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CHG: 'lf em4x' - the em4x50 demod didn't calc ASKDemod_ext with a refenence bool.
[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
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, amp %d", *clk, start, amp);
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 //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 //by marshmellow
349 //take 10 and 01 and manchester decode
350 //run through 2 times and take least errCnt
351 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert){
352 int errCnt = 0, bestErr = 1000;
353 uint16_t bitnum = 0, MaxBits = 512, bestRun = 0;
354 size_t i, k;
355 if (*size < 16) return -1;
356 //find correct start position [alignment]
357 for (k=0; k < 2; ++k){
358 for (i=k; i<*size-3; i += 2)
359 if (BitStream[i] == BitStream[i+1])
360 errCnt++;
361
362 if (bestErr > errCnt){
363 bestErr = errCnt;
364 bestRun = k;
365 }
366 errCnt=0;
367 }
368 //decode
369 for (i=bestRun; i < *size-3; i += 2){
370 if (BitStream[i] == 1 && (BitStream[i+1] == 0)){
371 BitStream[bitnum++] = invert;
372 } else if ((BitStream[i] == 0) && BitStream[i+1] == 1){
373 BitStream[bitnum++] = invert^1;
374 } else {
375 BitStream[bitnum++] = 7;
376 }
377 if (bitnum>MaxBits) break;
378 }
379 *size=bitnum;
380 return bestErr;
381 }
382
383 uint32_t manchesterEncode2Bytes(uint16_t datain) {
384 uint32_t output = 0;
385 uint8_t curBit = 0;
386 for (uint8_t i=0; i<16; i++) {
387 curBit = (datain >> (15-i) & 1);
388 output |= (1<<(((15-i)*2)+curBit));
389 }
390 return output;
391 }
392
393 //by marshmellow
394 //encode binary data into binary manchester
395 int ManchesterEncode(uint8_t *BitStream, size_t size)
396 {
397 size_t modIdx=20000, i=0;
398 if (size>modIdx) return -1;
399 for (size_t idx=0; idx < size; idx++){
400 BitStream[idx+modIdx++] = BitStream[idx];
401 BitStream[idx+modIdx++] = BitStream[idx]^1;
402 }
403 for (; i<(size*2); i++){
404 BitStream[i] = BitStream[i+20000];
405 }
406 return i;
407 }
408
409 //by marshmellow
410 //take 01 or 10 = 1 and 11 or 00 = 0
411 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
412 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
413 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
414 {
415 uint16_t bitnum = 0;
416 uint16_t errCnt = 0;
417 size_t i = offset;
418 uint16_t MaxBits=512;
419 //if not enough samples - error
420 if (*size < 51) return -1;
421 //check for phase change faults - skip one sample if faulty
422 uint8_t offsetA = 1, offsetB = 1;
423 for (; i<48; i+=2){
424 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
425 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
426 }
427 if (!offsetA && offsetB) offset++;
428 for (i=offset; i<*size-3; i+=2){
429 //check for phase error
430 if (BitStream[i+1]==BitStream[i+2]) {
431 BitStream[bitnum++]=7;
432 errCnt++;
433 }
434 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
435 BitStream[bitnum++]=1^invert;
436 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
437 BitStream[bitnum++]=invert;
438 } else {
439 BitStream[bitnum++]=7;
440 errCnt++;
441 }
442 if(bitnum>MaxBits) break;
443 }
444 *size=bitnum;
445 return errCnt;
446 }
447
448 // by marshmellow
449 // demod gProxIIDemod
450 // error returns as -x
451 // success returns start position in BitStream
452 // BitStream must contain previously askrawdemod and biphasedemoded data
453 int gProxII_Demod(uint8_t BitStream[], size_t *size)
454 {
455 size_t startIdx=0;
456 uint8_t preamble[] = {1,1,1,1,1,0};
457
458 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
459 if (errChk == 0) return -3; //preamble not found
460 if (*size != 96) return -2; //should have found 96 bits
461 //check first 6 spacer bits to verify format
462 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
463 //confirmed proper separator bits found
464 //return start position
465 return (int) startIdx;
466 }
467 return -5; //spacer bits not found - not a valid gproxII
468 }
469
470 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
471 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
472 {
473 size_t last_transition = 0;
474 size_t idx = 1;
475 //uint32_t maxVal=0;
476 if (fchigh==0) fchigh=10;
477 if (fclow==0) fclow=8;
478 //set the threshold close to 0 (graph) or 128 std to avoid static
479 uint8_t threshold_value = 123;
480 size_t preLastSample = 0;
481 size_t LastSample = 0;
482 size_t currSample = 0;
483 // sync to first lo-hi transition, and threshold
484
485 // Need to threshold first sample
486 // skip 160 samples to allow antenna/samples to settle
487 if(dest[160] < threshold_value) dest[0] = 0;
488 else dest[0] = 1;
489
490 size_t numBits = 0;
491 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
492 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
493 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
494 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
495 for(idx = 161; idx < size-20; idx++) {
