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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 "lfdemod.h"
13 #include <string.h>
14
15 //un_comment to allow debug print calls when used not on device
16 void dummy(char *fmt, ...){}
17
18 #ifndef ON_DEVICE
19 #include "ui.h"
20 #include "cmdparser.h"
21 #include "cmddata.h"
22 #define prnt PrintAndLog
23 #else
24 uint8_t g_debugMode=0;
25 #define prnt dummy
26 #endif
27
28 //test samples are not just noise
29 uint8_t justNoise(uint8_t *bits, size_t size) {
30 #define THRESHOLD 123
31 uint8_t val = 1;
32 for(size_t idx=0; idx < size && val ;idx++)
33 val = bits[idx] < THRESHOLD;
34 return val;
35 }
36
37 //by marshmellow
38 //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
39 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
40 {
41 *high=0;
42 *low=255;
43 // get high and low thresholds
44 for (size_t i=0; i < size; i++){
45 if (BitStream[i] > *high) *high = BitStream[i];
46 if (BitStream[i] < *low) *low = BitStream[i];
47 }
48 if (*high < 123) return -1; // just noise
49 *high = ((*high-128)*fuzzHi + 12800)/100;
50 *low = ((*low-128)*fuzzLo + 12800)/100;
51 return 1;
52 }
53
54 // by marshmellow
55 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
56 // returns 1 if passed
57 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
58 {
59 uint8_t ans = 0;
60 for (uint8_t i = 0; i < bitLen; i++){
61 ans ^= ((bits >> i) & 1);
62 }
63 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
64 return (ans == pType);
65 }
66
67 //by marshmellow
68 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
69 // Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
70 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
71 {
72 uint32_t parityWd = 0;
73 size_t j = 0, bitCnt = 0;
74 for (int word = 0; word < (bLen); word+=pLen){
75 for (int bit=0; bit < pLen; bit++){
76 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
77 BitStream[j++] = (BitStream[startIdx+word+bit]);
78 }
79 j--; // overwrite parity with next data
80 // if parity fails then return 0
81 switch (pType) {
82 case 3: if (BitStream[j]==1) { return 0; } break; //should be 0 spacer bit
83 case 2: if (BitStream[j]==0) { return 0; } break; //should be 1 spacer bit
84 default: if (parityTest(parityWd, pLen, pType) == 0) { return 0; } break; //test parity
85 }
86 bitCnt+=(pLen-1);
87 parityWd = 0;
88 }
89 // if we got here then all the parities passed
90 //return ID start index and size
91 return bitCnt;
92 }
93
94 // by marshmellow
95 // takes a array of binary values, length of bits per parity (includes parity bit),
96 // Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
97 // Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
98 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
99 {
100 uint32_t parityWd = 0;
101 size_t j = 0, bitCnt = 0;
102 for (int word = 0; word < sourceLen; word+=pLen-1) {
103 for (int bit=0; bit < pLen-1; bit++){
104 parityWd = (parityWd << 1) | BitSource[word+bit];
105 dest[j++] = (BitSource[word+bit]);
106 }
107
108 // if parity fails then return 0
109 switch (pType) {
110 case 3: dest[j++]=0; break; // marker bit which should be a 0
111 case 2: dest[j++]=1; break; // marker bit which should be a 1
112 default:
113 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
114 break;
115 }
116 bitCnt += pLen;
117 parityWd = 0;
118 }
119 // if we got here then all the parities passed
120 //return ID start index and size
121 return bitCnt;
122 }
123
124 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
125 {
126 uint32_t num = 0;
127 for(int i = 0 ; i < numbits ; i++) {
128 num = (num << 1) | (*src);
129 src++;
130 }
131 return num;
132 }
133
134 //least significant bit first
135 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
136 {
137 uint32_t num = 0;
138 for(int i = 0 ; i < numbits ; i++) {
139 num = (num << 1) | *(src + (numbits-(i+1)));
140 }
141 return num;
142 }
143
144 //by marshmellow
145 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
146 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
147 {
148 // Sanity check. If preamble length is bigger than bitstream length.
149 if ( *size <= pLen ) return 0;
150
151 uint8_t foundCnt = 0;
152 for (int idx = 0; idx < *size - pLen; idx++){
153 if (memcmp(BitStream+idx, preamble, pLen) == 0){
154 //first index found
155 foundCnt++;
156 if (foundCnt == 1){
157 *startIdx = idx;
158 }
159 if (foundCnt == 2){
160 *size = idx - *startIdx;
161 return 1;
162 }
163 }
164 }
165 return 0;
166 }
167
168 //by marshmellow
169 //takes 1s and 0s and searches for EM410x format - output EM ID
170 int Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
171 {
172 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
173 // otherwise could be a void with no arguments
174 //set defaults
175 uint32_t i = 0;
176 if (BitStream[1]>1) return -1; //allow only 1s and 0s
177
178 // 111111111 bit pattern represent start of frame
179 // include 0 in front to help get start pos
180 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
181 uint32_t idx = 0;
182 uint32_t parityBits = 0;
183 uint8_t errChk = 0;
184 uint8_t FmtLen = 10;
185 *startIdx = 0;
186 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
187 if (errChk == 0 ) return -4;
188 if (*size < 64) return -3;
189 if (*size > 64) FmtLen = 22;
190 *startIdx += 1; //get rid of 0 from preamble
191 idx = *startIdx + 9;
192 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
193 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
194 //check even parity - quit if failed
195 if (parityTest(parityBits, 5, 0) == 0) return -5;
196 //set uint64 with ID from BitStream
197 for (uint8_t ii=0; ii<4; ii++){
198 *hi = (*hi << 1) | (*lo >> 63);
199 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
200 }
201 }
202 if (errChk != 0) return 1;
203 //skip last 5 bit parity test for simplicity.
