Add Viking demod,
[proxmark3-svn] / common / lfdemod.c
1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // Low frequency demod/decode commands
9 //-----------------------------------------------------------------------------
10
11 #include <stdlib.h>
12 #include <string.h>
13 #include "lfdemod.h"
14 uint8_t justNoise(uint8_t *BitStream, size_t size)
15 {
16 static const uint8_t THRESHOLD = 123;
17 //test samples are not just noise
18 uint8_t justNoise1 = 1;
19 for(size_t idx=0; idx < size && justNoise1 ;idx++){
20 justNoise1 = BitStream[idx] < THRESHOLD;
21 }
22 return justNoise1;
23 }
24
25 //by marshmellow
26 //get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
27 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
28 {
29 *high=0;
30 *low=255;
31 // get high and low thresholds
32 for (size_t i=0; i < size; i++){
33 if (BitStream[i] > *high) *high = BitStream[i];
34 if (BitStream[i] < *low) *low = BitStream[i];
35 }
36 if (*high < 123) return -1; // just noise
37 *high = ((*high-128)*fuzzHi + 12800)/100;
38 *low = ((*low-128)*fuzzLo + 12800)/100;
39 return 1;
40 }
41
42 // by marshmellow
43 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
44 // returns 1 if passed
45 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
46 {
47 uint8_t ans = 0;
48 for (uint8_t i = 0; i < bitLen; i++){
49 ans ^= ((bits >> i) & 1);
50 }
51 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
52 return (ans == pType);
53 }
54
55 //by marshmellow
56 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
57 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
58 {
59 uint8_t foundCnt=0;
60 for (int idx=0; idx < *size - pLen; idx++){
61 if (memcmp(BitStream+idx, preamble, pLen) == 0){
62 //first index found
63 foundCnt++;
64 if (foundCnt == 1){
65 *startIdx = idx;
66 }
67 if (foundCnt == 2){
68 *size = idx - *startIdx;
69 return 1;
70 }
71 }
72 }
73 return 0;
74 }
75
76 //by marshmellow
77 //takes 1s and 0s and searches for EM410x format - output EM ID
78 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
79 {
80 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
81 // otherwise could be a void with no arguments
82 //set defaults
83 uint32_t i = 0;
84 if (BitStream[1]>1) return 0; //allow only 1s and 0s
85
86 // 111111111 bit pattern represent start of frame
87 // include 0 in front to help get start pos
88 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
89 uint32_t idx = 0;
90 uint32_t parityBits = 0;
91 uint8_t errChk = 0;
92 uint8_t FmtLen = 10;
93 *startIdx = 0;
94 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
95 if (errChk == 0 || *size < 64) return 0;
96 if (*size > 64) FmtLen = 22;
97 *startIdx += 1; //get rid of 0 from preamble
98 idx = *startIdx + 9;
99 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
100 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
101 //check even parity - quit if failed
102 if (parityTest(parityBits, 5, 0) == 0) return 0;
103 //set uint64 with ID from BitStream
104 for (uint8_t ii=0; ii<4; ii++){
105 *hi = (*hi << 1) | (*lo >> 63);
106 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
107 }
108 }
109 if (errChk != 0) return 1;
110 //skip last 5 bit parity test for simplicity.
111 // *size = 64 | 128;
112 return 0;
113 }
114
115 //by marshmellow
116 //demodulates strong heavily clipped samples
117 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
118 {
119 size_t bitCnt=0, smplCnt=0, errCnt=0;
120 uint8_t waveHigh = 0;
121 for (size_t i=0; i < *size; i++){
122 if (BinStream[i] >= high && waveHigh){
123 smplCnt++;
124 } else if (BinStream[i] <= low && !waveHigh){
125 smplCnt++;
126 } else { //transition
127 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
128 if (smplCnt > clk-(clk/4)-1) { //full clock
129 if (smplCnt > clk + (clk/4)+1) { //too many samples
130 errCnt++;
131 BinStream[bitCnt++]=7;
132 } else if (waveHigh) {
133 BinStream[bitCnt++] = invert;
134 BinStream[bitCnt++] = invert;
135 } else if (!waveHigh) {
136 BinStream[bitCnt++] = invert ^ 1;
137 BinStream[bitCnt++] = invert ^ 1;
138 }
139 waveHigh ^= 1;
140 smplCnt = 0;
141 } else if (smplCnt > (clk/2) - (clk/4)-1) {
142 if (waveHigh) {
143 BinStream[bitCnt++] = invert;
144 } else if (!waveHigh) {
145 BinStream[bitCnt++] = invert ^ 1;
146 }
147 waveHigh ^= 1;
148 smplCnt = 0;
149 } else if (!bitCnt) {
150 //first bit
151 waveHigh = (BinStream[i] >= high);
152 smplCnt = 1;
153 } else {
154 smplCnt++;
155 //transition bit oops
156 }
157 } else { //haven't hit new high or new low yet
158 smplCnt++;
159 }
160 }
161 }
162 *size = bitCnt;
163 return errCnt;
164 }
165
166 //by marshmellow
167 void askAmp(uint8_t *BitStream, size_t size)
168 {
169 for(size_t i = 1; i<size; i++){
170 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
171 BitStream[i]=127;
172 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
173 BitStream[i]=-127;
174 }
175 return;
176 }
177
178 //by marshmellow
179 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
180 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
181 {
182 if (*size==0) return -1;
183 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
184 if (*clk==0 || start < 0) return -3;
185 if (*invert != 1) *invert = 0;
186 if (amp==1) askAmp(BinStream, *size);
187
188 uint8_t initLoopMax = 255;
189 if (initLoopMax > *size) initLoopMax = *size;
190 // Detect high and lows
191 //25% clip in case highs and lows aren't clipped [marshmellow]
192 int high, low;
193 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
194 return -2; //just noise
195
196 size_t errCnt = 0;
197 // if clean clipped waves detected run alternate demod
198 if (DetectCleanAskWave(BinStream, *size, high, low)) {
