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1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // Low frequency demod/decode commands
9 //-----------------------------------------------------------------------------
10
11 #include <stdlib.h>
12 #include <string.h>
13 #include "lfdemod.h"
14 uint8_t justNoise(uint8_t *BitStream, size_t size)
15 {
16 static const uint8_t THRESHOLD = 123;
17 //test samples are not just noise
18 uint8_t justNoise1 = 1;
19 for(size_t idx=0; idx < size && justNoise1 ;idx++){
20 justNoise1 = BitStream[idx] < THRESHOLD;
21 }
22 return justNoise1;
23 }
24
25 //by marshmellow
26 //get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
27 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
28 {
29 *high=0;
30 *low=255;
31 // get high and low thresholds
32 for (size_t i=0; i < size; i++){
33 if (BitStream[i] > *high) *high = BitStream[i];
34 if (BitStream[i] < *low) *low = BitStream[i];
35 }
36 if (*high < 123) return -1; // just noise
37 *high = ((*high-128)*fuzzHi + 12800)/100;
38 *low = ((*low-128)*fuzzLo + 12800)/100;
39 return 1;
40 }
41
42 // by marshmellow
43 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
44 // returns 1 if passed
45 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
46 {
47 uint8_t ans = 0;
48 for (uint8_t i = 0; i < bitLen; i++){
49 ans ^= ((bits >> i) & 1);
50 }
51 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
52 return (ans == pType);
53 }
54
55 //by marshmellow
56 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
57 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
58 {
59 uint8_t foundCnt=0;
60 for (int idx=0; idx < *size - pLen; idx++){
61 if (memcmp(BitStream+idx, preamble, pLen) == 0){
62 //first index found
63 foundCnt++;
64 if (foundCnt == 1){
65 *startIdx = idx;
66 }
67 if (foundCnt == 2){
68 *size = idx - *startIdx;
69 return 1;
70 }
71 }
72 }
73 return 0;
74 }
75
76 //by marshmellow
77 //takes 1s and 0s and searches for EM410x format - output EM ID
78 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
79 {
80 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
81 // otherwise could be a void with no arguments
82 //set defaults
83 uint32_t i = 0;
84 if (BitStream[1]>1) 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 //make sure buffer has data
606 if (*size < 64*2) return -2;
607
608 size_t startIdx = 0;
609 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};
610 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
611 if (errChk == 0) return -4; //preamble not found
612 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
613 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
614 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
615 if ( checkCalc != 0xA8 ) return -5;
616 if (*size != 64) return -6;
617 //return start position
618 return (int) startIdx;
619 }
620
621 // by marshmellow
622 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
623 // Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
624 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
625 {
626 uint32_t parityWd = 0;
627 size_t j = 0, bitCnt = 0;
628 for (int word = 0; word < (bLen); word+=pLen){
629 for (int bit=0; bit < pLen; bit++){
630 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
631 BitStream[j++] = (BitStream[startIdx+word+bit]);
632 }
633 j--; // overwrite parity with next data
634 // if parity fails then return 0
635 if (pType == 2) { // then marker bit which should be a 1
636 if (!BitStream[j]) return 0;
637 } else {
638 if (parityTest(parityWd, pLen, pType) == 0) return 0;
639 }
640 bitCnt+=(pLen-1);
641 parityWd = 0;
642 }
643 // if we got here then all the parities passed
644 //return ID start index and size
645 return bitCnt;
646 }
647
648 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
649 // BitStream must contain previously askrawdemod and biphasedemoded data
650 int FDXBdemodBI(uint8_t *dest, size_t *size)
651 {
652 //make sure buffer has enough data
653 if (*size < 128) return -1;
654
655 size_t startIdx = 0;
656 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
657
658 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
659 if (errChk == 0) return -2; //preamble not found
660 return (int)startIdx;
661 }
662
663 // by marshmellow
664 // FSK Demod then try to locate an AWID ID
665 int AWIDdemodFSK(uint8_t *dest, size_t *size)
666 {
667 //make sure buffer has enough data
668 if (*size < 96*50) return -1;
669
670 if (justNoise(dest, *size)) return -2;
671
672 // FSK demodulator
673 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
674 if (*size < 96) return -3; //did we get a good demod?
