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FIX: coverity scan found some bugs in EMV code. These are the fixes to:
[proxmark3-svn] / common / lfdemod.c
1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // Low frequency demod/decode commands
9 //-----------------------------------------------------------------------------
10 #include "lfdemod.h"
11
12 //un_comment to allow debug print calls when used not on device
13 void dummy(char *fmt, ...){}
14
15
16 #ifndef ON_DEVICE
17 # include "ui.h"
18 # include "cmdparser.h"
19 # include "cmddata.h"
20 # define prnt PrintAndLog
21 #else
22 uint8_t g_debugMode=0;
23 # define prnt dummy
24 #endif
25
26 //test samples are not just noise
27 uint8_t justNoise(uint8_t *bits, size_t size) {
28 #define THRESHOLD 123
29 uint8_t val = 1;
30 for(size_t idx=0; idx < size && val ;idx++)
31 val = bits[idx] < THRESHOLD;
32 return val;
33 }
34
35 //by marshmellow
36 //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
37 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
38 {
39 *high=0;
40 *low=255;
41 // get high and low thresholds
42 for (size_t i=0; i < size; i++){
43 if (BitStream[i] > *high) *high = BitStream[i];
44 if (BitStream[i] < *low) *low = BitStream[i];
45 }
46 if (*high < 123) return -1; // just noise
47 *high = ((*high-128)*fuzzHi + 12800)/100;
48 *low = ((*low-128)*fuzzLo + 12800)/100;
49 return 1;
50 }
51
52 // by marshmellow
53 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
54 // returns 1 if passed
55 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
56 {
57 uint8_t ans = 0;
58 for (uint8_t i = 0; i < bitLen; i++){
59 ans ^= ((bits >> i) & 1);
60 }
61 //prnt("DEBUG: ans: %d, ptype: %d",ans,pType);
62 return (ans == pType);
63 }
64
65 //by marshmellow
66 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
67 // Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
68 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
69 {
70 uint32_t parityWd = 0;
71 size_t j = 0, bitCnt = 0;
72 for (int word = 0; word < (bLen); word += pLen){
73 for (int bit=0; bit < pLen; bit++){
74 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
75 BitStream[j++] = (BitStream[startIdx+word+bit]);
76 }
77 j--; // overwrite parity with next data
78 // if parity fails then return 0
79 switch (pType) {
80 case 3: if (BitStream[j]==1) { return 0; } break; //should be 0 spacer bit
81 case 2: if (BitStream[j]==0) { return 0; } break; //should be 1 spacer bit
82 default: if (parityTest(parityWd, pLen, pType) == 0) { return 0; } break; //test parity
83 }
84 bitCnt += (pLen-1);
85 parityWd = 0;
86 }
87 // if we got here then all the parities passed
88 //return ID start index and size
89 return bitCnt;
90 }
91
92 // by marshmellow
93 // takes a array of binary values, length of bits per parity (includes parity bit),
94 // Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
95 // Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
96 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
97 {
98 uint32_t parityWd = 0;
99 size_t j = 0, bitCnt = 0;
100 for (int word = 0; word < sourceLen; word+=pLen-1) {
101 for (int bit=0; bit < pLen-1; bit++){
102 parityWd = (parityWd << 1) | BitSource[word+bit];
103 dest[j++] = (BitSource[word+bit]);
104 }
105
106 // if parity fails then return 0
107 switch (pType) {
108 case 3: dest[j++]=0; break; // marker bit which should be a 0
109 case 2: dest[j++]=1; break; // marker bit which should be a 1
110 default:
111 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
112 break;
113 }
114 bitCnt += pLen;
115 parityWd = 0;
116 }
117 // if we got here then all the parities passed
118 //return ID start index and size
119 return bitCnt;
120 }
121
122 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
123 {
124 uint32_t num = 0;
125 for(int i = 0 ; i < numbits ; i++) {
126 num = (num << 1) | (*src);
127 src++;
128 }
129 return num;
130 }
131
132 //least significant bit first
133 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
134 {
135 uint32_t num = 0;
136 for(int i = 0 ; i < numbits ; i++) {
137 num = (num << 1) | *(src + (numbits-(i+1)));
138 }
139 return num;
140 }
141
142 //by marshmellow
143 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
144 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
145 {
146 // Sanity check. If preamble length is bigger than bitstream length.
147 if ( *size <= pLen ) return 0;
148
149 uint8_t foundCnt = 0;
150 for (int idx = 0; idx < *size - pLen; idx++){
151 if (memcmp(BitStream+idx, preamble, pLen) == 0){
152 //first index found
153 foundCnt++;
154 if (foundCnt == 1){
155 *startIdx = idx;
156 }
157 if (foundCnt == 2){
158 *size = idx - *startIdx;
159 return 1;
160 }
161 }
162 }
163 return 0;
164 }
165
166 //by marshmellow
167 //takes 1s and 0s and searches for EM410x format - output EM ID
168 int Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
169 {
170 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
171 // otherwise could be a void with no arguments
172 //set defaults
173 uint32_t i = 0;
174 if (BitStream[1]>1) return -1; //allow only 1s and 0s
175
176 // 111111111 bit pattern represent start of frame
177 // include 0 in front to help get start pos
178 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
179 uint32_t idx = 0;
180 uint32_t parityBits = 0;
181 uint8_t errChk = 0;
182 uint8_t FmtLen = 10;
183 *startIdx = 0;
184 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
185 if (errChk == 0 ) return -4;
186 if (*size < 64) return -3;
187 if (*size > 64) FmtLen = 22;
188 *startIdx += 1; //get rid of 0 from preamble
189 idx = *startIdx + 9;
190 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
191 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
192 //check even parity - quit if failed
193 if (parityTest(parityBits, 5, 0) == 0) return -5;
194 //set uint64 with ID from BitStream
195 for (uint8_t ii=0; ii<4; ii++){
196 *hi = (*hi << 1) | (*lo >> 63);
197 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
198 }
199 }
200 if (errChk != 0) return 1;
201 //skip last 5 bit parity test for simplicity.
