnt != 0) highCnt2 = highCnt;
725 highCnt = cnt;
726 } else if (cnt > highCnt2) {
727 highCnt2 = cnt;
728 }
729 cnt=1;
730 } else {
731 cnt++;
732 }
733 } else if (dest[idx] <= 128){
734 if (high) {
735 high=0;
736 if (cnt > highCnt) {
737 if (highCnt != 0) highCnt2 = highCnt;
738 highCnt = cnt;
739 } else if (cnt > highCnt2) {
740 highCnt2 = cnt;
741 }
742 cnt=1;
743 } else {
744 cnt++;
745 }
746 }
747 }
748 uint8_t tol;
749 for (idx=8; idx>0; idx--){
750 tol = clk[idx]/8;
751 if (clk[idx] >= highCnt - tol && clk[idx] <= highCnt + tol)
752 return clk[idx];
753 if (clk[idx] >= highCnt2 - tol && clk[idx] <= highCnt2 + tol)
754 return clk[idx];
755 }
756 return -1;
757 }
758
759 // by marshmellow
760 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
761 // maybe somehow adjust peak trimming value based on samples to fix?
762 // return start index of best starting position for that clock and return clock (by reference)
763 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
764 {
765 size_t i=1;
766 uint8_t clk[]={255,8,16,32,40,50,64,100,128,255};
767 uint8_t loopCnt = 255; //don't need to loop through entire array...
768 if (size==0) return -1;
769 if (size <= loopCnt) loopCnt = size-1; //not enough samples
770
771 //if we already have a valid clock
772 uint8_t clockFnd=0;
773 for (;i<9;++i)
774 if (clk[i] == *clock) clockFnd=i;
775 //clock found but continue to find best startpos
776
777 //get high and low peak
778 int peak, low;
779 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
780
781 //test for large clean peaks
782 if (DetectCleanAskWave(dest, size, peak, low)==1){
783 int ans = DetectStrongAskClock(dest, size);
784 for (i=8; i>1; i--){
785 if (clk[i] == ans) {
786 *clock = ans;
787 clockFnd = i;
788 break; //clock found but continue to find best startpos
789 }
790 }
791 }
792 uint8_t ii;
793 uint8_t clkCnt, tol = 0;
794 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
795 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
796 size_t errCnt = 0;
797 size_t arrLoc, loopEnd;
798 //test each valid clock from smallest to greatest to see which lines up
799 uint8_t clkEnd=9;
800 if (clockFnd>0) clkEnd=clockFnd+1;
801 else clockFnd=1;
802
803 for(clkCnt=clockFnd; clkCnt < clkEnd; clkCnt++){
804 if (clk[clkCnt] == 32){
805 tol=1;
806 }else{
807 tol=0;
808 }
809 if (!maxErr && loopCnt>clk[clkCnt]*3) loopCnt=clk[clkCnt]*3;
810 bestErr[clkCnt]=1000;
811 //try lining up the peaks by moving starting point (try first few clocks)
812 for (ii=0; ii < loopCnt-tol-clk[clkCnt]; ii++){
813 if (dest[ii] < peak && dest[ii] > low) continue;
814
815 errCnt=0;
816 // now that we have the first one lined up test rest of wave array
817 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
818 for (i=0; i < loopEnd; ++i){
819 arrLoc = ii + (i * clk[clkCnt]);
820 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
821 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
822 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
823 }else{ //error no peak detected
824 errCnt++;
825 }
826 }
827 //if we found no errors then we can stop here
828 // this is correct one - return this clock
829 //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
830 if(errCnt==0 && clkCnt<6) {
831 *clock = clk[clkCnt];
832 return ii;
833 }
834 //if we found errors see if it is lowest so far and save it as best run
835 if(errCnt<bestErr[clkCnt]){
836 bestErr[clkCnt]=errCnt;
837 bestStart[clkCnt]=ii;
838 }
839 }
840 }
841 uint8_t iii=0;
842 uint8_t best=0;
843 for (iii=0; iii<8; ++iii){
844 if (bestErr[iii] < bestErr[best]){
845 if (bestErr[iii] == 0) bestErr[iii]=1;
846 // current best bit to error ratio vs new bit to error ratio
847 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
848 best = iii;
849 }
850 }
851 }
852 if (bestErr[best] > maxErr) return -1;
853 *clock = clk[best];
854 return bestStart[best];
855 }
856
857 //by marshmellow
858 //detect psk clock by reading each phase shift
859 // a phase shift is determined by measuring the sample length of each wave
860 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
861 {
862 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
863 uint16_t loopCnt = 4096; //don't need to loop through entire array...
