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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
15
16 uint8_t justNoise(uint8_t *BitStream, size_t size)
17 {
18 static const uint8_t THRESHOLD = 123;
19 //test samples are not just noise
20 uint8_t justNoise1 = 1;
21 for(size_t idx=0; idx < size && justNoise1 ;idx++){
22 justNoise1 = BitStream[idx] < THRESHOLD;
23 }
24 return justNoise1;
25 }
26
27 //by marshmellow
28 //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
29 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
30 {
31 *high=0;
32 *low=255;
33 // get high and low thresholds
34 for (int i=0; i < size; i++){
35 if (BitStream[i] > *high) *high = BitStream[i];
36 if (BitStream[i] < *low) *low = BitStream[i];
37 }
38 if (*high < 123) return -1; // just noise
39 *high = (int)(((*high-128)*(((float)fuzzHi)/100))+128);
40 *low = (int)(((*low-128)*(((float)fuzzLo)/100))+128);
41 return 1;
42 }
43
44 // by marshmellow
45 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
46 // returns 1 if passed
47 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
48 {
49 uint8_t ans = 0;
50 for (uint8_t i = 0; i < bitLen; i++){
51 ans ^= ((bits >> i) & 1);
52 }
53 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
54 return (ans == pType);
55 }
56
57 //by marshmellow
58 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
59 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
60 {
61 uint8_t foundCnt=0;
62 for (int idx=0; idx < *size - pLen; idx++){
63 if (memcmp(BitStream+idx, preamble, pLen) == 0){
64 //first index found
65 foundCnt++;
66 if (foundCnt == 1){
67 *startIdx = idx;
68 }
69 if (foundCnt == 2){
70 *size = idx - *startIdx;
71 return 1;
72 }
73 }
74 }
75 return 0;
76 }
77
78 //by marshmellow
79 //takes 1s and 0s and searches for EM410x format - output EM ID
80 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
81 {
82 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
83 // otherwise could be a void with no arguments
84 //set defaults
85 uint32_t i = 0;
86 if (BitStream[1]>1){ //allow only 1s and 0s
87 // PrintAndLog("no data found");
88 return 0;
89 }
90 // 111111111 bit pattern represent start of frame
91 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1};
92 uint32_t idx = 0;
93 uint32_t parityBits = 0;
94 uint8_t errChk = 0;
95 uint8_t FmtLen = 10;
96 *startIdx = 0;
97 for (uint8_t extraBitChk=0; extraBitChk<5; extraBitChk++){
98 errChk = preambleSearch(BitStream+extraBitChk+*startIdx, preamble, sizeof(preamble), size, startIdx);
99 if (errChk == 0) return 0;
100 if (*size<64) return 0;
101 if (*size>64) FmtLen = 22;
102 if (*size<64) return 0;
103 idx = *startIdx + 9;
104 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
105 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
106 //check even parity
107 if (parityTest(parityBits, 5, 0) == 0){
108 //parity failed try next bit (in the case of 1111111111) but last 9 = preamble
109 startIdx++;
110 errChk = 0;
111 break;
112 }
113 //set uint64 with ID from BitStream
114 for (uint8_t ii=0; ii<4; ii++){
115 *hi = (*hi << 1) | (*lo >> 63);
116 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
117 }
118 }
119 if (errChk != 0) return 1;
120 //skip last 5 bit parity test for simplicity.
121 // *size = 64 | 128;
122 }
123 return 0;
124 }
125
126 //by marshmellow
127 //takes 3 arguments - clock, invert, maxErr as integers
128 //attempts to demodulate ask while decoding manchester
129 //prints binary found and saves in graphbuffer for further commands
130 int askmandemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr)
131 {
132 int i;
133 //int clk2=*clk;
134 int start = DetectASKClock(BinStream, *size, clk, 20); //clock default
135 if (*clk==0) return -3;
136 if (start < 0) return -3;
137 // if autodetected too low then adjust //MAY NEED ADJUSTMENT
138 //if (clk2==0 && *clk<8) *clk =64;
139 //if (clk2==0 && *clk<32) *clk=32;
140 if (*invert != 0 && *invert != 1) *invert=0;
141 uint32_t initLoopMax = 200;
142 if (initLoopMax > *size) initLoopMax=*size;
143 // Detect high and lows
144 // 25% fuzz in case highs and lows aren't clipped [marshmellow]
145 int high, low, ans;
146 ans = getHiLo(BinStream, initLoopMax, &high, &low, 75, 75);
147 if (ans<1) return -2; //just noise
148
149 // PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
150 int lastBit = 0; //set first clock check
151 uint32_t bitnum = 0; //output counter
152 int tol = 0; //clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave
153 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
154 int iii = 0;
155 uint32_t gLen = *size;
156 if (gLen > 3000) gLen=3000;
157 //if 0 errors allowed then only try first 2 clock cycles as we want a low tolerance
158 if (!maxErr) gLen=*clk*2;
159 uint8_t errCnt =0;
160 uint16_t MaxBits = 500;
161 uint32_t bestStart = *size;
162 int bestErrCnt = maxErr+1;
163 // PrintAndLog("DEBUG - lastbit - %d",lastBit);
164 // loop to find first wave that works
165 for (iii=0; iii < gLen; ++iii){
166 if ((BinStream[iii] >= high) || (BinStream[iii] <= low)){
167 lastBit=iii-*clk;
168 errCnt=0;
169 // loop through to see if this start location works
170 for (i = iii; i < *size; ++i) {
171 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
172 lastBit+=*clk;
173 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
174 //low found and we are expecting a bar
175 lastBit+=*clk;
176 } else {
177 //mid value found or no bar supposed to be here
178 if ((i-lastBit)>(*clk+tol)){
179 //should have hit a high or low based on clock!!
180
181 //debug
182 //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);
183
184 errCnt++;
185 lastBit+=*clk;//skip over until hit too many errors
186 if (errCnt>(maxErr)) break; //allow 1 error for every 1000 samples else start over
187 }
188 }
189 if ((i-iii) >(MaxBits * *clk)) break; //got plenty of bits
190 }
191 //we got more than 64 good bits and not all errors
192 if ((((i-iii)/ *clk) > (64)) && (errCnt<=maxErr)) {
193 //possible good read
194 if (errCnt==0){
195 bestStart=iii;
196 bestErrCnt=errCnt;
197 break; //great read - finish
198 }
199 if (errCnt<bestErrCnt){ //set this as new best run
200 bestErrCnt=errCnt;
201 bestStart = iii;
202 }
203 }
204 }
205 }
206 if (bestErrCnt<=maxErr){
207 //best run is good enough set to best run and set overwrite BinStream
208 iii=bestStart;
209 lastBit = bestStart - *clk;
210 bitnum=0;
211 for (i = iii; i < *size; ++i) {
212 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
213 lastBit += *clk;
214 BinStream[bitnum] = *invert;
215 bitnum++;
216 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
217 //low found and we are expecting a bar
218 lastBit+=*clk;
219 BinStream[bitnum] = 1-*invert;
220 bitnum++;
221 } else {
222 //mid value found or no bar supposed to be here
223 if ((i-lastBit)>(*clk+tol)){
224 //should have hit a high or low based on clock!!