202 // *size = 64 | 128;
203 return 0;
204 }
205
206 //by marshmellow
207 //demodulates strong heavily clipped samples
208 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
209 {
210 size_t bitCnt=0, smplCnt=0, errCnt=0;
211 uint8_t waveHigh = 0;
212 for (size_t i=0; i < *size; i++){
213 if (BinStream[i] >= high && waveHigh){
214 smplCnt++;
215 } else if (BinStream[i] <= low && !waveHigh){
216 smplCnt++;
217 } else { //transition
218 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
219
220 if (smplCnt > clk-(clk/4)-1) { //full clock
221 if (smplCnt > clk + (clk/4)+1) { //too many samples
222 errCnt++;
223 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
224 BinStream[bitCnt++] = 7;
225 } else if (waveHigh) {
226 BinStream[bitCnt++] = invert;
227 BinStream[bitCnt++] = invert;
228 } else if (!waveHigh) {
229 BinStream[bitCnt++] = invert ^ 1;
230 BinStream[bitCnt++] = invert ^ 1;
231 }
232 waveHigh ^= 1;
233 smplCnt = 0;
234 } else if (smplCnt > (clk/2) - (clk/4)-1) {
235 if (waveHigh) {
236 BinStream[bitCnt++] = invert;
237 } else if (!waveHigh) {
238 BinStream[bitCnt++] = invert ^ 1;
239 }
240 waveHigh ^= 1;
241 smplCnt = 0;
242 } else if (!bitCnt) {
243 //first bit
244 waveHigh = (BinStream[i] >= high);
245 smplCnt = 1;
246 } else {
247 smplCnt++;
248 //transition bit oops
249 }
250 } else { //haven't hit new high or new low yet
251 smplCnt++;
252 }
253 }
254 }
255 *size = bitCnt;
256 return errCnt;
257 }
258
259 //by marshmellow
260 void askAmp(uint8_t *BitStream, size_t size)
261 {
262 uint8_t last = 128;
263 for(size_t i = 1; i < size; ++i){
264 if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
265 last = 255;
266 else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
267 last = 0;
268
269 BitStream[i] = last;
270 }
271 }
272
273 //by marshmellow
274 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
275 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
276 {
277 if (*size==0) return -1;
278 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
279 if (*clk==0 || start < 0) return -3;
280 if (*invert != 1) *invert = 0;
281 if (amp==1) askAmp(BinStream, *size);
282 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d, amp %d", *clk, start, amp);
283
284 uint8_t initLoopMax = 255;
285 if (initLoopMax > *size) initLoopMax = *size;
286 // Detect high and lows
287 //25% clip in case highs and lows aren't clipped [marshmellow]
288 int high, low;
289 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
290 return -2; //just noise
291
292 size_t errCnt = 0;
293 // if clean clipped waves detected run alternate demod
294 if (DetectCleanAskWave(BinStream, *size, high, low)) {
295 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
296 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
297 if (askType) //askman
298 return manrawdecode(BinStream, size, 0);
299 //askraw
300 return errCnt;
301 }
302 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
303
304 int lastBit; //set first clock check - can go negative
305 size_t i, bitnum = 0; //output counter
306 uint8_t midBit = 0;
307 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
308 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
309 size_t MaxBits = 3072; //max bits to collect
310 lastBit = start - *clk;
311
312 for (i = start; i < *size; ++i) {
313 if (i-lastBit >= *clk-tol){
314 if (BinStream[i] >= high) {
315 BinStream[bitnum++] = *invert;
316 } else if (BinStream[i] <= low) {
317 BinStream[bitnum++] = *invert ^ 1;
318 } else if (i-lastBit >= *clk+tol) {
319 if (bitnum > 0) {
320 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
321 BinStream[bitnum++]=7;
322 errCnt++;
323 }
324 } else { //in tolerance - looking for peak
325 continue;
326 }
327 midBit = 0;
328 lastBit += *clk;
329 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
330 if (BinStream[i] >= high) {
331 BinStream[bitnum++] = *invert;
332 } else if (BinStream[i] <= low) {
333 BinStream[bitnum++] = *invert ^ 1;
334 } else if (i-lastBit >= *clk/2+tol) {
335 BinStream[bitnum] = BinStream[bitnum-1];
336 bitnum++;
337 } else { //in tolerance - looking for peak
338 continue;
339 }
340 midBit = 1;
341 }
342 if (bitnum >= MaxBits) break;
343 }
344 *size = bitnum;
345 return errCnt;
346 }
347 //by marshmellow
348 //take 10 and 01 and manchester decode
349 //run through 2 times and take least errCnt
350 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert){
351 int errCnt = 0, bestErr = 1000;
352 uint16_t bitnum = 0, MaxBits = 512, bestRun = 0;
353 size_t i, k;
354 if (*size < 16) return -1;
355 //find correct start position [alignment]
356 for (k=0; k < 2; ++k){
357 for (i=k; i<*size-3; i += 2)
358 if (BitStream[i] == BitStream[i+1])
359 errCnt++;
360
361 if (bestErr > errCnt){
362 bestErr = errCnt;
363 bestRun = k;
364 }
365 errCnt=0;
366 }
367 //decode
368 for (i=bestRun; i < *size-3; i += 2){
369 if (BitStream[i] == 1 && (BitStream[i+1] == 0)){
370 BitStream[bitnum++] = invert;
371 } else if ((BitStream[i] == 0) && BitStream[i+1] == 1){
372 BitStream[bitnum++] = invert^1;
373 } else {
374 BitStream[bitnum++] = 7;
375 }
376 if (bitnum>MaxBits) break;
377 }
378 *size=bitnum;
379 return bestErr;
380 }
381
382 uint32_t manchesterEncode2Bytes(uint16_t datain) {
383 uint32_t output = 0;
384 uint8_t curBit = 0;
385 for (uint8_t i=0; i<16; i++) {
386 curBit = (datain >> (15-i) & 1);
387 output |= (1<<(((15-i)*2)+curBit));
388 }
389 return output;
390 }
391
392 //by marshmellow
393 //encode binary data into binary manchester
394 int ManchesterEncode(uint8_t *BitStream, size_t size)
395 {
396 size_t modIdx=20000, i=0;
397 if (size>modIdx) return -1;
398 for (size_t idx=0; idx < size; idx++){
399 BitStream[idx+modIdx++] = BitStream[idx];
400 BitStream[idx+modIdx++] = BitStream[idx]^1;
401 }
402 for (; i<(size*2); i++){
403 BitStream[i] = BitStream[i+20000];
404 }
405 return i;
406 }
407
408 //by marshmellow
409 //take 01 or 10 = 1 and 11 or 00 = 0
410 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
411 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
412 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
413 {
414 uint16_t bitnum = 0;
415 uint16_t errCnt = 0;
416 size_t i = offset;
417 uint16_t MaxBits=512;
418 //if not enough samples - error
419 if (*size < 51) return -1;
420 //check for phase change faults - skip one sample if faulty
421 uint8_t offsetA = 1, offsetB = 1;
422 for (; i<48; i+=2){
423 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
424 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
425 }
426 if (!offsetA && offsetB) offset++;
427 for (i=offset; i<*size-3; i+=2){
428 //check for phase error
429 if (BitStream[i+1]==BitStream[i+2]) {
430 BitStream[bitnum++]=7;
431 errCnt++;
432 }
433 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
434 BitStream[bitnum++]=1^invert;
435 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