864 if (size == 0) return 0;
865 if (size<loopCnt) loopCnt = size;
866
867 //if we already have a valid clock quit
868 size_t i=1;
869 for (; i < 8; ++i)
870 if (clk[i] == clock) return clock;
871
872 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
873 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
874 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
875 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
876 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
877 fc = countFC(dest, size, 0);
878 if (fc!=2 && fc!=4 && fc!=8) return -1;
879 //PrintAndLog("DEBUG: FC: %d",fc);
880
881 //find first full wave
882 for (i=0; i<loopCnt; i++){
883 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
884 if (waveStart == 0) {
885 waveStart = i+1;
886 //PrintAndLog("DEBUG: waveStart: %d",waveStart);
887 } else {
888 waveEnd = i+1;
889 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
890 waveLenCnt = waveEnd-waveStart;
891 if (waveLenCnt > fc){
892 firstFullWave = waveStart;
893 fullWaveLen=waveLenCnt;
894 break;
895 }
896 waveStart=0;
897 }
898 }
899 }
900 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
901
902 //test each valid clock from greatest to smallest to see which lines up
903 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
904 lastClkBit = firstFullWave; //set end of wave as clock align
905 waveStart = 0;
906 errCnt=0;
907 peakcnt=0;
908 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
909
910 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
911 //top edge of wave = start of new wave
912 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
913 if (waveStart == 0) {
914 waveStart = i+1;
915 waveLenCnt=0;
916 } else { //waveEnd
917 waveEnd = i+1;
918 waveLenCnt = waveEnd-waveStart;
919 if (waveLenCnt > fc){
920 //if this wave is a phase shift
921 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
922 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
923 peakcnt++;
924 lastClkBit+=clk[clkCnt];
925 } else if (i<lastClkBit+8){
926 //noise after a phase shift - ignore
927 } else { //phase shift before supposed to based on clock
928 errCnt++;
929 }
930 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
931 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
932 }
933 waveStart=i+1;
934 }
935 }
936 }
937 if (errCnt == 0){
938 return clk[clkCnt];
939 }
940 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
941 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
942 }
943 //all tested with errors
944 //return the highest clk with the most peaks found
945 uint8_t best=7;
946 for (i=7; i>=1; i--){
947 if (peaksdet[i] > peaksdet[best]) {
948 best = i;
949 }
950 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
951 }
952 return clk[best];
953 }
954
955 //by marshmellow
956 //detect nrz clock by reading #peaks vs no peaks(or errors)
957 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
958 {
959 size_t i=0;
960 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
961 size_t loopCnt = 4096; //don't need to loop through entire array...
962 if (size == 0) return 0;
963 if (size<loopCnt) loopCnt = size;
964
965 //if we already have a valid clock quit
966 for (; i < 8; ++i)
967 if (clk[i] == clock) return clock;
968
969 //get high and low peak
970 int peak, low;
971 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
972
973 //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
974 size_t ii;
975 uint8_t clkCnt;
976 uint8_t tol = 0;
977 uint16_t peakcnt=0;
978 uint16_t peaksdet[]={0,0,0,0,0,0,0,0};
979 uint16_t maxPeak=0;
980 //test for large clipped waves
981 for (i=0; i<loopCnt; i++){
982 if (dest[i] >= peak || dest[i] <= low){
983 peakcnt++;