199 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
200 if (askType) //askman
201 return manrawdecode(BinStream, size, 0);
202 else //askraw
203 return errCnt;
204 }
205
206 int lastBit; //set first clock check - can go negative
207 size_t i, bitnum = 0; //output counter
208 uint8_t midBit = 0;
209 uint8_t tol = 0; //clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave
210 if (*clk <= 32) tol = 1; //clock tolerance may not be needed anymore currently set to + or - 1 but could be increased for poor waves or removed entirely
211 size_t MaxBits = 1024;
212 lastBit = start - *clk;
213
214 for (i = start; i < *size; ++i) {
215 if (i-lastBit >= *clk-tol){
216 if (BinStream[i] >= high) {
217 BinStream[bitnum++] = *invert;
218 } else if (BinStream[i] <= low) {
219 BinStream[bitnum++] = *invert ^ 1;
220 } else if (i-lastBit >= *clk+tol) {
221 if (bitnum > 0) {
222 BinStream[bitnum++]=7;
223 errCnt++;
224 }
225 } else { //in tolerance - looking for peak
226 continue;
227 }
228 midBit = 0;
229 lastBit += *clk;
230 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
231 if (BinStream[i] >= high) {
232 BinStream[bitnum++] = *invert;
233 } else if (BinStream[i] <= low) {
234 BinStream[bitnum++] = *invert ^ 1;
235 } else if (i-lastBit >= *clk/2+tol) {
236 BinStream[bitnum] = BinStream[bitnum-1];
237 bitnum++;
238 } else { //in tolerance - looking for peak
239 continue;
240 }
241 midBit = 1;
242 }
243 if (bitnum >= MaxBits) break;
244 }
245 *size = bitnum;
246 return errCnt;
247 }
248
249 //by marshmellow
250 //take 10 and 01 and manchester decode
251 //run through 2 times and take least errCnt
252 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
253 {
254 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
255 size_t i, ii;
256 uint16_t bestErr = 1000, bestRun = 0;
257 if (*size < 16) return -1;
258 //find correct start position [alignment]
259 for (ii=0;ii<2;++ii){
260 for (i=ii; i<*size-3; i+=2)
261 if (BitStream[i]==BitStream[i+1])
262 errCnt++;
263
264 if (bestErr>errCnt){
265 bestErr=errCnt;
266 bestRun=ii;
267 }
268 errCnt=0;
269 }
270 //decode
271 for (i=bestRun; i < *size-3; i+=2){
272 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
273 BitStream[bitnum++]=invert;
274 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
275 BitStream[bitnum++]=invert^1;
276 } else {
277 BitStream[bitnum++]=7;
278 }
279 if(bitnum>MaxBits) break;
280 }
281 *size=bitnum;
282 return bestErr;
283 }
284
285 uint32_t manchesterEncode2Bytes(uint16_t datain) {
286 uint32_t output = 0;
287 uint8_t curBit = 0;
288 for (uint8_t i=0; i<16; i++) {
289 curBit = (datain >> (15-i) & 1);
290 output |= (1<<(((15-i)*2)+curBit));
291 }
292 return output;
293 }
294
295 //by marshmellow
296 //encode binary data into binary manchester
297 int ManchesterEncode(uint8_t *BitStream, size_t size)
298 {
299 size_t modIdx=20000, i=0;
300 if (size>modIdx) return -1;
301 for (size_t idx=0; idx < size; idx++){
302 BitStream[idx+modIdx++] = BitStream[idx];
303 BitStream[idx+modIdx++] = BitStream[idx]^1;
304 }
305 for (; i<(size*2); i++){
306 BitStream[i] = BitStream[i+20000];
307 }
308 return i;
309 }
310
311 //by marshmellow
312 //take 01 or 10 = 1 and 11 or 00 = 0
313 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
314 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
315 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
316 {
317 uint16_t bitnum = 0;
318 uint16_t errCnt = 0;
319 size_t i = offset;
320 uint16_t MaxBits=512;
321 //if not enough samples - error
322 if (*size < 51) return -1;
323 //check for phase change faults - skip one sample if faulty
324 uint8_t offsetA = 1, offsetB = 1;
325 for (; i<48; i+=2){
326 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
327 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
328 }
329 if (!offsetA && offsetB) offset++;
330 for (i=offset; i<*size-3; i+=2){
331 //check for phase error
332 if (BitStream[i+1]==BitStream[i+2]) {
333 BitStream[bitnum++]=7;
334 errCnt++;
335 }
336 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
337 BitStream[bitnum++]=1^invert;
338 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
339 BitStream[bitnum++]=invert;
340 } else {
341 BitStream[bitnum++]=7;
342 errCnt++;
343 }
344 if(bitnum>MaxBits) break;
345 }
346 *size=bitnum;
347 return errCnt;
348 }
349
350 // by marshmellow
351 // demod gProxIIDemod
352 // error returns as -x
353 // success returns start position in BitStream
354 // BitStream must contain previously askrawdemod and biphasedemoded data
355 int gProxII_Demod(uint8_t BitStream[], size_t *size)
356 {
357 size_t startIdx=0;
358 uint8_t preamble[] = {1,1,1,1,1,0};
359
360 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
361 if (errChk == 0) return -3; //preamble not found
362 if (*size != 96) return -2; //should have found 96 bits
363 //check first 6 spacer bits to verify format
364 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
365 //confirmed proper separator bits found
366 //return start position
367 return (int) startIdx;
368 }
369 return -5;
370 }
371
372 //translate wave to 11111100000 (1 for each short wave 0 for each long wave)
373 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
374 {
375 size_t last_transition = 0;
376 size_t idx = 1;
377 //uint32_t maxVal=0;
378 if (fchigh==0) fchigh=10;
379 if (fclow==0) fclow=8;
380 //set the threshold close to 0 (graph) or 128 std to avoid static
381 uint8_t threshold_value = 123;
382 size_t preLastSample = 0;
383 size_t LastSample = 0;
384 size_t currSample = 0;
385 // sync to first lo-hi transition, and threshold
386
387 // Need to threshold first sample
388
389 if(dest[0] < threshold_value) dest[0] = 0;