204 // *size = 64 | 128;
205 return 0;
206 }
207
208 //by marshmellow
209 //demodulates strong heavily clipped samples
210 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
211 {
212 size_t bitCnt=0, smplCnt=0, errCnt=0;
213 uint8_t waveHigh = 0;
214 for (size_t i=0; i < *size; i++){
215 if (BinStream[i] >= high && waveHigh){
216 smplCnt++;
217 } else if (BinStream[i] <= low && !waveHigh){
218 smplCnt++;
219 } else { //transition
220 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
221 if (smplCnt > clk-(clk/4)-1) { //full clock
222 if (smplCnt > clk + (clk/4)+1) { //too many samples
223 errCnt++;
224 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
225 BinStream[bitCnt++]=7;
226 } else if (waveHigh) {
227 BinStream[bitCnt++] = invert;
228 BinStream[bitCnt++] = invert;
229 } else if (!waveHigh) {
230 BinStream[bitCnt++] = invert ^ 1;
231 BinStream[bitCnt++] = invert ^ 1;
232 }
233 waveHigh ^= 1;
234 smplCnt = 0;
235 } else if (smplCnt > (clk/2) - (clk/4)-1) {
236 if (waveHigh) {
237 BinStream[bitCnt++] = invert;
238 } else if (!waveHigh) {
239 BinStream[bitCnt++] = invert ^ 1;
240 }
241 waveHigh ^= 1;
242 smplCnt = 0;
243 } else if (!bitCnt) {
244 //first bit
245 waveHigh = (BinStream[i] >= high);
246 smplCnt = 1;
247 } else {
248 smplCnt++;
249 //transition bit oops
250 }
251 } else { //haven't hit new high or new low yet
252 smplCnt++;
253 }
254 }
255 }
256 *size = bitCnt;
257 return errCnt;
258 }
259
260 //by marshmellow
261 void askAmp(uint8_t *BitStream, size_t size)
262 {
263 uint8_t last = 128;
264 for(size_t i = 1; i < size; ++i){
265 if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
266 last = 255;
267 else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
268 last = 0;
269
270 BitStream[i] = last;
271 }
272 }
273
274 //by marshmellow
275 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
276 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
277 {
278 if (*size==0) return -1;
279 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
280 if (*clk==0 || start < 0) return -3;
281 if (*invert != 1) *invert = 0;
282 if (amp==1) askAmp(BinStream, *size);
283 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
284
285 uint8_t initLoopMax = 255;
286 if (initLoopMax > *size) initLoopMax = *size;
287 // Detect high and lows
288 //25% clip in case highs and lows aren't clipped [marshmellow]
289 int high, low;
290 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
291 return -2; //just noise
292
293 size_t errCnt = 0;
294 // if clean clipped waves detected run alternate demod
295 if (DetectCleanAskWave(BinStream, *size, high, low)) {
296 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
297 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
298 if (askType) //askman
299 return manrawdecode(BinStream, size, 0);
300 else //askraw
301 return errCnt;
302 }
303 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
304
305 int lastBit; //set first clock check - can go negative
306 size_t i, bitnum = 0; //output counter
307 uint8_t midBit = 0;
308 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
309 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
310 size_t MaxBits = 3072; //max bits to collect
311 lastBit = start - *clk;
312
313 for (i = start; i < *size; ++i) {
314 if (i-lastBit >= *clk-tol){
315 if (BinStream[i] >= high) {
316 BinStream[bitnum++] = *invert;
317 } else if (BinStream[i] <= low) {
318 BinStream[bitnum++] = *invert ^ 1;
319 } else if (i-lastBit >= *clk+tol) {
320 if (bitnum > 0) {
321 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
322 BinStream[bitnum++]=7;
323 errCnt++;
324 }
325 } else { //in tolerance - looking for peak
326 continue;
327 }
328 midBit = 0;
329 lastBit += *clk;
330 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
331 if (BinStream[i] >= high) {
332 BinStream[bitnum++] = *invert;
333 } else if (BinStream[i] <= low) {
334 BinStream[bitnum++] = *invert ^ 1;
335 } else if (i-lastBit >= *clk/2+tol) {
336 BinStream[bitnum] = BinStream[bitnum-1];
337 bitnum++;
338 } else { //in tolerance - looking for peak
339 continue;
340 }
341 midBit = 1;
342 }
343 if (bitnum >= MaxBits) break;
344 }
345 *size = bitnum;
346 return errCnt;
347 }
348
349 //by marshmellow
350 //take 10 and 01 and manchester decode
351 //run through 2 times and take least errCnt
352 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
353 {
354 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
355 size_t i, ii;
356 uint16_t bestErr = 1000, bestRun = 0;
357 if (*size < 16) return -1;
358 //find correct start position [alignment]
359 for (ii=0;ii<2;++ii){
360 for (i=ii; i<*size-3; i+=2)
361 if (BitStream[i]==BitStream[i+1])
362 errCnt++;
363
364 if (bestErr>errCnt){
365 bestErr=errCnt;
366 bestRun=ii;
367 }
368 errCnt=0;
369 }
370 //decode
371 for (i=bestRun; i < *size-3; i+=2){
372 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
373 BitStream[bitnum++]=invert;
374 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
375 BitStream[bitnum++]=invert^1;
376 } else {
377 BitStream[bitnum++]=7;
378 }
379 if(bitnum>MaxBits) break;
380 }
381 *size=bitnum;
382 return bestErr;
383 }
384
385 uint32_t manchesterEncode2Bytes(uint16_t datain) {
386 uint32_t output = 0;
387 uint8_t curBit = 0;
388 for (uint8_t i=0; i<16; i++) {
389 curBit = (datain >> (15-i) & 1);
390 output |= (1<<(((15-i)*2)+curBit));
391 }
392 return output;
393 }
394
395 //by marshmellow
396 //encode binary data into binary manchester
397 int ManchesterEncode(uint8_t *BitStream, size_t size)
398 {
399 size_t modIdx=20000, i=0;
400 if (size>modIdx) return -1;
401 for (size_t idx=0; idx < size; idx++){
402 BitStream[idx+modIdx++] = BitStream[idx];
403 BitStream[idx+modIdx++] = BitStream[idx]^1;
404 }
405 for (; i<(size*2); i++){
406 BitStream[i] = BitStream[i+20000];
407 }
408 return i;
409 }
410
411 //by marshmellow
412 //take 01 or 10 = 1 and 11 or 00 = 0
413 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
414 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
415 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
416 {
417 uint16_t bitnum = 0;
418 uint16_t errCnt = 0;
419 size_t i = offset;
420 uint16_t MaxBits=512;
421 //if not enough samples - error
422 if (*size < 51) return -1;
423 //check for phase change faults - skip one sample if faulty
424 uint8_t offsetA = 1, offsetB = 1;
425 for (; i<48; i+=2){
426 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
427 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
428 }
429 if (!offsetA && offsetB) offset++;
430 for (i=offset; i<*size-3; i+=2){
431 //check for phase error
432 if (BitStream[i+1]==BitStream[i+2]) {
433 BitStream[bitnum++]=7;
434 errCnt++;
435 }
436 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
437 BitStream[bitnum++]=1^invert;
438 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