675
676 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
677 size_t startIdx = 0;
678 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
679 if (errChk == 0) return -4; //preamble not found
680 if (*size != 96) return -5;
681 return (int)startIdx;
682 }
683
684 // by marshmellow
685 // FSK Demod then try to locate an Farpointe Data (pyramid) ID
686 int PyramiddemodFSK(uint8_t *dest, size_t *size)
687 {
688 //make sure buffer has data
689 if (*size < 128*50) return -5;
690
691 //test samples are not just noise
692 if (justNoise(dest, *size)) return -1;
693
694 // FSK demodulator
695 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
696 if (*size < 128) return -2; //did we get a good demod?
697
698 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
699 size_t startIdx = 0;
700 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
701 if (errChk == 0) return -4; //preamble not found
702 if (*size != 128) return -3;
703 return (int)startIdx;
704 }
705
706 // by marshmellow
707 // to detect a wave that has heavily clipped (clean) samples
708 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
709 {
710 uint16_t allPeaks=1;
711 uint16_t cntPeaks=0;
712 size_t loopEnd = 512+60;
713 if (loopEnd > size) loopEnd = size;
714 for (size_t i=60; i<loopEnd; i++){
715 if (dest[i]>low && dest[i]<high)
716 allPeaks=0;
717 else
718 cntPeaks++;
719 }
720 if (allPeaks == 0){
721 if (cntPeaks > 300) return 1;
722 }
723 return allPeaks;
724 }
725
726 // by marshmellow
727 // to help detect clocks on heavily clipped samples
728 // based on count of low to low
729 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
730 {
731 uint8_t fndClk[] = {8,16,32,40,50,64,128};
732 size_t startwave;
733 size_t i = 0;
734 size_t minClk = 255;
735 // get to first full low to prime loop and skip incomplete first pulse
736 while ((dest[i] < high) && (i < size))
737 ++i;
738 while ((dest[i] > low) && (i < size))
739 ++i;
740
741 // loop through all samples
742 while (i < size) {
743 // measure from low to low
744 while ((dest[i] > low) && (i < size))
745 ++i;
746 startwave= i;
747 while ((dest[i] < high) && (i < size))
748 ++i;
749 while ((dest[i] > low) && (i < size))
750 ++i;
751 //get minimum measured distance
752 if (i-startwave < minClk && i < size)
753 minClk = i - startwave;
754 }
755 // set clock
756 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
757 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
758 return fndClk[clkCnt];
759 }
760 return 0;
761 }
762
763 // by marshmellow
764 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
765 // maybe somehow adjust peak trimming value based on samples to fix?
766 // return start index of best starting position for that clock and return clock (by reference)
767 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
768 {
769 size_t i=1;
770 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
771 uint8_t clkEnd = 9;
772 uint8_t loopCnt = 255; //don't need to loop through entire array...
773 if (size <= loopCnt) return -1; //not enough samples
774
775 //if we already have a valid clock
776 uint8_t clockFnd=0;
777 for (;i<clkEnd;++i)
778 if (clk[i] == *clock) clockFnd = i;
779 //clock found but continue to find best startpos
780
781 //get high and low peak
782 int peak, low;
783 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
784
785 //test for large clean peaks
786 if (!clockFnd){
787 if (DetectCleanAskWave(dest, size, peak, low)==1){
788 int ans = DetectStrongAskClock(dest, size, peak, low);
789 for (i=clkEnd-1; i>0; i--){
790 if (clk[i] == ans) {
791 *clock = ans;
792 //clockFnd = i;
793 return 0; // for strong waves i don't use the 'best start position' yet...