390 else dest[0] = 1;
391
392 size_t numBits = 0;
393 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
394 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
395 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
396 for(idx = 1; idx < size; idx++) {
397 // threshold current value
398
399 if (dest[idx] < threshold_value) dest[idx] = 0;
400 else dest[idx] = 1;
401
402 // Check for 0->1 transition
403 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
404 preLastSample = LastSample;
405 LastSample = currSample;
406 currSample = idx-last_transition;
407 if (currSample < (fclow-2)){ //0-5 = garbage noise
408 //do nothing with extra garbage
409 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves
410 if (LastSample > (fchigh-2) && preLastSample < (fchigh-1)){
411 dest[numBits-1]=1; //correct last 9 wave surrounded by 8 waves
412 }
413 dest[numBits++]=1;
414
415 } else if (currSample > (fchigh+1) && !numBits) { //12 + and first bit = garbage
416 //do nothing with beginning garbage
417 } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
418 dest[numBits++]=1;
419 } else { //9+ = 10 sample waves
420 dest[numBits++]=0;
421 }
422 last_transition = idx;
423 }
424 }
425 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
426 }
427
428 //translate 11111100000 to 10
429 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
430 uint8_t invert, uint8_t fchigh, uint8_t fclow)
431 {
432 uint8_t lastval=dest[0];
433 size_t idx=0;
434 size_t numBits=0;
435 uint32_t n=1;
436 for( idx=1; idx < size; idx++) {
437 n++;
438 if (dest[idx]==lastval) continue;
439
440 //if lastval was 1, we have a 1->0 crossing
441 if (dest[idx-1]==1) {
442 if (!numBits && n < rfLen/fclow) {
443 n=0;
444 lastval = dest[idx];
445 continue;
446 }
447 n = (n * fclow + rfLen/2) / rfLen;
448 } else {// 0->1 crossing
449 //test first bitsample too small
450 if (!numBits && n < rfLen/fchigh) {
451 n=0;
452 lastval = dest[idx];
453 continue;
454 }
455 n = (n * fchigh + rfLen/2) / rfLen;
456 }
457 if (n == 0) n = 1;
458
459 memset(dest+numBits, dest[idx-1]^invert , n);
460 numBits += n;
461 n=0;
462 lastval=dest[idx];
463 }//end for
464 // if valid extra bits at the end were all the same frequency - add them in
465 if (n > rfLen/fchigh) {
466 if (dest[idx-2]==1) {
467 n = (n * fclow + rfLen/2) / rfLen;
468 } else {
469 n = (n * fchigh + rfLen/2) / rfLen;
470 }
471 memset(dest+numBits, dest[idx-1]^invert , n);
472 numBits += n;
473 }
474 return numBits;
475 }
476 //by marshmellow (from holiman's base)
477 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
478 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
479 {
480 // FSK demodulator
481 size = fsk_wave_demod(dest, size, fchigh, fclow);
482 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
483 return size;
484 }
485
486 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
487 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
488 {
489 if (justNoise(dest, *size)) return -1;
490
491 size_t numStart=0, size2=*size, startIdx=0;
492 // FSK demodulator
493 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
494 if (*size < 96*2) return -2;
495 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
496 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
497 // find bitstring in array
498 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
499 if (errChk == 0) return -3; //preamble not found
500
501 numStart = startIdx + sizeof(preamble);
502 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
503 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
504 if (dest[idx] == dest[idx+1]){
505 return -4; //not manchester data
506 }
507 *hi2 = (*hi2<<1)|(*hi>>31);
508 *hi = (*hi<<1)|(*lo>>31);
509 //Then, shift in a 0 or one into low
510 if (dest[idx] && !dest[idx+1]) // 1 0
511 *lo=(*lo<<1)|1;
512 else // 0 1
513 *lo=(*lo<<1)|0;
514 }
515 return (int)startIdx;
516 }
517
518 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
519 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
520 {
521 if (justNoise(dest, *size)) return -1;
522
523 size_t numStart=0, size2=*size, startIdx=0;
524 // FSK demodulator
525 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
526 if (*size < 96) return -2;
527
528 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
529 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
530
531 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
532 if (errChk == 0) return -3; //preamble not found
533
534 numStart = startIdx + sizeof(preamble);
535 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
536 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
537 if (dest[idx] == dest[idx+1])
538 return -4; //not manchester data
539 *hi2 = (*hi2<<1)|(*hi>>31);
540 *hi = (*hi<<1)|(*lo>>31);
541 //Then, shift in a 0 or one into low
542 if (dest[idx] && !dest[idx+1]) // 1 0
543 *lo=(*lo<<1)|1;
544 else // 0 1
545 *lo=(*lo<<1)|0;
546 }
547 return (int)startIdx;
548 }
549
550 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
551 {
552 uint32_t num = 0;
553 for(int i = 0 ; i < numbits ; i++)
554 {
555 num = (num << 1) | (*src);
556 src++;
557 }
558 return num;
559 }
560
561 //least significant bit first
562 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
563 {
564 uint32_t num = 0;
565 for(int i = 0 ; i < numbits ; i++)
566 {
567 num = (num << 1) | *(src + (numbits-(i+1)));
568 }
569 return num;
570 }
571
572 int IOdemodFSK(uint8_t *dest, size_t size)
573 {
574 if (justNoise(dest, size)) return -1;
575 //make sure buffer has data
576 if (size < 66*64) return -2;
577 // FSK demodulator
578 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
579 if (size < 65) return -3; //did we get a good demod?