436 BitStream[bitnum++]=invert;
437 } else {
438 BitStream[bitnum++]=7;
439 errCnt++;
440 }
441 if(bitnum>MaxBits) break;
442 }
443 *size=bitnum;
444 return errCnt;
445 }
446
447 // by marshmellow
448 // demod gProxIIDemod
449 // error returns as -x
450 // success returns start position in BitStream
451 // BitStream must contain previously askrawdemod and biphasedemoded data
452 int gProxII_Demod(uint8_t BitStream[], size_t *size)
453 {
454 size_t startIdx=0;
455 uint8_t preamble[] = {1,1,1,1,1,0};
456
457 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
458 if (errChk == 0) return -3; //preamble not found
459 if (*size != 96) return -2; //should have found 96 bits
460 //check first 6 spacer bits to verify format
461 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
462 //confirmed proper separator bits found
463 //return start position
464 return (int) startIdx;
465 }
466 return -5; //spacer bits not found - not a valid gproxII
467 }
468
469 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
470 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
471 {
472 size_t last_transition = 0;
473 size_t idx = 1;
474 //uint32_t maxVal=0;
475 if (fchigh==0) fchigh=10;
476 if (fclow==0) fclow=8;
477 //set the threshold close to 0 (graph) or 128 std to avoid static
478 uint8_t threshold_value = 123;
479 size_t preLastSample = 0;
480 size_t LastSample = 0;
481 size_t currSample = 0;
482 // sync to first lo-hi transition, and threshold
483
484 // Need to threshold first sample
485 // skip 160 samples to allow antenna/samples to settle
486 if(dest[160] < threshold_value) dest[0] = 0;
487 else dest[0] = 1;
488
489 size_t numBits = 0;
490 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
491 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
492 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
493 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
494 for(idx = 161; idx < size-20; idx++) {
495 // threshold current value
496
497 if (dest[idx] < threshold_value) dest[idx] = 0;
498 else dest[idx] = 1;
499
500 // Check for 0->1 transition
501 if (dest[idx-1] < dest[idx]) {
502 preLastSample = LastSample;
503 LastSample = currSample;
504 currSample = idx-last_transition;
505 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
506 //do nothing with extra garbage
507 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
508 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
509 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
510 dest[numBits-1]=1;
511 }
512 dest[numBits++]=1;
513
514 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
515 //do nothing with beginning garbage
516 } 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)
517 dest[numBits++]=1;
518 } else { //9+ = 10 sample waves (or 6+ = 7)
519 dest[numBits++]=0;
520 }
521 last_transition = idx;
522 }
523 }
524 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
525 }
526
527 //translate 11111100000 to 10
528 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
529 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
530 uint8_t invert, uint8_t fchigh, uint8_t fclow)
531 {
532 uint8_t lastval=dest[0];
533 size_t idx=0;
534 size_t numBits=0;
535 uint32_t n=1;
536 for( idx=1; idx < size; idx++) {
537 n++;
538 if (dest[idx]==lastval) continue; //skip until we hit a transition
539
540 //find out how many bits (n) we collected
541 //if lastval was 1, we have a 1->0 crossing
542 if (dest[idx-1]==1) {
543 n = (n * fclow + rfLen/2) / rfLen;
544 } else {// 0->1 crossing
545 n = (n * fchigh + rfLen/2) / rfLen;
546 }
547 if (n == 0) n = 1;
548
549 //add to our destination the bits we collected
550 memset(dest+numBits, dest[idx-1]^invert , n);
551 numBits += n;
552 n=0;
553 lastval=dest[idx];
554 }//end for
555 // if valid extra bits at the end were all the same frequency - add them in
556 if (n > rfLen/fchigh) {
557 if (dest[idx-2]==1) {
558 n = (n * fclow + rfLen/2) / rfLen;
559 } else {
560 n = (n * fchigh + rfLen/2) / rfLen;
561 }
562 memset(dest+numBits, dest[idx-1]^invert , n);
563 numBits += n;
564 }
565 return numBits;
566 }
567
568 //by marshmellow (from holiman's base)
569 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
570 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
571 {
572 // FSK demodulator
573 size = fsk_wave_demod(dest, size, fchigh, fclow);
574 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
575 return size;
576 }
577
578 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
579 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
580 {
581 if (justNoise(dest, *size)) return -1;
582
583 size_t numStart=0, size2 = *size, startIdx=0;
584 // FSK demodulator
585 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
586 if (*size < 96*2) return -2;
587 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
588 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
589 // find bitstring in array
590 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
591 if (errChk == 0) return -3; //preamble not found
592
593 numStart = startIdx + sizeof(preamble);
594 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
595 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
596 if (dest[idx] == dest[idx+1]){
597 return -4; //not manchester data
598 }
599 *hi2 = (*hi2<<1)|(*hi>>31);
600 *hi = (*hi<<1)|(*lo>>31);
601 //Then, shift in a 0 or one into low
602 *lo <<= 1;
603 if (dest[idx] && !dest[idx+1]) // 1 0
604 *lo |= 1;
605 else // 0 1
606 *lo |= 0;
607 }
608 return (int)startIdx;
609 }
610
611 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
612 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
613 {
614 if (justNoise(dest, *size)) return -1;
615
616 size_t numStart=0, size2 = *size, startIdx=0;
617 // FSK demodulator
618 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
619 if (*size < 96) return -2;
620
621 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
622 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
623
624 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
625 if (errChk == 0) return -3; //preamble not found
626
627 numStart = startIdx + sizeof(preamble);
628 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
629 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
630 if (dest[idx] == dest[idx+1])
631 return -4; //not manchester data
632 *hi2 = (*hi2<<1)|(*hi>>31);
633 *hi = (*hi<<1)|(*lo>>31);
634 //Then, shift in a 0 or one into low
635 if (dest[idx] && !dest[idx+1]) // 1 0
636 *lo=(*lo<<1)|1;
637 else // 0 1
638 *lo=(*lo<<1)|0;
639 }
640 return (int)startIdx;
641 }
642
643 int IOdemodFSK(uint8_t *dest, size_t size)
644 {
645 if (justNoise(dest, size)) return -1;
646 //make sure buffer has data
647 if (size < 66*64) return -2;
648 // FSK demodulator
649 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
650 if (size < 65) return -3; //did we get a good demod?