225
226 //debug
227 //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);
228 if (bitnum > 0){
229 BinStream[bitnum]=77;
230 bitnum++;
231 }
232
233 lastBit+=*clk;//skip over error
234 }
235 }
236 if (bitnum >=MaxBits) break;
237 }
238 *size=bitnum;
239 } else{
240 *invert=bestStart;
241 *clk=iii;
242 return -1;
243 }
244 return bestErrCnt;
245 }
246
247 //by marshmellow
248 //encode binary data into binary manchester
249 int ManchesterEncode(uint8_t *BitStream, size_t size)
250 {
251 size_t modIdx=20000, i=0;
252 if (size>modIdx) return -1;
253 for (size_t idx=0; idx < size; idx++){
254 BitStream[idx+modIdx++] = BitStream[idx];
255 BitStream[idx+modIdx++] = BitStream[idx]^1;
256 }
257 for (; i<(size*2); i++){
258 BitStream[i] = BitStream[i+20000];
259 }
260 return i;
261 }
262
263 //by marshmellow
264 //take 10 and 01 and manchester decode
265 //run through 2 times and take least errCnt
266 int manrawdecode(uint8_t * BitStream, size_t *size)
267 {
268 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
269 size_t i, ii;
270 uint16_t bestErr = 1000, bestRun = 0;
271 if (size == 0) return -1;
272 for (ii=0;ii<2;++ii){
273 i=0;
274 for (i=i+ii;i<*size-2;i+=2){
275 if(BitStream[i]==1 && (BitStream[i+1]==0)){
276 } else if((BitStream[i]==0)&& BitStream[i+1]==1){
277 } else {
278 errCnt++;
279 }
280 if(bitnum>MaxBits) break;
281 }
282 if (bestErr>errCnt){
283 bestErr=errCnt;
284 bestRun=ii;
285 }
286 errCnt=0;
287 }
288 errCnt=bestErr;
289 if (errCnt<20){
290 ii=bestRun;
291 i=0;
292 for (i=i+ii; i < *size-2; i+=2){
293 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
294 BitStream[bitnum++]=0;
295 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
296 BitStream[bitnum++]=1;
297 } else {
298 BitStream[bitnum++]=77;
299 //errCnt++;
300 }
301 if(bitnum>MaxBits) break;
302 }
303 *size=bitnum;
304 }
305 return errCnt;
306 }
307
308 //by marshmellow
309 //take 01 or 10 = 1 and 11 or 00 = 0
310 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
311 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
312 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
313 {
314 uint16_t bitnum=0;
315 uint32_t errCnt =0;
316 size_t i=offset;
317 uint16_t MaxBits=512;
318 //if not enough samples - error
319 if (*size < 51) return -1;
320 //check for phase change faults - skip one sample if faulty
321 uint8_t offsetA = 1, offsetB = 1;
322 for (; i<48; i+=2){
323 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
324 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
325 }
326 if (!offsetA && offsetB) offset++;
327 for (i=offset; i<*size-3; i+=2){
328 //check for phase error
329 if (BitStream[i+1]==BitStream[i+2]) {
330 BitStream[bitnum++]=77;
331 errCnt++;
332 }
333 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
334 BitStream[bitnum++]=1^invert;
335 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
336 BitStream[bitnum++]=invert;
337 } else {
338 BitStream[bitnum++]=77;
339 errCnt++;
340 }
341 if(bitnum>MaxBits) break;
342 }
343 *size=bitnum;
344 return errCnt;
345 }
346
347 //by marshmellow
348 void askAmp(uint8_t *BitStream, size_t size)
349 {
350 int shift = 127;
351 int shiftedVal=0;
352 for(int i = 1; i<size; i++){
353 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
354 shift=127;
355 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
356 shift=-127;
357
358 shiftedVal=BitStream[i]+shift;
359
360 if (shiftedVal>255)
361 shiftedVal=255;
362 else if (shiftedVal<0)
363 shiftedVal=0;
364 BitStream[i-1] = shiftedVal;
365 }
366 return;
367 }
368
369 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
370 {
371 size_t bitCnt=0, smplCnt=0, errCnt=0;
372 uint8_t waveHigh = 0;
373 //PrintAndLog("clk: %d", clk);
374 for (size_t i=0; i < *size; i++){
375 if (BinStream[i] >= high && waveHigh){
376 smplCnt++;
377 } else if (BinStream[i] <= low && !waveHigh){
378 smplCnt++;
379 } else { //transition
380 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
381 if (smplCnt > clk-(clk/4)-1) { //full clock
382 if (smplCnt > clk + (clk/4)+1) { //too many samples
383 errCnt++;
384 BinStream[bitCnt++]=77;
385 } else if (waveHigh) {
386 BinStream[bitCnt++] = invert;
387 BinStream[bitCnt++] = invert;
388 } else if (!waveHigh) {
389 BinStream[bitCnt++] = invert ^ 1;
390 BinStream[bitCnt++] = invert ^ 1;
391 }
392 waveHigh ^= 1;
393 smplCnt = 0;
394 } else if (smplCnt > (clk/2) - (clk/4)-1) {
395 if (waveHigh) {
396 BinStream[bitCnt++] = invert;
397 } else if (!waveHigh) {
398 BinStream[bitCnt++] = invert ^ 1;
399 }
400 waveHigh ^= 1;
401 smplCnt = 0;
402 } else if (!bitCnt) {
403 //first bit
404 waveHigh = (BinStream[i] >= high);
405 smplCnt = 1;
406 } else {
407 smplCnt++;
408 //transition bit oops
409 }
410 } else { //haven't hit new high or new low yet
411 smplCnt++;
412 }
413 }
414 }
415 *size = bitCnt;
416 return errCnt;
417 }
418
419 //by marshmellow
420 //takes 3 arguments - clock, invert and maxErr as integers
421 //attempts to demodulate ask only
422 int askrawdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp)
423 {
424 uint32_t i;
425 if (*size==0) return -1;
426 int start = DetectASKClock(BinStream, *size, clk, 20); //clock default
427 if (*clk==0) return -1;
428 if (start<0) return -1;
429 if (*invert != 0 && *invert != 1) *invert =0;
430 if (amp==1) askAmp(BinStream, *size);
431
432 uint32_t initLoopMax = 200;
433 if (initLoopMax > *size) initLoopMax=*size;
434 // Detect high and lows
435 //25% clip in case highs and lows aren't clipped [marshmellow]
436 uint8_t clip = 75;
437 int high, low, ans;
438 ans = getHiLo(BinStream, initLoopMax, &high, &low, clip, clip);
439 if (ans<1) return -1; //just noise
440
441 if (DetectCleanAskWave(BinStream, *size, high, low)) {
442 //PrintAndLog("Clean");
443 return cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
444 }
445
446 //PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
447 int lastBit = 0; //set first clock check
448 uint32_t bitnum = 0; //output counter
449 uint8_t tol = 0; //clock tolerance adjust - waves will be accepted as within the clock
450 // if they fall + or - this value + clock from last valid wave
451 if (*clk == 32) tol=0; //clock tolerance may not be needed anymore currently set to
452 // + or - 1 but could be increased for poor waves or removed entirely
453 uint32_t iii = 0;
454 uint32_t gLen = *size;
455 if (gLen > 500) gLen=500;
456 //if 0 errors allowed then only try first 2 clock cycles as we want a low tolerance
457 if (!maxErr) gLen = *clk * 2;
458 uint8_t errCnt =0;
459 uint32_t bestStart = *size;
460 uint32_t bestErrCnt = maxErr; //(*size/1000);
461 uint8_t midBit=0;
462 uint16_t MaxBits=1000;
463
464 //PrintAndLog("DEBUG - lastbit - %d",lastBit);
465 //loop to find first wave that works
466 for (iii=start; iii < gLen; ++iii){
467 if ((BinStream[iii]>=high) || (BinStream[iii]<=low)){
468 lastBit=iii-*clk;
469 errCnt=0;
470 //loop through to see if this start location works
471 for (i = iii; i < *size; ++i) {
472 if ((BinStream[i] >= high) && ((i-lastBit)>(*clk-tol))){
473 lastBit+=*clk;
474 midBit=0;
475 } else if ((BinStream[i] <= low) && ((i-lastBit)>(*clk-tol))){
476 //low found and we are expecting a bar
477 lastBit+=*clk;
478 midBit=0;
479 } else if ((BinStream[i]<=low) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
480 //mid bar?