439 BitStream[bitnum++]=invert;
440 } else {
441 BitStream[bitnum++]=7;
442 errCnt++;
443 }
444 if(bitnum>MaxBits) break;
445 }
446 *size=bitnum;
447 return errCnt;
448 }
449
450 // by marshmellow
451 // demod gProxIIDemod
452 // error returns as -x
453 // success returns start position in BitStream
454 // BitStream must contain previously askrawdemod and biphasedemoded data
455 int gProxII_Demod(uint8_t BitStream[], size_t *size)
456 {
457 size_t startIdx=0;
458 uint8_t preamble[] = {1,1,1,1,1,0};
459
460 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
461 if (errChk == 0) return -3; //preamble not found
462 if (*size != 96) return -2; //should have found 96 bits
463 //check first 6 spacer bits to verify format
464 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
465 //confirmed proper separator bits found
466 //return start position
467 return (int) startIdx;
468 }
469 return -5; //spacer bits not found - not a valid gproxII
470 }
471
472 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
473 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
474 {
475 size_t last_transition = 0;
476 size_t idx = 1;
477 //uint32_t maxVal=0;
478 if (fchigh==0) fchigh=10;
479 if (fclow==0) fclow=8;
480 //set the threshold close to 0 (graph) or 128 std to avoid static
481 uint8_t threshold_value = 123;
482 size_t preLastSample = 0;
483 size_t LastSample = 0;
484 size_t currSample = 0;
485 // sync to first lo-hi transition, and threshold
486
487 // Need to threshold first sample
488 // skip 160 samples to allow antenna/samples to settle
489 if(dest[160] < threshold_value) dest[0] = 0;
490 else dest[0] = 1;
491
492 size_t numBits = 0;
493 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
494 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
495 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
496 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
497 for(idx = 161; idx < size-20; idx++) {
498 // threshold current value
499
500 if (dest[idx] < threshold_value) dest[idx] = 0;
501 else dest[idx] = 1;
502
503 // Check for 0->1 transition
504 if (dest[idx-1] < dest[idx]) {
505 preLastSample = LastSample;
506 LastSample = currSample;
507 currSample = idx-last_transition;
508 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
509 //do nothing with extra garbage
510 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
511 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
512 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
513 dest[numBits-1]=1;
514 }
515 dest[numBits++]=1;
516
517 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
518 //do nothing with beginning garbage
519 } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
520 dest[numBits++]=1;
521 } else { //9+ = 10 sample waves (or 6+ = 7)
522 dest[numBits++]=0;
523 }
524 last_transition = idx;
525 }
526 }
527 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
528 }
529
530 //translate 11111100000 to 10
531 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
532 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
533 uint8_t invert, uint8_t fchigh, uint8_t fclow)
534 {
535 uint8_t lastval=dest[0];
536 size_t idx=0;
537 size_t numBits=0;
538 uint32_t n=1;
539 for( idx=1; idx < size; idx++) {
540 n++;
541 if (dest[idx]==lastval) continue;
542
543 //find out how many bits (n) we collected
544 //if lastval was 1, we have a 1->0 crossing
545 if (dest[idx-1]==1) {
546 n = (n * fclow + rfLen/2) / rfLen;
547 } else {// 0->1 crossing
548 n = (n * fchigh + rfLen/2) / rfLen;
549 }
550 if (n == 0) n = 1;
551
552 //add to our destination the bits we collected
553 memset(dest+numBits, dest[idx-1]^invert , n);
554 numBits += n;
555 n=0;
556 lastval=dest[idx];
557 }//end for
558 // if valid extra bits at the end were all the same frequency - add them in
559 if (n > rfLen/fchigh) {
560 if (dest[idx-2]==1) {
561 n = (n * fclow + rfLen/2) / rfLen;
562 } else {
563 n = (n * fchigh + rfLen/2) / rfLen;
564 }
565 memset(dest+numBits, dest[idx-1]^invert , n);
566 numBits += n;
567 }
568 return numBits;
569 }
570
571 //by marshmellow (from holiman's base)
572 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
573 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
574 {
575 // FSK demodulator
576 size = fsk_wave_demod(dest, size, fchigh, fclow);
577 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
578 return size;
579 }
580
581 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
582 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
583 {
584 if (justNoise(dest, *size)) return -1;
585
586 size_t numStart=0, size2 = *size, startIdx=0;
587 // FSK demodulator
588 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
589 if (*size < 96*2) return -2;
590 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
591 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
592 // find bitstring in array
593 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
594 if (errChk == 0) return -3; //preamble not found
595
596 numStart = startIdx + sizeof(preamble);
597 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
598 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
599 if (dest[idx] == dest[idx+1]){
600 return -4; //not manchester data
601 }
602 *hi2 = (*hi2<<1)|(*hi>>31);
603 *hi = (*hi<<1)|(*lo>>31);
604 //Then, shift in a 0 or one into low
605 if (dest[idx] && !dest[idx+1]) // 1 0
606 *lo=(*lo<<1)|1;
607 else // 0 1
608 *lo=(*lo<<1)|0;
609 }
610 return (int)startIdx;
611 }
612
613 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
614 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
615 {
616 if (justNoise(dest, *size)) return -1;
617
618 size_t numStart=0, size2 = *size, startIdx=0;
619 // FSK demodulator
620 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
621 if (*size < 96) return -2;
622
623 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
624 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
625
626 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
627 if (errChk == 0) return -3; //preamble not found
628
629 numStart = startIdx + sizeof(preamble);
630 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
631 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
632 if (dest[idx] == dest[idx+1])
633 return -4; //not manchester data
634 *hi2 = (*hi2<<1)|(*hi>>31);
635 *hi = (*hi<<1)|(*lo>>31);
636 //Then, shift in a 0 or one into low
637 if (dest[idx] && !dest[idx+1]) // 1 0
638 *lo=(*lo<<1)|1;
639 else // 0 1
640 *lo=(*lo<<1)|0;
641 }
642 return (int)startIdx;
643 }
644
645 int IOdemodFSK(uint8_t *dest, size_t size)
646 {
647 if (justNoise(dest, size)) return -1;
648 //make sure buffer has data
649 if (size < 66*64) return -2;
650 // FSK demodulator
651 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
652 if (size < 65) return -3; //did we get a good demod?