984 } else {
985 if (peakcnt>0 && maxPeak < peakcnt){
986 maxPeak = peakcnt;
987 }
988 peakcnt=0;
989 }
990 }
991 peakcnt=0;
992 //test each valid clock from smallest to greatest to see which lines up
993 for(clkCnt=0; clkCnt < 8; ++clkCnt){
994 //ignore clocks smaller than largest peak
995 if (clk[clkCnt]<maxPeak) continue;
996
997 //try lining up the peaks by moving starting point (try first 256)
998 for (ii=0; ii< loopCnt; ++ii){
999 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1000 peakcnt=0;
1001 // now that we have the first one lined up test rest of wave array
1002 for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
1003 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
1004 peakcnt++;
1005 }
1006 }
1007 if(peakcnt>peaksdet[clkCnt]) {
1008 peaksdet[clkCnt]=peakcnt;
1009 }
1010 }
1011 }
1012 }
1013 int iii=7;
1014 uint8_t best=0;
1015 for (iii=7; iii > 0; iii--){
1016 if (peaksdet[iii] > peaksdet[best]){
1017 best = iii;
1018 }
1019 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
1020 }
1021 return clk[best];
1022 }
1023
1024 // by marshmellow
1025 // convert psk1 demod to psk2 demod
1026 // only transition waves are 1s
1027 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1028 {
1029 size_t i=1;
1030 uint8_t lastBit=BitStream[0];
1031 for (; i<size; i++){
1032 if (BitStream[i]==77){
1033 //ignore errors
1034 } else if (lastBit!=BitStream[i]){
1035 lastBit=BitStream[i];
1036 BitStream[i]=1;
1037 } else {
1038 BitStream[i]=0;
1039 }
1040 }
1041 return;
1042 }
1043
1044 // by marshmellow
1045 // convert psk2 demod to psk1 demod
1046 // from only transition waves are 1s to phase shifts change bit
1047 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1048 {
1049 uint8_t phase=0;
1050 for (size_t i=0; i<size; i++){
1051 if (BitStream[i]==1){
1052 phase ^=1;
1053 }
1054 BitStream[i]=phase;
1055 }
1056 return;
1057 }
1058
1059 // redesigned by marshmellow adjusted from existing decode functions
1060 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1061 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1062 {
1063 //26 bit 40134 format (don't know other formats)
1064 int i;
1065 int long_wait=29;//29 leading zeros in format
1066 int start;
1067 int first = 0;
1068 int first2 = 0;
1069 int bitCnt = 0;
1070 int ii;
1071 // Finding the start of a UID
1072 for (start = 0; start <= *size - 250; start++) {
1073 first = bitStream[start];
1074 for (i = start; i < start + long_wait; i++) {
1075 if (bitStream[i] != first) {
1076 break;
1077 }
1078 }
1079 if (i == (start + long_wait)) {
1080 break;
1081 }
1082 }
1083 if (start == *size - 250 + 1) {
1084 // did not find start sequence
1085 return -1;
1086 }
1087 // Inverting signal if needed
1088 if (first == 1) {
1089 for (i = start; i < *size; i++) {
1090 bitStream[i] = !bitStream[i];
1091 }
1092 *invert = 1;
1093 }else *invert=0;
1094
1095 int iii;
1096 //found start once now test length by finding next one
1097 for (ii=start+29; ii <= *size - 250; ii++) {
1098 first2 = bitStream[ii];
1099 for (iii = ii; iii < ii + long_wait; iii++) {
1100 if (bitStream[iii] != first2) {
1101 break;
1102 }
1103 }
1104 if (iii == (ii + long_wait)) {
1105 break;
1106 }
1107 }
1108 if (ii== *size - 250 + 1){
1109 // did not find second start sequence
1110 return -2;
1111 }
1112 bitCnt=ii-start;
1113
1114 // Dumping UID
1115 i = start;
1116 for (ii = 0; ii < bitCnt; ii++) {
1117 bitStream[ii] = bitStream[i++];
1118 }
1119 *size=bitCnt;
1120 return 1;
1121 }
1122
1123 // by marshmellow - demodulate NRZ wave (both similar enough)
1124 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1125 // there probably is a much simpler way to do this....