481 midBit=1;
482 } else if ((BinStream[i]>=high) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
483 //mid bar?
484 midBit=1;
485 } else if ((i-lastBit)>((*clk/2)+tol) && (midBit==0)){
486 //no mid bar found
487 midBit=1;
488 } else {
489 //mid value found or no bar supposed to be here
490
491 if ((i-lastBit)>(*clk+tol)){
492 //should have hit a high or low based on clock!!
493 //debug
494 //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);
495
496 errCnt++;
497 lastBit+=*clk;//skip over until hit too many errors
498 if (errCnt > maxErr){
499 //errCnt=0;
500 break;
501 }
502 }
503 }
504 if ((i-iii)>(MaxBits * *clk)) break; //got enough bits
505 }
506 //we got more than 64 good bits and not all errors
507 if ((((i-iii)/ *clk) > (64)) && (errCnt<=maxErr)) {
508 //possible good read
509 if (errCnt==0){
510 bestStart=iii;
511 bestErrCnt=errCnt;
512 break; //great read - finish
513 }
514 if (errCnt<bestErrCnt){ //set this as new best run
515 bestErrCnt=errCnt;
516 bestStart = iii;
517 }
518 }
519 }
520 }
521 if (bestErrCnt<=maxErr){
522 //best run is good enough - set to best run and overwrite BinStream
523 iii = bestStart;
524 lastBit = bestStart - *clk;
525 bitnum=0;
526 for (i = iii; i < *size; ++i) {
527 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
528 lastBit += *clk;
529 BinStream[bitnum] = *invert;
530 bitnum++;
531 midBit=0;
532 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
533 //low found and we are expecting a bar
534 lastBit+=*clk;
535 BinStream[bitnum] = 1 - *invert;
536 bitnum++;
537 midBit=0;
538 } else if ((BinStream[i]<=low) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
539 //mid bar?
540 midBit=1;
541 BinStream[bitnum] = 1 - *invert;
542 bitnum++;
543 } else if ((BinStream[i]>=high) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
544 //mid bar?
545 midBit=1;
546 BinStream[bitnum] = *invert;
547 bitnum++;
548 } else if ((i-lastBit)>((*clk/2)+tol) && (midBit==0)){
549 //no mid bar found
550 midBit=1;
551 if (bitnum!=0) BinStream[bitnum] = BinStream[bitnum-1];
552 bitnum++;
553
554 } else {
555 //mid value found or no bar supposed to be here
556 if ((i-lastBit)>(*clk+tol)){
557 //should have hit a high or low based on clock!!
558
559 //debug
560 //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);
561 if (bitnum > 0){
562 BinStream[bitnum]=77;
563 bitnum++;
564 }
565 lastBit+=*clk;//skip over error
566 }
567 }
568 if (bitnum >= MaxBits) break;
569 }
570 *size=bitnum;
571 } else{
572 *invert=bestStart;
573 *clk=iii;
574 return -1;
575 }
576 return bestErrCnt;
577 }
578
579 // demod gProxIIDemod
580 // error returns as -x
581 // success returns start position in BitStream
582 // BitStream must contain previously askrawdemod and biphasedemoded data
583 int gProxII_Demod(uint8_t BitStream[], size_t *size)
584 {
585 size_t startIdx=0;
586 uint8_t preamble[] = {1,1,1,1,1,0};
587
588 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
589 if (errChk == 0) return -3; //preamble not found
590 if (*size != 96) return -2; //should have found 96 bits
591 //check first 6 spacer bits to verify format
592 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
593 //confirmed proper separator bits found
594 //return start position
595 return (int) startIdx;
596 }
597 return -5;
598 }
599
600 //translate wave to 11111100000 (1 for each short wave 0 for each long wave)
601 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
602 {
603 uint32_t last_transition = 0;
604 uint32_t idx = 1;
605 //uint32_t maxVal=0;
606 if (fchigh==0) fchigh=10;
607 if (fclow==0) fclow=8;
608 //set the threshold close to 0 (graph) or 128 std to avoid static
609 uint8_t threshold_value = 123;
610
611 // sync to first lo-hi transition, and threshold
612
613 // Need to threshold first sample
614
615 if(dest[0] < threshold_value) dest[0] = 0;
616 else dest[0] = 1;
617
618 size_t numBits = 0;
619 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
620 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
621 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
622 for(idx = 1; idx < size; idx++) {
623 // threshold current value
624
625 if (dest[idx] < threshold_value) dest[idx] = 0;
626 else dest[idx] = 1;
627
628 // Check for 0->1 transition
629 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
630 if ((idx-last_transition)<(fclow-2)){ //0-5 = garbage noise
631 //do nothing with extra garbage
632 } else if ((idx-last_transition) < (fchigh-1)) { //6-8 = 8 waves
633 dest[numBits]=1;
634 } else if ((idx-last_transition) > (fchigh+1) && !numBits) { //12 + and first bit = garbage
635 //do nothing with beginning garbage
636 } else { //9+ = 10 waves
637 dest[numBits]=0;
638 }
639 last_transition = idx;
640 numBits++;
641 }
642 }
643 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
644 }
645
646 uint32_t myround2(float f)
647 {
648 if (f >= 2000) return 2000;//something bad happened
649 return (uint32_t) (f + (float)0.5);
650 }
651
652 //translate 11111100000 to 10
653 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t maxConsequtiveBits,
654 uint8_t invert, uint8_t fchigh, uint8_t fclow)
655 {
656 uint8_t lastval=dest[0];
657 uint32_t idx=0;
658 size_t numBits=0;
659 uint32_t n=1;
660 float lowWaves = (((float)(rfLen))/((float)fclow));
661 float highWaves = (((float)(rfLen))/((float)fchigh));
662 for( idx=1; idx < size; idx++) {
663
664 if (dest[idx]==lastval) {
665 n++;
666 continue;
667 }
668 n++;
669 //if lastval was 1, we have a 1->0 crossing
670 if (dest[idx-1]==1) {
671 if (!numBits && n < (uint8_t)lowWaves) {
672 n=0;
673 lastval = dest[idx];
674 continue;
675 }
676 n=myround2(((float)n)/lowWaves);
677 } else {// 0->1 crossing
678 //test first bitsample too small
679 if (!numBits && n < (uint8_t)highWaves) {
680 n=0;
681 lastval = dest[idx];
682 continue;
683 }
684 n = myround2(((float)n)/highWaves); //-1 for fudge factor
685 }
686 if (n == 0) n = 1;
687
688 if(n < maxConsequtiveBits) //Consecutive
689 {
690 if(invert==0){ //invert bits
691 memset(dest+numBits, dest[idx-1] , n);
692 }else{
693 memset(dest+numBits, dest[idx-1]^1 , n);
694 }
695 numBits += n;
696 }
697 n=0;
698 lastval=dest[idx];
699 }//end for
700
701 // if valid extra bits at the end were all the same frequency - add them in
702 if (n > lowWaves && n > highWaves) {
703 if (dest[idx-2]==1) {
704 n=myround2((float)(n+1)/((float)(rfLen)/(float)fclow));
705 } else {
706 n=myround2((float)(n+1)/((float)(rfLen-1)/(float)fchigh)); //-1 for fudge factor
707 }
708 memset(dest, dest[idx-1]^invert , n);
709 numBits += n;
710 }
711 return numBits;
712 }
713 //by marshmellow (from holiman's base)
714 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
715 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
716 {
717 // FSK demodulator
718 size = fsk_wave_demod(dest, size, fchigh, fclow);
719 size = aggregate_bits(dest, size, rfLen, 192, invert, fchigh, fclow);
720 return size;
721 }
722
723 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
