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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 //by marshmellow
16 //get high and low with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
17 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
18 {
19 *high=0;
20 *low=255;
21 // get high and low thresholds
22 for (int i=0; i < size; i++){
23 if (BitStream[i] > *high) *high = BitStream[i];
24 if (BitStream[i] < *low) *low = BitStream[i];
25 }
26 if (*high < 123) return -1; // just noise
27 *high = (int)(((*high-128)*(((float)fuzzHi)/100))+128);
28 *low = (int)(((*low-128)*(((float)fuzzLo)/100))+128);
29 return 1;
30 }
31
32 //by marshmellow
33 //takes 1s and 0s and searches for EM410x format - output EM ID
34 uint64_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx)
35 {
36 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
37 // otherwise could be a void with no arguments
38 //set defaults
39 uint64_t lo=0;
40 uint32_t i = 0;
41 if (BitStream[10]>1){ //allow only 1s and 0s
42 // PrintAndLog("no data found");
43 return 0;
44 }
45 uint8_t parityTest=0;
46 // 111111111 bit pattern represent start of frame
47 uint8_t frame_marker_mask[] = {1,1,1,1,1,1,1,1,1};
48 uint32_t idx = 0;
49 uint32_t ii=0;
50 uint8_t resetCnt = 0;
51 while( (idx + 64) < *size) {
52 restart:
53 // search for a start of frame marker
54 if ( memcmp(BitStream+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
55 { // frame marker found
56 *startIdx=idx;
57 idx+=9;
58 for (i=0; i<10;i++){
59 for(ii=0; ii<5; ++ii){
60 parityTest ^= BitStream[(i*5)+ii+idx];
61 }
62 if (!parityTest){ //even parity
63 parityTest=0;
64 for (ii=0; ii<4;++ii){
65 lo=(lo<<1LL)|(BitStream[(i*5)+ii+idx]);
66 }
67 //PrintAndLog("DEBUG: EM parity passed parity val: %d, i:%d, ii:%d,idx:%d, Buffer: %d%d%d%d%d,lo: %d",parityTest,i,ii,idx,BitStream[idx+ii+(i*5)-5],BitStream[idx+ii+(i*5)-4],BitStream[idx+ii+(i*5)-3],BitStream[idx+ii+(i*5)-2],BitStream[idx+ii+(i*5)-1],lo);
68 }else {//parity failed
69 //PrintAndLog("DEBUG: EM parity failed parity val: %d, i:%d, ii:%d,idx:%d, Buffer: %d%d%d%d%d",parityTest,i,ii,idx,BitStream[idx+ii+(i*5)-5],BitStream[idx+ii+(i*5)-4],BitStream[idx+ii+(i*5)-3],BitStream[idx+ii+(i*5)-2],BitStream[idx+ii+(i*5)-1]);
70 parityTest=0;
71 idx-=8;
72 if (resetCnt>5)return 0; //try 5 times
73 resetCnt++;
74 goto restart;//continue;
75 }
76 }
77 //skip last 5 bit parity test for simplicity.
78 *size = 64;
79 return lo;
80 }else{
81 idx++;
82 }
83 }
84 return 0;
85 }
86
87 //by marshmellow
88 //takes 2 arguments - clock and invert both as integers
89 //attempts to demodulate ask while decoding manchester
90 //prints binary found and saves in graphbuffer for further commands
91 int askmandemod(uint8_t *BinStream, size_t *size, int *clk, int *invert)
92 {
93 int i;
94 int clk2=*clk;
95 *clk=DetectASKClock(BinStream, *size, *clk); //clock default
96
97 // if autodetected too low then adjust //MAY NEED ADJUSTMENT
98 if (clk2==0 && *clk<8) *clk =64;
99 if (clk2==0 && *clk<32) *clk=32;
100 if (*invert != 0 && *invert != 1) *invert=0;
101 uint32_t initLoopMax = 200;
102 if (initLoopMax > *size) initLoopMax=*size;
103 // Detect high and lows
104 // 25% fuzz in case highs and lows aren't clipped [marshmellow]
105 int high, low, ans;
106 ans = getHiLo(BinStream, initLoopMax, &high, &low, 75, 75);
107 if (ans<1) return -2; //just noise
108
109 // PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
110 int lastBit = 0; //set first clock check
111 uint32_t bitnum = 0; //output counter
112 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
113 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
114 int iii = 0;
115 uint32_t gLen = *size;
116 if (gLen > 3000) gLen=3000;
117 uint8_t errCnt =0;
118 uint32_t bestStart = *size;
119 uint32_t bestErrCnt = (*size/1000);
120 uint32_t maxErr = (*size/1000);
121 // PrintAndLog("DEBUG - lastbit - %d",lastBit);
122 // loop to find first wave that works
123 for (iii=0; iii < gLen; ++iii){
124 if ((BinStream[iii] >= high) || (BinStream[iii] <= low)){
125 lastBit=iii-*clk;
126 errCnt=0;
127 // loop through to see if this start location works
128 for (i = iii; i < *size; ++i) {
129 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
130 lastBit+=*clk;
131 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
132 //low found and we are expecting a bar
133 lastBit+=*clk;
134 } else {
135 //mid value found or no bar supposed to be here
136 if ((i-lastBit)>(*clk+tol)){
137 //should have hit a high or low based on clock!!