496 // threshold current value
497
498 if (dest[idx] < threshold_value) dest[idx] = 0;
499 else dest[idx] = 1;
500
501 // Check for 0->1 transition
502 if (dest[idx-1] < dest[idx]) {
503 preLastSample = LastSample;
504 LastSample = currSample;
505 currSample = idx-last_transition;
506 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
507 //do nothing with extra garbage
508 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
509 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
510 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
511 dest[numBits-1]=1;
512 }
513 dest[numBits++]=1;
514
515 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
516 //do nothing with beginning garbage
517 } 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)
518 dest[numBits++]=1;
519 } else { //9+ = 10 sample waves (or 6+ = 7)
520 dest[numBits++]=0;
521 }
522 last_transition = idx;
523 }
524 }
525 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
526 }
527
528 //translate 11111100000 to 10
529 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
530 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
531 uint8_t invert, uint8_t fchigh, uint8_t fclow)
532 {
533 uint8_t lastval=dest[0];
534 size_t idx=0;
535 size_t numBits=0;
536 uint32_t n=1;
537 for( idx=1; idx < size; idx++) {
538 n++;
539 if (dest[idx]==lastval) continue; //skip until we hit a transition
540
541 //find out how many bits (n) we collected
542 //if lastval was 1, we have a 1->0 crossing
543 if (dest[idx-1]==1) {
544 n = (n * fclow + rfLen/2) / rfLen;
545 } else {// 0->1 crossing
546 n = (n * fchigh + rfLen/2) / rfLen;
547 }
548 if (n == 0) n = 1;
549
550 //add to our destination the bits we collected
551 memset(dest+numBits, dest[idx-1]^invert , n);
552 numBits += n;
553 n=0;
554 lastval=dest[idx];
555 }//end for
556 // if valid extra bits at the end were all the same frequency - add them in
557 if (n > rfLen/fchigh) {
558 if (dest[idx-2]==1) {
559 n = (n * fclow + rfLen/2) / rfLen;
560 } else {
561 n = (n * fchigh + rfLen/2) / rfLen;
562 }
563 memset(dest+numBits, dest[idx-1]^invert , n);
564 numBits += n;
565 }
566 return numBits;
567 }
568
569 //by marshmellow (from holiman's base)
570 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
571 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
572 {
573 // FSK demodulator
574 size = fsk_wave_demod(dest, size, fchigh, fclow);
575 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
576 return size;
577 }
578
579 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
580 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
581 {
582 if (justNoise(dest, *size)) return -1;
583
584 size_t numStart=0, size2 = *size, startIdx=0;
585 // FSK demodulator
586 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
587 if (*size < 96*2) return -2;
588 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
589 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
590 // find bitstring in array
591 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
592 if (errChk == 0) return -3; //preamble not found
593
594 numStart = startIdx + sizeof(preamble);
595 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
596 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
597 if (dest[idx] == dest[idx+1]){
598 return -4; //not manchester data
599 }
600 *hi2 = (*hi2<<1)|(*hi>>31);
601 *hi = (*hi<<1)|(*lo>>31);
602 //Then, shift in a 0 or one into low
603 *lo <<= 1;
604 if (dest[idx] && !dest[idx+1]) // 1 0
605 *lo |= 1;
606 else // 0 1
607 *lo |= 0;
608 }
609 return (int)startIdx;
610 }
611
612 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
613 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
614 {
615 if (justNoise(dest, *size)) return -1;
616
617 size_t numStart=0, size2 = *size, startIdx=0;
618 // FSK demodulator
619 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
620 if (*size < 96) return -2;
621
622 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
623 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
624
625 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
626 if (errChk == 0) return -3; //preamble not found
627
628 numStart = startIdx + sizeof(preamble);
629 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
630 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
631 if (dest[idx] == dest[idx+1])
632 return -4; //not manchester data
633 *hi2 = (*hi2<<1)|(*hi>>31);
634 *hi = (*hi<<1)|(*lo>>31);
635 //Then, shift in a 0 or one into low
636 if (dest[idx] && !dest[idx+1]) // 1 0
637 *lo=(*lo<<1)|1;
638 else // 0 1
639 *lo=(*lo<<1)|0;
640 }
641 return (int)startIdx;
642 }
643
644 int IOdemodFSK(uint8_t *dest, size_t size)
645 {
646 if (justNoise(dest, size)) return -1;
647 //make sure buffer has data
648 if (size < 66*64) return -2;
649 // FSK demodulator
650 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
651 if (size < 65) return -3; //did we get a good demod?