724 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
725 {
726 if (justNoise(dest, *size)) return -1;
727
728 size_t numStart=0, size2=*size, startIdx=0;
729 // FSK demodulator
730 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
731 if (*size < 96) return -2;
732 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
733 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
734 // find bitstring in array
735 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
736 if (errChk == 0) return -3; //preamble not found
737
738 numStart = startIdx + sizeof(preamble);
739 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
740 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
741 if (dest[idx] == dest[idx+1]){
742 return -4; //not manchester data
743 }
744 *hi2 = (*hi2<<1)|(*hi>>31);
745 *hi = (*hi<<1)|(*lo>>31);
746 //Then, shift in a 0 or one into low
747 if (dest[idx] && !dest[idx+1]) // 1 0
748 *lo=(*lo<<1)|1;
749 else // 0 1
750 *lo=(*lo<<1)|0;
751 }
752 return (int)startIdx;
753 }
754
755 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
756 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
757 {
758 if (justNoise(dest, *size)) return -1;
759
760 size_t numStart=0, size2=*size, startIdx=0;
761 // FSK demodulator
762 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
763 if (*size < 96) return -2;
764
765 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
766 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
767
768 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
769 if (errChk == 0) return -3; //preamble not found
770
771 numStart = startIdx + sizeof(preamble);
772 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
773 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
774 if (dest[idx] == dest[idx+1])
775 return -4; //not manchester data
776 *hi2 = (*hi2<<1)|(*hi>>31);
777 *hi = (*hi<<1)|(*lo>>31);
778 //Then, shift in a 0 or one into low
779 if (dest[idx] && !dest[idx+1]) // 1 0
780 *lo=(*lo<<1)|1;
781 else // 0 1
782 *lo=(*lo<<1)|0;
783 }
784 return (int)startIdx;
785 }
786
787 uint32_t bytebits_to_byte(uint8_t* src, size_t numbits)
788 {
789 uint32_t num = 0;
790 for(int i = 0 ; i < numbits ; i++)
791 {
792 num = (num << 1) | (*src);
793 src++;
794 }
795 return num;
796 }
797
798 int IOdemodFSK(uint8_t *dest, size_t size)
799 {
800 if (justNoise(dest, size)) return -1;
801 //make sure buffer has data
802 if (size < 66*64) return -2;
803 // FSK demodulator
804 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
805 if (size < 65) return -3; //did we get a good demod?
806 //Index map
807 //0 10 20 30 40 50 60
808 //| | | | | | |
809 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
810 //-----------------------------------------------------------------------------
811 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
812 //
813 //XSF(version)facility:codeone+codetwo
814 //Handle the data
815 size_t startIdx = 0;
816 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
817 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
818 if (errChk == 0) return -4; //preamble not found
819
820 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
821 //confirmed proper separator bits found
822 //return start position
823 return (int) startIdx;
824 }
825 return -5;
826 }
827
828 // by marshmellow
829 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
830 // Parity Type (1 for odd 0 for even), and binary Length (length to run)
831 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
832 {
833 uint32_t parityWd = 0;
834 size_t j = 0, bitCnt = 0;
835 for (int word = 0; word < (bLen); word+=pLen){
836 for (int bit=0; bit < pLen; bit++){
837 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
838 BitStream[j++] = (BitStream[startIdx+word+bit]);
839 }
840 j--;
841 // if parity fails then return 0
842 if (parityTest(parityWd, pLen, pType) == 0) return -1;
843 bitCnt+=(pLen-1);
844 parityWd = 0;
845 }
846 // if we got here then all the parities passed
847 //return ID start index and size
848 return bitCnt;
849 }
850
851 // by marshmellow
852 // FSK Demod then try to locate an AWID ID
853 int AWIDdemodFSK(uint8_t *dest, size_t *size)
854 {
855 //make sure buffer has enough data
856 if (*size < 96*50) return -1;
857
858 if (justNoise(dest, *size)) return -2;
859
860 // FSK demodulator
861 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
862 if (*size < 96) return -3; //did we get a good demod?
863
864 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
865 size_t startIdx = 0;
866 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
867 if (errChk == 0) return -4; //preamble not found
868 if (*size != 96) return -5;
869 return (int)startIdx;
870 }
871
872 // by marshmellow
873 // FSK Demod then try to locate an Farpointe Data (pyramid) ID
874 int PyramiddemodFSK(uint8_t *dest, size_t *size)
875 {
876 //make sure buffer has data
877 if (*size < 128*50) return -5;
878
879 //test samples are not just noise
880 if (justNoise(dest, *size)) return -1;
881
882 // FSK demodulator
883 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
884 if (*size < 128) return -2; //did we get a good demod?
885
886 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
887 size_t startIdx = 0;
888 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
889 if (errChk == 0) return -4; //preamble not found
890 if (*size != 128) return -3;
891 return (int)startIdx;
892 }
893
894
895 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, int high, int low)
896 {
897 uint16_t allPeaks=1;
898 uint16_t cntPeaks=0;
899 size_t loopEnd = 572;
900 if (loopEnd > size) loopEnd = size;
901 for (size_t i=60; i<loopEnd; i++){
902 if (dest[i]>low && dest[i]<high)
903 allPeaks=0;
904 else
905 cntPeaks++;
906 }
907 if (allPeaks == 0){
908 if (cntPeaks > 300) return 1;
909 }
910 return allPeaks;
911 }
912
913 int DetectStrongAskClock(uint8_t dest[], size_t size)
914 {
915 int clk[]={0,8,16,32,40,50,64,100,128,256};
916 size_t idx = 40;
917 uint8_t high=0;
918 size_t cnt = 0;
919 size_t highCnt = 0;
920 size_t highCnt2 = 0;
921 for (;idx < size; idx++){
922 if (dest[idx]>128) {
923 if (!high){
924 high=1;
925 if (cnt > highCnt){
926 if (highCnt != 0) highCnt2 = highCnt;
927 highCnt = cnt;
928 } else if (cnt > highCnt2) {
929 highCnt2 = cnt;
930 }
931 cnt=1;
932 } else {
933 cnt++;
934 }
935 } else if (dest[idx] <= 128){
936 if (high) {
937 high=0;
938 if (cnt > highCnt) {
939 if (highCnt != 0) highCnt2 = highCnt;
940 highCnt = cnt;
941 } else if (cnt > highCnt2) {
942 highCnt2 = cnt;
943 }
944 cnt=1;
945 } else {
946 cnt++;
947 }
948 }
949 }
950 uint8_t tol;
951 for (idx=8; idx>0; idx--){
952 tol = clk[idx]/8;
953 if (clk[idx] >= highCnt - tol && clk[idx] <= highCnt + tol)
954 return clk[idx];
955 if (clk[idx] >= highCnt2 - tol && clk[idx] <= highCnt2 + tol)
956 return clk[idx];
957 }
958 return -1;
959 }
960
961 // by marshmellow
962 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
963 // maybe somehow adjust peak trimming value based on samples to fix?