794 //break; //clock found but continue to find best startpos [not yet]
795 }
796 }
797 }
798 }
799
800 uint8_t ii;
801 uint8_t clkCnt, tol = 0;
802 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
803 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
804 size_t errCnt = 0;
805 size_t arrLoc, loopEnd;
806
807 if (clockFnd>0) {
808 clkCnt = clockFnd;
809 clkEnd = clockFnd+1;
810 }
811 else clkCnt=1;
812
813 //test each valid clock from smallest to greatest to see which lines up
814 for(; clkCnt < clkEnd; clkCnt++){
815 if (clk[clkCnt] <= 32){
816 tol=1;
817 }else{
818 tol=0;
819 }
820 //if no errors allowed - keep start within the first clock
821 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
822 bestErr[clkCnt]=1000;
823 //try lining up the peaks by moving starting point (try first few clocks)
824 for (ii=0; ii < loopCnt; ii++){
825 if (dest[ii] < peak && dest[ii] > low) continue;
826
827 errCnt=0;
828 // now that we have the first one lined up test rest of wave array
829 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
830 for (i=0; i < loopEnd; ++i){
831 arrLoc = ii + (i * clk[clkCnt]);
832 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
833 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
834 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
835 }else{ //error no peak detected
836 errCnt++;
837 }
838 }
839 //if we found no errors then we can stop here and a low clock (common clocks)
840 // this is correct one - return this clock
841 //PrintAndLog("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
842 if(errCnt==0 && clkCnt<7) {
843 if (!clockFnd) *clock = clk[clkCnt];
844 return ii;
845 }
846 //if we found errors see if it is lowest so far and save it as best run
847 if(errCnt<bestErr[clkCnt]){
848 bestErr[clkCnt]=errCnt;
849 bestStart[clkCnt]=ii;
850 }
851 }
852 }
853 uint8_t iii;
854 uint8_t best=0;
855 for (iii=1; iii<clkEnd; ++iii){
856 if (bestErr[iii] < bestErr[best]){
857 if (bestErr[iii] == 0) bestErr[iii]=1;
858 // current best bit to error ratio vs new bit to error ratio
859 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
860 best = iii;
861 }
862 }
863 }
864 //if (bestErr[best] > maxErr) return -1;
865 if (!clockFnd) *clock = clk[best];
866 return bestStart[best];
867 }
868
869 //by marshmellow
870 //detect psk clock by reading each phase shift
871 // a phase shift is determined by measuring the sample length of each wave
872 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
873 {
874 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
875 uint16_t loopCnt = 4096; //don't need to loop through entire array...
876 if (size == 0) return 0;
877 if (size<loopCnt) loopCnt = size;
878
879 //if we already have a valid clock quit
880 size_t i=1;
881 for (; i < 8; ++i)
882 if (clk[i] == clock) return clock;
883
884 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
885 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
886 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
887 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
888 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
889 fc = countFC(dest, size, 0);
890 if (fc!=2 && fc!=4 && fc!=8) return -1;
891 //PrintAndLog("DEBUG: FC: %d",fc);
892
893 //find first full wave
894 for (i=0; i<loopCnt; i++){
895 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
896 if (waveStart == 0) {
897 waveStart = i+1;
898 //PrintAndLog("DEBUG: waveStart: %d",waveStart);
899 } else {
900 waveEnd = i+1;
901 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
902 waveLenCnt = waveEnd-waveStart;
903 if (waveLenCnt > fc){
904 firstFullWave = waveStart;
905 fullWaveLen=waveLenCnt;
906 break;
907 }
908 waveStart=0;
909 }
910 }
911 }
912 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
913
914 //test each valid clock from greatest to smallest to see which lines up
915 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
916 lastClkBit = firstFullWave; //set end of wave as clock align
917 waveStart = 0;
918 errCnt=0;
919 peakcnt=0;
920 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
921
922 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
923 //top edge of wave = start of new wave
924 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
925 if (waveStart == 0) {
926 waveStart = i+1;
927 waveLenCnt=0;
928 } else { //waveEnd
929 waveEnd = i+1;
930 waveLenCnt = waveEnd-waveStart;
931 if (waveLenCnt > fc){
932 //if this wave is a phase shift
933 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
934 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
935 peakcnt++;
936 lastClkBit+=clk[clkCnt];
937 } else if (i<lastClkBit+8){
938 //noise after a phase shift - ignore
939 } else { //phase shift before supposed to based on clock
940 errCnt++;
941 }
942 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
943 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
944 }
945 waveStart=i+1;
946 }
947 }
948 }
949 if (errCnt == 0){
950 return clk[clkCnt];
951 }
952 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
953 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
954 }
955 //all tested with errors
956 //return the highest clk with the most peaks found
957 uint8_t best=7;
958 for (i=7; i>=1; i--){
959 if (peaksdet[i] > peaksdet[best]) {
960 best = i;
961 }
962 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
963 }
964 return clk[best];
965 }
966
967 //by marshmellow
968 //detect nrz clock by reading #peaks vs no peaks(or errors)
969 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
970 {
971 size_t i=0;
972 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
973 size_t loopCnt = 4096; //don't need to loop through entire array...