138
139 //debug
140 //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);
141
142 errCnt++;
143 lastBit+=*clk;//skip over until hit too many errors
144 if (errCnt>(maxErr)) break; //allow 1 error for every 1000 samples else start over
145 }
146 }
147 if ((i-iii) >(400 * *clk)) break; //got plenty of bits
148 }
149 //we got more than 64 good bits and not all errors
150 if ((((i-iii)/ *clk) > (64+errCnt)) && (errCnt<maxErr)) {
151 //possible good read
152 if (errCnt==0){
153 bestStart=iii;
154 bestErrCnt=errCnt;
155 break; //great read - finish
156 }
157 if (errCnt<bestErrCnt){ //set this as new best run
158 bestErrCnt=errCnt;
159 bestStart = iii;
160 }
161 }
162 }
163 }
164 if (bestErrCnt<maxErr){
165 //best run is good enough set to best run and set overwrite BinStream
166 iii=bestStart;
167 lastBit = bestStart - *clk;
168 bitnum=0;
169 for (i = iii; i < *size; ++i) {
170 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
171 lastBit += *clk;
172 BinStream[bitnum] = *invert;
173 bitnum++;
174 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
175 //low found and we are expecting a bar
176 lastBit+=*clk;
177 BinStream[bitnum] = 1-*invert;
178 bitnum++;
179 } else {
180 //mid value found or no bar supposed to be here
181 if ((i-lastBit)>(*clk+tol)){
182 //should have hit a high or low based on clock!!
183
184 //debug
185 //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);
186 if (bitnum > 0){
187 BinStream[bitnum]=77;
188 bitnum++;
189 }
190
191 lastBit+=*clk;//skip over error
192 }
193 }
194 if (bitnum >=400) break;
195 }
196 *size=bitnum;
197 } else{
198 *invert=bestStart;
199 *clk=iii;
200 return -1;
201 }
202 return bestErrCnt;
203 }
204
205 //by marshmellow
206 //encode binary data into binary manchester
207 int ManchesterEncode(uint8_t *BitStream, size_t size)
208 {
209 size_t modIdx=20000, i=0;
210 if (size>modIdx) return -1;
211 for (size_t idx=0; idx < size; idx++){
212 BitStream[idx+modIdx++] = BitStream[idx];
213 BitStream[idx+modIdx++] = BitStream[idx]^1;
214 }
215 for (; i<(size*2); i++){
216 BitStream[i] = BitStream[i+20000];
217 }
218 return i;
219 }
220
221 //by marshmellow
222 //take 10 and 01 and manchester decode
223 //run through 2 times and take least errCnt
224 int manrawdecode(uint8_t * BitStream, size_t *size)
225 {
226 int bitnum=0;
227 int errCnt =0;
228 int i=1;
229 int bestErr = 1000;
230 int bestRun = 0;
231 int ii=1;
232 for (ii=1;ii<3;++ii){
233 i=1;
234 for (i=i+ii;i<*size-2;i+=2){
235 if(BitStream[i]==1 && (BitStream[i+1]==0)){
236 } else if((BitStream[i]==0)&& BitStream[i+1]==1){
237 } else {
238 errCnt++;
239 }
240 if(bitnum>300) break;
241 }
242 if (bestErr>errCnt){
243 bestErr=errCnt;
244 bestRun=ii;
245 }
246 errCnt=0;
247 }
248 errCnt=bestErr;
249 if (errCnt<20){
250 ii=bestRun;
251 i=1;
252 for (i=i+ii;i < *size-2;i+=2){
253 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
254 BitStream[bitnum++]=0;
255 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
256 BitStream[bitnum++]=1;
257 } else {
258 BitStream[bitnum++]=77;
259 //errCnt++;
260 }
261 if(bitnum>300) break;
262 }
263 *size=bitnum;
264 }
265 return errCnt;
266 }
267
268 //by marshmellow
269 //take 01 or 10 = 0 and 11 or 00 = 1
270 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
271 {
272 uint8_t bitnum=0;
273 uint32_t errCnt =0;
274 uint32_t i;
275 i=offset;
276 for (;i<*size-2; i+=2){
277 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
278 BitStream[bitnum++]=1^invert;
279 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
280 BitStream[bitnum++]=invert;
281 } else {
282 BitStream[bitnum++]=77;
283 errCnt++;
284 }
285 if(bitnum>250) break;
286 }
287 *size=bitnum;
288 return errCnt;
289 }
290
291 //by marshmellow
292 //takes 2 arguments - clock and invert both as integers
293 //attempts to demodulate ask only
294 //prints binary found and saves in graphbuffer for further commands
295 int askrawdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert)
296 {
297 uint32_t i;
298 // int invert=0; //invert default
299 int clk2 = *clk;
300 *clk=DetectASKClock(BinStream, *size, *clk); //clock default
301 //uint8_t BitStream[502] = {0};
302
303 //HACK: if clock not detected correctly - default
304 if (clk2==0 && *clk<8) *clk =64;
305 if (clk2==0 && *clk<32 && clk2==0) *clk=32;
306 if (*invert != 0 && *invert != 1) *invert =0;
307 uint32_t initLoopMax = 200;
308 if (initLoopMax > *size) initLoopMax=*size;
309 // Detect high and lows
310 //25% fuzz in case highs and lows aren't clipped [marshmellow]
311 int high, low, ans;
312 ans = getHiLo(BinStream, initLoopMax, &high, &low, 75, 75);
313 if (ans<1) return -2; //just noise
314
315 //PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
316 int lastBit = 0; //set first clock check
317 uint32_t bitnum = 0; //output counter
318 uint8_t tol = 0; //clock tolerance adjust - waves will be accepted as within the clock
319 // if they fall + or - this value + clock from last valid wave
320 if (*clk == 32) tol=1; //clock tolerance may not be needed anymore currently set to
321 // + or - 1 but could be increased for poor waves or removed entirely
322 uint32_t iii = 0;
323 uint32_t gLen = *size;
324 if (gLen > 500) gLen=500;
325 uint8_t errCnt =0;
326 uint32_t bestStart = *size;
327 uint32_t bestErrCnt = (*size/1000);
328 uint32_t maxErr = bestErrCnt;
329 uint8_t midBit=0;
330 //PrintAndLog("DEBUG - lastbit - %d",lastBit);
331 //loop to find first wave that works
332 for (iii=0; iii < gLen; ++iii){
333 if ((BinStream[iii]>=high) || (BinStream[iii]<=low)){
334 lastBit=iii-*clk;
335 //loop through to see if this start location works
336 for (i = iii; i < *size; ++i) {
337 if ((BinStream[i] >= high) && ((i-lastBit)>(*clk-tol))){
338 lastBit+=*clk;
339 midBit=0;
340 } else if ((BinStream[i] <= low) && ((i-lastBit)>(*clk-tol))){
341 //low found and we are expecting a bar
342 lastBit+=*clk;
343 midBit=0;
344 } else if ((BinStream[i]<=low) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
345 //mid bar?