964 // return start index of best starting position for that clock and return clock (by reference)
965 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
966 {
967 int i=0;
968 int clk[]={8,16,32,40,50,64,100,128,256};
969 int loopCnt = 256; //don't need to loop through entire array...
970 if (size == 0) return -1;
971 if (size<loopCnt) loopCnt = size;
972 //if we already have a valid clock quit
973
974 for (;i<8;++i)
975 if (clk[i] == *clock) return 0;
976
977 //get high and low peak
978 int peak, low;
979 getHiLo(dest, loopCnt, &peak, &low, 75, 75);
980
981 //test for large clean peaks
982 if (DetectCleanAskWave(dest, size, peak, low)==1){
983 int ans = DetectStrongAskClock(dest, size);
984 for (i=7; i>0; i--){
985 if (clk[i] == ans) {
986 *clock=ans;
987 return 0;
988 }
989 }
990 }
991 int ii;
992 int clkCnt;
993 int tol = 0;
994 int bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
995 int bestStart[]={0,0,0,0,0,0,0,0,0};
996 int errCnt=0;
997 //test each valid clock from smallest to greatest to see which lines up
998 for(clkCnt=0; clkCnt < 8; clkCnt++){
999 if (clk[clkCnt] == 32){
1000 tol=1;
1001 }else{
1002 tol=0;
1003 }
1004 if (!maxErr) loopCnt=clk[clkCnt]*2;
1005 bestErr[clkCnt]=1000;
1006 //try lining up the peaks by moving starting point (try first 256)
1007 for (ii=0; ii < loopCnt; ii++){
1008 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1009 errCnt=0;
1010 // now that we have the first one lined up test rest of wave array
1011 for (i=0; i<((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
1012 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
1013 }else if(dest[ii+(i*clk[clkCnt])-tol]>=peak || dest[ii+(i*clk[clkCnt])-tol]<=low){
1014 }else if(dest[ii+(i*clk[clkCnt])+tol]>=peak || dest[ii+(i*clk[clkCnt])+tol]<=low){
1015 }else{ //error no peak detected
1016 errCnt++;
1017 }
1018 }
1019 //if we found no errors then we can stop here
1020 // this is correct one - return this clock
1021 //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
1022 if(errCnt==0 && clkCnt<6) {
1023 *clock = clk[clkCnt];
1024 return ii;
1025 }
1026 //if we found errors see if it is lowest so far and save it as best run
1027 if(errCnt<bestErr[clkCnt]){
1028 bestErr[clkCnt]=errCnt;
1029 bestStart[clkCnt]=ii;
1030 }
1031 }
1032 }
1033 }
1034 uint8_t iii=0;
1035 uint8_t best=0;
1036 for (iii=0; iii<8; ++iii){
1037 if (bestErr[iii]<bestErr[best]){
1038 if (bestErr[iii]==0) bestErr[iii]=1;
1039 // current best bit to error ratio vs new bit to error ratio
1040 if (((size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii]) ){
1041 best = iii;
1042 }
1043 }
1044 }
1045 if (bestErr[best]>maxErr) return -1;
1046 *clock=clk[best];
1047 return bestStart[best];
1048 }
1049
1050 //by marshmellow
1051 //detect psk clock by reading each phase shift
1052 // a phase shift is determined by measuring the sample length of each wave
1053 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
1054 {
1055 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
1056 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1057 if (size == 0) return 0;
1058 if (size<loopCnt) loopCnt = size;
1059
1060 //if we already have a valid clock quit
1061 size_t i=1;
1062 for (; i < 8; ++i)
1063 if (clk[i] == clock) return clock;
1064
1065 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
1066 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
1067 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
1068 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
1069 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
1070 countFC(dest, size, &fc);
1071 //PrintAndLog("DEBUG: FC: %d",fc);
1072
1073 //find first full wave
1074 for (i=0; i<loopCnt; i++){
1075 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1076 if (waveStart == 0) {
1077 waveStart = i+1;
1078 //PrintAndLog("DEBUG: waveStart: %d",waveStart);
1079 } else {
1080 waveEnd = i+1;
1081 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1082 waveLenCnt = waveEnd-waveStart;
1083 if (waveLenCnt > fc){
1084 firstFullWave = waveStart;
1085 fullWaveLen=waveLenCnt;
1086 break;
1087 }
1088 waveStart=0;
1089 }
1090 }
1091 }
1092 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1093
1094 //test each valid clock from greatest to smallest to see which lines up
1095 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1096 lastClkBit = firstFullWave; //set end of wave as clock align
1097 waveStart = 0;
1098 errCnt=0;
1099 peakcnt=0;
1100 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1101
1102 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1103 //top edge of wave = start of new wave
1104 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1105 if (waveStart == 0) {
1106 waveStart = i+1;
1107 waveLenCnt=0;
1108 } else { //waveEnd
1109 waveEnd = i+1;
1110 waveLenCnt = waveEnd-waveStart;
1111 if (waveLenCnt > fc){
1112 //if this wave is a phase shift
1113 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
1114 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1115 peakcnt++;
1116 lastClkBit+=clk[clkCnt];
1117 } else if (i<lastClkBit+8){
1118 //noise after a phase shift - ignore
1119 } else { //phase shift before supposed to based on clock
1120 errCnt++;
1121 }
1122 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1123 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1124 }
1125 waveStart=i+1;
1126 }
1127 }
1128 }
1129 if (errCnt == 0){
1130 return clk[clkCnt];
1131 }
1132 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1133 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1134 }
1135 //all tested with errors
1136 //return the highest clk with the most peaks found
1137 uint8_t best=7;
1138 for (i=7; i>=1; i--){
1139 if (peaksdet[i] > peaksdet[best]) {
1140 best = i;
1141 }
1142 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
1143 }
1144 return clk[best];
1145 }
1146
1147 //by marshmellow
1148 //detect nrz clock by reading #peaks vs no peaks(or errors)
1149 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1150 {
1151 int i=0;
1152 int clk[]={8,16,32,40,50,64,100,128,256};
1153 int loopCnt = 4096; //don't need to loop through entire array...