653 //Index map
654 //0 10 20 30 40 50 60
655 //| | | | | | |
656 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
657 //-----------------------------------------------------------------------------
658 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
659 //
660 //XSF(version)facility:codeone+codetwo
661 //Handle the data
662 size_t startIdx = 0;
663 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
664 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
665 if (errChk == 0) return -4; //preamble not found
666
667 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
668 //confirmed proper separator bits found
669 //return start position
670 return (int) startIdx;
671 }
672 return -5;
673 }
674
675 // by marshmellow
676 // find viking preamble 0xF200 in already demoded data
677 int VikingDemod_AM(uint8_t *dest, size_t *size) {
678 //make sure buffer has data
679 if (*size < 64*2) return -2;
680
681 size_t startIdx = 0;
682 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};
683 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
684 if (errChk == 0) return -4; //preamble not found
685 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^
686 bytebits_to_byte(dest+startIdx+8,8) ^
687 bytebits_to_byte(dest+startIdx+16,8) ^
688 bytebits_to_byte(dest+startIdx+24,8) ^
689 bytebits_to_byte(dest+startIdx+32,8) ^
690 bytebits_to_byte(dest+startIdx+40,8) ^
691 bytebits_to_byte(dest+startIdx+48,8) ^
692 bytebits_to_byte(dest+startIdx+56,8);
693 if ( checkCalc != 0xA8 ) return -5;
694 if (*size != 64) return -6;
695 //return start position
696 return (int) startIdx;
697 }
698
699 // by iceman
700 // find Visa2000 preamble in already demoded data
701 int Visa2kDemod_AM(uint8_t *dest, size_t *size) {
702 if (*size < 96*2) return -1; //make sure buffer has data
703 size_t startIdx = 0;
704 uint8_t preamble[] = {0,1,0,1,0,1,1,0,0,1,0,0,1,0,0,1,0,1,0,1,0,0,1,1,0,0,1,1,0,0,1,0};
705 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
706 if (errChk == 0) return -2; //preamble not found
707 if (*size != 96) return -3; //wrong demoded size
708 //return start position
709 return (int) startIdx;
710 }
711
712 // find presco preamble 0x10D in already demoded data
713 int PrescoDemod(uint8_t *dest, size_t *size) {
714 if (*size < 128*2) return -1; //make sure buffer has data
715 size_t startIdx = 0;
716 uint8_t preamble[] = {0,0,0,1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
717 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
718 if (errChk == 0) return -2; //preamble not found
719 if (*size != 128) return -3; //wrong demoded size
720 //return start position
721 return (int) startIdx;
722 }
723
724 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
725 // BitStream must contain previously askrawdemod and biphasedemoded data
726 int FDXBdemodBI(uint8_t *dest, size_t *size)
727 {
728 //make sure buffer has enough data
729 if (*size < 128) return -1;
730
731 size_t startIdx = 0;
732 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
733
734 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
735 if (errChk == 0) return -2; //preamble not found
736 return (int)startIdx;
737 }
738
739 // ASK/Diphase fc/64 (inverted Biphase)
740 // Note: this i s not a demod, this is only a detection
741 // the parameter *dest needs to be demoded before call
742 int JablotronDemod(uint8_t *dest, size_t *size){
743 //make sure buffer has enough data
744 if (*size < 64) return -1;
745
746 size_t startIdx = 0;
747 // 0xFFFF preamble, 64bits
748 uint8_t preamble[] = {
749 1,1,1,1,
750 1,1,1,1,
751 1,1,1,1,
752 1,1,1,1,
753 0
754 };
755
756 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
757 if (errChk == 0) return -4; //preamble not found
758 if (*size != 64) return -3;
759
760 uint8_t checkchksum = 0;
761 for (int i=16; i < 56; i += 8) {
762 checkchksum += bytebits_to_byte(dest+startIdx+i,8);
763 }
764 checkchksum ^= 0x3A;
765
766 uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
767
768 if ( checkchksum != crc ) return -5;
769 return (int)startIdx;
770 }
771
772 // by marshmellow
773 // FSK Demod then try to locate an AWID ID
774 int AWIDdemodFSK(uint8_t *dest, size_t *size)
775 {
776 //make sure buffer has enough data
777 if (*size < 96*50) return -1;
778
779 if (justNoise(dest, *size)) return -2;
780
781 // FSK demodulator
782 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
783 if (*size < 96) return -3; //did we get a good demod?
784
785 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
786 size_t startIdx = 0;
787 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
788 if (errChk == 0) return -4; //preamble not found
789 if (*size != 96) return -5;
790 return (int)startIdx;
791 }
792
793 // by marshmellow
794 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
795 int PyramiddemodFSK(uint8_t *dest, size_t *size)
796 {
797 //make sure buffer has data
798 if (*size < 128*50) return -5;
799
800 //test samples are not just noise
801 if (justNoise(dest, *size)) return -1;
802
803 // FSK demodulator
804 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
805 if (*size < 128) return -2; //did we get a good demod?
806
807 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
808 size_t startIdx = 0;
809 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
810 if (errChk == 0) return -4; //preamble not found
811 if (*size != 128) return -3;
812 return (int)startIdx;
813 }
814
815 // find nedap preamble in already demoded data
816 int NedapDemod(uint8_t *dest, size_t *size) {
817 //make sure buffer has data
818 if (*size < 128) return -3;
819
820 size_t startIdx = 0;
821 //uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
822 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
823 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
824 if (errChk == 0) return -4; //preamble not found
825 return (int) startIdx;
826 }
827
828 // by marshmellow
829 // to detect a wave that has heavily clipped (clean) samples
830 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
831 {
832 bool allArePeaks = true;
833 uint16_t cntPeaks=0;
834 size_t loopEnd = 512+160;
835 if (loopEnd > size) loopEnd = size;
836 for (size_t i=160; i<loopEnd; i++){
837 if (dest[i]>low && dest[i]<high)
838 allArePeaks = false;
839 else
840 cntPeaks++;
841 }
842 if (!allArePeaks){
843 if (cntPeaks > 300) return true;
844 }
845 return allArePeaks;
846 }
847 // by marshmellow
848 // to help detect clocks on heavily clipped samples
849 // based on count of low to low
850 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
851 {
852 uint8_t fndClk[] = {8,16,32,40,50,64,128};
853 size_t startwave;
854 size_t i = 100;
855 size_t minClk = 255;
856 // get to first full low to prime loop and skip incomplete first pulse
857 while ((dest[i] < high) && (i < size))
858 ++i;
859 while ((dest[i] > low) && (i < size))
860 ++i;
861
862 // loop through all samples
863 while (i < size) {
864 // measure from low to low
865 while ((dest[i] > low) && (i < size))
866 ++i;
867 startwave= i;
868 while ((dest[i] < high) && (i < size))
869 ++i;
870 while ((dest[i] > low) && (i < size))
871 ++i;
872 //get minimum measured distance
873 if (i-startwave < minClk && i < size)
874 minClk = i - startwave;
875 }
876 // set clock
877 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
878 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
879 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
880 return fndClk[clkCnt];
881 }
882 return 0;
883 }
884
885 // by marshmellow
886 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
887 // maybe somehow adjust peak trimming value based on samples to fix?
888 // return start index of best starting position for that clock and return clock (by reference)
889 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
890 {
891 size_t i=1;
892 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
893 uint8_t clkEnd = 9;
894 uint8_t loopCnt = 255; //don't need to loop through entire array...
895 if (size <= loopCnt+60) return -1; //not enough samples
896 size -= 60; //sometimes there is a strange end wave - filter out this....