652 //Index map
653 //0 10 20 30 40 50 60
654 //| | | | | | |
655 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
656 //-----------------------------------------------------------------------------
657 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
658 //
659 //XSF(version)facility:codeone+codetwo
660 //Handle the data
661 size_t startIdx = 0;
662 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
663 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
664 if (errChk == 0) return -4; //preamble not found
665
666 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
667 //confirmed proper separator bits found
668 //return start position
669 return (int) startIdx;
670 }
671 return -5;
672 }
673
674 // by marshmellow
675 // find viking preamble 0xF200 in already demoded data
676 int VikingDemod_AM(uint8_t *dest, size_t *size) {
677 //make sure buffer has data
678 if (*size < 64*2) return -2;
679 size_t startIdx = 0;
680 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};
681 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
682 if (errChk == 0) return -4; //preamble not found
683 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^
684 bytebits_to_byte(dest+startIdx+8,8) ^
685 bytebits_to_byte(dest+startIdx+16,8) ^
686 bytebits_to_byte(dest+startIdx+24,8) ^
687 bytebits_to_byte(dest+startIdx+32,8) ^
688 bytebits_to_byte(dest+startIdx+40,8) ^
689 bytebits_to_byte(dest+startIdx+48,8) ^
690 bytebits_to_byte(dest+startIdx+56,8);
691 if ( checkCalc != 0xA8 ) return -5;
692 if (*size != 64) return -6;
693 //return start position
694 return (int)startIdx;
695 }
696
697 // by iceman
698 // find Visa2000 preamble in already demoded data
699 int Visa2kDemod_AM(uint8_t *dest, size_t *size) {
700 if (*size < 96) return -1; //make sure buffer has data
701 size_t startIdx = 0;
702 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};
703 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
704 if (errChk == 0) return -2; //preamble not found
705 if (*size != 96) return -3; //wrong demoded size
706 //return start position
707 return (int)startIdx;
708 }
709 // by iceman
710 // find Noralsy preamble in already demoded data
711 int NoralsyDemod_AM(uint8_t *dest, size_t *size) {
712 if (*size < 96) return -1; //make sure buffer has data
713 size_t startIdx = 0;
714 uint8_t preamble[] = {1,0,1,1,1,0,1,1,0,0,0,0};
715 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
716 if (errChk == 0) return -2; //preamble not found
717 if (*size != 96) return -3; //wrong demoded size
718 //return start position
719 return (int)startIdx;
720 }
721 // find presco preamble 0x10D in already demoded data
722 int PrescoDemod(uint8_t *dest, size_t *size) {
723 if (*size < 128*2) return -1; //make sure buffer has data
724 size_t startIdx = 0;
725 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};
726 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
727 if (errChk == 0) return -2; //preamble not found
728 if (*size != 128) return -3; //wrong demoded size
729 //return start position
730 return (int)startIdx;
731 }
732
733 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
734 // BitStream must contain previously askrawdemod and biphasedemoded data
735 int FDXBdemodBI(uint8_t *dest, size_t *size) {
736 if (*size < 128*2) return -1; //make sure buffer has enough data
737 size_t startIdx = 0;
738 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
739 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
740 if (errChk == 0) return -2; //preamble not found
741 if (*size != 128) return -3; //wrong demoded size
742 //return start position
743 return (int)startIdx;
744 }
745
746 // ASK/Diphase fc/64 (inverted Biphase)
747 // Note: this i s not a demod, this is only a detection
748 // the parameter *dest needs to be demoded before call
749 // 0xFFFF preamble, 64bits
750 int JablotronDemod(uint8_t *dest, size_t *size){
751 if (*size < 64*2) return -1; //make sure buffer has enough data
752 size_t startIdx = 0;
753 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0};
754 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
755 if (errChk == 0) return -2; //preamble not found
756 if (*size != 64) return -3; // wrong demoded size
757
758 uint8_t checkchksum = 0;
759 for (int i=16; i < 56; i += 8) {
760 checkchksum += bytebits_to_byte(dest+startIdx+i,8);
761 }
762 checkchksum ^= 0x3A;
763 uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
764 if ( checkchksum != crc ) return -5;
765 return (int)startIdx;
766 }
767
768 // by marshmellow
769 // FSK Demod then try to locate an AWID ID
770 int AWIDdemodFSK(uint8_t *dest, size_t *size)
771 {
772 //make sure buffer has enough data
773 if (*size < 96*50) return -1;
774
775 if (justNoise(dest, *size)) return -2;
776
777 // FSK demodulator
778 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
779 if (*size < 96) return -3; //did we get a good demod?
780
781 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
782 size_t startIdx = 0;
783 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
784 if (errChk == 0) return -4; //preamble not found
785 if (*size != 96) return -5;
786 return (int)startIdx;
787 }
788
789 // by marshmellow
790 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
791 int PyramiddemodFSK(uint8_t *dest, size_t *size)
792 {
793 //make sure buffer has data
794 if (*size < 128*50) return -5;
795
796 //test samples are not just noise
797 if (justNoise(dest, *size)) return -1;
798
799 // FSK demodulator
800 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
801 if (*size < 128) return -2; //did we get a good demod?