1154 if (size == 0) return 0;
1155 if (size<loopCnt) loopCnt = size;
1156
1157 //if we already have a valid clock quit
1158 for (; i < 8; ++i)
1159 if (clk[i] == clock) return clock;
1160
1161 //get high and low peak
1162 int peak, low;
1163 getHiLo(dest, loopCnt, &peak, &low, 75, 75);
1164
1165 //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
1166 int ii;
1167 uint8_t clkCnt;
1168 uint8_t tol = 0;
1169 int peakcnt=0;
1170 int peaksdet[]={0,0,0,0,0,0,0,0};
1171 int maxPeak=0;
1172 //test for large clipped waves
1173 for (i=0; i<loopCnt; i++){
1174 if (dest[i] >= peak || dest[i] <= low){
1175 peakcnt++;
1176 } else {
1177 if (peakcnt>0 && maxPeak < peakcnt){
1178 maxPeak = peakcnt;
1179 }
1180 peakcnt=0;
1181 }
1182 }
1183 peakcnt=0;
1184 //test each valid clock from smallest to greatest to see which lines up
1185 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1186 //ignore clocks smaller than largest peak
1187 if (clk[clkCnt]<maxPeak) continue;
1188
1189 //try lining up the peaks by moving starting point (try first 256)
1190 for (ii=0; ii< loopCnt; ++ii){
1191 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1192 peakcnt=0;
1193 // now that we have the first one lined up test rest of wave array
1194 for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
1195 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
1196 peakcnt++;
1197 }
1198 }
1199 if(peakcnt>peaksdet[clkCnt]) {
1200 peaksdet[clkCnt]=peakcnt;
1201 }
1202 }
1203 }
1204 }
1205 int iii=7;
1206 int best=0;
1207 for (iii=7; iii > 0; iii--){
1208 if (peaksdet[iii] > peaksdet[best]){
1209 best = iii;
1210 }
1211 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
1212 }
1213 return clk[best];
1214 }
1215
1216 // by marshmellow
1217 // convert psk1 demod to psk2 demod
1218 // only transition waves are 1s
1219 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1220 {
1221 size_t i=1;
1222 uint8_t lastBit=BitStream[0];
1223 for (; i<size; i++){
1224 if (BitStream[i]==77){
1225 //ignore errors
1226 } else if (lastBit!=BitStream[i]){
1227 lastBit=BitStream[i];
1228 BitStream[i]=1;
1229 } else {
1230 BitStream[i]=0;
1231 }
1232 }
1233 return;
1234 }
1235
1236 // by marshmellow
1237 // convert psk2 demod to psk1 demod
1238 // from only transition waves are 1s to phase shifts change bit
1239 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1240 {
1241 uint8_t phase=0;
1242 for (size_t i=0; i<size; i++){
1243 if (BitStream[i]==1){
1244 phase ^=1;
1245 }
1246 BitStream[i]=phase;
1247 }
1248 return;
1249 }
1250
1251 // redesigned by marshmellow adjusted from existing decode functions
1252 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1253 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1254 {
1255 //26 bit 40134 format (don't know other formats)
1256 int i;
1257 int long_wait=29;//29 leading zeros in format
1258 int start;
1259 int first = 0;
1260 int first2 = 0;
1261 int bitCnt = 0;
1262 int ii;
1263 // Finding the start of a UID
1264 for (start = 0; start <= *size - 250; start++) {
1265 first = bitStream[start];
1266 for (i = start; i < start + long_wait; i++) {
1267 if (bitStream[i] != first) {
1268 break;
1269 }
1270 }
1271 if (i == (start + long_wait)) {
1272 break;
1273 }
1274 }
1275 if (start == *size - 250 + 1) {
1276 // did not find start sequence
1277 return -1;
1278 }
1279 // Inverting signal if needed
1280 if (first == 1) {
1281 for (i = start; i < *size; i++) {
1282 bitStream[i] = !bitStream[i];
1283 }
1284 *invert = 1;
1285 }else *invert=0;
1286
1287 int iii;
1288 //found start once now test length by finding next one
1289 for (ii=start+29; ii <= *size - 250; ii++) {
1290 first2 = bitStream[ii];
1291 for (iii = ii; iii < ii + long_wait; iii++) {
1292 if (bitStream[iii] != first2) {
1293 break;
1294 }
1295 }
1296 if (iii == (ii + long_wait)) {
1297 break;
1298 }
1299 }
1300 if (ii== *size - 250 + 1){
1301 // did not find second start sequence
1302 return -2;
1303 }
1304 bitCnt=ii-start;
1305
1306 // Dumping UID
1307 i = start;
1308 for (ii = 0; ii < bitCnt; ii++) {
1309 bitStream[ii] = bitStream[i++];
1310 }
1311 *size=bitCnt;
1312 return 1;
1313 }
1314
1315 // by marshmellow - demodulate NRZ wave (both similar enough)
1316 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1317 // there probably is a much simpler way to do this....
1318 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert, int maxErr)
1319 {
1320 if (justNoise(dest, *size)) return -1;
1321 *clk = DetectNRZClock(dest, *size, *clk);
1322 if (*clk==0) return -2;
1323 uint32_t i;
1324 uint32_t gLen = 4096;
1325 if (gLen>*size) gLen = *size;
1326 int high, low;
1327 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1328 int lastBit = 0; //set first clock check
1329 uint32_t bitnum = 0; //output counter
1330 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
1331 uint32_t iii = 0;
1332 uint16_t errCnt =0;
1333 uint16_t MaxBits = 1000;
1334 uint32_t bestErrCnt = maxErr+1;
1335 uint32_t bestPeakCnt = 0;
1336 uint32_t bestPeakStart=0;
1337 uint8_t bestFirstPeakHigh=0;
1338 uint8_t firstPeakHigh=0;
1339 uint8_t curBit=0;
1340 uint8_t bitHigh=0;
1341 uint8_t errBitHigh=0;
1342 uint16_t peakCnt=0;
1343 uint8_t ignoreWindow=4;
1344 uint8_t ignoreCnt=ignoreWindow; //in case of noice near peak
1345 //loop to find first wave that works - align to clock
1346 for (iii=0; iii < gLen; ++iii){
1347 if ((dest[iii]>=high) || (dest[iii]<=low)){
1348 if (dest[iii]>=high) firstPeakHigh=1;
1349 else firstPeakHigh=0;
1350 lastBit=iii-*clk;
1351 peakCnt=0;
1352 errCnt=0;
1353 bitnum=0;
1354 //loop through to see if this start location works
1355 for (i = iii; i < *size; ++i) {
1356 //if we found a high bar and we are at a clock bit
1357 if ((dest[i]>=high ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1358 bitHigh=1;
1359 lastBit+=*clk;
1360 bitnum++;
1361 peakCnt++;
1362 errBitHigh=0;
1363 ignoreCnt=ignoreWindow;
1364 //else if low bar found and we are at a clock point
1365 }else if ((dest[i]<=low ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1366 bitHigh=1;
1367 lastBit+=*clk;
1368 bitnum++;
1369 peakCnt++;
1370 errBitHigh=0;
1371 ignoreCnt=ignoreWindow;
1372 //else if no bars found
1373 }else if(dest[i] < high && dest[i] > low) {
1374 if (ignoreCnt==0){
1375 bitHigh=0;
1376 if (errBitHigh==1){
1377 errCnt++;
1378 }
1379 errBitHigh=0;
1380 } else {
1381 ignoreCnt--;
1382 }
1383 //if we are past a clock point
1384 if (i >= lastBit+*clk+tol){ //clock val
1385 lastBit+=*clk;
1386 bitnum++;
1387 }
1388 //else if bar found but we are not at a clock bit and we did not just have a clock bit
1389 }else if ((dest[i]>=high || dest[i]<=low) && (i<lastBit+*clk-tol || i>lastBit+*clk+tol) && (bitHigh==0)){
1390 //error bar found no clock...