346 midBit=1;
347 } else if ((BinStream[i]>=high) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
348 //mid bar?
349 midBit=1;
350 } else if ((i-lastBit)>((*clk/2)+tol) && (midBit==0)){
351 //no mid bar found
352 midBit=1;
353 } else {
354 //mid value found or no bar supposed to be here
355
356 if ((i-lastBit)>(*clk+tol)){
357 //should have hit a high or low based on clock!!
358 //debug
359 //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);
360
361 errCnt++;
362 lastBit+=*clk;//skip over until hit too many errors
363 if (errCnt > ((*size/1000))){ //allow 1 error for every 1000 samples else start over
364 errCnt=0;
365 break;
366 }
367 }
368 }
369 if ((i-iii)>(500 * *clk)) break; //got enough bits
370 }
371 //we got more than 64 good bits and not all errors
372 if ((((i-iii)/ *clk) > (64+errCnt)) && (errCnt<(*size/1000))) {
373 //possible good read
374 if (errCnt==0){
375 bestStart=iii;
376 bestErrCnt=errCnt;
377 break; //great read - finish
378 }
379 if (errCnt<bestErrCnt){ //set this as new best run
380 bestErrCnt=errCnt;
381 bestStart = iii;
382 }
383 }
384 }
385 }
386 if (bestErrCnt<maxErr){
387 //best run is good enough - set to best run and overwrite BinStream
388 iii=bestStart;
389 lastBit = bestStart - *clk;
390 bitnum=0;
391 for (i = iii; i < *size; ++i) {
392 if ((BinStream[i] >= high) && ((i-lastBit) > (*clk-tol))){
393 lastBit += *clk;
394 BinStream[bitnum] = *invert;
395 bitnum++;
396 midBit=0;
397 } else if ((BinStream[i] <= low) && ((i-lastBit) > (*clk-tol))){
398 //low found and we are expecting a bar
399 lastBit+=*clk;
400 BinStream[bitnum] = 1-*invert;
401 bitnum++;
402 midBit=0;
403 } else if ((BinStream[i]<=low) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
404 //mid bar?
405 midBit=1;
406 BinStream[bitnum] = 1 - *invert;
407 bitnum++;
408 } else if ((BinStream[i]>=high) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){
409 //mid bar?
410 midBit=1;
411 BinStream[bitnum] = *invert;
412 bitnum++;
413 } else if ((i-lastBit)>((*clk/2)+tol) && (midBit==0)){
414 //no mid bar found
415 midBit=1;
416 if (bitnum!=0) BinStream[bitnum] = BinStream[bitnum-1];
417 bitnum++;
418
419 } else {
420 //mid value found or no bar supposed to be here
421 if ((i-lastBit)>(*clk+tol)){
422 //should have hit a high or low based on clock!!
423
424 //debug
425 //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);
426 if (bitnum > 0){
427 BinStream[bitnum]=77;
428 bitnum++;
429 }
430
431 lastBit+=*clk;//skip over error
432 }
433 }
434 if (bitnum >=400) break;
435 }
436 *size=bitnum;
437 } else{
438 *invert=bestStart;
439 *clk=iii;
440 return -1;
441 }
442 return bestErrCnt;
443 }
444 //translate wave to 11111100000 (1 for each short wave 0 for each long wave)
445 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
446 {
447 uint32_t last_transition = 0;
448 uint32_t idx = 1;
449 //uint32_t maxVal=0;
450 if (fchigh==0) fchigh=10;
451 if (fclow==0) fclow=8;
452 //set the threshold close to 0 (graph) or 128 std to avoid static
453 uint8_t threshold_value = 123;
454
455 // sync to first lo-hi transition, and threshold
456
457 // Need to threshold first sample
458
459 if(dest[0] < threshold_value) dest[0] = 0;
460 else dest[0] = 1;
461
462 size_t numBits = 0;
463 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
464 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
465 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
466 for(idx = 1; idx < size; idx++) {
467 // threshold current value
468
469 if (dest[idx] < threshold_value) dest[idx] = 0;
470 else dest[idx] = 1;
471
472 // Check for 0->1 transition
473 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
474 if ((idx-last_transition)<(fclow-2)){ //0-5 = garbage noise
475 //do nothing with extra garbage
476 } else if ((idx-last_transition) < (fchigh-1)) { //6-8 = 8 waves
477 dest[numBits]=1;
478 } else { //9+ = 10 waves
479 dest[numBits]=0;
480 }
481 last_transition = idx;
482 numBits++;
483 }
484 }
485 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
486 }
487
488 uint32_t myround2(float f)
489 {
490 if (f >= 2000) return 2000;//something bad happened
491 return (uint32_t) (f + (float)0.5);
492 }
493
494 //translate 11111100000 to 10
495 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t maxConsequtiveBits,
496 uint8_t invert, uint8_t fchigh, uint8_t fclow)
497 {
498 uint8_t lastval=dest[0];
499 uint32_t idx=0;
500 size_t numBits=0;
501 uint32_t n=1;
502
503 for( idx=1; idx < size; idx++) {
504
505 if (dest[idx]==lastval) {
506 n++;
507 continue;
508 }
509 //if lastval was 1, we have a 1->0 crossing
510 if ( dest[idx-1]==1 ) {
511 n=myround2((float)(n+1)/((float)(rfLen)/(float)fclow));
512 } else {// 0->1 crossing