580 //Index map
581 //0 10 20 30 40 50 60
582 //| | | | | | |
583 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
584 //-----------------------------------------------------------------------------
585 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
586 //
587 //XSF(version)facility:codeone+codetwo
588 //Handle the data
589 size_t startIdx = 0;
590 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
591 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
592 if (errChk == 0) return -4; //preamble not found
593
594 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
595 //confirmed proper separator bits found
596 //return start position
597 return (int) startIdx;
598 }
599 return -5;
600 }
601
602 // by marshmellow
603 // find viking preamble 0xF200 in already demoded data
604 int VikingDemod_AM(uint8_t *dest, size_t *size) {
605 if (justNoise(dest, *size)) return -1;
606 //make sure buffer has data
607 if (*size < 64*2) return -2;
608
609 size_t startIdx = 0;
610 uint8_t preamble[] = {1,1,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
611 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
612 if (errChk == 0) return -4; //preamble not found
613
614 if (*size != 64) return -5;
615 //return start position
616 return (int) startIdx;
617 }
618
619 // by marshmellow
620 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
621 // Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
622 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
623 {
624 uint32_t parityWd = 0;
625 size_t j = 0, bitCnt = 0;
626 for (int word = 0; word < (bLen); word+=pLen){
627 for (int bit=0; bit < pLen; bit++){
628 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
629 BitStream[j++] = (BitStream[startIdx+word+bit]);
630 }
631 j--; // overwrite parity with next data
632 // if parity fails then return 0
633 if (pType == 2) { // then marker bit which should be a 1
634 if (!BitStream[j]) return 0;
635 } else {
636 if (parityTest(parityWd, pLen, pType) == 0) return 0;
637 }
638 bitCnt+=(pLen-1);
639 parityWd = 0;
640 }
641 // if we got here then all the parities passed
642 //return ID start index and size
643 return bitCnt;
644 }
645
646 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
647 // BitStream must contain previously askrawdemod and biphasedemoded data
648 int FDXBdemodBI(uint8_t *dest, size_t *size)
649 {
650 //make sure buffer has enough data
651 if (*size < 128) return -1;
652
653 size_t startIdx = 0;
654 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
655
656 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
657 if (errChk == 0) return -2; //preamble not found
658 return (int)startIdx;
659 }
660
661 // by marshmellow
662 // FSK Demod then try to locate an AWID ID
663 int AWIDdemodFSK(uint8_t *dest, size_t *size)
664 {
665 //make sure buffer has enough data
666 if (*size < 96*50) return -1;
667
668 if (justNoise(dest, *size)) return -2;
669
670 // FSK demodulator
671 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
672 if (*size < 96) return -3; //did we get a good demod?
673
674 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
675 size_t startIdx = 0;
676 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
677 if (errChk == 0) return -4; //preamble not found
678 if (*size != 96) return -5;
679 return (int)startIdx;
680 }
681
682 // by marshmellow
683 // FSK Demod then try to locate an Farpointe Data (pyramid) ID
684 int PyramiddemodFSK(uint8_t *dest, size_t *size)
685 {
686 //make sure buffer has data
687 if (*size < 128*50) return -5;
688
689 //test samples are not just noise
690 if (justNoise(dest, *size)) return -1;
691
692 // FSK demodulator
693 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
694 if (*size < 128) return -2; //did we get a good demod?
695
696 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
697 size_t startIdx = 0;
698 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
699 if (errChk == 0) return -4; //preamble not found
700 if (*size != 128) return -3;
701 return (int)startIdx;
702 }
703
704 // by marshmellow
705 // to detect a wave that has heavily clipped (clean) samples
706 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
707 {
708 uint16_t allPeaks=1;
709 uint16_t cntPeaks=0;
710 size_t loopEnd = 512+60;
711 if (loopEnd > size) loopEnd = size;
712 for (size_t i=60; i<loopEnd; i++){
713 if (dest[i]>low && dest[i]<high)
714 allPeaks=0;
715 else
716 cntPeaks++;
717 }
718 if (allPeaks == 0){
719 if (cntPeaks > 300) return 1;
720 }
721 return allPeaks;
722 }
723
724 // by marshmellow
725 // to help detect clocks on heavily clipped samples
726 // based on count of low to low
727 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
728 {
729 uint8_t fndClk[] = {8,16,32,40,50,64,128};
730 size_t startwave;
731 size_t i = 0;
732 size_t minClk = 255;
733 // get to first full low to prime loop and skip incomplete first pulse
734 while ((dest[i] < high) && (i < size))
735 ++i;
736 while ((dest[i] > low) && (i < size))
737 ++i;
738
739 // loop through all samples
740 while (i < size) {
741 // measure from low to low
742 while ((dest[i] > low) && (i < size))
743 ++i;
744 startwave= i;
745 while ((dest[i] < high) && (i < size))
746 ++i;
747 while ((dest[i] > low) && (i < size))
748 ++i;
749 //get minimum measured distance
750 if (i-startwave < minClk && i < size)
751 minClk = i - startwave;
752 }
753 // set clock
754 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
755 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
756 return fndClk[clkCnt];
757 }
758 return 0;
759 }
760
761 // by marshmellow
762 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
763 // maybe somehow adjust peak trimming value based on samples to fix?
764 // return start index of best starting position for that clock and return clock (by reference)
765 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
766 {
767 size_t i=1;
768 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
769 uint8_t clkEnd = 9;
770 uint8_t loopCnt = 255; //don't need to loop through entire array...
771 if (size <= loopCnt) return -1; //not enough samples
772
773 //if we already have a valid clock
774 uint8_t clockFnd=0;
775 for (;i<clkEnd;++i)
776 if (clk[i] == *clock) clockFnd = i;
777 //clock found but continue to find best startpos
778
779 //get high and low peak
780 int peak, low;
781 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
782
783 //test for large clean peaks
784 if (!clockFnd){
785 if (DetectCleanAskWave(dest, size, peak, low)==1){
786 int ans = DetectStrongAskClock(dest, size, peak, low);
787 for (i=clkEnd-1; i>0; i--){
788 if (clk[i] == ans) {
789 *clock = ans;
790 //clockFnd = i;
791 return 0; // for strong waves i don't use the 'best start position' yet...