1391 errBitHigh=1;
1392 }
1393 if (bitnum>=MaxBits) break;
1394 }
1395 //we got more than 64 good bits and not all errors
1396 if (bitnum > (64) && (errCnt <= (maxErr))) {
1397 //possible good read
1398 if (errCnt == 0){
1399 //bestStart = iii;
1400 bestFirstPeakHigh=firstPeakHigh;
1401 bestErrCnt = errCnt;
1402 bestPeakCnt = peakCnt;
1403 bestPeakStart = iii;
1404 break; //great read - finish
1405 }
1406 if (errCnt < bestErrCnt){ //set this as new best run
1407 bestErrCnt = errCnt;
1408 //bestStart = iii;
1409 }
1410 if (peakCnt > bestPeakCnt){
1411 bestFirstPeakHigh=firstPeakHigh;
1412 bestPeakCnt=peakCnt;
1413 bestPeakStart=iii;
1414 }
1415 }
1416 }
1417 }
1418 //PrintAndLog("DEBUG: bestErrCnt: %d, maxErr: %d, bestStart: %d, bestPeakCnt: %d, bestPeakStart: %d",bestErrCnt,maxErr,bestStart,bestPeakCnt,bestPeakStart);
1419 if (bestErrCnt <= maxErr){
1420 //best run is good enough set to best run and set overwrite BinStream
1421 iii=bestPeakStart;
1422 lastBit=bestPeakStart-*clk;
1423 bitnum=0;
1424 memset(dest, bestFirstPeakHigh^1, bestPeakStart / *clk);
1425 bitnum += (bestPeakStart / *clk);
1426 for (i = iii; i < *size; ++i) {
1427 //if we found a high bar and we are at a clock bit
1428 if ((dest[i] >= high ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1429 bitHigh=1;
1430 lastBit+=*clk;
1431 curBit=1-*invert;
1432 dest[bitnum]=curBit;
1433 bitnum++;
1434 errBitHigh=0;
1435 ignoreCnt=ignoreWindow;
1436 //else if low bar found and we are at a clock point
1437 }else if ((dest[i]<=low ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1438 bitHigh=1;
1439 lastBit+=*clk;
1440 curBit=*invert;
1441 dest[bitnum]=curBit;
1442 bitnum++;
1443 errBitHigh=0;
1444 ignoreCnt=ignoreWindow;
1445 //else if no bars found
1446 }else if(dest[i]<high && dest[i]>low) {
1447 if (ignoreCnt==0){
1448 bitHigh=0;
1449 //if peak is done was it an error peak?
1450 if (errBitHigh==1){
1451 dest[bitnum]=77;
1452 bitnum++;
1453 errCnt++;
1454 }
1455 errBitHigh=0;
1456 } else {
1457 ignoreCnt--;
1458 }
1459 //if we are past a clock point
1460 if (i>=lastBit+*clk+tol){ //clock val
1461 lastBit+=*clk;
1462 dest[bitnum]=curBit;
1463 bitnum++;
1464 }
1465 //else if bar found but we are not at a clock bit and we did not just have a clock bit
1466 }else if ((dest[i]>=high || dest[i]<=low) && ((i<lastBit+*clk-tol) || (i>lastBit+*clk+tol)) && (bitHigh==0)){
1467 //error bar found no clock...
1468 errBitHigh=1;
1469 }
1470 if (bitnum >= MaxBits) break;
1471 }
1472 *size=bitnum;
1473 } else{
1474 *size=bitnum;
1475 return bestErrCnt;
1476 }
1477
1478 if (bitnum>16){
1479 *size=bitnum;
1480 } else return -5;
1481 return errCnt;
1482 }
1483
1484 //by marshmellow
1485 //detects the bit clock for FSK given the high and low Field Clocks
1486 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1487 {
1488 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1489 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1490 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1491 uint8_t rfLensFnd = 0;
1492 uint8_t lastFCcnt=0;
1493 uint32_t fcCounter = 0;
1494 uint16_t rfCounter = 0;
1495 uint8_t firstBitFnd = 0;
1496 size_t i;
1497 if (size == 0) return 0;
1498
1499 uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1500 rfLensFnd=0;
1501 fcCounter=0;
1502 rfCounter=0;
1503 firstBitFnd=0;
1504 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1505 // prime i to first up transition
1506 for (i = 1; i < size-1; i++)
1507 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1508 break;
1509
1510 for (; i < size-1; i++){
1511 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1]){
1512 // new peak
1513 fcCounter++;
1514 rfCounter++;
1515 // if we got less than the small fc + tolerance then set it to the small fc
1516 if (fcCounter < fcLow+fcTol)
1517 fcCounter = fcLow;
1518 else //set it to the large fc
1519 fcCounter = fcHigh;
1520
1521 //look for bit clock (rf/xx)
1522 if ((fcCounter<lastFCcnt || fcCounter>lastFCcnt)){
1523 //not the same size as the last wave - start of new bit sequence
1524
1525 if (firstBitFnd>1){ //skip first wave change - probably not a complete bit
1526 for (int ii=0; ii<15; ii++){
1527 if (rfLens[ii]==rfCounter){
1528 rfCnts[ii]++;
1529 rfCounter=0;
1530 break;
1531 }
1532 }
1533 if (rfCounter>0 && rfLensFnd<15){
1534 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1535 rfCnts[rfLensFnd]++;
1536 rfLens[rfLensFnd++]=rfCounter;
1537 }
1538 } else {
1539 firstBitFnd++;
1540 }
1541 rfCounter=0;
1542 lastFCcnt=fcCounter;
1543 }
1544 fcCounter=0;
1545 } else {
1546 // count sample
1547 fcCounter++;
1548 rfCounter++;
1549 }
1550 }
1551 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1552
1553 for (i=0; i<15; i++){
1554 //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1555 //get highest 2 RF values (might need to get more values to compare or compare all?)
1556 if (rfCnts[i]>rfCnts[rfHighest]){
1557 rfHighest3=rfHighest2;
1558 rfHighest2=rfHighest;
1559 rfHighest=i;
1560 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1561 rfHighest3=rfHighest2;
1562 rfHighest2=i;
1563 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1564 rfHighest3=i;
1565 }
1566 }
1567 // set allowed clock remainder tolerance to be 1 large field clock length+1
1568 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1569 uint8_t tol1 = fcHigh+1;
1570
1571 //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1572
1573 // loop to find the highest clock that has a remainder less than the tolerance
1574 // compare samples counted divided by
1575 int ii=7;
1576 for (; ii>=0; ii--){
1577 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1578 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1579 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1580 break;
1581 }
1582 }
1583 }
1584 }
1585
1586 if (ii<0) return 0; // oops we went too far
1587
1588 return clk[ii];
1589 }
1590
1591 //by marshmellow
1592 //countFC is to detect the field clock lengths.