513 n=myround2((float)(n+1)/((float)(rfLen-1)/(float)fchigh)); //-1 for fudge factor
514 }
515 if (n == 0) n = 1;
516
517 if(n < maxConsequtiveBits) //Consecutive
518 {
519 if(invert==0){ //invert bits
520 memset(dest+numBits, dest[idx-1] , n);
521 }else{
522 memset(dest+numBits, dest[idx-1]^1 , n);
523 }
524 numBits += n;
525 }
526 n=0;
527 lastval=dest[idx];
528 }//end for
529 return numBits;
530 }
531 //by marshmellow (from holiman's base)
532 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
533 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
534 {
535 // FSK demodulator
536 size = fsk_wave_demod(dest, size, fchigh, fclow);
537 size = aggregate_bits(dest, size, rfLen, 192, invert, fchigh, fclow);
538 return size;
539 }
540 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
541 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
542 {
543
544 size_t idx=0, size2=*size, startIdx=0;
545 // FSK demodulator
546
547 *size = fskdemod(dest, size2,50,0,10,8);
548
549 // final loop, go over previously decoded manchester data and decode into usable tag ID
550 // 111000 bit pattern represent start of frame, 01 pattern represents a 1 and 10 represents a 0
551 uint8_t frame_marker_mask[] = {1,1,1,0,0,0};
552 int numshifts = 0;
553 idx = 0;
554 //one scan
555 while( idx + sizeof(frame_marker_mask) < *size) {
556 // search for a start of frame marker
557 if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
558 { // frame marker found
559 startIdx=idx;
560 idx+=sizeof(frame_marker_mask);
561 while(dest[idx] != dest[idx+1] && idx < *size-2)
562 {
563 // Keep going until next frame marker (or error)
564 // Shift in a bit. Start by shifting high registers
565 *hi2 = (*hi2<<1)|(*hi>>31);
566 *hi = (*hi<<1)|(*lo>>31);
567 //Then, shift in a 0 or one into low
568 if (dest[idx] && !dest[idx+1]) // 1 0
569 *lo=(*lo<<1)|0;
570 else // 0 1
571 *lo=(*lo<<1)|1;
572 numshifts++;
573 idx += 2;
574 }
575 // Hopefully, we read a tag and hit upon the next frame marker
576 if(idx + sizeof(frame_marker_mask) < *size)
577 {
578 if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
579 {
580 //good return
581 *size=idx-startIdx;
582 return startIdx;
583 }
584 }
585 // reset
586 *hi2 = *hi = *lo = 0;
587 numshifts = 0;
588 }else {
589 idx++;
590 }
591 }
592 return -1;
593 }
594
595 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
596 size_t ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
597 {
598
599 size_t idx=0, size2=*size;
600 // FSK demodulator
601
602 *size = fskdemod(dest, size2,50,1,10,8);
603
604 // final loop, go over previously decoded manchester data and decode into usable tag ID
605 // 00001111 bit pattern represent start of frame, 01 pattern represents a 1 and 10 represents a 0
606 uint8_t frame_marker_mask[] = {0,0,0,0,1,1,1,1};
607 uint16_t numshifts = 0;
608 idx = 0;
609 //one scan
610 while( idx + sizeof(frame_marker_mask) < *size) {
611 // search for a start of frame marker
612 if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
613 { // frame marker found
614 size2=idx;
615 idx+=sizeof(frame_marker_mask);
616 while(dest[idx] != dest[idx+1] && idx < *size-2)
617 {
618 // Keep going until next frame marker (or error)
619 // Shift in a bit. Start by shifting high registers
620 *hi2 = (*hi2<<1)|(*hi>>31);
621 *hi = (*hi<<1)|(*lo>>31);
622 //Then, shift in a 0 or one into low
623 if (dest[idx] && !dest[idx+1]) // 1 0
624 *lo=(*lo<<1)|1;
625 else // 0 1
626 *lo=(*lo<<1)|0;
627 numshifts++;
628 idx += 2;
629 }
630 // Hopefully, we read a tag and hit upon the next frame marker and got enough bits
631 if(idx + sizeof(frame_marker_mask) < *size && numshifts > 40)
632 {
633 if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
634 {
635 //good return - return start grid position and bits found
636 *size = ((numshifts*2)+8);
637 return size2;
638 }
639 }
640 // reset
641 *hi2 = *hi = *lo = 0;
642 numshifts = 0;
643 }else {
644 idx++;
645 }
646 }
647 return 0;
648 }
649
650 uint32_t bytebits_to_byte(uint8_t* src, size_t numbits)
651 {
652 uint32_t num = 0;
653 for(int i = 0 ; i < numbits ; i++)
654 {
655 num = (num << 1) | (*src);
656 src++;
657 }
658 return num;
659 }
660
661 int IOdemodFSK(uint8_t *dest, size_t size)
662 {
663 static const uint8_t THRESHOLD = 129;
664 uint32_t idx=0;
665 //make sure buffer has data
666 if (size < 66) return -1;
667 //test samples are not just noise
668 uint8_t justNoise = 1;
669 for(idx=0;idx< size && justNoise ;idx++){
670 justNoise = dest[idx] < THRESHOLD;
671 }
672 if(justNoise) return 0;
673
674 // FSK demodulator
675 size = fskdemod(dest, size, 64, 1, 10, 8); // RF/64 and invert
676 if (size < 65) return -1; //did we get a good demod?