792 //break; //clock found but continue to find best startpos [not yet]
793 }
794 }
795 }
796 }
797
798 uint8_t ii;
799 uint8_t clkCnt, tol = 0;
800 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
801 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
802 size_t errCnt = 0;
803 size_t arrLoc, loopEnd;
804
805 if (clockFnd>0) {
806 clkCnt = clockFnd;
807 clkEnd = clockFnd+1;
808 }
809 else clkCnt=1;
810
811 //test each valid clock from smallest to greatest to see which lines up
812 for(; clkCnt < clkEnd; clkCnt++){
813 if (clk[clkCnt] <= 32){
814 tol=1;
815 }else{
816 tol=0;
817 }
818 //if no errors allowed - keep start within the first clock
819 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
820 bestErr[clkCnt]=1000;
821 //try lining up the peaks by moving starting point (try first few clocks)
822 for (ii=0; ii < loopCnt; ii++){
823 if (dest[ii] < peak && dest[ii] > low) continue;
824
825 errCnt=0;
826 // now that we have the first one lined up test rest of wave array
827 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
828 for (i=0; i < loopEnd; ++i){
829 arrLoc = ii + (i * clk[clkCnt]);
830 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
831 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
832 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
833 }else{ //error no peak detected
834 errCnt++;
835 }
836 }
837 //if we found no errors then we can stop here and a low clock (common clocks)
838 // this is correct one - return this clock
839 //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
840 if(errCnt==0 && clkCnt<7) {
841 if (!clockFnd) *clock = clk[clkCnt];
842 return ii;
843 }
844 //if we found errors see if it is lowest so far and save it as best run
845 if(errCnt<bestErr[clkCnt]){
846 bestErr[clkCnt]=errCnt;
847 bestStart[clkCnt]=ii;
848 }
849 }
850 }
851 uint8_t iii;
852 uint8_t best=0;
853 for (iii=1; iii<clkEnd; ++iii){
854 if (bestErr[iii] < bestErr[best]){
855 if (bestErr[iii] == 0) bestErr[iii]=1;
856 // current best bit to error ratio vs new bit to error ratio
857 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
858 best = iii;
859 }
860 }
861 }
862 //if (bestErr[best] > maxErr) return -1;
863 if (!clockFnd) *clock = clk[best];
864 return bestStart[best];
865 }
866
867 //by marshmellow
868 //detect psk clock by reading each phase shift
869 // a phase shift is determined by measuring the sample length of each wave
870 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
871 {
872 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
873 uint16_t loopCnt = 4096; //don't need to loop through entire array...
874 if (size == 0) return 0;
875 if (size<loopCnt) loopCnt = size;
876
877 //if we already have a valid clock quit
878 size_t i=1;
879 for (; i < 8; ++i)
880 if (clk[i] == clock) return clock;
881
882 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
883 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
884 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
885 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
886 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
887 fc = countFC(dest, size, 0);
888 if (fc!=2 && fc!=4 && fc!=8) return -1;
889 //PrintAndLog("DEBUG: FC: %d",fc);
890
891 //find first full wave
892 for (i=0; i<loopCnt; i++){
893 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
894 if (waveStart == 0) {
895 waveStart = i+1;
896 //PrintAndLog("DEBUG: waveStart: %d",waveStart);
897 } else {
898 waveEnd = i+1;
899 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
900 waveLenCnt = waveEnd-waveStart;
901 if (waveLenCnt > fc){
902 firstFullWave = waveStart;
903 fullWaveLen=waveLenCnt;
904 break;
905 }
906 waveStart=0;
907 }
908 }
909 }
910 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
911
912 //test each valid clock from greatest to smallest to see which lines up
913 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
914 lastClkBit = firstFullWave; //set end of wave as clock align
915 waveStart = 0;
916 errCnt=0;
917 peakcnt=0;
918 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
919
920 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
921 //top edge of wave = start of new wave
922 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
923 if (waveStart == 0) {
924 waveStart = i+1;
925 waveLenCnt=0;
926 } else { //waveEnd
927 waveEnd = i+1;
928 waveLenCnt = waveEnd-waveStart;
929 if (waveLenCnt > fc){
930 //if this wave is a phase shift
931 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
932 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
933 peakcnt++;
934 lastClkBit+=clk[clkCnt];
935 } else if (i<lastClkBit+8){
936 //noise after a phase shift - ignore
937 } else { //phase shift before supposed to based on clock
938 errCnt++;
939 }
940 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
941 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
942 }
943 waveStart=i+1;
944 }
945 }
946 }
947 if (errCnt == 0){
948 return clk[clkCnt];
949 }
950 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
951 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
952 }
953 //all tested with errors
954 //return the highest clk with the most peaks found
955 uint8_t best=7;
956 for (i=7; i>=1; i--){
957 if (peaksdet[i] > peaksdet[best]) {
958 best = i;
959 }
960 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
961 }
962 return clk[best];
963 }
964
965 //by marshmellow
966 //detect nrz clock by reading #peaks vs no peaks(or errors)
967 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
968 {
969 size_t i=0;
970 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
971 size_t loopCnt = 4096; //don't need to loop through entire array...