651 //Index map
652 //0 10 20 30 40 50 60
653 //| | | | | | |
654 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
655 //-----------------------------------------------------------------------------
656 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
657 //
658 //XSF(version)facility:codeone+codetwo
659 //Handle the data
660 size_t startIdx = 0;
661 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
662 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
663 if (errChk == 0) return -4; //preamble not found
664
665 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
666 //confirmed proper separator bits found
667 //return start position
668 return (int) startIdx;
669 }
670 return -5;
671 }
672
673 // by marshmellow
674 // find viking preamble 0xF200 in already demoded data
675 int VikingDemod_AM(uint8_t *dest, size_t *size) {
676 //make sure buffer has data
677 if (*size < 64*2) return -2;
678 size_t startIdx = 0;
679 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};
680 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
681 if (errChk == 0) return -4; //preamble not found
682 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^
683 bytebits_to_byte(dest+startIdx+8,8) ^
684 bytebits_to_byte(dest+startIdx+16,8) ^
685 bytebits_to_byte(dest+startIdx+24,8) ^
686 bytebits_to_byte(dest+startIdx+32,8) ^
687 bytebits_to_byte(dest+startIdx+40,8) ^
688 bytebits_to_byte(dest+startIdx+48,8) ^
689 bytebits_to_byte(dest+startIdx+56,8);
690 if ( checkCalc != 0xA8 ) return -5;
691 if (*size != 64) return -6;
692 //return start position
693 return (int)startIdx;
694 }
695
696 // by iceman
697 // find Visa2000 preamble in already demoded data
698 int Visa2kDemod_AM(uint8_t *dest, size_t *size) {
699 if (*size < 96) return -1; //make sure buffer has data
700 size_t startIdx = 0;
701 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};
702 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
703 if (errChk == 0) return -2; //preamble not found
704 if (*size != 96) return -3; //wrong demoded size
705 //return start position
706 return (int)startIdx;
707 }
708 // by iceman
709 // find Noralsy preamble in already demoded data
710 int NoralsyDemod_AM(uint8_t *dest, size_t *size) {
711 if (*size < 96) return -1; //make sure buffer has data
712 size_t startIdx = 0;
713 uint8_t preamble[] = {1,0,1,1,1,0,1,1,0,0,0,0};
714 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
715 if (errChk == 0) return -2; //preamble not found
716 if (*size != 96) return -3; //wrong demoded size
717 //return start position
718 return (int)startIdx;
719 }
720 // find presco preamble 0x10D in already demoded data
721 int PrescoDemod(uint8_t *dest, size_t *size) {
722 if (*size < 128*2) return -1; //make sure buffer has data
723 size_t startIdx = 0;
724 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};
725 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
726 if (errChk == 0) return -2; //preamble not found
727 if (*size != 128) return -3; //wrong demoded size
728 //return start position
729 return (int)startIdx;
730 }
731
732 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
733 // BitStream must contain previously askrawdemod and biphasedemoded data
734 int FDXBdemodBI(uint8_t *dest, size_t *size) {
735 if (*size < 128*2) return -1; //make sure buffer has enough data
736 size_t startIdx = 0;
737 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
738 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
739 if (errChk == 0) return -2; //preamble not found
740 if (*size != 128) return -3; //wrong demoded size
741 //return start position
742 return (int)startIdx;
743 }
744
745 // ASK/Diphase fc/64 (inverted Biphase)
746 // Note: this i s not a demod, this is only a detection
747 // the parameter *dest needs to be demoded before call
748 // 0xFFFF preamble, 64bits
749 int JablotronDemod(uint8_t *dest, size_t *size){
750 if (*size < 64*2) return -1; //make sure buffer has enough data
751 size_t startIdx = 0;
752 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0};
753 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
754 if (errChk == 0) return -2; //preamble not found
755 if (*size != 64) return -3; // wrong demoded size
756
757 uint8_t checkchksum = 0;
758 for (int i=16; i < 56; i += 8) {
759 checkchksum += bytebits_to_byte(dest+startIdx+i,8);
760 }
761 checkchksum ^= 0x3A;
762 uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
763 if ( checkchksum != crc ) return -5;
764 return (int)startIdx;
765 }
766
767 // by marshmellow
768 // FSK Demod then try to locate an AWID ID
769 int AWIDdemodFSK(uint8_t *dest, size_t *size)
770 {
771 //make sure buffer has enough data
772 if (*size < 96*50) return -1;
773
774 if (justNoise(dest, *size)) return -2;
775
776 // FSK demodulator
777 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
778 if (*size < 96) return -3; //did we get a good demod?
779
780 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
781 size_t startIdx = 0;
782 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
783 if (errChk == 0) return -4; //preamble not found
784 if (*size != 96) return -5;
785 return (int)startIdx;
786 }
787
788 // by marshmellow
789 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
790 int PyramiddemodFSK(uint8_t *dest, size_t *size)
791 {
792 //make sure buffer has data
793 if (*size < 128*50) return -5;
794
795 //test samples are not just noise
796 if (justNoise(dest, *size)) return -1;
797
798 // FSK demodulator
799 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
800 if (*size < 128) return -2; //did we get a good demod?
801
802 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1};
803 size_t startIdx = 0;
804 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
805 if (errChk == 0) return -4; //preamble not found
806 if (*size != 128) return -3;
807 return (int)startIdx;
808 }
809
810 // find nedap preamble in already demoded data
811 int NedapDemod(uint8_t *dest, size_t *size) {
812 //make sure buffer has data
813 if (*size < 128) return -3;
814
815 size_t startIdx = 0;
816 //uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
817 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
818 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
819 if (errChk == 0) return -4; //preamble not found
820 return (int) startIdx;
821 }
822
823 // Find IDTEC PSK1, RF Preamble == 0x4944544B, Demodsize 64bits
824 // by iceman
825 int IdteckDemodPSK(uint8_t *dest, size_t *size) {
826 //make sure buffer has data
827 if (*size < 64*2) return -1;
828 size_t startIdx = 0;
829 uint8_t preamble[] = {0,1,0,0,1,0,0,1,0,1,0,0,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,0,1,0,1,1};
830 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
831 if (errChk == 0) return -2; //preamble not found
832 if (*size != 64) return -3; // wrong demoded size
833 return (int) startIdx;
834 }
835
836 // by marshmellow
837 // to detect a wave that has heavily clipped (clean) samples
838 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
839 {
840 bool allArePeaks = true;
841 uint16_t cntPeaks=0;
842 size_t loopEnd = 512+160;
843 if (loopEnd > size) loopEnd = size;
844 for (size_t i=160; i<loopEnd; i++){
845 if (dest[i]>low && dest[i]<high)
846 allArePeaks = false;
847 else
848 cntPeaks++;
849 }
850 if (!allArePeaks){
851 if (cntPeaks > 300) return true;
852 }
853 return allArePeaks;
854 }
855 // by marshmellow
856 // to help detect clocks on heavily clipped samples
857 // based on count of low to low
858 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
859 {
860 uint8_t fndClk[] = {8,16,32,40,50,64,128};
861 size_t startwave;
862 size_t i = 100;
863 size_t minClk = 255;
864 // get to first full low to prime loop and skip incomplete first pulse
865 while ((dest[i] < high) && (i < size))
866 ++i;
867 while ((dest[i] > low) && (i < size))
868 ++i;
869
870 // loop through all samples
871 while (i < size) {
872 // measure from low to low
873 while ((dest[i] > low) && (i < size))
874 ++i;
875 startwave= i;
876 while ((dest[i] < high) && (i < size))
877 ++i;
878 while ((dest[i] > low) && (i < size))
879 ++i;
880 //get minimum measured distance
881 if (i-startwave < minClk && i < size)
882 minClk = i - startwave;
883 }
884 // set clock
885 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
886 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
887 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
888 return fndClk[clkCnt];
889 }
890 return 0;
891 }
892
893 // by marshmellow
894 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
895 // maybe somehow adjust peak trimming value based on samples to fix?