974 if (size == 0) return 0;
975 if (size<loopCnt) loopCnt = size;
976
977 //if we already have a valid clock quit
978 for (; i < 8; ++i)
979 if (clk[i] == clock) return clock;
980
981 //get high and low peak
982 int peak, low;
983 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
984
985 //PrintAndLog("DEBUG: peak: %d, low: %d",peak,low);
986 size_t ii;
987 uint8_t clkCnt;
988 uint8_t tol = 0;
989 uint16_t peakcnt=0;
990 uint16_t peaksdet[]={0,0,0,0,0,0,0,0};
991 uint16_t maxPeak=0;
992 //test for large clipped waves
993 for (i=0; i<loopCnt; i++){
994 if (dest[i] >= peak || dest[i] <= low){
995 peakcnt++;
996 } else {
997 if (peakcnt>0 && maxPeak < peakcnt){
998 maxPeak = peakcnt;
999 }
1000 peakcnt=0;
1001 }
1002 }
1003 peakcnt=0;
1004 //test each valid clock from smallest to greatest to see which lines up
1005 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1006 //ignore clocks smaller than largest peak
1007 if (clk[clkCnt]<maxPeak) continue;
1008
1009 //try lining up the peaks by moving starting point (try first 256)
1010 for (ii=0; ii< loopCnt; ++ii){
1011 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1012 peakcnt=0;
1013 // now that we have the first one lined up test rest of wave array
1014 for (i=0; i < ((int)((size-ii-tol)/clk[clkCnt])-1); ++i){
1015 if (dest[ii+(i*clk[clkCnt])]>=peak || dest[ii+(i*clk[clkCnt])]<=low){
1016 peakcnt++;
1017 }
1018 }
1019 if(peakcnt>peaksdet[clkCnt]) {
1020 peaksdet[clkCnt]=peakcnt;
1021 }
1022 }
1023 }
1024 }
1025 int iii=7;
1026 uint8_t best=0;
1027 for (iii=7; iii > 0; iii--){
1028 if (peaksdet[iii] > peaksdet[best]){
1029 best = iii;
1030 }
1031 //PrintAndLog("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
1032 }
1033 return clk[best];
1034 }
1035
1036 // by marshmellow
1037 // convert psk1 demod to psk2 demod
1038 // only transition waves are 1s
1039 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1040 {
1041 size_t i=1;
1042 uint8_t lastBit=BitStream[0];
1043 for (; i<size; i++){
1044 if (BitStream[i]==7){
1045 //ignore errors
1046 } else if (lastBit!=BitStream[i]){
1047 lastBit=BitStream[i];
1048 BitStream[i]=1;
1049 } else {
1050 BitStream[i]=0;
1051 }
1052 }
1053 return;
1054 }
1055
1056 // by marshmellow
1057 // convert psk2 demod to psk1 demod
1058 // from only transition waves are 1s to phase shifts change bit
1059 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1060 {
1061 uint8_t phase=0;
1062 for (size_t i=0; i<size; i++){
1063 if (BitStream[i]==1){
1064 phase ^=1;
1065 }
1066 BitStream[i]=phase;
1067 }
1068 return;
1069 }
1070
1071 // redesigned by marshmellow adjusted from existing decode functions
1072 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1073 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1074 {
1075 //26 bit 40134 format (don't know other formats)
1076 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
1077 uint8_t preamble_i[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0};
1078 size_t startidx = 0;
1079 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1080 // if didn't find preamble try again inverting
1081 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1082 *invert ^= 1;
1083 }
1084 if (*size != 64 && *size != 224) return -2;
1085 if (*invert==1)
1086 for (size_t i = startidx; i < *size; i++)
1087 bitStream[i] ^= 1;
1088
1089 return (int) startidx;
1090 }
1091
1092 // by marshmellow - demodulate NRZ wave (both similar enough)
1093 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1094 // there probably is a much simpler way to do this....