1593 //counts and returns the 2 most common wave lengths
1594 //mainly used for FSK field clock detection
1595 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t *mostFC)
1596 {
1597 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1598 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1599 uint8_t fcLensFnd = 0;
1600 uint8_t lastFCcnt=0;
1601 uint32_t fcCounter = 0;
1602 size_t i;
1603 if (size == 0) return 0;
1604
1605 // prime i to first up transition
1606 for (i = 1; i < size-1; i++)
1607 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1608 break;
1609
1610 for (; i < size-1; i++){
1611 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1612 // new up transition
1613 fcCounter++;
1614
1615 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1616 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1617 //if odd and not rc/5 add one (for when we get a fc 9 instead of 10)
1618 if ((fcCounter==9 && fcCounter & 1) || fcCounter==4) fcCounter++;
1619
1620 // save last field clock count (fc/xx)
1621 // find which fcLens to save it to:
1622 for (int ii=0; ii<10; ii++){
1623 if (fcLens[ii]==fcCounter){
1624 fcCnts[ii]++;
1625 fcCounter=0;
1626 break;
1627 }
1628 }
1629 if (fcCounter>0 && fcLensFnd<10){
1630 //add new fc length
1631 fcCnts[fcLensFnd]++;
1632 fcLens[fcLensFnd++]=fcCounter;
1633 }
1634 fcCounter=0;
1635 } else {
1636 // count sample
1637 fcCounter++;
1638 }
1639 }
1640
1641 uint8_t best1=9, best2=9, best3=9;
1642 uint16_t maxCnt1=0;
1643 // go through fclens and find which ones are bigest 2
1644 for (i=0; i<10; i++){
1645 // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);
1646 // get the 3 best FC values
1647 if (fcCnts[i]>maxCnt1) {
1648 best3=best2;
1649 best2=best1;
1650 maxCnt1=fcCnts[i];
1651 best1=i;
1652 } else if(fcCnts[i]>fcCnts[best2]){
1653 best3=best2;
1654 best2=i;
1655 } else if(fcCnts[i]>fcCnts[best3]){
1656 best3=i;
1657 }
1658 }
1659 uint8_t fcH=0, fcL=0;
1660 if (fcLens[best1]>fcLens[best2]){
1661 fcH=fcLens[best1];
1662 fcL=fcLens[best2];
1663 } else{
1664 fcH=fcLens[best2];
1665 fcL=fcLens[best1];
1666 }
1667
1668 *mostFC=fcLens[best1];
1669 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1670
1671 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1672 // PrintAndLog("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
1673
1674 return fcs;
1675 }
1676
1677 //by marshmellow
1678 //countPSK_FC is to detect the psk carrier clock length.
1679 //counts and returns the 1 most common wave length
1680 uint8_t countPSK_FC(uint8_t *BitStream, size_t size)
1681 {
1682 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1683 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1684 uint8_t fcLensFnd = 0;
1685 uint32_t fcCounter = 0;
1686 size_t i;
1687 if (size == 0) return 0;
1688
1689 // prime i to first up transition
1690 for (i = 1; i < size-1; i++)
1691 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1692 break;
1693
1694 for (; i < size-1; i++){
1695 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1696 // new up transition
1697 fcCounter++;
1698
1699 // save last field clock count (fc/xx)
1700 // find which fcLens to save it to:
1701 for (int ii=0; ii<10; ii++){
1702 if (fcLens[ii]==fcCounter){
1703 fcCnts[ii]++;
1704 fcCounter=0;
1705 break;
1706 }
1707 }
1708 if (fcCounter>0 && fcLensFnd<10){
1709 //add new fc length
1710 fcCnts[fcLensFnd]++;
1711 fcLens[fcLensFnd++]=fcCounter;
1712 }
1713 fcCounter=0;
1714 } else {
1715 // count sample
1716 fcCounter++;
1717 }
1718 }
1719
1720 uint8_t best1=9;
1721 uint16_t maxCnt1=0;
1722 // go through fclens and find which ones are bigest
1723 for (i=0; i<10; i++){
1724 //PrintAndLog("DEBUG: FC %d, Cnt %d",fcLens[i],fcCnts[i]);
1725 // get the best FC value
1726 if (fcCnts[i]>maxCnt1) {
1727 maxCnt1=fcCnts[i];
1728 best1=i;
1729 }
1730 }
1731 return fcLens[best1];
1732 }
1733
1734 //by marshmellow - demodulate PSK1 wave
1735 //uses wave lengths (# Samples)
1736 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1737 {
1738 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1739 if (size == 0) return -1;
1740 if (*size<loopCnt) loopCnt = *size;
1741
1742 uint8_t curPhase = *invert;
1743 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1744 uint8_t fc=0, fullWaveLen=0, tol=1;
1745 uint16_t errCnt=0, waveLenCnt=0;
1746 fc = countPSK_FC(dest, *size);
1747 if (fc!=2 && fc!=4 && fc!=8) return -1;
1748 //PrintAndLog("DEBUG: FC: %d",fc);
1749 *clock = DetectPSKClock(dest, *size, *clock);
1750 if (*clock==0) return -1;
1751 int avgWaveVal=0, lastAvgWaveVal=0;
1752 //find first phase shift
1753 for (i=0; i<loopCnt; i++){
1754 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1755 waveEnd = i+1;
1756 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1757 waveLenCnt = waveEnd-waveStart;
1758 if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave
1759 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1760 firstFullWave = waveStart;
1761 fullWaveLen=waveLenCnt;
1762 //if average wave value is > graph 0 then it is an up wave or a 1
1763 if (lastAvgWaveVal > 123) curPhase^=1; //fudge graph 0 a little 123 vs 128
1764 break;
1765 }
1766 waveStart = i+1;
1767 avgWaveVal = 0;
1768 }
1769 avgWaveVal+=dest[i+2];
1770 }
1771 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1772 lastClkBit = firstFullWave; //set start of wave as clock align
1773 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1774 waveStart = 0;
1775 errCnt=0;
1776 size_t numBits=0;
1777 //set skipped bits
1778 memset(dest,curPhase^1,firstFullWave / *clock);
1779 numBits += (firstFullWave / *clock);
1780 dest[numBits++] = curPhase; //set first read bit
1781 for (i = firstFullWave+fullWaveLen-1; i < *size-3; i++){
1782 //top edge of wave = start of new wave
1783 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1784 if (waveStart == 0) {
1785 waveStart = i+1;
1786 waveLenCnt=0;
1787 avgWaveVal = dest[i+1];
1788 } else { //waveEnd
1789 waveEnd = i+1;
1790 waveLenCnt = waveEnd-waveStart;
1791 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1792 if (waveLenCnt > fc){
1793 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1794 //if this wave is a phase shift
1795 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1796 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1797 curPhase^=1;
1798 dest[numBits++] = curPhase;
1799 lastClkBit += *clock;
1800 } else if (i<lastClkBit+10+fc){
1801 //noise after a phase shift - ignore
1802 } else { //phase shift before supposed to based on clock
1803 errCnt++;
1804 dest[numBits++] = 77;
1805 }
1806 } else if (i+1 > lastClkBit + *clock + tol + fc){
1807 lastClkBit += *clock; //no phase shift but clock bit
1808 dest[numBits++] = curPhase;
1809 }
1810 avgWaveVal=0;
1811 waveStart=i+1;
1812 }
1813 }
1814 avgWaveVal+=dest[i+1];
1815 }
1816 *size = numBits;
1817 return errCnt;
1818 }
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