896 // return start index of best starting position for that clock and return clock (by reference)
897 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
898 {
899 size_t i=1;
900 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
901 uint8_t clkEnd = 9;
902 uint8_t loopCnt = 255; //don't need to loop through entire array...
903 if (size <= loopCnt+60) return -1; //not enough samples
904 size -= 60; //sometimes there is a strange end wave - filter out this....
905 //if we already have a valid clock
906 uint8_t clockFnd=0;
907 for (;i<clkEnd;++i)
908 if (clk[i] == *clock) clockFnd = i;
909 //clock found but continue to find best startpos
910
911 //get high and low peak
912 int peak, low;
913 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
914
915 //test for large clean peaks
916 if (!clockFnd){
917 if (DetectCleanAskWave(dest, size, peak, low)==1){
918 int ans = DetectStrongAskClock(dest, size, peak, low);
919 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
920 for (i=clkEnd-1; i>0; i--){
921 if (clk[i] == ans) {
922 *clock = ans;
923 //clockFnd = i;
924 return 0; // for strong waves i don't use the 'best start position' yet...
925 //break; //clock found but continue to find best startpos [not yet]
926 }
927 }
928 }
929 }
930 uint8_t ii;
931 uint8_t clkCnt, tol = 0;
932 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
933 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
934 size_t errCnt = 0;
935 size_t arrLoc, loopEnd;
936
937 if (clockFnd>0) {
938 clkCnt = clockFnd;
939 clkEnd = clockFnd+1;
940 } else {
941 clkCnt=1;
942 }
943
944 //test each valid clock from smallest to greatest to see which lines up
945 for(; clkCnt < clkEnd; clkCnt++) {
946 if (clk[clkCnt] <= 32) {
947 tol=1;
948 } else {
949 tol=0;
950 }
951 //if no errors allowed - keep start within the first clock
952 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128)
953 loopCnt = clk[clkCnt] * 2;
954
955 bestErr[clkCnt] = 1000;
956
957 //try lining up the peaks by moving starting point (try first few clocks)
958 for (ii=0; ii < loopCnt; ii++){
959 if (dest[ii] < peak && dest[ii] > low) continue;
960
961 errCnt = 0;
962 // now that we have the first one lined up test rest of wave array
963 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
964 for (i=0; i < loopEnd; ++i){
965 arrLoc = ii + (i * clk[clkCnt]);
966 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
967 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
968 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
969 }else{ //error no peak detected
970 errCnt++;
971 }
972 }
973 //if we found no errors then we can stop here and a low clock (common clocks)
974 // this is correct one - return this clock
975 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d", clk[clkCnt], errCnt, ii, i);
976 if (errCnt==0 && clkCnt<7) {
977 if (!clockFnd) *clock = clk[clkCnt];
978 return ii;
979 }
980 //if we found errors see if it is lowest so far and save it as best run
981 if (errCnt < bestErr[clkCnt]) {
982 bestErr[clkCnt] = errCnt;
983 bestStart[clkCnt] = ii;
984 }
985 }
986 }
987 uint8_t k;
988 uint8_t best = 0;
989 for (k=1; k < clkEnd; ++k){
990 if (bestErr[k] < bestErr[best]){
991 if (bestErr[k] == 0) bestErr[k]=1;
992 // current best bit to error ratio vs new bit to error ratio
993 if ( (size/clk[best])/bestErr[best] < (size/clk[k])/bestErr[k] ){
994 best = k;
995 }
996 }
997 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d", clk[k], bestErr[k], clk[best], bestStart[best]);
998 }
999 if (!clockFnd) *clock = clk[best];
1000 return bestStart[best];
1001 }
1002
1003 //by marshmellow
1004 //detect psk clock by reading each phase shift
1005 // a phase shift is determined by measuring the sample length of each wave
1006 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
1007 {
1008 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
1009 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1010 if (size == 0) return 0;
1011 if (size<loopCnt) loopCnt = size-20;
1012
1013 //if we already have a valid clock quit
1014 size_t i=1;
1015 for (; i < 8; ++i)
1016 if (clk[i] == clock) return clock;
1017
1018 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
1019 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
1020 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
1021 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
1022 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
1023 fc = countFC(dest, size, 0);
1024 if (fc!=2 && fc!=4 && fc!=8) return -1;
1025 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
1026
1027 //find first full wave
1028 for (i=160; i<loopCnt; i++){
1029 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1030 if (waveStart == 0) {
1031 waveStart = i+1;
1032 //prnt("DEBUG: waveStart: %d",waveStart);
1033 } else {
1034 waveEnd = i+1;
1035 //prnt("DEBUG: waveEnd: %d",waveEnd);
1036 waveLenCnt = waveEnd-waveStart;
1037 if (waveLenCnt > fc){
1038 firstFullWave = waveStart;
1039 fullWaveLen=waveLenCnt;
1040 break;
1041 }
1042 waveStart=0;
1043 }
1044 }
1045 }
1046 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1047
1048 //test each valid clock from greatest to smallest to see which lines up
1049 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1050 lastClkBit = firstFullWave; //set end of wave as clock align
1051 waveStart = 0;
1052 errCnt=0;
1053 peakcnt=0;
1054 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1055
1056 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1057 //top edge of wave = start of new wave
1058 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1059 if (waveStart == 0) {
1060 waveStart = i+1;
1061 waveLenCnt=0;
1062 } else { //waveEnd
1063 waveEnd = i+1;
1064 waveLenCnt = waveEnd-waveStart;
1065 if (waveLenCnt > fc){
1066 //if this wave is a phase shift
1067 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);
1068 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1069 peakcnt++;
1070 lastClkBit+=clk[clkCnt];
1071 } else if (i<lastClkBit+8){
1072 //noise after a phase shift - ignore
1073 } else { //phase shift before supposed to based on clock
1074 errCnt++;
1075 }
1076 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1077 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1078 }
1079 waveStart=i+1;
1080 }
1081 }
1082 }
1083 if (errCnt == 0){
1084 return clk[clkCnt];
1085 }
1086 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1087 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1088 }
1089 //all tested with errors
1090 //return the highest clk with the most peaks found
1091 uint8_t best=7;
1092 for (i=7; i>=1; i--){
1093 if (peaksdet[i] > peaksdet[best]) {
1094 best = i;
1095 }
1096 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1097 }
1098 return clk[best];
1099 }
1100
1101 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1102 //find shortest transition from high to low
1103 size_t i = 0;
1104 size_t transition1 = 0;
1105 int lowestTransition = 255;
1106 bool lastWasHigh = false;
1107
1108 //find first valid beginning of a high or low wave
1109 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1110 ++i;
1111 while ((dest[i] < peak && dest[i] > low) && (i < size))
1112 ++i;
1113 lastWasHigh = (dest[i] >= peak);
1114
1115 if (i==size) return 0;
1116 transition1 = i;
1117
1118 for (;i < size; i++) {
1119 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1120 lastWasHigh = (dest[i] >= peak);
1121 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1122 transition1 = i;
1123 }
1124 }
1125 if (lowestTransition == 255) lowestTransition = 0;
1126 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1127 return lowestTransition;
1128 }
1129
1130 //by marshmellow
1131 //detect nrz clock by reading #peaks vs no peaks(or errors)
1132 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1133 {
1134 size_t i=0;
1135 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1136 size_t loopCnt = 4096; //don't need to loop through entire array...