897 //if we already have a valid clock
898 uint8_t clockFnd=0;
899 for (;i<clkEnd;++i)
900 if (clk[i] == *clock) clockFnd = i;
901 //clock found but continue to find best startpos
902
903 //get high and low peak
904 int peak, low;
905 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
906
907 //test for large clean peaks
908 if (!clockFnd){
909 if (DetectCleanAskWave(dest, size, peak, low)==1){
910 int ans = DetectStrongAskClock(dest, size, peak, low);
911 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
912 for (i=clkEnd-1; i>0; i--){
913 if (clk[i] == ans) {
914 *clock = ans;
915 //clockFnd = i;
916 return 0; // for strong waves i don't use the 'best start position' yet...
917 //break; //clock found but continue to find best startpos [not yet]
918 }
919 }
920 }
921 }
922 uint8_t ii;
923 uint8_t clkCnt, tol = 0;
924 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
925 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
926 size_t errCnt = 0;
927 size_t arrLoc, loopEnd;
928
929 if (clockFnd>0) {
930 clkCnt = clockFnd;
931 clkEnd = clockFnd+1;
932 }
933 else clkCnt=1;
934
935 //test each valid clock from smallest to greatest to see which lines up
936 for(; clkCnt < clkEnd; clkCnt++){
937 if (clk[clkCnt] <= 32){
938 tol=1;
939 }else{
940 tol=0;
941 }
942 //if no errors allowed - keep start within the first clock
943 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
944 bestErr[clkCnt]=1000;
945 //try lining up the peaks by moving starting point (try first few clocks)
946 for (ii=0; ii < loopCnt; ii++){
947 if (dest[ii] < peak && dest[ii] > low) continue;
948
949 errCnt=0;
950 // now that we have the first one lined up test rest of wave array
951 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
952 for (i=0; i < loopEnd; ++i){
953 arrLoc = ii + (i * clk[clkCnt]);
954 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
955 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
956 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
957 }else{ //error no peak detected
958 errCnt++;
959 }
960 }
961 //if we found no errors then we can stop here and a low clock (common clocks)
962 // this is correct one - return this clock
963 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
964 if(errCnt==0 && clkCnt<7) {
965 if (!clockFnd) *clock = clk[clkCnt];
966 return ii;
967 }
968 //if we found errors see if it is lowest so far and save it as best run
969 if(errCnt<bestErr[clkCnt]){
970 bestErr[clkCnt]=errCnt;
971 bestStart[clkCnt]=ii;
972 }
973 }
974 }
975 uint8_t iii;
976 uint8_t best=0;
977 for (iii=1; iii<clkEnd; ++iii){
978 if (bestErr[iii] < bestErr[best]){
979 if (bestErr[iii] == 0) bestErr[iii]=1;
980 // current best bit to error ratio vs new bit to error ratio
981 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
982 best = iii;
983 }
984 }
985 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d",clk[iii],bestErr[iii],clk[best],bestStart[best]);
986 }
987 if (!clockFnd) *clock = clk[best];
988 return bestStart[best];
989 }
990
991 //by marshmellow
992 //detect psk clock by reading each phase shift
993 // a phase shift is determined by measuring the sample length of each wave
994 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
995 {
996 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
997 uint16_t loopCnt = 4096; //don't need to loop through entire array...
998 if (size == 0) return 0;
999 if (size<loopCnt) loopCnt = size-20;
1000
1001 //if we already have a valid clock quit
1002 size_t i=1;
1003 for (; i < 8; ++i)
1004 if (clk[i] == clock) return clock;
1005
1006 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
1007 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
1008 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
1009 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
1010 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
1011 fc = countFC(dest, size, 0);
1012 if (fc!=2 && fc!=4 && fc!=8) return -1;
1013 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
1014
1015 //find first full wave
1016 for (i=160; i<loopCnt; i++){
1017 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1018 if (waveStart == 0) {
1019 waveStart = i+1;
1020 //prnt("DEBUG: waveStart: %d",waveStart);
1021 } else {
1022 waveEnd = i+1;
1023 //prnt("DEBUG: waveEnd: %d",waveEnd);
1024 waveLenCnt = waveEnd-waveStart;
1025 if (waveLenCnt > fc){
1026 firstFullWave = waveStart;
1027 fullWaveLen=waveLenCnt;
1028 break;
1029 }
1030 waveStart=0;
1031 }
1032 }
1033 }
1034 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1035
1036 //test each valid clock from greatest to smallest to see which lines up
1037 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1038 lastClkBit = firstFullWave; //set end of wave as clock align
1039 waveStart = 0;
1040 errCnt=0;
1041 peakcnt=0;
1042 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1043
1044 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1045 //top edge of wave = start of new wave
1046 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1047 if (waveStart == 0) {
1048 waveStart = i+1;
1049 waveLenCnt=0;
1050 } else { //waveEnd
1051 waveEnd = i+1;
1052 waveLenCnt = waveEnd-waveStart;
1053 if (waveLenCnt > fc){
1054 //if this wave is a phase shift
1055 if (g_debugMode == 2) prnt("DEBUG PSK: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,i+1,fc);
1056 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1057 peakcnt++;
1058 lastClkBit+=clk[clkCnt];
1059 } else if (i<lastClkBit+8){
1060 //noise after a phase shift - ignore
1061 } else { //phase shift before supposed to based on clock
1062 errCnt++;
1063 }
1064 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1065 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1066 }
1067 waveStart=i+1;
1068 }
1069 }
1070 }
1071 if (errCnt == 0){
1072 return clk[clkCnt];
1073 }
1074 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1075 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1076 }
1077 //all tested with errors
1078 //return the highest clk with the most peaks found
1079 uint8_t best=7;
1080 for (i=7; i>=1; i--){
1081 if (peaksdet[i] > peaksdet[best]) {
1082 best = i;
1083 }
1084 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1085 }
1086 return clk[best];
1087 }
1088
1089 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1090 //find shortest transition from high to low
1091 size_t i = 0;
1092 size_t transition1 = 0;
1093 int lowestTransition = 255;
1094 bool lastWasHigh = false;
1095
1096 //find first valid beginning of a high or low wave
1097 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1098 ++i;
1099 while ((dest[i] < peak && dest[i] > low) && (i < size))
1100 ++i;
1101 lastWasHigh = (dest[i] >= peak);
1102
1103 if (i==size) return 0;
1104 transition1 = i;
1105
1106 for (;i < size; i++) {
1107 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1108 lastWasHigh = (dest[i] >= peak);
1109 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1110 transition1 = i;
1111 }
1112 }
1113 if (lowestTransition == 255) lowestTransition = 0;
1114 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1115 return lowestTransition;
1116 }
1117
1118 //by marshmellow
1119 //detect nrz clock by reading #peaks vs no peaks(or errors)
1120 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1121 {
1122 size_t i=0;
1123 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1124 size_t loopCnt = 4096; //don't need to loop through entire array...