802
803 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};
804 size_t startIdx = 0;
805 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
806 if (errChk == 0) return -4; //preamble not found
807 if (*size != 128) return -3;
808 return (int)startIdx;
809 }
810
811 // find nedap preamble in already demoded data
812 int NedapDemod(uint8_t *dest, size_t *size) {
813 //make sure buffer has data
814 if (*size < 128) return -3;
815
816 size_t startIdx = 0;
817 //uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
818 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
819 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
820 if (errChk == 0) return -4; //preamble not found
821 return (int) startIdx;
822 }
823
824 // Find IDTEC PSK1, RF Preamble == 0x4944544B, Demodsize 64bits
825 // by iceman
826 int IdteckDemodPSK(uint8_t *dest, size_t *size) {
827 //make sure buffer has data
828 if (*size < 64*2) return -1;
829 size_t startIdx = 0;
830 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};
831 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
832 if (errChk == 0) return -2; //preamble not found
833 if (*size != 64) return -3; // wrong demoded size
834 return (int) startIdx;
835 }
836
837 // by marshmellow
838 // to detect a wave that has heavily clipped (clean) samples
839 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
840 {
841 bool allArePeaks = true;
842 uint16_t cntPeaks=0;
843 size_t loopEnd = 512+160;
844 if (loopEnd > size) loopEnd = size;
845 for (size_t i=160; i<loopEnd; i++){
846 if (dest[i]>low && dest[i]<high)
847 allArePeaks = false;
848 else
849 cntPeaks++;
850 }
851 if (!allArePeaks){
852 if (cntPeaks > 300) return true;
853 }
854 return allArePeaks;
855 }
856 // by marshmellow
857 // to help detect clocks on heavily clipped samples
858 // based on count of low to low
859 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
860 {
861 uint8_t fndClk[] = {8,16,32,40,50,64,128};
862 size_t startwave;
863 size_t i = 100;
864 size_t minClk = 255;
865 // get to first full low to prime loop and skip incomplete first pulse
866 while ((dest[i] < high) && (i < size))
867 ++i;
868 while ((dest[i] > low) && (i < size))
869 ++i;
870
871 // loop through all samples
872 while (i < size) {
873 // measure from low to low
874 while ((dest[i] > low) && (i < size))
875 ++i;
876 startwave= i;
877 while ((dest[i] < high) && (i < size))
878 ++i;
879 while ((dest[i] > low) && (i < size))
880 ++i;
881 //get minimum measured distance
882 if (i-startwave < minClk && i < size)
883 minClk = i - startwave;
884 }
885 // set clock
886 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
887 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
888 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
889 return fndClk[clkCnt];
890 }
891 return 0;
892 }
893
894 // by marshmellow
895 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
896 // maybe somehow adjust peak trimming value based on samples to fix?
897 // return start index of best starting position for that clock and return clock (by reference)
898 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
899 {
900 size_t i=1;
901 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
902 uint8_t clkEnd = 9;
903 uint8_t loopCnt = 255; //don't need to loop through entire array...
904 if (size <= loopCnt+60) return -1; //not enough samples
905 size -= 60; //sometimes there is a strange end wave - filter out this....
906 //if we already have a valid clock
907 uint8_t clockFnd=0;
908 for (;i<clkEnd;++i)
909 if (clk[i] == *clock) clockFnd = i;
910 //clock found but continue to find best startpos
911
912 //get high and low peak
913 int peak, low;
914 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
915
916 //test for large clean peaks
917 if (!clockFnd){
918 if (DetectCleanAskWave(dest, size, peak, low)==1){
919 int ans = DetectStrongAskClock(dest, size, peak, low);
920 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
921 for (i=clkEnd-1; i>0; i--){
922 if (clk[i] == ans) {
923 *clock = ans;
924 //clockFnd = i;
925 return 0; // for strong waves i don't use the 'best start position' yet...
926 //break; //clock found but continue to find best startpos [not yet]
927 }
928 }
929 }
930 }
931 uint8_t ii;
932 uint8_t clkCnt, tol = 0;
933 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
934 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
935 size_t errCnt = 0;
936 size_t arrLoc, loopEnd;
937
938 if (clockFnd>0) {
939 clkCnt = clockFnd;
940 clkEnd = clockFnd+1;
941 } else {
942 clkCnt=1;
943 }
944
945 //test each valid clock from smallest to greatest to see which lines up
946 for(; clkCnt < clkEnd; clkCnt++) {
947 if (clk[clkCnt] <= 32) {
948 tol=1;
949 } else {
950 tol=0;
951 }
952 //if no errors allowed - keep start within the first clock
953 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128)
954 loopCnt = clk[clkCnt] * 2;
955
956 bestErr[clkCnt] = 1000;
957
958 //try lining up the peaks by moving starting point (try first few clocks)
959 for (ii=0; ii < loopCnt; ii++){
960 if (dest[ii] < peak && dest[ii] > low) continue;
961
962 errCnt = 0;
963 // now that we have the first one lined up test rest of wave array
964 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
965 for (i=0; i < loopEnd; ++i){
966 arrLoc = ii + (i * clk[clkCnt]);
967 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
968 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