677 //Index map
678 //0 10 20 30 40 50 60
679 //| | | | | | |
680 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
681 //-----------------------------------------------------------------------------
682 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
683 //
684 //XSF(version)facility:codeone+codetwo
685 //Handle the data
686 uint8_t mask[] = {0,0,0,0,0,0,0,0,0,1};
687 for( idx=0; idx < (size - 65); idx++) {
688 if ( memcmp(dest + idx, mask, sizeof(mask))==0) {
689 //frame marker found
690 if (!dest[idx+8] && dest[idx+17]==1 && dest[idx+26]==1 && dest[idx+35]==1 && dest[idx+44]==1 && dest[idx+53]==1){
691 //confirmed proper separator bits found
692 //return start position
693 return (int) idx;
694 }
695 }
696 }
697 return 0;
698 }
699
700 // by marshmellow
701 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
702 // returns 1 if passed
703 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
704 {
705 uint8_t ans = 0;
706 for (uint8_t i = 0; i < bitLen; i++){
707 ans ^= ((bits >> i) & 1);
708 }
709 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
710 return (ans == pType);
711 }
712
713 // by marshmellow
714 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
715 // Parity Type (1 for odd 0 for even), and binary Length (length to run)
716 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
717 {
718 uint32_t parityWd = 0;
719 size_t j = 0, bitCnt = 0;
720 for (int word = 0; word < (bLen); word+=pLen){
721 for (int bit=0; bit < pLen; bit++){
722 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
723 BitStream[j++] = (BitStream[startIdx+word+bit]);
724 }
725 j--;
726 // if parity fails then return 0
727 if (parityTest(parityWd, pLen, pType) == 0) return -1;
728 bitCnt+=(pLen-1);
729 parityWd = 0;
730 }
731 // if we got here then all the parities passed
732 //return ID start index and size
733 return bitCnt;
734 }
735
736 // by marshmellow
737 // FSK Demod then try to locate an AWID ID
738 int AWIDdemodFSK(uint8_t *dest, size_t size)
739 {
740 static const uint8_t THRESHOLD = 123;
741 uint32_t idx=0, idx2=0;
742 //make sure buffer has data
743 if (size < 96*50) return -1;
744 //test samples are not just noise
745 uint8_t justNoise = 1;
746 for(idx=0; idx < size && justNoise ;idx++){
747 justNoise = dest[idx] < THRESHOLD;
748 }
749 if(justNoise) return -2;
750
751 // FSK demodulator
752 size = fskdemod(dest, size, 50, 1, 10, 8); // RF/64 and invert
753 if (size < 96) return -3; //did we get a good demod?
754
755 uint8_t mask[] = {0,0,0,0,0,0,0,1};
756 for( idx=0; idx < (size - 96); idx++) {
757 if ( memcmp(dest + idx, mask, sizeof(mask))==0) {
758 // frame marker found
759 //return ID start index
760 if (idx2 == 0) idx2=idx;
761 else if(idx-idx2==96) return idx2;
762 else return -5;
763
764 // should always get 96 bits if it is awid
765 }
766 }
767 //never found mask
768 return -4;
769 }
770
771 // by marshmellow
772 // FSK Demod then try to locate an Farpointe Data (pyramid) ID
773 int PyramiddemodFSK(uint8_t *dest, size_t size)
774 {
775 static const uint8_t THRESHOLD = 123;
776 uint32_t idx=0, idx2=0;
777 // size_t size2 = size;
778 //make sure buffer has data
779 if (size < 128*50) return -5;
780 //test samples are not just noise
781 uint8_t justNoise = 1;
782 for(idx=0; idx < size && justNoise ;idx++){
783 justNoise = dest[idx] < THRESHOLD;
784 }
785 if(justNoise) return -1;
786
787 // FSK demodulator
788 size = fskdemod(dest, size, 50, 1, 10, 8); // RF/64 and invert
789 if (size < 128) return -2; //did we get a good demod?
790
791 uint8_t mask[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
792 for( idx=0; idx < (size - 128); idx++) {
793 if ( memcmp(dest + idx, mask, sizeof(mask))==0) {
794 // frame marker found
795 if (idx2==0) idx2=idx;
796 else if (idx-idx2==128) return idx2;
797 else return -3;
798 }
799 }
800 //never found mask
801 return -4;
802 }
803
804 // by marshmellow
805 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
806 // maybe somehow adjust peak trimming value based on samples to fix?
807 int DetectASKClock(uint8_t dest[], size_t size, int clock)
808 {
809 int i=0;
810 int clk[]={8,16,32,40,50,64,100,128,256};
811 int loopCnt = 256; //don't need to loop through entire array...
812 if (size<loopCnt) loopCnt = size;
813
814 //if we already have a valid clock quit
815
816 for (;i<8;++i)
817 if (clk[i] == clock) return clock;
818
819 //get high and low peak
820 int peak, low;
821 getHiLo(dest, loopCnt, &peak, &low, 75, 75);
822
823 int ii;
824 int clkCnt;
825 int tol = 0;
826 int bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
827 int errCnt=0;
828 //test each valid clock from smallest to greatest to see which lines up
829 for(clkCnt=0; clkCnt < 8; ++clkCnt){
830 if (clk[clkCnt] == 32){
831 tol=1;
832 }else{
833 tol=0;
834 }
835 bestErr[clkCnt]=1000;
836 //try lining up the peaks by moving starting point (try first 256)
837 for (ii=0; ii < loopCnt; ++ii){
838 if ((dest[ii] >= peak) || (dest[ii] <= low)){
839 errCnt=0;
840 // now that we have the first one lined up test rest of wave array
841 for (i=0; i<((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
842 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
843 }else if(dest[ii+(i*clk[clkCnt])-tol]>=peak || dest[ii+(i*clk[clkCnt])-tol]<=low){
844 }else if(dest[ii+(i*clk[clkCnt])+tol]>=peak || dest[ii+(i*clk[clkCnt])+tol]<=low){
845 }else{ //error no peak detected
846 errCnt++;
847 }
848 }
849 //if we found no errors then we can stop here
850 // this is correct one - return this clock
851 //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
852 if(errCnt==0 && clkCnt<6) return clk[clkCnt];
853 //if we found errors see if it is lowest so far and save it as best run
854 if(errCnt<bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
855 }
856 }
857 }
858 uint8_t iii=0;
859 uint8_t best=0;
860 for (iii=0; iii<8; ++iii){
861 if (bestErr[iii]<bestErr[best]){
862 if (bestErr[iii]==0) bestErr[iii]=1;
863 // current best bit to error ratio vs new bit to error ratio
864 if (((size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii]) ){
865 best = iii;
866 }
867 }
868 }
869 return clk[best];
870 }
871
872 //by marshmellow
873 //detect psk clock by reading #peaks vs no peaks(or errors)
874 int DetectpskNRZClock(uint8_t dest[], size_t size, int clock)
875 {
876 int i=0;
877 int clk[]={16,32,40,50,64,100,128,256};
878 int loopCnt = 2048; //don't need to loop through entire array...