1125 if (size == 0) return 0;
1126 if (size<loopCnt) loopCnt = size-20;
1127 //if we already have a valid clock quit
1128 for (; i < 8; ++i)
1129 if (clk[i] == clock) return clock;
1130
1131 //get high and low peak
1132 int peak, low;
1133 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1134
1135 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1136 size_t ii;
1137 uint8_t clkCnt;
1138 uint8_t tol = 0;
1139 uint16_t smplCnt = 0;
1140 int16_t peakcnt = 0;
1141 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1142 uint16_t maxPeak = 255;
1143 bool firstpeak = false;
1144 //test for large clipped waves
1145 for (i=0; i<loopCnt; i++){
1146 if (dest[i] >= peak || dest[i] <= low){
1147 if (!firstpeak) continue;
1148 smplCnt++;
1149 } else {
1150 firstpeak=true;
1151 if (smplCnt > 6 ){
1152 if (maxPeak > smplCnt){
1153 maxPeak = smplCnt;
1154 //prnt("maxPk: %d",maxPeak);
1155 }
1156 peakcnt++;
1157 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1158 smplCnt=0;
1159 }
1160 }
1161 }
1162 bool errBitHigh = 0;
1163 bool bitHigh = 0;
1164 uint8_t ignoreCnt = 0;
1165 uint8_t ignoreWindow = 4;
1166 bool lastPeakHigh = 0;
1167 int lastBit = 0;
1168 peakcnt=0;
1169 //test each valid clock from smallest to greatest to see which lines up
1170 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1171 //ignore clocks smaller than smallest peak
1172 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1173 //try lining up the peaks by moving starting point (try first 256)
1174 for (ii=20; ii < loopCnt; ++ii){
1175 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1176 peakcnt=0;
1177 bitHigh = false;
1178 ignoreCnt = 0;
1179 lastBit = ii-clk[clkCnt];
1180 //loop through to see if this start location works
1181 for (i = ii; i < size-20; ++i) {
1182 //if we are at a clock bit
1183 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1184 //test high/low
1185 if (dest[i] >= peak || dest[i] <= low) {
1186 //if same peak don't count it
1187 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1188 peakcnt++;
1189 }
1190 lastPeakHigh = (dest[i] >= peak);
1191 bitHigh = true;
1192 errBitHigh = false;
1193 ignoreCnt = ignoreWindow;
1194 lastBit += clk[clkCnt];
1195 } else if (i == lastBit + clk[clkCnt] + tol) {
1196 lastBit += clk[clkCnt];
1197 }
1198 //else if not a clock bit and no peaks
1199 } else if (dest[i] < peak && dest[i] > low){
1200 if (ignoreCnt==0){
1201 bitHigh=false;
1202 if (errBitHigh==true) peakcnt--;
1203 errBitHigh=false;
1204 } else {
1205 ignoreCnt--;
1206 }
1207 // else if not a clock bit but we have a peak
1208 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1209 //error bar found no clock...
1210 errBitHigh=true;
1211 }
1212 }
1213 if(peakcnt>peaksdet[clkCnt]) {
1214 peaksdet[clkCnt]=peakcnt;
1215 }
1216 }
1217 }
1218 }
1219 int iii=7;
1220 uint8_t best=0;
1221 for (iii=7; iii > 0; iii--){
1222 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1223 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1224 best = iii;
1225 }
1226 } else if (peaksdet[iii] > peaksdet[best]){
1227 best = iii;
1228 }
1229 if (g_debugMode==2) prnt("DEBUG NRZ: Clk: %d, peaks: %d, maxPeak: %d, bestClk: %d, lowestTrs: %d",clk[iii],peaksdet[iii],maxPeak, clk[best], lowestTransition);
1230 }
1231
1232 return clk[best];
1233 }
1234
1235 // by marshmellow
1236 // convert psk1 demod to psk2 demod
1237 // only transition waves are 1s
1238 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1239 {
1240 size_t i=1;
1241 uint8_t lastBit=BitStream[0];
1242 for (; i<size; i++){
1243 if (BitStream[i]==7){
1244 //ignore errors
1245 } else if (lastBit!=BitStream[i]){
1246 lastBit=BitStream[i];
1247 BitStream[i]=1;
1248 } else {
1249 BitStream[i]=0;
1250 }
1251 }
1252 return;
1253 }
1254
1255 // by marshmellow
1256 // convert psk2 demod to psk1 demod
1257 // from only transition waves are 1s to phase shifts change bit
1258 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1259 {
1260 uint8_t phase=0;
1261 for (size_t i=0; i<size; i++){
1262 if (BitStream[i]==1){
1263 phase ^=1;
1264 }
1265 BitStream[i]=phase;
1266 }
1267 return;
1268 }
1269
1270 // redesigned by marshmellow adjusted from existing decode functions
1271 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1272 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1273 {
1274 //26 bit 40134 format (don't know other formats)
1275 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};
1276 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};
1277 size_t startidx = 0;
1278 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1279 // if didn't find preamble try again inverting
1280 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1281 *invert ^= 1;
1282 }
1283 if (*size != 64 && *size != 224) return -2;
1284 if (*invert==1)
1285 for (size_t i = startidx; i < *size; i++)
1286 bitStream[i] ^= 1;
1287
1288 return (int) startidx;
1289 }
1290
1291 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1292 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1293 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1294 if (justNoise(dest, *size)) return -1;
1295 *clk = DetectNRZClock(dest, *size, *clk);
1296 if (*clk==0) return -2;
1297 size_t i, gLen = 4096;
1298 if (gLen>*size) gLen = *size-20;
1299 int high, low;
1300 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1301
1302 uint8_t bit=0;
1303 //convert wave samples to 1's and 0's
1304 for(i=20; i < *size-20; i++){
1305 if (dest[i] >= high) bit = 1;
1306 if (dest[i] <= low) bit = 0;
1307 dest[i] = bit;
1308 }
1309 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1310 size_t lastBit = 0;
1311 size_t numBits = 0;
1312 for(i=21; i < *size-20; i++) {
1313 //if transition detected or large number of same bits - store the passed bits
1314 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1315 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1316 numBits += (i - lastBit + (*clk/4)) / *clk;
1317 lastBit = i-1;
1318 }
1319 }
1320 *size = numBits;
1321 return 0;
1322 }
1323
1324 //by marshmellow
1325 //detects the bit clock for FSK given the high and low Field Clocks
1326 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1327 {
1328 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1329 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1330 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1331 uint8_t rfLensFnd = 0;
1332 uint8_t lastFCcnt = 0;
1333 uint16_t fcCounter = 0;
1334 uint16_t rfCounter = 0;
1335 uint8_t firstBitFnd = 0;
1336 size_t i;
1337 if (size == 0) return 0;
1338
1339 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1340 rfLensFnd=0;
1341 fcCounter=0;
1342 rfCounter=0;
1343 firstBitFnd=0;
1344 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1345 // prime i to first peak / up transition
1346 for (i = 160; i < size-20; i++)
1347 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1348 break;
1349
1350 for (; i < size-20; i++){
1351 fcCounter++;
1352 rfCounter++;
1353
1354 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1355 continue;
1356 // else new peak
1357 // if we got less than the small fc + tolerance then set it to the small fc
1358 if (fcCounter < fcLow+fcTol)
1359 fcCounter = fcLow;
1360 else //set it to the large fc
1361 fcCounter = fcHigh;
1362
1363 //look for bit clock (rf/xx)
1364 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1365 //not the same size as the last wave - start of new bit sequence
1366 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1367 for (int ii=0; ii<15; ii++){
1368 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1369 rfCnts[ii]++;
1370 rfCounter = 0;
1371 break;
1372 }
1373 }
1374 if (rfCounter > 0 && rfLensFnd < 15){
1375 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1376 rfCnts[rfLensFnd]++;
1377 rfLens[rfLensFnd++] = rfCounter;
1378 }
1379 } else {
1380 firstBitFnd++;
1381 }
1382 rfCounter=0;
1383 lastFCcnt=fcCounter;
1384 }
1385 fcCounter=0;
1386 }
1387 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1388
1389 for (i=0; i<15; i++){
1390 //get highest 2 RF values (might need to get more values to compare or compare all?)