969 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
970 }else{ //error no peak detected
971 errCnt++;
972 }
973 }
974 //if we found no errors then we can stop here and a low clock (common clocks)
975 // this is correct one - return this clock
976 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d", clk[clkCnt], errCnt, ii, i);
977 if (errCnt==0 && clkCnt<7) {
978 if (!clockFnd) *clock = clk[clkCnt];
979 return ii;
980 }
981 //if we found errors see if it is lowest so far and save it as best run
982 if (errCnt < bestErr[clkCnt]) {
983 bestErr[clkCnt] = errCnt;
984 bestStart[clkCnt] = ii;
985 }
986 }
987 }
988 uint8_t k;
989 uint8_t best = 0;
990 for (k=1; k < clkEnd; ++k){
991 if (bestErr[k] < bestErr[best]){
992 if (bestErr[k] == 0) bestErr[k]=1;
993 // current best bit to error ratio vs new bit to error ratio
994 if ( (size/clk[best])/bestErr[best] < (size/clk[k])/bestErr[k] ){
995 best = k;
996 }
997 }
998 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]);
999 }
1000 if (!clockFnd) *clock = clk[best];
1001 return bestStart[best];
1002 }
1003
1004 //by marshmellow
1005 //detect psk clock by reading each phase shift
1006 // a phase shift is determined by measuring the sample length of each wave
1007 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
1008 {
1009 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
1010 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1011 if (size == 0) return 0;
1012 if (size<loopCnt) loopCnt = size-20;
1013
1014 //if we already have a valid clock quit
1015 size_t i=1;
1016 for (; i < 8; ++i)
1017 if (clk[i] == clock) return clock;
1018
1019 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
1020 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
1021 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
1022 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
1023 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
1024 fc = countFC(dest, size, 0);
1025 if (fc!=2 && fc!=4 && fc!=8) return -1;
1026 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
1027
1028 //find first full wave
1029 for (i=160; i<loopCnt; i++){
1030 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1031 if (waveStart == 0) {
1032 waveStart = i+1;
1033 //prnt("DEBUG: waveStart: %d",waveStart);
1034 } else {
1035 waveEnd = i+1;
1036 //prnt("DEBUG: waveEnd: %d",waveEnd);
1037 waveLenCnt = waveEnd-waveStart;
1038 if (waveLenCnt > fc){
1039 firstFullWave = waveStart;
1040 fullWaveLen=waveLenCnt;
1041 break;
1042 }
1043 waveStart=0;
1044 }
1045 }
1046 }
1047 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1048
1049 //test each valid clock from greatest to smallest to see which lines up
1050 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1051 lastClkBit = firstFullWave; //set end of wave as clock align
1052 waveStart = 0;
1053 errCnt=0;
1054 peakcnt=0;
1055 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1056
1057 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1058 //top edge of wave = start of new wave
1059 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1060 if (waveStart == 0) {
1061 waveStart = i+1;
1062 waveLenCnt=0;
1063 } else { //waveEnd
1064 waveEnd = i+1;
1065 waveLenCnt = waveEnd-waveStart;
1066 if (waveLenCnt > fc){
1067 //if this wave is a phase shift
1068 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);
1069 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1070 peakcnt++;
1071 lastClkBit+=clk[clkCnt];
1072 } else if (i<lastClkBit+8){
1073 //noise after a phase shift - ignore
1074 } else { //phase shift before supposed to based on clock
1075 errCnt++;
1076 }
1077 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1078 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1079 }
1080 waveStart=i+1;
1081 }
1082 }
1083 }
1084 if (errCnt == 0){
1085 return clk[clkCnt];
1086 }
1087 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1088 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1089 }
1090 //all tested with errors
1091 //return the highest clk with the most peaks found
1092 uint8_t best=7;
1093 for (i=7; i>=1; i--){
1094 if (peaksdet[i] > peaksdet[best]) {
1095 best = i;
1096 }
1097 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1098 }
1099 return clk[best];
1100 }
1101
1102 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1103 //find shortest transition from high to low
1104 size_t i = 0;
1105 size_t transition1 = 0;
1106 int lowestTransition = 255;
1107 bool lastWasHigh = false;
1108
1109 //find first valid beginning of a high or low wave
1110 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1111 ++i;
1112 while ((dest[i] < peak && dest[i] > low) && (i < size))
1113 ++i;
1114 lastWasHigh = (dest[i] >= peak);
1115
1116 if (i==size) return 0;
1117 transition1 = i;
1118
1119 for (;i < size; i++) {
1120 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1121 lastWasHigh = (dest[i] >= peak);
1122 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1123 transition1 = i;
1124 }
1125 }
1126 if (lowestTransition == 255) lowestTransition = 0;
1127 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1128 return lowestTransition;
1129 }
1130
1131 //by marshmellow
1132 //detect nrz clock by reading #peaks vs no peaks(or errors)
1133 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1134 {
1135 size_t i=0;
1136 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1137 size_t loopCnt = 4096; //don't need to loop through entire array...