1126 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert, int maxErr)
1127 {
1128 if (justNoise(dest, *size)) return -1;
1129 *clk = DetectNRZClock(dest, *size, *clk);
1130 if (*clk==0) return -2;
1131 size_t i, gLen = 4096;
1132 if (gLen>*size) gLen = *size;
1133 int high, low;
1134 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1135 int lastBit = 0; //set first clock check
1136 size_t iii = 0, bitnum = 0; //bitnum counter
1137 uint16_t errCnt = 0, MaxBits = 1000;
1138 size_t bestErrCnt = maxErr+1;
1139 size_t bestPeakCnt = 0, bestPeakStart = 0;
1140 uint8_t bestFirstPeakHigh=0, firstPeakHigh=0, curBit=0, bitHigh=0, errBitHigh=0;
1141 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
1142 uint16_t peakCnt=0;
1143 uint8_t ignoreWindow=4;
1144 uint8_t ignoreCnt=ignoreWindow; //in case of noise near peak
1145 //loop to find first wave that works - align to clock
1146 for (iii=0; iii < gLen; ++iii){
1147 if ((dest[iii]>=high) || (dest[iii]<=low)){
1148 if (dest[iii]>=high) firstPeakHigh=1;
1149 else firstPeakHigh=0;
1150 lastBit=iii-*clk;
1151 peakCnt=0;
1152 errCnt=0;
1153 //loop through to see if this start location works
1154 for (i = iii; i < *size; ++i) {
1155 // if we are at a clock bit
1156 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1157 //test high/low
1158 if (dest[i] >= high || dest[i] <= low) {
1159 bitHigh = 1;
1160 peakCnt++;
1161 errBitHigh = 0;
1162 ignoreCnt = ignoreWindow;
1163 lastBit += *clk;
1164 } else if (i == lastBit + *clk + tol) {
1165 lastBit += *clk;
1166 }
1167 //else if no bars found
1168 } else if (dest[i] < high && dest[i] > low){
1169 if (ignoreCnt==0){
1170 bitHigh=0;
1171 if (errBitHigh==1) errCnt++;
1172 errBitHigh=0;
1173 } else {
1174 ignoreCnt--;
1175 }
1176 } else if ((dest[i]>=high || dest[i]<=low) && (bitHigh==0)) {
1177 //error bar found no clock...
1178 errBitHigh=1;
1179 }
1180 if (((i-iii) / *clk)>=MaxBits) break;
1181 }
1182 //we got more than 64 good bits and not all errors
1183 if (((i-iii) / *clk) > 64 && (errCnt <= (maxErr))) {
1184 //possible good read
1185 if (!errCnt || peakCnt > bestPeakCnt){
1186 bestFirstPeakHigh=firstPeakHigh;
1187 bestErrCnt = errCnt;
1188 bestPeakCnt = peakCnt;
1189 bestPeakStart = iii;
1190 if (!errCnt) break; //great read - finish
1191 }
1192 }
1193 }
1194 }
1195 //PrintAndLog("DEBUG: bestErrCnt: %d, maxErr: %d, bestStart: %d, bestPeakCnt: %d, bestPeakStart: %d",bestErrCnt,maxErr,bestStart,bestPeakCnt,bestPeakStart);
1196 if (bestErrCnt > maxErr) return bestErrCnt;
1197
1198 //best run is good enough set to best run and set overwrite BinStream
1199 lastBit = bestPeakStart - *clk;
1200 memset(dest, bestFirstPeakHigh^1, bestPeakStart / *clk);
1201 bitnum += (bestPeakStart / *clk);
1202 for (i = bestPeakStart; i < *size; ++i) {
1203 // if expecting a clock bit
1204 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1205 // test high/low
1206 if (dest[i] >= high || dest[i] <= low) {
1207 peakCnt++;
1208 bitHigh = 1;
1209 errBitHigh = 0;
1210 ignoreCnt = ignoreWindow;
1211 curBit = *invert;
1212 if (dest[i] >= high) curBit ^= 1;
1213 dest[bitnum++] = curBit;
1214 lastBit += *clk;
1215 //else no bars found in clock area
1216 } else if (i == lastBit + *clk + tol) {
1217 dest[bitnum++] = curBit;
1218 lastBit += *clk;
1219 }
1220 //else if no bars found
1221 } else if (dest[i] < high && dest[i] > low){
1222 if (ignoreCnt == 0){
1223 bitHigh = 0;
1224 if (errBitHigh == 1){
1225 dest[bitnum++] = 77;
1226 errCnt++;
1227 }
1228 errBitHigh=0;
1229 } else {
1230 ignoreCnt--;
1231 }
1232 } else if ((dest[i] >= high || dest[i] <= low) && (bitHigh == 0)) {
1233 //error bar found no clock...