1095 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert, int maxErr)
1096 {
1097 if (justNoise(dest, *size)) return -1;
1098 *clk = DetectNRZClock(dest, *size, *clk);
1099 if (*clk==0) return -2;
1100 size_t i, gLen = 4096;
1101 if (gLen>*size) gLen = *size;
1102 int high, low;
1103 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1104 int lastBit = 0; //set first clock check
1105 size_t iii = 0, bitnum = 0; //bitnum counter
1106 uint16_t errCnt = 0, MaxBits = 1000;
1107 size_t bestErrCnt = maxErr+1;
1108 size_t bestPeakCnt = 0, bestPeakStart = 0;
1109 uint8_t bestFirstPeakHigh=0, firstPeakHigh=0, curBit=0, bitHigh=0, errBitHigh=0;
1110 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
1111 uint16_t peakCnt=0;
1112 uint8_t ignoreWindow=4;
1113 uint8_t ignoreCnt=ignoreWindow; //in case of noise near peak
1114 //loop to find first wave that works - align to clock
1115 for (iii=0; iii < gLen; ++iii){
1116 if ((dest[iii]>=high) || (dest[iii]<=low)){
1117 if (dest[iii]>=high) firstPeakHigh=1;
1118 else firstPeakHigh=0;
1119 lastBit=iii-*clk;
1120 peakCnt=0;
1121 errCnt=0;
1122 //loop through to see if this start location works
1123 for (i = iii; i < *size; ++i) {
1124 // if we are at a clock bit
1125 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1126 //test high/low
1127 if (dest[i] >= high || dest[i] <= low) {
1128 bitHigh = 1;
1129 peakCnt++;
1130 errBitHigh = 0;
1131 ignoreCnt = ignoreWindow;
1132 lastBit += *clk;
1133 } else if (i == lastBit + *clk + tol) {
1134 lastBit += *clk;
1135 }
1136 //else if no bars found
1137 } else if (dest[i] < high && dest[i] > low){
1138 if (ignoreCnt==0){
1139 bitHigh=0;
1140 if (errBitHigh==1) errCnt++;
1141 errBitHigh=0;
1142 } else {
1143 ignoreCnt--;
1144 }
1145 } else if ((dest[i]>=high || dest[i]<=low) && (bitHigh==0)) {
1146 //error bar found no clock...
1147 errBitHigh=1;
1148 }
1149 if (((i-iii) / *clk)>=MaxBits) break;
1150 }
1151 //we got more than 64 good bits and not all errors
1152 if (((i-iii) / *clk) > 64 && (errCnt <= (maxErr))) {
1153 //possible good read
1154 if (!errCnt || peakCnt > bestPeakCnt){
1155 bestFirstPeakHigh=firstPeakHigh;
1156 bestErrCnt = errCnt;
1157 bestPeakCnt = peakCnt;
1158 bestPeakStart = iii;
1159 if (!errCnt) break; //great read - finish
1160 }
1161 }
1162 }
1163 }
1164 //PrintAndLog("DEBUG: bestErrCnt: %d, maxErr: %d, bestStart: %d, bestPeakCnt: %d, bestPeakStart: %d",bestErrCnt,maxErr,bestStart,bestPeakCnt,bestPeakStart);
1165 if (bestErrCnt > maxErr) return bestErrCnt;
1166
1167 //best run is good enough set to best run and set overwrite BinStream
1168 lastBit = bestPeakStart - *clk;
1169 memset(dest, bestFirstPeakHigh^1, bestPeakStart / *clk);
1170 bitnum += (bestPeakStart / *clk);
1171 for (i = bestPeakStart; i < *size; ++i) {
1172 // if expecting a clock bit
1173 if ((i >= lastBit + *clk - tol) && (i <= lastBit + *clk + tol)) {
1174 // test high/low
1175 if (dest[i] >= high || dest[i] <= low) {
1176 peakCnt++;
1177 bitHigh = 1;
1178 errBitHigh = 0;
1179 ignoreCnt = ignoreWindow;
1180 curBit = *invert;
1181 if (dest[i] >= high) curBit ^= 1;
1182 dest[bitnum++] = curBit;
1183 lastBit += *clk;
1184 //else no bars found in clock area
1185 } else if (i == lastBit + *clk + tol) {
1186 dest[bitnum++] = curBit;
1187 lastBit += *clk;
1188 }
1189 //else if no bars found
1190 } else if (dest[i] < high && dest[i] > low){
1191 if (ignoreCnt == 0){
1192 bitHigh = 0;
1193 if (errBitHigh == 1){
1194 dest[bitnum++] = 7;
1195 errCnt++;
1196 }
1197 errBitHigh=0;
1198 } else {
1199 ignoreCnt--;
1200 }
1201 } else if ((dest[i] >= high || dest[i] <= low) && (bitHigh == 0)) {
1202 //error bar found no clock...