1138 if (size == 0) return 0;
1139 if (size<loopCnt) loopCnt = size-20;
1140 //if we already have a valid clock quit
1141 for (; i < 8; ++i)
1142 if (clk[i] == clock) return clock;
1143
1144 //get high and low peak
1145 int peak, low;
1146 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1147
1148 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1149 size_t ii;
1150 uint8_t clkCnt;
1151 uint8_t tol = 0;
1152 uint16_t smplCnt = 0;
1153 int16_t peakcnt = 0;
1154 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1155 uint16_t maxPeak = 255;
1156 bool firstpeak = false;
1157 //test for large clipped waves
1158 for (i=0; i<loopCnt; i++){
1159 if (dest[i] >= peak || dest[i] <= low){
1160 if (!firstpeak) continue;
1161 smplCnt++;
1162 } else {
1163 firstpeak=true;
1164 if (smplCnt > 6 ){
1165 if (maxPeak > smplCnt){
1166 maxPeak = smplCnt;
1167 //prnt("maxPk: %d",maxPeak);
1168 }
1169 peakcnt++;
1170 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1171 smplCnt=0;
1172 }
1173 }
1174 }
1175 bool errBitHigh = 0;
1176 bool bitHigh = 0;
1177 uint8_t ignoreCnt = 0;
1178 uint8_t ignoreWindow = 4;
1179 bool lastPeakHigh = 0;
1180 int lastBit = 0;
1181 peakcnt=0;
1182 //test each valid clock from smallest to greatest to see which lines up
1183 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1184 //ignore clocks smaller than smallest peak
1185 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1186 //try lining up the peaks by moving starting point (try first 256)
1187 for (ii=20; ii < loopCnt; ++ii){
1188 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1189 peakcnt=0;
1190 bitHigh = false;
1191 ignoreCnt = 0;
1192 lastBit = ii-clk[clkCnt];
1193 //loop through to see if this start location works
1194 for (i = ii; i < size-20; ++i) {
1195 //if we are at a clock bit
1196 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1197 //test high/low
1198 if (dest[i] >= peak || dest[i] <= low) {
1199 //if same peak don't count it
1200 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1201 peakcnt++;
1202 }
1203 lastPeakHigh = (dest[i] >= peak);
1204 bitHigh = true;
1205 errBitHigh = false;
1206 ignoreCnt = ignoreWindow;
1207 lastBit += clk[clkCnt];
1208 } else if (i == lastBit + clk[clkCnt] + tol) {
1209 lastBit += clk[clkCnt];
1210 }
1211 //else if not a clock bit and no peaks
1212 } else if (dest[i] < peak && dest[i] > low){
1213 if (ignoreCnt==0){
1214 bitHigh=false;
1215 if (errBitHigh==true) peakcnt--;
1216 errBitHigh=false;
1217 } else {
1218 ignoreCnt--;
1219 }
1220 // else if not a clock bit but we have a peak
1221 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1222 //error bar found no clock...
1223 errBitHigh=true;
1224 }
1225 }
1226 if(peakcnt>peaksdet[clkCnt]) {
1227 peaksdet[clkCnt]=peakcnt;
1228 }
1229 }
1230 }
1231 }
1232 int iii=7;
1233 uint8_t best=0;
1234 for (iii=7; iii > 0; iii--){
1235 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1236 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1237 best = iii;
1238 }
1239 } else if (peaksdet[iii] > peaksdet[best]){
1240 best = iii;
1241 }
1242 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);
1243 }
1244
1245 return clk[best];
1246 }
1247
1248 // by marshmellow
1249 // convert psk1 demod to psk2 demod
1250 // only transition waves are 1s
1251 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1252 {
1253 size_t i=1;
1254 uint8_t lastBit=BitStream[0];
1255 for (; i<size; i++){
1256 if (BitStream[i]==7){
1257 //ignore errors
1258 } else if (lastBit!=BitStream[i]){
1259 lastBit=BitStream[i];
1260 BitStream[i]=1;
1261 } else {
1262 BitStream[i]=0;
1263 }
1264 }
1265 return;
1266 }
1267
1268 // by marshmellow
1269 // convert psk2 demod to psk1 demod
1270 // from only transition waves are 1s to phase shifts change bit
1271 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1272 {
1273 uint8_t phase=0;
1274 for (size_t i=0; i<size; i++){
1275 if (BitStream[i]==1){
1276 phase ^=1;
1277 }
1278 BitStream[i]=phase;
1279 }
1280 return;
1281 }
1282
1283 // redesigned by marshmellow adjusted from existing decode functions
1284 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1285 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1286 {
1287 //26 bit 40134 format (don't know other formats)
1288 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};
1289 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};
1290 size_t startidx = 0;
1291 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1292 // if didn't find preamble try again inverting
1293 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1294 *invert ^= 1;
1295 }
1296 if (*size != 64 && *size != 224) return -2;
1297 if (*invert==1)
1298 for (size_t i = startidx; i < *size; i++)
1299 bitStream[i] ^= 1;
1300
1301 return (int) startidx;
1302 }
1303
1304 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1305 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1306 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1307 if (justNoise(dest, *size)) return -1;
1308 *clk = DetectNRZClock(dest, *size, *clk);
1309 if (*clk==0) return -2;
1310 size_t i, gLen = 4096;
1311 if (gLen>*size) gLen = *size-20;
1312 int high, low;
1313 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1314
1315 uint8_t bit=0;
1316 //convert wave samples to 1's and 0's
1317 for(i=20; i < *size-20; i++){
1318 if (dest[i] >= high) bit = 1;
1319 if (dest[i] <= low) bit = 0;
1320 dest[i] = bit;
1321 }
1322 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1323 size_t lastBit = 0;
1324 size_t numBits = 0;
1325 for(i=21; i < *size-20; i++) {
1326 //if transition detected or large number of same bits - store the passed bits
1327 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1328 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1329 numBits += (i - lastBit + (*clk/4)) / *clk;
1330 lastBit = i-1;
1331 }
1332 }
1333 *size = numBits;
1334 return 0;
1335 }
1336
1337 //by marshmellow
1338 //detects the bit clock for FSK given the high and low Field Clocks
1339 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1340 {
1341 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1342 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1343 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1344 uint8_t rfLensFnd = 0;
1345 uint8_t lastFCcnt = 0;
1346 uint16_t fcCounter = 0;
1347 uint16_t rfCounter = 0;
1348 uint8_t firstBitFnd = 0;
1349 size_t i;
1350 if (size == 0) return 0;
1351
1352 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1353 rfLensFnd=0;
1354 fcCounter=0;
1355 rfCounter=0;
1356 firstBitFnd=0;
1357 //prnt("DEBUG: fcTol: %d",fcTol);
1358 // prime i to first peak / up transition
1359 for (i = 160; i < size-20; i++)
1360 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1361 break;
1362
1363 for (; i < size-20; i++){
1364 fcCounter++;
1365 rfCounter++;
1366
1367 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1368 continue;
1369 // else new peak
1370 // if we got less than the small fc + tolerance then set it to the small fc
1371 if (fcCounter < fcLow+fcTol)
1372 fcCounter = fcLow;
1373 else //set it to the large fc
1374 fcCounter = fcHigh;
1375
1376 //look for bit clock (rf/xx)
1377 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1378 //not the same size as the last wave - start of new bit sequence
1379 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1380 for (int ii=0; ii<15; ii++){
1381 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1382 rfCnts[ii]++;
1383 rfCounter = 0;
1384 break;
1385 }
1386 }
1387 if (rfCounter > 0 && rfLensFnd < 15){
1388 //prnt("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1389 rfCnts[rfLensFnd]++;
1390 rfLens[rfLensFnd++] = rfCounter;
1391 }
1392 } else {
1393 firstBitFnd++;
1394 }
1395 rfCounter=0;
1396 lastFCcnt=fcCounter;
1397 }
1398 fcCounter=0;
1399 }
1400 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1401
1402 for (i=0; i<15; i++){
1403 //get highest 2 RF values (might need to get more values to compare or compare all?)