1137 if (size == 0) return 0;
1138 if (size<loopCnt) loopCnt = size-20;
1139 //if we already have a valid clock quit
1140 for (; i < 8; ++i)
1141 if (clk[i] == clock) return clock;
1142
1143 //get high and low peak
1144 int peak, low;
1145 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1146
1147 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1148 size_t ii;
1149 uint8_t clkCnt;
1150 uint8_t tol = 0;
1151 uint16_t smplCnt = 0;
1152 int16_t peakcnt = 0;
1153 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1154 uint16_t maxPeak = 255;
1155 bool firstpeak = false;
1156 //test for large clipped waves
1157 for (i=0; i<loopCnt; i++){
1158 if (dest[i] >= peak || dest[i] <= low){
1159 if (!firstpeak) continue;
1160 smplCnt++;
1161 } else {
1162 firstpeak=true;
1163 if (smplCnt > 6 ){
1164 if (maxPeak > smplCnt){
1165 maxPeak = smplCnt;
1166 //prnt("maxPk: %d",maxPeak);
1167 }
1168 peakcnt++;
1169 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1170 smplCnt=0;
1171 }
1172 }
1173 }
1174 bool errBitHigh = 0;
1175 bool bitHigh = 0;
1176 uint8_t ignoreCnt = 0;
1177 uint8_t ignoreWindow = 4;
1178 bool lastPeakHigh = 0;
1179 int lastBit = 0;
1180 peakcnt=0;
1181 //test each valid clock from smallest to greatest to see which lines up
1182 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1183 //ignore clocks smaller than smallest peak
1184 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1185 //try lining up the peaks by moving starting point (try first 256)
1186 for (ii=20; ii < loopCnt; ++ii){
1187 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1188 peakcnt=0;
1189 bitHigh = false;
1190 ignoreCnt = 0;
1191 lastBit = ii-clk[clkCnt];
1192 //loop through to see if this start location works
1193 for (i = ii; i < size-20; ++i) {
1194 //if we are at a clock bit
1195 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1196 //test high/low
1197 if (dest[i] >= peak || dest[i] <= low) {
1198 //if same peak don't count it
1199 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1200 peakcnt++;
1201 }
1202 lastPeakHigh = (dest[i] >= peak);
1203 bitHigh = true;
1204 errBitHigh = false;
1205 ignoreCnt = ignoreWindow;
1206 lastBit += clk[clkCnt];
1207 } else if (i == lastBit + clk[clkCnt] + tol) {
1208 lastBit += clk[clkCnt];
1209 }
1210 //else if not a clock bit and no peaks
1211 } else if (dest[i] < peak && dest[i] > low){
1212 if (ignoreCnt==0){
1213 bitHigh=false;
1214 if (errBitHigh==true) peakcnt--;
1215 errBitHigh=false;
1216 } else {
1217 ignoreCnt--;
1218 }
1219 // else if not a clock bit but we have a peak
1220 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1221 //error bar found no clock...
1222 errBitHigh=true;
1223 }
1224 }
1225 if(peakcnt>peaksdet[clkCnt]) {
1226 peaksdet[clkCnt]=peakcnt;
1227 }
1228 }
1229 }
1230 }
1231 int iii=7;
1232 uint8_t best=0;
1233 for (iii=7; iii > 0; iii--){
1234 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1235 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1236 best = iii;
1237 }
1238 } else if (peaksdet[iii] > peaksdet[best]){
1239 best = iii;
1240 }
1241 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);
1242 }
1243
1244 return clk[best];
1245 }
1246
1247 // by marshmellow
1248 // convert psk1 demod to psk2 demod
1249 // only transition waves are 1s
1250 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1251 {
1252 size_t i=1;
1253 uint8_t lastBit=BitStream[0];
1254 for (; i<size; i++){
1255 if (BitStream[i]==7){
1256 //ignore errors
1257 } else if (lastBit!=BitStream[i]){
1258 lastBit=BitStream[i];
1259 BitStream[i]=1;
1260 } else {
1261 BitStream[i]=0;
1262 }
1263 }
1264 return;
1265 }
1266
1267 // by marshmellow
1268 // convert psk2 demod to psk1 demod
1269 // from only transition waves are 1s to phase shifts change bit
1270 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1271 {
1272 uint8_t phase=0;
1273 for (size_t i=0; i<size; i++){
1274 if (BitStream[i]==1){
1275 phase ^=1;
1276 }
1277 BitStream[i]=phase;
1278 }
1279 return;
1280 }
1281
1282 // redesigned by marshmellow adjusted from existing decode functions
1283 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1284 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1285 {
1286 //26 bit 40134 format (don't know other formats)
1287 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};
1288 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};
1289 size_t startidx = 0;
1290 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1291 // if didn't find preamble try again inverting
1292 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1293 *invert ^= 1;
1294 }
1295 if (*size != 64 && *size != 224) return -2;
1296 if (*invert==1)
1297 for (size_t i = startidx; i < *size; i++)
1298 bitStream[i] ^= 1;
1299
1300 return (int) startidx;
1301 }
1302
1303 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1304 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1305 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1306 if (justNoise(dest, *size)) return -1;
1307 *clk = DetectNRZClock(dest, *size, *clk);
1308 if (*clk==0) return -2;
1309 size_t i, gLen = 4096;
1310 if (gLen>*size) gLen = *size-20;
1311 int high, low;
1312 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1313
1314 uint8_t bit=0;
1315 //convert wave samples to 1's and 0's
1316 for(i=20; i < *size-20; i++){
1317 if (dest[i] >= high) bit = 1;
1318 if (dest[i] <= low) bit = 0;
1319 dest[i] = bit;
1320 }
1321 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1322 size_t lastBit = 0;
1323 size_t numBits = 0;
1324 for(i=21; i < *size-20; i++) {
1325 //if transition detected or large number of same bits - store the passed bits
1326 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1327 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1328 numBits += (i - lastBit + (*clk/4)) / *clk;
1329 lastBit = i-1;
1330 }
1331 }
1332 *size = numBits;
1333 return 0;
1334 }
1335
1336 //by marshmellow
1337 //detects the bit clock for FSK given the high and low Field Clocks
1338 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1339 {
1340 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1341 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1342 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1343 uint8_t rfLensFnd = 0;
1344 uint8_t lastFCcnt = 0;
1345 uint16_t fcCounter = 0;
1346 uint16_t rfCounter = 0;
1347 uint8_t firstBitFnd = 0;
1348 size_t i;
1349 if (size == 0) return 0;
1350
1351 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1352 rfLensFnd=0;
1353 fcCounter=0;
1354 rfCounter=0;
1355 firstBitFnd=0;
1356 //prnt("DEBUG: fcTol: %d",fcTol);
1357 // prime i to first peak / up transition
1358 for (i = 160; i < size-20; i++)
1359 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1360 break;
1361
1362 for (; i < size-20; i++){
1363 fcCounter++;
1364 rfCounter++;
1365
1366 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1367 continue;
1368 // else new peak
1369 // if we got less than the small fc + tolerance then set it to the small fc
1370 if (fcCounter < fcLow+fcTol)
1371 fcCounter = fcLow;
1372 else //set it to the large fc
1373 fcCounter = fcHigh;
1374
1375 //look for bit clock (rf/xx)
1376 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1377 //not the same size as the last wave - start of new bit sequence
1378 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1379 for (int ii=0; ii<15; ii++){
1380 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1381 rfCnts[ii]++;
1382 rfCounter = 0;
1383 break;
1384 }
1385 }
1386 if (rfCounter > 0 && rfLensFnd < 15){
1387 //prnt("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1388 rfCnts[rfLensFnd]++;
1389 rfLens[rfLensFnd++] = rfCounter;
1390 }
1391 } else {
1392 firstBitFnd++;
1393 }
1394 rfCounter=0;
1395 lastFCcnt=fcCounter;
1396 }
1397 fcCounter=0;
1398 }
1399 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1400
1401 for (i=0; i<15; i++){
1402 //get highest 2 RF values (might need to get more values to compare or compare all?)