1391 if (rfCnts[i]>rfCnts[rfHighest]){
1392 rfHighest3=rfHighest2;
1393 rfHighest2=rfHighest;
1394 rfHighest=i;
1395 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1396 rfHighest3=rfHighest2;
1397 rfHighest2=i;
1398 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1399 rfHighest3=i;
1400 }
1401 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1402 }
1403 // set allowed clock remainder tolerance to be 1 large field clock length+1
1404 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1405 uint8_t tol1 = fcHigh+1;
1406
1407 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1408
1409 // loop to find the highest clock that has a remainder less than the tolerance
1410 // compare samples counted divided by
1411 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1412 int ii=7;
1413 for (; ii>=2; ii--){
1414 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1415 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1416 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1417 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1418 break;
1419 }
1420 }
1421 }
1422 }
1423
1424 if (ii<0) return 0; // oops we went too far
1425
1426 return clk[ii];
1427 }
1428
1429 //by marshmellow
1430 //countFC is to detect the field clock lengths.
1431 //counts and returns the 2 most common wave lengths
1432 //mainly used for FSK field clock detection
1433 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1434 {
1435 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1436 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1437 uint8_t fcLensFnd = 0;
1438 uint8_t lastFCcnt=0;
1439 uint8_t fcCounter = 0;
1440 size_t i;
1441 if (size == 0) return 0;
1442
1443 // prime i to first up transition
1444 for (i = 160; i < size-20; i++)
1445 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1446 break;
1447
1448 for (; i < size-20; i++){
1449 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1450 // new up transition
1451 fcCounter++;
1452 if (fskAdj){
1453 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1454 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1455 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1456 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1457 // save last field clock count (fc/xx)
1458 lastFCcnt = fcCounter;
1459 }
1460 // find which fcLens to save it to:
1461 for (int ii=0; ii<15; ii++){
1462 if (fcLens[ii]==fcCounter){
1463 fcCnts[ii]++;
1464 fcCounter=0;
1465 break;
1466 }
1467 }
1468 if (fcCounter>0 && fcLensFnd<15){
1469 //add new fc length
1470 fcCnts[fcLensFnd]++;
1471 fcLens[fcLensFnd++]=fcCounter;
1472 }
1473 fcCounter=0;
1474 } else {
1475 // count sample
1476 fcCounter++;
1477 }
1478 }
1479
1480 uint8_t best1=14, best2=14, best3=14;
1481 uint16_t maxCnt1=0;
1482 // go through fclens and find which ones are bigest 2
1483 for (i=0; i<15; i++){
1484 // get the 3 best FC values
1485 if (fcCnts[i]>maxCnt1) {
1486 best3=best2;
1487 best2=best1;
1488 maxCnt1=fcCnts[i];
1489 best1=i;
1490 } else if(fcCnts[i]>fcCnts[best2]){
1491 best3=best2;
1492 best2=i;
1493 } else if(fcCnts[i]>fcCnts[best3]){
1494 best3=i;
1495 }
1496 if (g_debugMode==2) prnt("DEBUG countfc: FC %u, Cnt %u, best fc: %u, best2 fc: %u",fcLens[i],fcCnts[i],fcLens[best1],fcLens[best2]);
1497 }
1498 if (fcLens[best1]==0) return 0;
1499 uint8_t fcH=0, fcL=0;
1500 if (fcLens[best1]>fcLens[best2]){
1501 fcH=fcLens[best1];
1502 fcL=fcLens[best2];
1503 } else{
1504 fcH=fcLens[best2];
1505 fcL=fcLens[best1];
1506 }
1507 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1508 if (g_debugMode==2) prnt("DEBUG countfc: fc is too large: %u > %u. Not psk or fsk",(size-180)/fcH/3,fcCnts[best1]+fcCnts[best2]);
1509 return 0; //lots of waves not psk or fsk
1510 }
1511 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1512
1513 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1514 if (fskAdj) return fcs;
1515 return fcLens[best1];
1516 }
1517
1518 //by marshmellow - demodulate PSK1 wave
1519 //uses wave lengths (# Samples)
1520 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1521 {
1522 if (size == 0) return -1;
1523 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1524 if (*size<loopCnt) loopCnt = *size;
1525
1526 size_t numBits=0;
1527 uint8_t curPhase = *invert;
1528 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1529 uint8_t fc=0, fullWaveLen=0, tol=1;
1530 uint16_t errCnt=0, waveLenCnt=0;
1531 fc = countFC(dest, *size, 0);
1532 if (fc!=2 && fc!=4 && fc!=8) return -1;
1533 //PrintAndLog("DEBUG: FC: %d",fc);
1534 *clock = DetectPSKClock(dest, *size, *clock);
1535 if (*clock == 0) return -1;
1536 int avgWaveVal=0, lastAvgWaveVal=0;
1537 //find first phase shift
1538 for (i=0; i<loopCnt; i++){
1539 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1540 waveEnd = i+1;
1541 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1542 waveLenCnt = waveEnd-waveStart;
1543 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1544 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1545 firstFullWave = waveStart;
1546 fullWaveLen=waveLenCnt;
1547 //if average wave value is > graph 0 then it is an up wave or a 1
1548 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1549 break;
1550 }
1551 waveStart = i+1;
1552 avgWaveVal = 0;
1553 }
1554 avgWaveVal += dest[i+2];
1555 }
1556 if (firstFullWave == 0) {
1557 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1558 // so skip a little to ensure we are past any Start Signal
1559 firstFullWave = 160;
1560 memset(dest, curPhase, firstFullWave / *clock);
1561 } else {
1562 memset(dest, curPhase^1, firstFullWave / *clock);
1563 }
1564 //advance bits
1565 numBits += (firstFullWave / *clock);
1566 //set start of wave as clock align
1567 lastClkBit = firstFullWave;
1568 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1569 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1570 waveStart = 0;
1571 dest[numBits++] = curPhase; //set first read bit
1572 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1573 //top edge of wave = start of new wave
1574 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1575 if (waveStart == 0) {