1404 if (rfCnts[i]>rfCnts[rfHighest]){
1405 rfHighest3=rfHighest2;
1406 rfHighest2=rfHighest;
1407 rfHighest=i;
1408 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1409 rfHighest3=rfHighest2;
1410 rfHighest2=i;
1411 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1412 rfHighest3=i;
1413 }
1414 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1415 }
1416 // set allowed clock remainder tolerance to be 1 large field clock length+1
1417 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1418 uint8_t tol1 = fcHigh+1;
1419
1420 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1421
1422 // loop to find the highest clock that has a remainder less than the tolerance
1423 // compare samples counted divided by
1424 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1425 int ii=7;
1426 for (; ii>=2; ii--){
1427 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1428 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1429 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1430 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1431 break;
1432 }
1433 }
1434 }
1435 }
1436
1437 if (ii<0) return 0; // oops we went too far
1438
1439 return clk[ii];
1440 }
1441
1442 //by marshmellow
1443 //countFC is to detect the field clock lengths.
1444 //counts and returns the 2 most common wave lengths
1445 //mainly used for FSK field clock detection
1446 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1447 {
1448 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1449 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1450 uint8_t fcLensFnd = 0;
1451 uint8_t lastFCcnt=0;
1452 uint8_t fcCounter = 0;
1453 size_t i;
1454 if (size == 0) return 0;
1455
1456 // prime i to first up transition
1457 for (i = 160; i < size-20; i++)
1458 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1459 break;
1460
1461 for (; i < size-20; i++){
1462 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1463 // new up transition
1464 fcCounter++;
1465 if (fskAdj){
1466 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1467 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1468 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1469 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1470 // save last field clock count (fc/xx)
1471 lastFCcnt = fcCounter;
1472 }
1473 // find which fcLens to save it to:
1474 for (int ii=0; ii<15; ii++){
1475 if (fcLens[ii]==fcCounter){
1476 fcCnts[ii]++;
1477 fcCounter=0;
1478 break;
1479 }
1480 }
1481 if (fcCounter>0 && fcLensFnd<15){
1482 //add new fc length
1483 fcCnts[fcLensFnd]++;
1484 fcLens[fcLensFnd++]=fcCounter;
1485 }
1486 fcCounter=0;
1487 } else {
1488 // count sample
1489 fcCounter++;
1490 }
1491 }
1492
1493 uint8_t best1=14, best2=14, best3=14;
1494 uint16_t maxCnt1=0;
1495 // go through fclens and find which ones are bigest 2
1496 for (i=0; i<15; i++){
1497 // get the 3 best FC values
1498 if (fcCnts[i]>maxCnt1) {
1499 best3=best2;
1500 best2=best1;
1501 maxCnt1=fcCnts[i];
1502 best1=i;
1503 } else if(fcCnts[i]>fcCnts[best2]){
1504 best3=best2;
1505 best2=i;
1506 } else if(fcCnts[i]>fcCnts[best3]){
1507 best3=i;
1508 }
1509 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]);
1510 }
1511 if (fcLens[best1]==0) return 0;
1512 uint8_t fcH=0, fcL=0;
1513 if (fcLens[best1]>fcLens[best2]){
1514 fcH=fcLens[best1];
1515 fcL=fcLens[best2];
1516 } else{
1517 fcH=fcLens[best2];
1518 fcL=fcLens[best1];
1519 }
1520 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1521 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]);
1522 return 0; //lots of waves not psk or fsk
1523 }
1524 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1525
1526 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1527 if (fskAdj) return fcs;
1528 return fcLens[best1];
1529 }
1530
1531 //by marshmellow - demodulate PSK1 wave
1532 //uses wave lengths (# Samples)
1533 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1534 {
1535 if (size == 0) return -1;
1536 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1537 if (*size<loopCnt) loopCnt = *size;
1538
1539 size_t numBits=0;
1540 uint8_t curPhase = *invert;
1541 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1542 uint8_t fc=0, fullWaveLen=0, tol=1;
1543 uint16_t errCnt=0, waveLenCnt=0;
1544 fc = countFC(dest, *size, 0);
1545 if (fc!=2 && fc!=4 && fc!=8) return -1;
1546 //prnt("DEBUG: FC: %d",fc);
1547 *clock = DetectPSKClock(dest, *size, *clock);
1548 if (*clock == 0) return -1;
1549 int avgWaveVal=0, lastAvgWaveVal=0;