1234 errBitHigh=1;
1235 }
1236 if (bitnum >= MaxBits) break;
1237 }
1238 *size = bitnum;
1239 return bestErrCnt;
1240 }
1241
1242 //by marshmellow
1243 //detects the bit clock for FSK given the high and low Field Clocks
1244 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1245 {
1246 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1247 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1248 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1249 uint8_t rfLensFnd = 0;
1250 uint8_t lastFCcnt = 0;
1251 uint16_t fcCounter = 0;
1252 uint16_t rfCounter = 0;
1253 uint8_t firstBitFnd = 0;
1254 size_t i;
1255 if (size == 0) return 0;
1256
1257 uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1258 rfLensFnd=0;
1259 fcCounter=0;
1260 rfCounter=0;
1261 firstBitFnd=0;
1262 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1263 // prime i to first up transition
1264 for (i = 1; i < size-1; i++)
1265 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1266 break;
1267
1268 for (; i < size-1; i++){
1269 fcCounter++;
1270 rfCounter++;
1271
1272 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1273 continue;
1274 // else new peak
1275 // if we got less than the small fc + tolerance then set it to the small fc
1276 if (fcCounter < fcLow+fcTol)
1277 fcCounter = fcLow;
1278 else //set it to the large fc
1279 fcCounter = fcHigh;
1280
1281 //look for bit clock (rf/xx)
1282 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1283 //not the same size as the last wave - start of new bit sequence
1284 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1285 for (int ii=0; ii<15; ii++){
1286 if (rfLens[ii] == rfCounter){
1287 rfCnts[ii]++;
1288 rfCounter = 0;
1289 break;
1290 }
1291 }
1292 if (rfCounter > 0 && rfLensFnd < 15){
1293 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1294 rfCnts[rfLensFnd]++;
1295 rfLens[rfLensFnd++] = rfCounter;
1296 }
1297 } else {
1298 firstBitFnd++;
1299 }
1300 rfCounter=0;
1301 lastFCcnt=fcCounter;
1302 }
1303 fcCounter=0;
1304 }
1305 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1306
1307 for (i=0; i<15; i++){
1308 //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1309 //get highest 2 RF values (might need to get more values to compare or compare all?)
1310 if (rfCnts[i]>rfCnts[rfHighest]){
1311 rfHighest3=rfHighest2;
1312 rfHighest2=rfHighest;
1313 rfHighest=i;
1314 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1315 rfHighest3=rfHighest2;
1316 rfHighest2=i;
1317 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1318 rfHighest3=i;
1319 }
1320 }
1321 // set allowed clock remainder tolerance to be 1 large field clock length+1
1322 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1323 uint8_t tol1 = fcHigh+1;
1324
1325 //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1326
1327 // loop to find the highest clock that has a remainder less than the tolerance
1328 // compare samples counted divided by
1329 int ii=7;
1330 for (; ii>=0; ii--){
1331 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1332 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1333 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1334 break;
1335 }
1336 }
1337 }
1338 }
1339
1340 if (ii<0) return 0; // oops we went too far
1341
1342 return clk[ii];
1343 }
1344
1345 //by marshmellow
1346 //countFC is to detect the field clock lengths.