1576 waveStart = i+1;
1577 waveLenCnt = 0;
1578 avgWaveVal = dest[i+1];
1579 } else { //waveEnd
1580 waveEnd = i+1;
1581 waveLenCnt = waveEnd-waveStart;
1582 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1583 if (waveLenCnt > fc){
1584 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1585 //this wave is a phase shift
1586 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1587 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1588 curPhase ^= 1;
1589 dest[numBits++] = curPhase;
1590 lastClkBit += *clock;
1591 } else if (i < lastClkBit+10+fc){
1592 //noise after a phase shift - ignore
1593 } else { //phase shift before supposed to based on clock
1594 errCnt++;
1595 dest[numBits++] = 7;
1596 }
1597 } else if (i+1 > lastClkBit + *clock + tol + fc){
1598 lastClkBit += *clock; //no phase shift but clock bit
1599 dest[numBits++] = curPhase;
1600 }
1601 avgWaveVal = 0;
1602 waveStart = i+1;
1603 }
1604 }
1605 avgWaveVal += dest[i+1];
1606 }
1607 *size = numBits;
1608 return errCnt;
1609 }
1610
1611 //by marshmellow
1612 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1613 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1614 size_t bufsize = *size;
1615 //need to loop through all samples and identify our clock, look for the ST pattern
1616 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1617 int clk = 0;
1618 int tol = 0;
1619 int i, j, skip, start, end, low, high, minClk, waveStart;
1620 bool complete = false;
1621 int tmpbuff[bufsize / 64];
1622 int waveLen[bufsize / 64];
1623 size_t testsize = (bufsize < 512) ? bufsize : 512;
1624 int phaseoff = 0;
1625 high = low = 128;
1626 memset(tmpbuff, 0, sizeof(tmpbuff));
1627
1628 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1629 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1630 return false; //just noise
1631 }
1632 i = 0;
1633 j = 0;
1634 minClk = 255;
1635 // get to first full low to prime loop and skip incomplete first pulse
1636 while ((buffer[i] < high) && (i < bufsize))
1637 ++i;
1638 while ((buffer[i] > low) && (i < bufsize))
1639 ++i;
1640 skip = i;
1641
1642 // populate tmpbuff buffer with pulse lengths
1643 while (i < bufsize) {
1644 // measure from low to low
1645 while ((buffer[i] > low) && (i < bufsize))
1646 ++i;
1647 start= i;
1648 while ((buffer[i] < high) && (i < bufsize))
1649 ++i;
1650 //first high point for this wave
1651 waveStart = i;
1652 while ((buffer[i] > low) && (i < bufsize))
1653 ++i;
1654 if (j >= (bufsize/64)) {
1655 break;
1656 }
1657 waveLen[j] = i - waveStart; //first high to first low
1658 tmpbuff[j++] = i - start;
1659 if (i-start < minClk && i < bufsize) {
1660 minClk = i - start;
1661 }
1662 }
1663 // set clock - might be able to get this externally and remove this work...
1664 if (!clk) {
1665 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1666 tol = fndClk[clkCnt]/8;
1667 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1668 clk=fndClk[clkCnt];
1669 break;
1670 }
1671 }
1672 // clock not found - ERROR
1673 if (!clk) {
1674 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1675 return false;
1676 }
1677 } else tol = clk/8;
1678
1679 *foundclock = clk;
1680
1681 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1682 start = -1;
1683 for (i = 0; i < j - 4; ++i) {
1684 skip += tmpbuff[i];
1685 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1686 if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
1687 if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
1688 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1689 start = i + 3;
1690 break;
1691 }
1692 }
1693 }
1694 }
1695 }
1696 // first ST not found - ERROR
1697 if (start < 0) {
1698 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1699 return false;
1700 }
1701 if (waveLen[i+2] > clk*1+tol)
1702 phaseoff = 0;
1703 else
1704 phaseoff = clk/2;
1705
1706 // skip over the remainder of ST
1707 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1708
1709 // now do it again to find the end
1710 end = skip;
1711 for (i += 3; i < j - 4; ++i) {
1712 end += tmpbuff[i];
1713 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) { //1 to 2 clocks depending on 2 bits prior
1714 if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
1715 if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
1716 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1717 complete = true;
1718 break;
1719 }
1720 }
1721 }
1722 }
1723 }
1724 end -= phaseoff;
1725 //didn't find second ST - ERROR
1726 if (!complete) {
1727 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1728 return false;
1729 }
1730 if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d, phaseoff: %d", skip, end, end-skip, clk, (end-skip)/clk, phaseoff);
1731 //now begin to trim out ST so we can use normal demod cmds
1732 start = skip;
1733 size_t datalen = end - start;
1734 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1735 if (datalen % clk > clk/8) {
1736 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1737 return false;
1738 } else {
1739 // padd the amount off - could be problematic... but shouldn't happen often
1740 datalen += datalen % clk;
1741 }
1742 // if datalen is less than one t55xx block - ERROR
1743 if (datalen/clk < 8*4) {
1744 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1745 return false;
1746 }
1747 size_t dataloc = start;
1748 size_t newloc = 0;
1749 i=0;
1750 // warning - overwriting buffer given with raw wave data with ST removed...
1751 while ( dataloc < bufsize-(clk/2) ) {
1752 //compensate for long high at end of ST not being high due to signal loss... (and we cut out the start of wave high part)
1753 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1754 for(i=0; i < clk/2-tol; ++i) {
1755 buffer[dataloc+i] = high+5;
1756 }
1757 }
1758 for (i=0; i<datalen; ++i) {
1759 if (i+newloc < bufsize) {
1760 if (i+newloc < dataloc)
1761 buffer[i+newloc] = buffer[dataloc];
1762
1763 dataloc++;
1764 }
1765 }
1766 newloc += i;
1767 //skip next ST - we just assume it will be there from now on...
1768 dataloc += clk*4;
1769 }
1770 *size = newloc;
1771 return true;
1772 }
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