972 if (size == 0) return 0;
973 if (size<loopCnt) loopCnt = size;
974
975 //if we already have a valid clock quit
976 for (; i < 8; ++i)
977 if (clk[i] == clock) return clock;
978
979 //get high and low peak
980 int peak, low;
981 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
982
983 //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
984 size_t ii;
985 uint8_t clkCnt;
986 uint8_t tol = 0;
987 uint16_t peakcnt=0;
988 uint16_t peaksdet[]={0,0,0,0,0,0,0,0};
989 uint16_t maxPeak=0;
990 //test for large clipped waves
991 for (i=0; i<loopCnt; i++){
992 if (dest[i] >= peak || dest[i] <= low){
993 peakcnt++;
994 } else {
995 if (peakcnt>0 && maxPeak < peakcnt){
996 maxPeak = peakcnt;
997 }
998 peakcnt=0;
999 }
1000 }
1001 peakcnt=0;
1002 //test each valid clock from smallest to greatest to see which lines up
1003 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1004 //ignore clocks smaller than largest peak
1005 if (clk[clkCnt]<maxPeak) continue;
1006
1007 //try lining up the peaks by moving starting point (try first 256)
1008 for (ii=0; ii< loopCnt; ++ii){
1009 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1010 peakcnt=0;
1011 // now that we have the first one lined up test rest of wave array
1012 for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
1013 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
1014 peakcnt++;
1015 }
1016 }
1017 if(peakcnt>peaksdet[clkCnt]) {
1018 peaksdet[clkCnt]=peakcnt;
1019 }
1020 }
1021 }
1022 }
1023 int iii=7;
1024 uint8_t best=0;
1025 for (iii=7; iii > 0; iii--){
1026 if (peaksdet[iii] > peaksdet[best]){
1027 best = iii;
1028 }
1029 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
1030 }
1031 return clk[best];
1032 }
1033
1034 // by marshmellow
1035 // convert psk1 demod to psk2 demod
1036 // only transition waves are 1s
1037 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1038 {
1039 size_t i=1;
1040 uint8_t lastBit=BitStream[0];
1041 for (; i<size; i++){
1042 if (BitStream[i]==7){
1043 //ignore errors
1044 } else if (lastBit!=BitStream[i]){
1045 lastBit=BitStream[i];
1046 BitStream[i]=1;
1047 } else {
1048 BitStream[i]=0;
1049 }
1050 }
1051 return;
1052 }
1053
1054 // by marshmellow
1055 // convert psk2 demod to psk1 demod
1056 // from only transition waves are 1s to phase shifts change bit
1057 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1058 {
1059 uint8_t phase=0;
1060 for (size_t i=0; i<size; i++){
1061 if (BitStream[i]==1){
1062 phase ^=1;
1063 }
1064 BitStream[i]=phase;
1065 }
1066 return;
1067 }
1068
1069 // redesigned by marshmellow adjusted from existing decode functions
1070 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1071 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1072 {
1073 //26 bit 40134 format (don't know other formats)
1074 int i;
1075 int long_wait=29;//29 leading zeros in format
1076 int start;
1077 int first = 0;
1078 int first2 = 0;
1079 int bitCnt = 0;
1080 int ii;
1081 // Finding the start of a UID
1082 for (start = 0; start <= *size - 250; start++) {
1083 first = bitStream[start];
1084 for (i = start; i < start + long_wait; i++) {
1085 if (bitStream[i] != first) {
1086 break;
1087 }
1088 }
1089 if (i == (start + long_wait)) {
1090 break;
1091 }
1092 }
1093 if (start == *size - 250 + 1) {
1094 // did not find start sequence
1095 return -1;
1096 }
1097 // Inverting signal if needed
1098 if (first == 1) {
1099 for (i = start; i < *size; i++) {
1100 bitStream[i] = !bitStream[i];
1101 }
1102 *invert = 1;
1103 }else *invert=0;
1104
1105 int iii;
1106 //found start once now test length by finding next one
1107 for (ii=start+29; ii <= *size - 250; ii++) {
1108 first2 = bitStream[ii];
1109 for (iii = ii; iii < ii + long_wait; iii++) {
1110 if (bitStream[iii] != first2) {
1111 break;
1112 }
1113 }
1114 if (iii == (ii + long_wait)) {
1115 break;
1116 }
1117 }
1118 if (ii== *size - 250 + 1){
1119 // did not find second start sequence
1120 return -2;
1121 }
1122 bitCnt=ii-start;
1123
1124 // Dumping UID
1125 i = start;
1126 for (ii = 0; ii < bitCnt; ii++) {
1127 bitStream[ii] = bitStream[i++];
1128 }
1129 *size=bitCnt;
1130 return 1;
1131 }
1132
1133 // by marshmellow - demodulate NRZ wave (both similar enough)
1134 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1135 // there probably is a much simpler way to do this....
1136 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert, int maxErr)
1137 {
1138 if (justNoise(dest, *size)) return -1;
1139 *clk = DetectNRZClock(dest, *size, *clk);
1140 if (*clk==0) return -2;
1141 size_t i, gLen = 4096;
1142 if (gLen>*size) gLen = *size;
1143 int high, low;
1144 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1145 int lastBit = 0; //set first clock check
1146 size_t iii = 0, bitnum = 0; //bitnum counter
1147 uint16_t errCnt = 0, MaxBits = 1000;
1148 size_t bestErrCnt = maxErr+1;
1149 size_t bestPeakCnt = 0, bestPeakStart = 0;
1150 uint8_t bestFirstPeakHigh=0, firstPeakHigh=0, curBit=0, bitHigh=0, errBitHigh=0;
1151 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
1152 uint16_t peakCnt=0;
1153 uint8_t ignoreWindow=4;
1154 uint8_t ignoreCnt=ignoreWindow; //in case of noise near peak
1155 //loop to find first wave that works - align to clock
1156 for (iii=0; iii < gLen; ++iii){
1157 if ((dest[iii]>=high) || (dest[iii]<=low)){
1158 if (dest[iii]>=high) firstPeakHigh=1;
1159 else firstPeakHigh=0;
1160 lastBit=iii-*clk;
1161 peakCnt=0;
1162 errCnt=0;
1163 //loop through to see if this start location works
1164 for (i = iii; i < *size; ++i) {
1165 // if we are at a clock bit
1166 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1167 //test high/low
1168 if (dest[i] >= high || dest[i] <= low) {
1169 bitHigh = 1;
1170 peakCnt++;
1171 errBitHigh = 0;
1172 ignoreCnt = ignoreWindow;
1173 lastBit += *clk;
1174 } else if (i == lastBit + *clk + tol) {
1175 lastBit += *clk;
1176 }
1177 //else if no bars found
1178 } else if (dest[i] < high && dest[i] > low){
1179 if (ignoreCnt==0){
1180 bitHigh=0;
1181 if (errBitHigh==1) errCnt++;
1182 errBitHigh=0;
1183 } else {
1184 ignoreCnt--;
1185 }
1186 } else if ((dest[i]>=high || dest[i]<=low) && (bitHigh==0)) {
1187 //error bar found no clock...