1403 if (rfCnts[i]>rfCnts[rfHighest]){
1404 rfHighest3=rfHighest2;
1405 rfHighest2=rfHighest;
1406 rfHighest=i;
1407 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1408 rfHighest3=rfHighest2;
1409 rfHighest2=i;
1410 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1411 rfHighest3=i;
1412 }
1413 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1414 }
1415 // set allowed clock remainder tolerance to be 1 large field clock length+1
1416 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1417 uint8_t tol1 = fcHigh+1;
1418
1419 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1420
1421 // loop to find the highest clock that has a remainder less than the tolerance
1422 // compare samples counted divided by
1423 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1424 int ii=7;
1425 for (; ii>=2; ii--){
1426 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1427 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1428 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1429 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1430 break;
1431 }
1432 }
1433 }
1434 }
1435
1436 if (ii<0) return 0; // oops we went too far
1437
1438 return clk[ii];
1439 }
1440
1441 //by marshmellow
1442 //countFC is to detect the field clock lengths.
1443 //counts and returns the 2 most common wave lengths
1444 //mainly used for FSK field clock detection
1445 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1446 {
1447 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1448 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1449 uint8_t fcLensFnd = 0;
1450 uint8_t lastFCcnt=0;
1451 uint8_t fcCounter = 0;
1452 size_t i;
1453 if (size == 0) return 0;
1454
1455 // prime i to first up transition
1456 for (i = 160; i < size-20; i++)
1457 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1458 break;
1459
1460 for (; i < size-20; i++){
1461 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1462 // new up transition
1463 fcCounter++;
1464 if (fskAdj){
1465 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1466 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1467 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1468 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1469 // save last field clock count (fc/xx)
1470 lastFCcnt = fcCounter;
1471 }
1472 // find which fcLens to save it to:
1473 for (int ii=0; ii<15; ii++){
1474 if (fcLens[ii]==fcCounter){
1475 fcCnts[ii]++;
1476 fcCounter=0;
1477 break;
1478 }
1479 }
1480 if (fcCounter>0 && fcLensFnd<15){
1481 //add new fc length
1482 fcCnts[fcLensFnd]++;
1483 fcLens[fcLensFnd++]=fcCounter;
1484 }
1485 fcCounter=0;
1486 } else {
1487 // count sample
1488 fcCounter++;
1489 }
1490 }
1491
1492 uint8_t best1=14, best2=14, best3=14;
1493 uint16_t maxCnt1=0;
1494 // go through fclens and find which ones are bigest 2
1495 for (i=0; i<15; i++){
1496 // get the 3 best FC values
1497 if (fcCnts[i]>maxCnt1) {
1498 best3=best2;
1499 best2=best1;
1500 maxCnt1=fcCnts[i];
1501 best1=i;
1502 } else if(fcCnts[i]>fcCnts[best2]){
1503 best3=best2;
1504 best2=i;
1505 } else if(fcCnts[i]>fcCnts[best3]){
1506 best3=i;
1507 }
1508 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]);
1509 }
1510 if (fcLens[best1]==0) return 0;
1511 uint8_t fcH=0, fcL=0;
1512 if (fcLens[best1]>fcLens[best2]){
1513 fcH=fcLens[best1];
1514 fcL=fcLens[best2];
1515 } else{
1516 fcH=fcLens[best2];
1517 fcL=fcLens[best1];
1518 }
1519 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1520 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]);
1521 return 0; //lots of waves not psk or fsk
1522 }
1523 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1524
1525 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1526 if (fskAdj) return fcs;
1527 return fcLens[best1];
1528 }
1529
1530 //by marshmellow - demodulate PSK1 wave
1531 //uses wave lengths (# Samples)
1532 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1533 {
1534 if (size == 0) return -1;
1535 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1536 if (*size<loopCnt) loopCnt = *size;
1537
1538 size_t numBits=0;
1539 uint8_t curPhase = *invert;
1540 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1541 uint8_t fc=0, fullWaveLen=0, tol=1;
1542 uint16_t errCnt=0, waveLenCnt=0;
1543 fc = countFC(dest, *size, 0);
1544 if (fc!=2 && fc!=4 && fc!=8) return -1;
1545 //prnt("DEBUG: FC: %d",fc);
1546 *clock = DetectPSKClock(dest, *size, *clock);
1547 if (*clock == 0) return -1;
1548 int avgWaveVal=0, lastAvgWaveVal=0;
1549 //find first phase shift
1550 for (i=0; i<loopCnt; i++){
1551 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1552 waveEnd = i+1;
1553 //prnt("DEBUG: waveEnd: %d",waveEnd);
1554 waveLenCnt = waveEnd-waveStart;
1555 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1556 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1557 firstFullWave = waveStart;
1558 fullWaveLen=waveLenCnt;
1559 //if average wave value is > graph 0 then it is an up wave or a 1
1560 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1561 break;
1562 }
1563 waveStart = i+1;
1564 avgWaveVal = 0;
1565 }
1566 avgWaveVal += dest[i+2];
1567 }
1568 if (firstFullWave == 0) {
1569 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1570 // so skip a little to ensure we are past any Start Signal
1571 firstFullWave = 160;
1572 memset(dest, curPhase, firstFullWave / *clock);
1573 } else {
1574 memset(dest, curPhase^1, firstFullWave / *clock);
1575 }
1576 //advance bits
1577 numBits += (firstFullWave / *clock);
1578 //set start of wave as clock align
1579 lastClkBit = firstFullWave;
1580 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1581 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1582 waveStart = 0;
1583 dest[numBits++] = curPhase; //set first read bit
1584 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1585 //top edge of wave = start of new wave
1586 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1587 if (waveStart == 0) {
1588 waveStart = i+1;
1589 waveLenCnt = 0;
1590 avgWaveVal = dest[i+1];
1591 } else { //waveEnd
1592 waveEnd = i+1;
1593 waveLenCnt = waveEnd-waveStart;
1594 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1595 if (waveLenCnt > fc){
1596 //prnt("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1597 //this wave is a phase shift
1598 //prnt("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1599 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1600 curPhase ^= 1;
1601 dest[numBits++] = curPhase;
1602 lastClkBit += *clock;
1603 } else if (i < lastClkBit+10+fc){
1604 //noise after a phase shift - ignore
1605 } else { //phase shift before supposed to based on clock
1606 errCnt++;
1607 dest[numBits++] = 7;
1608 }
1609 } else if (i+1 > lastClkBit + *clock + tol + fc){
1610 lastClkBit += *clock; //no phase shift but clock bit
1611 dest[numBits++] = curPhase;
1612 }
1613 avgWaveVal = 0;
1614 waveStart = i+1;
1615 }
1616 }
1617 avgWaveVal += dest[i+1];
1618 }
1619 *size = numBits;
1620 return errCnt;
1621 }
1622
1623 //by marshmellow
1624 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1625 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1626 size_t bufsize = *size;
1627 //need to loop through all samples and identify our clock, look for the ST pattern
1628 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1629 int clk = 0;
1630 int tol = 0;
1631 int i, j, skip, start, end, low, high, minClk, waveStart;
1632 bool complete = false;
1633 int tmpbuff[bufsize / 32]; //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
1634 int waveLen[bufsize / 32]; // if clock is larger then we waste memory in array size that is not needed...