879 if (size<loopCnt) loopCnt = size;
880
881 //if we already have a valid clock quit
882 for (; i < 7; ++i)
883 if (clk[i] == clock) return clock;
884
885 //get high and low peak
886 int peak, low;
887 getHiLo(dest, loopCnt, &peak, &low, 75, 75);
888
889 //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
890 int ii;
891 uint8_t clkCnt;
892 uint8_t tol = 0;
893 int peakcnt=0;
894 int errCnt=0;
895 int bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000};
896 int peaksdet[]={0,0,0,0,0,0,0,0};
897 //test each valid clock from smallest to greatest to see which lines up
898 for(clkCnt=0; clkCnt < 7; ++clkCnt){
899 if (clk[clkCnt] <= 32){
900 tol=1;
901 }else{
902 tol=0;
903 }
904 //try lining up the peaks by moving starting point (try first 256)
905 for (ii=0; ii< loopCnt; ++ii){
906 if ((dest[ii] >= peak) || (dest[ii] <= low)){
907 errCnt=0;
908 peakcnt=0;
909 // now that we have the first one lined up test rest of wave array
910 for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
911 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
912 peakcnt++;
913 }else if(dest[ii+(i*clk[clkCnt])-tol]>=peak || dest[ii+(i*clk[clkCnt])-tol]<=low){
914 peakcnt++;
915 }else if(dest[ii+(i*clk[clkCnt])+tol]>=peak || dest[ii+(i*clk[clkCnt])+tol]<=low){
916 peakcnt++;
917 }else{ //error no peak detected
918 errCnt++;
919 }
920 }
921 if(peakcnt>peaksdet[clkCnt]) {
922 peaksdet[clkCnt]=peakcnt;
923 bestErr[clkCnt]=errCnt;
924 }
925 }
926 }
927 }
928 int iii=0;
929 int best=0;
930 //int ratio2; //debug
931 int ratio;
932 //int bits;
933 for (iii=0; iii < 7; ++iii){
934 ratio=1000;
935 //ratio2=1000; //debug
936 //bits=size/clk[iii]; //debug
937 if (peaksdet[iii] > 0){
938 ratio=bestErr[iii]/peaksdet[iii];
939 if (((bestErr[best]/peaksdet[best]) > (ratio)+1)){
940 best = iii;
941 }
942 //ratio2=bits/peaksdet[iii]; //debug
943 }
944 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d, ratio: %d, bits: %d, peakbitr: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best],ratio, bits,ratio2);
945 }
946 return clk[best];
947 }
948
949 // by marshmellow (attempt to get rid of high immediately after a low)
950 void pskCleanWave(uint8_t *BitStream, size_t size)
951 {
952 int i;
953 int gap = 4;
954 int newLow=0;
955 int newHigh=0;
956 int high, low;
957 getHiLo(BitStream, size, &high, &low, 80, 90);
958
959 for (i=0; i < size; ++i){
960 if (newLow == 1){
961 if (BitStream[i]>low){
962 BitStream[i]=low+8;
963 gap--;
964 }
965 if (gap == 0){
966 newLow=0;
967 gap=4;
968 }
969 }else if (newHigh == 1){
970 if (BitStream[i]<high){
971 BitStream[i]=high-8;
972 gap--;
973 }
974 if (gap == 0){
975 newHigh=0;
976 gap=4;
977 }
978 }
979 if (BitStream[i] <= low) newLow=1;
980 if (BitStream[i] >= high) newHigh=1;
981 }
982 return;
983 }
984
985 // by marshmellow
986 // convert psk1 demod to psk2 demod
987 // only transition waves are 1s
988 void psk1TOpsk2(uint8_t *BitStream, size_t size)
989 {
990 size_t i=1;
991 uint8_t lastBit=BitStream[0];
992 for (; i<size; i++){
993 if (lastBit!=BitStream[i]){
994 lastBit=BitStream[i];
995 BitStream[i]=1;
996 } else {
997 BitStream[i]=0;
998 }
999 }
1000 return;
1001 }
1002
1003 // redesigned by marshmellow adjusted from existing decode functions
1004 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1005 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1006 {
1007 //26 bit 40134 format (don't know other formats)
1008 int i;
1009 int long_wait=29;//29 leading zeros in format
1010 int start;
1011 int first = 0;
1012 int first2 = 0;
1013 int bitCnt = 0;
1014 int ii;
1015 // Finding the start of a UID
1016 for (start = 0; start <= *size - 250; start++) {
1017 first = bitStream[start];
1018 for (i = start; i < start + long_wait; i++) {
1019 if (bitStream[i] != first) {
1020 break;
1021 }
1022 }
1023 if (i == (start + long_wait)) {
1024 break;
1025 }
1026 }
1027 if (start == *size - 250 + 1) {
1028 // did not find start sequence
1029 return -1;
1030 }
1031 // Inverting signal if needed
1032 if (first == 1) {
1033 for (i = start; i < *size; i++) {
1034 bitStream[i] = !bitStream[i];
1035 }
1036 *invert = 1;
1037 }else *invert=0;
1038
1039 int iii;
1040 //found start once now test length by finding next one
1041 for (ii=start+29; ii <= *size - 250; ii++) {
1042 first2 = bitStream[ii];
1043 for (iii = ii; iii < ii + long_wait; iii++) {
1044 if (bitStream[iii] != first2) {
1045 break;
1046 }
1047 }