1347 //counts and returns the 2 most common wave lengths
1348 //mainly used for FSK field clock detection
1349 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1350 {
1351 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1352 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1353 uint8_t fcLensFnd = 0;
1354 uint8_t lastFCcnt=0;
1355 uint8_t fcCounter = 0;
1356 size_t i;
1357 if (size == 0) return 0;
1358
1359 // prime i to first up transition
1360 for (i = 1; i < size-1; i++)
1361 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1362 break;
1363
1364 for (; i < size-1; i++){
1365 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1366 // new up transition
1367 fcCounter++;
1368 if (fskAdj){
1369 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1370 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1371 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1372 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1373 // save last field clock count (fc/xx)
1374 lastFCcnt = fcCounter;
1375 }
1376 // find which fcLens to save it to:
1377 for (int ii=0; ii<10; ii++){
1378 if (fcLens[ii]==fcCounter){
1379 fcCnts[ii]++;
1380 fcCounter=0;
1381 break;
1382 }
1383 }
1384 if (fcCounter>0 && fcLensFnd<10){
1385 //add new fc length
1386 fcCnts[fcLensFnd]++;
1387 fcLens[fcLensFnd++]=fcCounter;
1388 }
1389 fcCounter=0;
1390 } else {
1391 // count sample
1392 fcCounter++;
1393 }
1394 }
1395
1396 uint8_t best1=9, best2=9, best3=9;
1397 uint16_t maxCnt1=0;
1398 // go through fclens and find which ones are bigest 2
1399 for (i=0; i<10; i++){
1400 // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);
1401 // get the 3 best FC values
1402 if (fcCnts[i]>maxCnt1) {
1403 best3=best2;
1404 best2=best1;
1405 maxCnt1=fcCnts[i];
1406 best1=i;
1407 } else if(fcCnts[i]>fcCnts[best2]){
1408 best3=best2;
1409 best2=i;
1410 } else if(fcCnts[i]>fcCnts[best3]){
1411 best3=i;
1412 }
1413 }
1414 uint8_t fcH=0, fcL=0;
1415 if (fcLens[best1]>fcLens[best2]){
1416 fcH=fcLens[best1];
1417 fcL=fcLens[best2];
1418 } else{
1419 fcH=fcLens[best2];
1420 fcL=fcLens[best1];
1421 }
1422
1423 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1424
1425 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1426 // PrintAndLog("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
1427 if (fskAdj) return fcs;
1428 return fcLens[best1];
1429 }
1430
1431 //by marshmellow - demodulate PSK1 wave
1432 //uses wave lengths (# Samples)
1433 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1434 {
1435 if (size == 0) return -1;
1436 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1437 if (*size<loopCnt) loopCnt = *size;
1438
1439 uint8_t curPhase = *invert;
1440 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1441 uint8_t fc=0, fullWaveLen=0, tol=1;
1442 uint16_t errCnt=0, waveLenCnt=0;
1443 fc = countFC(dest, *size, 0);
1444 if (fc!=2 && fc!=4 && fc!=8) return -1;
1445 //PrintAndLog("DEBUG: FC: %d",fc);
1446 *clock = DetectPSKClock(dest, *size, *clock);
1447 if (*clock == 0) return -1;
1448 int avgWaveVal=0, lastAvgWaveVal=0;
1449 //find first phase shift
1450 for (i=0; i<loopCnt; i++){
1451 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1452 waveEnd = i+1;
1453 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1454 waveLenCnt = waveEnd-waveStart;
1455 if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave
1456 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1457 firstFullWave = waveStart;
1458 fullWaveLen=waveLenCnt;
1459 //if average wave value is > graph 0 then it is an up wave or a 1
1460 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1461 break;
1462 }
1463 waveStart = i+1;
1464 avgWaveVal = 0;
1465 }
1466 avgWaveVal += dest[i+2];
1467 }
1468 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1469 lastClkBit = firstFullWave; //set start of wave as clock align
1470 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1471 waveStart = 0;
1472 size_t numBits=0;
1473 //set skipped bits
1474 memset(dest, curPhase^1, firstFullWave / *clock);
1475 numBits += (firstFullWave / *clock);
1476 dest[numBits++] = curPhase; //set first read bit
1477 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1478 //top edge of wave = start of new wave
1479 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1480 if (waveStart == 0) {
1481 waveStart = i+1;
1482 waveLenCnt = 0;
1483 avgWaveVal = dest[i+1];
1484 } else { //waveEnd
1485 waveEnd = i+1;
1486 waveLenCnt = waveEnd-waveStart;
1487 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1488 if (waveLenCnt > fc){
1489 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1490 //this wave is a phase shift
1491 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1492 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1493 curPhase ^= 1;
1494 dest[numBits++] = curPhase;
1495 lastClkBit += *clock;
1496 } else if (i < lastClkBit+10+fc){
1497 //noise after a phase shift - ignore
1498 } else { //phase shift before supposed to based on clock
1499 errCnt++;
1500 dest[numBits++] = 77;
1501 }
1502 } else if (i+1 > lastClkBit + *clock + tol + fc){
1503 lastClkBit += *clock; //no phase shift but clock bit
1504 dest[numBits++] = curPhase;
1505 }
1506 avgWaveVal = 0;
1507 waveStart = i+1;
1508 }
1509 }
1510 avgWaveVal += dest[i+1];
1511 }
1512 *size = numBits;
1513 return errCnt;
1514 }
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