1188 errBitHigh=1;
1189 }
1190 if (((i-iii) / *clk)>=MaxBits) break;
1191 }
1192 //we got more than 64 good bits and not all errors
1193 if (((i-iii) / *clk) > 64 && (errCnt <= (maxErr))) {
1194 //possible good read
1195 if (!errCnt || peakCnt > bestPeakCnt){
1196 bestFirstPeakHigh=firstPeakHigh;
1197 bestErrCnt = errCnt;
1198 bestPeakCnt = peakCnt;
1199 bestPeakStart = iii;
1200 if (!errCnt) break; //great read - finish
1201 }
1202 }
1203 }
1204 }
1205 //PrintAndLog("DEBUG: bestErrCnt: %d, maxErr: %d, bestStart: %d, bestPeakCnt: %d, bestPeakStart: %d",bestErrCnt,maxErr,bestStart,bestPeakCnt,bestPeakStart);
1206 if (bestErrCnt > maxErr) return bestErrCnt;
1207
1208 //best run is good enough set to best run and set overwrite BinStream
1209 lastBit = bestPeakStart - *clk;
1210 memset(dest, bestFirstPeakHigh^1, bestPeakStart / *clk);
1211 bitnum += (bestPeakStart / *clk);
1212 for (i = bestPeakStart; i < *size; ++i) {
1213 // if expecting a clock bit
1214 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1215 // test high/low
1216 if (dest[i] >= high || dest[i] <= low) {
1217 peakCnt++;
1218 bitHigh = 1;
1219 errBitHigh = 0;
1220 ignoreCnt = ignoreWindow;
1221 curBit = *invert;
1222 if (dest[i] >= high) curBit ^= 1;
1223 dest[bitnum++] = curBit;
1224 lastBit += *clk;
1225 //else no bars found in clock area
1226 } else if (i == lastBit + *clk + tol) {
1227 dest[bitnum++] = curBit;
1228 lastBit += *clk;
1229 }
1230 //else if no bars found
1231 } else if (dest[i] < high && dest[i] > low){
1232 if (ignoreCnt == 0){
1233 bitHigh = 0;
1234 if (errBitHigh == 1){
1235 dest[bitnum++] = 7;
1236 errCnt++;
1237 }
1238 errBitHigh=0;
1239 } else {
1240 ignoreCnt--;
1241 }
1242 } else if ((dest[i] >= high || dest[i] <= low) && (bitHigh == 0)) {
1243 //error bar found no clock...
1244 errBitHigh=1;
1245 }
1246 if (bitnum >= MaxBits) break;
1247 }
1248 *size = bitnum;
1249 return bestErrCnt;
1250 }
1251
1252 //by marshmellow
1253 //detects the bit clock for FSK given the high and low Field Clocks
1254 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1255 {
1256 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1257 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1258 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1259 uint8_t rfLensFnd = 0;
1260 uint8_t lastFCcnt = 0;
1261 uint16_t fcCounter = 0;
1262 uint16_t rfCounter = 0;
1263 uint8_t firstBitFnd = 0;
1264 size_t i;
1265 if (size == 0) return 0;
1266
1267 uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1268 rfLensFnd=0;
1269 fcCounter=0;
1270 rfCounter=0;
1271 firstBitFnd=0;
1272 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1273 // prime i to first up transition
1274 for (i = 1; i < size-1; i++)
1275 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1276 break;
1277
1278 for (; i < size-1; i++){
1279 fcCounter++;
1280 rfCounter++;
1281
1282 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1283 continue;
1284 // else new peak
1285 // if we got less than the small fc + tolerance then set it to the small fc
1286 if (fcCounter < fcLow+fcTol)
1287 fcCounter = fcLow;
1288 else //set it to the large fc
1289 fcCounter = fcHigh;
1290
1291 //look for bit clock (rf/xx)
1292 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1293 //not the same size as the last wave - start of new bit sequence
1294 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1295 for (int ii=0; ii<15; ii++){
1296 if (rfLens[ii] == rfCounter){
1297 rfCnts[ii]++;
1298 rfCounter = 0;
1299 break;
1300 }
1301 }
1302 if (rfCounter > 0 && rfLensFnd < 15){
1303 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1304 rfCnts[rfLensFnd]++;
1305 rfLens[rfLensFnd++] = rfCounter;
1306 }
1307 } else {
1308 firstBitFnd++;
1309 }
1310 rfCounter=0;
1311 lastFCcnt=fcCounter;
1312 }
1313 fcCounter=0;
1314 }
1315 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1316
1317 for (i=0; i<15; i++){
1318 //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1319 //get highest 2 RF values (might need to get more values to compare or compare all?)
1320 if (rfCnts[i]>rfCnts[rfHighest]){
1321 rfHighest3=rfHighest2;
1322 rfHighest2=rfHighest;
1323 rfHighest=i;
1324 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1325 rfHighest3=rfHighest2;
1326 rfHighest2=i;
1327 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1328 rfHighest3=i;
1329 }
1330 }
1331 // set allowed clock remainder tolerance to be 1 large field clock length+1
1332 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1333 uint8_t tol1 = fcHigh+1;
1334
1335 //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1336
1337 // loop to find the highest clock that has a remainder less than the tolerance
1338 // compare samples counted divided by
1339 int ii=7;
1340 for (; ii>=0; ii--){
1341 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1342 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1343 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1344 break;
1345 }
1346 }
1347 }
1348 }
1349
1350 if (ii<0) return 0; // oops we went too far
1351
1352 return clk[ii];
1353 }
1354
1355 //by marshmellow
1356 //countFC is to detect the field clock lengths.