1048 if (iii == (ii + long_wait)) {
1049 break;
1050 }
1051 }
1052 if (ii== *size - 250 + 1){
1053 // did not find second start sequence
1054 return -2;
1055 }
1056 bitCnt=ii-start;
1057
1058 // Dumping UID
1059 i = start;
1060 for (ii = 0; ii < bitCnt; ii++) {
1061 bitStream[ii] = bitStream[i++];
1062 }
1063 *size=bitCnt;
1064 return 1;
1065 }
1066
1067 // by marshmellow - demodulate PSK1 wave or NRZ wave (both similar enough)
1068 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1069 int pskNRZrawDemod(uint8_t *dest, size_t *size, int *clk, int *invert)
1070 {
1071 pskCleanWave(dest,*size);
1072 int clk2 = DetectpskNRZClock(dest, *size, *clk);
1073 *clk=clk2;
1074 uint32_t i;
1075 int high, low, ans;
1076 ans = getHiLo(dest, 1260, &high, &low, 75, 80); //25% fuzz on high 20% fuzz on low
1077 if (ans<1) return -2; //just noise
1078 uint32_t gLen = *size;
1079 //PrintAndLog("DEBUG - valid high: %d - valid low: %d",high,low);
1080 int lastBit = 0; //set first clock check
1081 uint32_t bitnum = 0; //output counter
1082 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
1083 if (*clk==32) tol = 2; //clock tolerance may not be needed anymore currently set to + or - 1 but could be increased for poor waves or removed entirely
1084 uint32_t iii = 0;
1085 uint8_t errCnt =0;
1086 uint32_t bestStart = *size;
1087 uint32_t maxErr = (*size/1000);
1088 uint32_t bestErrCnt = maxErr;
1089 uint8_t curBit=0;
1090 uint8_t bitHigh=0;
1091 uint8_t ignorewin=*clk/8;
1092 //PrintAndLog("DEBUG - lastbit - %d",lastBit);
1093 //loop to find first wave that works - align to clock
1094 for (iii=0; iii < gLen; ++iii){
1095 if ((dest[iii]>=high) || (dest[iii]<=low)){
1096 lastBit=iii-*clk;
1097 //loop through to see if this start location works
1098 for (i = iii; i < *size; ++i) {
1099 //if we found a high bar and we are at a clock bit
1100 if ((dest[i]>=high ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1101 bitHigh=1;
1102 lastBit+=*clk;
1103 ignorewin=*clk/8;
1104 bitnum++;
1105 //else if low bar found and we are at a clock point
1106 }else if ((dest[i]<=low ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1107 bitHigh=1;
1108 lastBit+=*clk;
1109 ignorewin=*clk/8;
1110 bitnum++;
1111 //else if no bars found
1112 }else if(dest[i] < high && dest[i] > low) {
1113 if (ignorewin==0){
1114 bitHigh=0;
1115 }else ignorewin--;
1116 //if we are past a clock point
1117 if (i >= lastBit+*clk+tol){ //clock val
1118 lastBit+=*clk;
1119 bitnum++;
1120 }
1121 //else if bar found but we are not at a clock bit and we did not just have a clock bit
1122 }else if ((dest[i]>=high || dest[i]<=low) && (i<lastBit+*clk-tol || i>lastBit+*clk+tol) && (bitHigh==0)){
1123 //error bar found no clock...
1124 errCnt++;
1125 }
1126 if (bitnum>=1000) break;
1127 }
1128 //we got more than 64 good bits and not all errors
1129 if ((bitnum > (64+errCnt)) && (errCnt < (maxErr))) {
1130 //possible good read
1131 if (errCnt == 0){
1132 bestStart = iii;
1133 bestErrCnt = errCnt;
1134 break; //great read - finish
1135 }
1136 if (errCnt < bestErrCnt){ //set this as new best run
1137 bestErrCnt = errCnt;
1138 bestStart = iii;
1139 }
1140 }
1141 }
1142 }
1143 if (bestErrCnt < maxErr){
1144 //best run is good enough set to best run and set overwrite BinStream
1145 iii=bestStart;
1146 lastBit=bestStart-*clk;
1147 bitnum=0;
1148 for (i = iii; i < *size; ++i) {
1149 //if we found a high bar and we are at a clock bit
1150 if ((dest[i] >= high ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1151 bitHigh=1;
1152 lastBit+=*clk;
1153 curBit=1-*invert;
1154 dest[bitnum]=curBit;
1155 ignorewin=*clk/8;
1156 bitnum++;
1157 //else if low bar found and we are at a clock point
1158 }else if ((dest[i]<=low ) && (i>=lastBit+*clk-tol && i<=lastBit+*clk+tol)){
1159 bitHigh=1;
1160 lastBit+=*clk;
1161 curBit=*invert;
1162 dest[bitnum]=curBit;
1163 ignorewin=*clk/8;
1164 bitnum++;
1165 //else if no bars found
1166 }else if(dest[i]<high && dest[i]>low) {
1167 if (ignorewin==0){
1168 bitHigh=0;
1169 }else ignorewin--;
1170 //if we are past a clock point
1171 if (i>=lastBit+*clk+tol){ //clock val
1172 lastBit+=*clk;
1173 dest[bitnum]=curBit;
1174 bitnum++;
1175 }
1176 //else if bar found but we are not at a clock bit and we did not just have a clock bit
1177 }else if ((dest[i]>=high || dest[i]<=low) && ((i<lastBit+*clk-tol) || (i>lastBit+*clk+tol)) && (bitHigh==0)){
1178 //error bar found no clock...