1635 size_t testsize = (bufsize < 512) ? bufsize : 512;
1636 int phaseoff = 0;
1637 high = low = 128;
1638 memset(tmpbuff, 0, sizeof(tmpbuff));
1639 memset(waveLen, 0, sizeof(waveLen));
1640
1641
1642 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1643 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1644 return false; //just noise
1645 }
1646 i = 0;
1647 j = 0;
1648 minClk = 255;
1649 // get to first full low to prime loop and skip incomplete first pulse
1650 while ((buffer[i] < high) && (i < bufsize))
1651 ++i;
1652 while ((buffer[i] > low) && (i < bufsize))
1653 ++i;
1654 skip = i;
1655
1656 // populate tmpbuff buffer with pulse lengths
1657 while (i < bufsize) {
1658 // measure from low to low
1659 while ((buffer[i] > low) && (i < bufsize))
1660 ++i;
1661 start= i;
1662 while ((buffer[i] < high) && (i < bufsize))
1663 ++i;
1664 //first high point for this wave
1665 waveStart = i;
1666 while ((buffer[i] > low) && (i < bufsize))
1667 ++i;
1668 if (j >= (bufsize/32)) {
1669 break;
1670 }
1671 waveLen[j] = i - waveStart; //first high to first low
1672 tmpbuff[j++] = i - start;
1673 if (i-start < minClk && i < bufsize) {
1674 minClk = i - start;
1675 }
1676 }
1677 // set clock - might be able to get this externally and remove this work...
1678 if (!clk) {
1679 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1680 tol = fndClk[clkCnt]/8;
1681 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1682 clk=fndClk[clkCnt];
1683 break;
1684 }
1685 }
1686 // clock not found - ERROR
1687 if (!clk) {
1688 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1689 return false;
1690 }
1691 } else tol = clk/8;
1692
1693 *foundclock = clk;
1694
1695 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1696 start = -1;
1697 for (i = 0; i < j - 4; ++i) {
1698 skip += tmpbuff[i];
1699 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1700 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
1701 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
1702 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1703 start = i + 3;
1704 break;
1705 }
1706 }
1707 }
1708 }
1709 }
1710 // first ST not found - ERROR
1711 if (start < 0) {
1712 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1713 return false;
1714 } else {
1715 if (g_debugMode==2) prnt("DEBUG STT: first STT found at: %d, j=%d",start, j);
1716 }
1717 if (waveLen[i+2] > clk*1+tol)
1718 phaseoff = 0;
1719 else
1720 phaseoff = clk/2;
1721
1722 // skip over the remainder of ST
1723 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1724
1725 // now do it again to find the end
1726 end = skip;
1727 for (i += 3; i < j - 4; ++i) {
1728 end += tmpbuff[i];
1729 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1730 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
1731 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
1732 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1733 complete = true;
1734 break;
1735 }
1736 }
1737 }
1738 }
1739 }
1740 end -= phaseoff;
1741 //didn't find second ST - ERROR
1742 if (!complete) {
1743 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1744 return false;
1745 }
1746 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);
1747 //now begin to trim out ST so we can use normal demod cmds
1748 start = skip;
1749 size_t datalen = end - start;
1750 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1751 if ( clk - (datalen % clk) <= clk/8) {
1752 // padd the amount off - could be problematic... but shouldn't happen often
1753 datalen += clk - (datalen % clk);
1754 } else if ( (datalen % clk) <= clk/8 ) {
1755 // padd the amount off - could be problematic... but shouldn't happen often
1756 datalen -= datalen % clk;
1757 } else {
1758 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1759 return false;
1760 }
1761 // if datalen is less than one t55xx block - ERROR
1762 if (datalen/clk < 8*4) {
1763 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1764 return false;
1765 }
1766 size_t dataloc = start;
1767 if (buffer[dataloc-(clk*4)-(clk/8)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
1768 //we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start
1769 for ( i=0; i <= (clk/8); ++i ) {
1770 if ( buffer[dataloc - (clk*4) - i] <= low ) {
1771 dataloc -= i;
1772 break;
1773 }
1774 }
1775 }
1776
1777 size_t newloc = 0;
1778 i=0;
1779 if (g_debugMode==2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);
1780
1781 // warning - overwriting buffer given with raw wave data with ST removed...
1782 while ( dataloc < bufsize-(clk/2) ) {
1783 //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)
1784 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1785 for(i=0; i < clk/2-tol; ++i) {
1786 buffer[dataloc+i] = high+5;
1787 }
1788 }
1789 for (i=0; i<datalen; ++i) {
1790 if (i+newloc < bufsize) {
1791 if (i+newloc < dataloc)
1792 buffer[i+newloc] = buffer[dataloc];
1793
1794 dataloc++;
1795 }
1796 }
1797 newloc += i;
1798 //skip next ST - we just assume it will be there from now on...
1799 if (g_debugMode==2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
1800 dataloc += clk*4;
1801 }
1802 *size = newloc;
1803 return true;
1804 }
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