1203 errBitHigh=1;
1204 }
1205 if (bitnum >= MaxBits) break;
1206 }
1207 *size = bitnum;
1208 return bestErrCnt;
1209 }
1210
1211 //by marshmellow
1212 //detects the bit clock for FSK given the high and low Field Clocks
1213 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1214 {
1215 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1216 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1217 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1218 uint8_t rfLensFnd = 0;
1219 uint8_t lastFCcnt = 0;
1220 uint16_t fcCounter = 0;
1221 uint16_t rfCounter = 0;
1222 uint8_t firstBitFnd = 0;
1223 size_t i;
1224 if (size == 0) return 0;
1225
1226 uint8_t fcTol = (uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1227 rfLensFnd=0;
1228 fcCounter=0;
1229 rfCounter=0;
1230 firstBitFnd=0;
1231 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1232 // prime i to first up transition
1233 for (i = 1; i < size-1; i++)
1234 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1235 break;
1236
1237 for (; i < size-1; i++){
1238 fcCounter++;
1239 rfCounter++;
1240
1241 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1242 continue;
1243 // else new peak
1244 // if we got less than the small fc + tolerance then set it to the small fc
1245 if (fcCounter < fcLow+fcTol)
1246 fcCounter = fcLow;
1247 else //set it to the large fc
1248 fcCounter = fcHigh;
1249
1250 //look for bit clock (rf/xx)
1251 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1252 //not the same size as the last wave - start of new bit sequence
1253 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1254 for (int ii=0; ii<15; ii++){
1255 if (rfLens[ii] == rfCounter){
1256 rfCnts[ii]++;
1257 rfCounter = 0;
1258 break;
1259 }
1260 }
1261 if (rfCounter > 0 && rfLensFnd < 15){
1262 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1263 rfCnts[rfLensFnd]++;
1264 rfLens[rfLensFnd++] = rfCounter;
1265 }
1266 } else {
1267 firstBitFnd++;
1268 }
1269 rfCounter=0;
1270 lastFCcnt=fcCounter;
1271 }
1272 fcCounter=0;
1273 }
1274 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1275
1276 for (i=0; i<15; i++){
1277 //PrintAndLog("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1278 //get highest 2 RF values (might need to get more values to compare or compare all?)
1279 if (rfCnts[i]>rfCnts[rfHighest]){
1280 rfHighest3=rfHighest2;
1281 rfHighest2=rfHighest;
1282 rfHighest=i;
1283 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1284 rfHighest3=rfHighest2;
1285 rfHighest2=i;
1286 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1287 rfHighest3=i;
1288 }
1289 }
1290 // set allowed clock remainder tolerance to be 1 large field clock length+1
1291 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1292 uint8_t tol1 = fcHigh+1;
1293
1294 //PrintAndLog("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1295
1296 // loop to find the highest clock that has a remainder less than the tolerance
1297 // compare samples counted divided by
1298 int ii=7;
1299 for (; ii>=0; ii--){
1300 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1301 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1302 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1303 break;
1304 }
1305 }
1306 }
1307 }
1308
1309 if (ii<0) return 0; // oops we went too far
1310
1311 return clk[ii];
1312 }
1313
1314 //by marshmellow
1315 //countFC is to detect the field clock lengths.