1179 bitHigh=1;
1180 dest[bitnum]=77;
1181 bitnum++;
1182 errCnt++;
1183 }
1184 if (bitnum >=1000) break;
1185 }
1186 *size=bitnum;
1187 } else{
1188 *size=bitnum;
1189 *clk=bestStart;
1190 return -1;
1191 }
1192
1193 if (bitnum>16){
1194 *size=bitnum;
1195 } else return -1;
1196 return errCnt;
1197 }
1198
1199 //by marshmellow
1200 //detects the bit clock for FSK given the high and low Field Clocks
1201 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1202 {
1203 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1204 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1205 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1206 uint8_t rfLensFnd = 0;
1207 uint8_t lastFCcnt=0;
1208 uint32_t fcCounter = 0;
1209 uint16_t rfCounter = 0;
1210 uint8_t firstBitFnd = 0;
1211 size_t i;
1212
1213 uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1214 rfLensFnd=0;
1215 fcCounter=0;
1216 rfCounter=0;
1217 firstBitFnd=0;
1218 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1219 // prime i to first up transition
1220 for (i = 1; i < size-1; i++)
1221 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1222 break;
1223
1224 for (; i < size-1; i++){
1225 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1]){
1226 // new peak
1227 fcCounter++;
1228 rfCounter++;
1229 // if we got less than the small fc + tolerance then set it to the small fc
1230 if (fcCounter < fcLow+fcTol)
1231 fcCounter = fcLow;
1232 else //set it to the large fc
1233 fcCounter = fcHigh;
1234
1235 //look for bit clock (rf/xx)
1236 if ((fcCounter<lastFCcnt || fcCounter>lastFCcnt)){
1237 //not the same size as the last wave - start of new bit sequence
1238
1239 if (firstBitFnd>1){ //skip first wave change - probably not a complete bit
1240 for (int ii=0; ii<15; ii++){
1241 if (rfLens[ii]==rfCounter){
1242 rfCnts[ii]++;
1243 rfCounter=0;
1244 break;
1245 }
1246 }
1247 if (rfCounter>0 && rfLensFnd<15){
1248 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1249 rfCnts[rfLensFnd]++;
1250 rfLens[rfLensFnd++]=rfCounter;
1251 }
1252 } else {
1253 firstBitFnd++;
1254 }
1255 rfCounter=0;
1256 lastFCcnt=fcCounter;
1257 }
1258 fcCounter=0;
1259 } else {
1260 // count sample
1261 fcCounter++;
1262 rfCounter++;
1263 }
1264 }
1265 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1266
1267 for (i=0; i<15; i++){
1268 //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1269 //get highest 2 RF values (might need to get more values to compare or compare all?)
1270 if (rfCnts[i]>rfCnts[rfHighest]){
1271 rfHighest3=rfHighest2;
1272 rfHighest2=rfHighest;
1273 rfHighest=i;
1274 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1275 rfHighest3=rfHighest2;
1276 rfHighest2=i;
1277 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1278 rfHighest3=i;
1279 }
1280 }
1281 // set allowed clock remainder tolerance to be 1 large field clock length+1
1282 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1283 uint8_t tol1 = fcHigh+1;
1284
1285 //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1286
1287 // loop to find the highest clock that has a remainder less than the tolerance
1288 // compare samples counted divided by
1289 int ii=7;
1290 for (; ii>=0; ii--){
1291 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1292 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1293 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1294 break;
1295 }
1296 }
1297 }
1298 }
1299
1300 if (ii<0) return 0; // oops we went too far
1301
1302 return clk[ii];
1303 }
1304
1305 //by marshmellow
1306 //countFC is to detect the field clock lengths.
1307 //counts and returns the 2 most common wave lengths
1308 uint16_t countFC(uint8_t *BitStream, size_t size)
1309 {
1310 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1311 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1312 uint8_t fcLensFnd = 0;
1313 uint8_t lastFCcnt=0;
1314 uint32_t fcCounter = 0;
1315 size_t i;
1316
1317 // prime i to first up transition
1318 for (i = 1; i < size-1; i++)
1319 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1320 break;
1321
1322 for (; i < size-1; i++){
1323 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1324 // new up transition
1325 fcCounter++;
1326
1327 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1328 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1329 //if odd and not rc/5 add one (for when we get a fc 9 instead of 10)
1330 if ((fcCounter==9 && fcCounter & 1) || fcCounter==4) fcCounter++;
1331
1332 // save last field clock count (fc/xx)
1333 // find which fcLens to save it to:
1334 for (int ii=0; ii<10; ii++){
1335 if (fcLens[ii]==fcCounter){
1336 fcCnts[ii]++;
1337 fcCounter=0;
1338 break;
1339 }
1340 }
1341 if (fcCounter>0 && fcLensFnd<10){
1342 //add new fc length
1343 fcCnts[fcLensFnd]++;
1344 fcLens[fcLensFnd++]=fcCounter;
1345 }
1346 fcCounter=0;
1347 } else {
1348 // count sample
1349 fcCounter++;
1350 }
1351 }
1352
1353 uint8_t best1=9, best2=9, best3=9;
1354 uint16_t maxCnt1=0;
1355 // go through fclens and find which ones are bigest 2
1356 for (i=0; i<10; i++){
1357 // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);
1358 // get the 3 best FC values
1359 if (fcCnts[i]>maxCnt1) {
1360 best3=best2;
1361 best2=best1;
1362 maxCnt1=fcCnts[i];
1363 best1=i;
1364 } else if(fcCnts[i]>fcCnts[best2]){
1365 best3=best2;
1366 best2=i;
1367 } else if(fcCnts[i]>fcCnts[best3]){
1368 best3=i;
1369 }
1370 }
1371 uint8_t fcH=0, fcL=0;
1372 if (fcLens[best1]>fcLens[best2]){
1373 fcH=fcLens[best1];
1374 fcL=fcLens[best2];
1375 } else{
1376 fcH=fcLens[best2];
1377 fcL=fcLens[best1];
1378 }
1379
1380 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1381
1382 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1383 // PrintAndLog("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
1384
1385 return fcs;
1386 }
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