1357 //counts and returns the 2 most common wave lengths
1358 //mainly used for FSK field clock detection
1359 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1360 {
1361 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1362 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1363 uint8_t fcLensFnd = 0;
1364 uint8_t lastFCcnt=0;
1365 uint8_t fcCounter = 0;
1366 size_t i;
1367 if (size == 0) return 0;
1368
1369 // prime i to first up transition
1370 for (i = 1; i < size-1; i++)
1371 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1372 break;
1373
1374 for (; i < size-1; i++){
1375 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1376 // new up transition
1377 fcCounter++;
1378 if (fskAdj){
1379 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1380 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1381 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1382 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1383 // save last field clock count (fc/xx)
1384 lastFCcnt = fcCounter;
1385 }
1386 // find which fcLens to save it to:
1387 for (int ii=0; ii<10; ii++){
1388 if (fcLens[ii]==fcCounter){
1389 fcCnts[ii]++;
1390 fcCounter=0;
1391 break;
1392 }
1393 }
1394 if (fcCounter>0 && fcLensFnd<10){
1395 //add new fc length
1396 fcCnts[fcLensFnd]++;
1397 fcLens[fcLensFnd++]=fcCounter;
1398 }
1399 fcCounter=0;
1400 } else {
1401 // count sample
1402 fcCounter++;
1403 }
1404 }
1405
1406 uint8_t best1=9, best2=9, best3=9;
1407 uint16_t maxCnt1=0;
1408 // go through fclens and find which ones are bigest 2
1409 for (i=0; i<10; i++){
1410 // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);
1411 // get the 3 best FC values
1412 if (fcCnts[i]>maxCnt1) {
1413 best3=best2;
1414 best2=best1;
1415 maxCnt1=fcCnts[i];
1416 best1=i;
1417 } else if(fcCnts[i]>fcCnts[best2]){
1418 best3=best2;
1419 best2=i;
1420 } else if(fcCnts[i]>fcCnts[best3]){
1421 best3=i;
1422 }
1423 }
1424 uint8_t fcH=0, fcL=0;
1425 if (fcLens[best1]>fcLens[best2]){
1426 fcH=fcLens[best1];
1427 fcL=fcLens[best2];
1428 } else{
1429 fcH=fcLens[best2];
1430 fcL=fcLens[best1];
1431 }
1432
1433 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1434
1435 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1436 // PrintAndLog("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
1437 if (fskAdj) return fcs;
1438 return fcLens[best1];
1439 }
1440
1441 //by marshmellow - demodulate PSK1 wave
1442 //uses wave lengths (# Samples)
1443 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1444 {
1445 if (size == 0) return -1;
1446 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1447 if (*size<loopCnt) loopCnt = *size;
1448
1449 uint8_t curPhase = *invert;
1450 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1451 uint8_t fc=0, fullWaveLen=0, tol=1;
1452 uint16_t errCnt=0, waveLenCnt=0;
1453 fc = countFC(dest, *size, 0);
1454 if (fc!=2 && fc!=4 && fc!=8) return -1;
1455 //PrintAndLog("DEBUG: FC: %d",fc);
1456 *clock = DetectPSKClock(dest, *size, *clock);
1457 if (*clock == 0) return -1;
1458 int avgWaveVal=0, lastAvgWaveVal=0;
1459 //find first phase shift
1460 for (i=0; i<loopCnt; i++){
1461 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1462 waveEnd = i+1;
1463 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1464 waveLenCnt = waveEnd-waveStart;
1465 if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave
1466 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1467 firstFullWave = waveStart;
1468 fullWaveLen=waveLenCnt;
1469 //if average wave value is > graph 0 then it is an up wave or a 1
1470 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1471 break;
1472 }
1473 waveStart = i+1;
1474 avgWaveVal = 0;
1475 }
1476 avgWaveVal += dest[i+2];
1477 }
1478 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1479 lastClkBit = firstFullWave; //set start of wave as clock align
1480 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1481 waveStart = 0;
1482 size_t numBits=0;
1483 //set skipped bits
1484 memset(dest, curPhase^1, firstFullWave / *clock);
1485 numBits += (firstFullWave / *clock);
1486 dest[numBits++] = curPhase; //set first read bit
1487 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1488 //top edge of wave = start of new wave
1489 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1490 if (waveStart == 0) {
1491 waveStart = i+1;
1492 waveLenCnt = 0;
1493 avgWaveVal = dest[i+1];
1494 } else { //waveEnd
1495 waveEnd = i+1;
1496 waveLenCnt = waveEnd-waveStart;
1497 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1498 if (waveLenCnt > fc){
1499 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1500 //this wave is a phase shift
1501 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1502 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1503 curPhase ^= 1;
1504 dest[numBits++] = curPhase;
1505 lastClkBit += *clock;
1506 } else if (i < lastClkBit+10+fc){
1507 //noise after a phase shift - ignore
1508 } else { //phase shift before supposed to based on clock
1509 errCnt++;
1510 dest[numBits++] = 7;
1511 }
1512 } else if (i+1 > lastClkBit + *clock + tol + fc){
1513 lastClkBit += *clock; //no phase shift but clock bit
1514 dest[numBits++] = curPhase;
1515 }
1516 avgWaveVal = 0;
1517 waveStart = i+1;
1518 }
1519 }
1520 avgWaveVal += dest[i+1];
1521 }
1522 *size = numBits;
1523 return errCnt;
1524 }
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