1316 //counts and returns the 2 most common wave lengths
1317 //mainly used for FSK field clock detection
1318 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1319 {
1320 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0};
1321 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0};
1322 uint8_t fcLensFnd = 0;
1323 uint8_t lastFCcnt=0;
1324 uint8_t fcCounter = 0;
1325 size_t i;
1326 if (size == 0) return 0;
1327
1328 // prime i to first up transition
1329 for (i = 1; i < size-1; i++)
1330 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1331 break;
1332
1333 for (; i < size-1; i++){
1334 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1335 // new up transition
1336 fcCounter++;
1337 if (fskAdj){
1338 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1339 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1340 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1341 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1342 // save last field clock count (fc/xx)
1343 lastFCcnt = fcCounter;
1344 }
1345 // find which fcLens to save it to:
1346 for (int ii=0; ii<10; ii++){
1347 if (fcLens[ii]==fcCounter){
1348 fcCnts[ii]++;
1349 fcCounter=0;
1350 break;
1351 }
1352 }
1353 if (fcCounter>0 && fcLensFnd<10){
1354 //add new fc length
1355 fcCnts[fcLensFnd]++;
1356 fcLens[fcLensFnd++]=fcCounter;
1357 }
1358 fcCounter=0;
1359 } else {
1360 // count sample
1361 fcCounter++;
1362 }
1363 }
1364
1365 uint8_t best1=9, best2=9, best3=9;
1366 uint16_t maxCnt1=0;
1367 // go through fclens and find which ones are bigest 2
1368 for (i=0; i<10; i++){
1369 // PrintAndLog("DEBUG: FC %d, Cnt %d, Errs %d",fcLens[i],fcCnts[i],errCnt);
1370 // get the 3 best FC values
1371 if (fcCnts[i]>maxCnt1) {
1372 best3=best2;
1373 best2=best1;
1374 maxCnt1=fcCnts[i];
1375 best1=i;
1376 } else if(fcCnts[i]>fcCnts[best2]){
1377 best3=best2;
1378 best2=i;
1379 } else if(fcCnts[i]>fcCnts[best3]){
1380 best3=i;
1381 }
1382 }
1383 uint8_t fcH=0, fcL=0;
1384 if (fcLens[best1]>fcLens[best2]){
1385 fcH=fcLens[best1];
1386 fcL=fcLens[best2];
1387 } else{
1388 fcH=fcLens[best2];
1389 fcL=fcLens[best1];
1390 }
1391
1392 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1393
1394 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1395 // PrintAndLog("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
1396 if (fskAdj) return fcs;
1397 return fcLens[best1];
1398 }
1399
1400 //by marshmellow - demodulate PSK1 wave
1401 //uses wave lengths (# Samples)
1402 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1403 {
1404 if (size == 0) return -1;
1405 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1406 if (*size<loopCnt) loopCnt = *size;
1407
1408 uint8_t curPhase = *invert;
1409 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1410 uint8_t fc=0, fullWaveLen=0, tol=1;
1411 uint16_t errCnt=0, waveLenCnt=0;
1412 fc = countFC(dest, *size, 0);
1413 if (fc!=2 && fc!=4 && fc!=8) return -1;
1414 //PrintAndLog("DEBUG: FC: %d",fc);
1415 *clock = DetectPSKClock(dest, *size, *clock);
1416 if (*clock == 0) return -1;
1417 int avgWaveVal=0, lastAvgWaveVal=0;
1418 //find first phase shift
1419 for (i=0; i<loopCnt; i++){
1420 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1421 waveEnd = i+1;
1422 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1423 waveLenCnt = waveEnd-waveStart;
1424 if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave
1425 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1426 firstFullWave = waveStart;
1427 fullWaveLen=waveLenCnt;
1428 //if average wave value is > graph 0 then it is an up wave or a 1
1429 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1430 break;
1431 }
1432 waveStart = i+1;
1433 avgWaveVal = 0;
1434 }
1435 avgWaveVal += dest[i+2];
1436 }
1437 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1438 lastClkBit = firstFullWave; //set start of wave as clock align
1439 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1440 waveStart = 0;
1441 size_t numBits=0;
1442 //set skipped bits
1443 memset(dest, curPhase^1, firstFullWave / *clock);
1444 numBits += (firstFullWave / *clock);
1445 dest[numBits++] = curPhase; //set first read bit
1446 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1447 //top edge of wave = start of new wave
1448 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1449 if (waveStart == 0) {
1450 waveStart = i+1;
1451 waveLenCnt = 0;
1452 avgWaveVal = dest[i+1];
1453 } else { //waveEnd
1454 waveEnd = i+1;
1455 waveLenCnt = waveEnd-waveStart;
1456 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1457 if (waveLenCnt > fc){
1458 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1459 //this wave is a phase shift
1460 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1461 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1462 curPhase ^= 1;
1463 dest[numBits++] = curPhase;
1464 lastClkBit += *clock;
1465 } else if (i < lastClkBit+10+fc){
1466 //noise after a phase shift - ignore
1467 } else { //phase shift before supposed to based on clock
1468 errCnt++;
1469 dest[numBits++] = 7;
1470 }
1471 } else if (i+1 > lastClkBit + *clock + tol + fc){
1472 lastClkBit += *clock; //no phase shift but clock bit
1473 dest[numBits++] = curPhase;
1474 }
1475 avgWaveVal = 0;
1476 waveStart = i+1;
1477 }
1478 }
1479 avgWaveVal += dest[i+1];
1480 }
1481 *size = numBits;
1482 return errCnt;
1483 }
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