1550 //find first phase shift
1551 for (i=0; i<loopCnt; i++){
1552 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1553 waveEnd = i+1;
1554 //prnt("DEBUG: waveEnd: %d",waveEnd);
1555 waveLenCnt = waveEnd-waveStart;
1556 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1557 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1558 firstFullWave = waveStart;
1559 fullWaveLen=waveLenCnt;
1560 //if average wave value is > graph 0 then it is an up wave or a 1
1561 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1562 break;
1563 }
1564 waveStart = i+1;
1565 avgWaveVal = 0;
1566 }
1567 avgWaveVal += dest[i+2];
1568 }
1569 if (firstFullWave == 0) {
1570 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1571 // so skip a little to ensure we are past any Start Signal
1572 firstFullWave = 160;
1573 memset(dest, curPhase, firstFullWave / *clock);
1574 } else {
1575 memset(dest, curPhase^1, firstFullWave / *clock);
1576 }
1577 //advance bits
1578 numBits += (firstFullWave / *clock);
1579 //set start of wave as clock align
1580 lastClkBit = firstFullWave;
1581 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1582 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1583 waveStart = 0;
1584 dest[numBits++] = curPhase; //set first read bit
1585 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1586 //top edge of wave = start of new wave
1587 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1588 if (waveStart == 0) {
1589 waveStart = i+1;
1590 waveLenCnt = 0;
1591 avgWaveVal = dest[i+1];
1592 } else { //waveEnd
1593 waveEnd = i+1;
1594 waveLenCnt = waveEnd-waveStart;
1595 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1596 if (waveLenCnt > fc){
1597 //prnt("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1598 //this wave is a phase shift
1599 //prnt("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1600 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1601 curPhase ^= 1;
1602 dest[numBits++] = curPhase;
1603 lastClkBit += *clock;
1604 } else if (i < lastClkBit+10+fc){
1605 //noise after a phase shift - ignore
1606 } else { //phase shift before supposed to based on clock
1607 errCnt++;
1608 dest[numBits++] = 7;
1609 }
1610 } else if (i+1 > lastClkBit + *clock + tol + fc){
1611 lastClkBit += *clock; //no phase shift but clock bit
1612 dest[numBits++] = curPhase;
1613 }
1614 avgWaveVal = 0;
1615 waveStart = i+1;
1616 }
1617 }
1618 avgWaveVal += dest[i+1];
1619 }
1620 *size = numBits;
1621 return errCnt;
1622 }
1623
1624 //by marshmellow
1625 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1626 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1627 size_t bufsize = *size;
1628 //need to loop through all samples and identify our clock, look for the ST pattern
1629 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1630 int clk = 0;
1631 int tol = 0;
1632 int i, j, skip, start, end, low, high, minClk, waveStart;
1633 bool complete = false;
1634 int tmpbuff[bufsize / 32]; //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
1635 int waveLen[bufsize / 32]; // if clock is larger then we waste memory in array size that is not needed...
1636 size_t testsize = (bufsize < 512) ? bufsize : 512;
1637 int phaseoff = 0;
1638 high = low = 128;
1639 memset(tmpbuff, 0, sizeof(tmpbuff));
1640 memset(waveLen, 0, sizeof(waveLen));
1641
1642
1643 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1644 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1645 return false; //just noise
1646 }
1647 i = 0;
1648 j = 0;
1649 minClk = 255;
1650 // get to first full low to prime loop and skip incomplete first pulse
1651 while ((buffer[i] < high) && (i < bufsize))
1652 ++i;
1653 while ((buffer[i] > low) && (i < bufsize))
1654 ++i;
1655 skip = i;
1656
1657 // populate tmpbuff buffer with pulse lengths
1658 while (i < bufsize) {
1659 // measure from low to low
1660 while ((buffer[i] > low) && (i < bufsize))
1661 ++i;
1662 start= i;
1663 while ((buffer[i] < high) && (i < bufsize))
1664 ++i;
1665 //first high point for this wave
1666 waveStart = i;
1667 while ((buffer[i] > low) && (i < bufsize))
1668 ++i;
1669 if (j >= (bufsize/32)) {
1670 break;
1671 }
1672 waveLen[j] = i - waveStart; //first high to first low
1673 tmpbuff[j++] = i - start;
1674 if (i-start < minClk && i < bufsize) {
1675 minClk = i - start;
1676 }
1677 }
1678 // set clock - might be able to get this externally and remove this work...
1679 if (!clk) {
1680 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1681 tol = fndClk[clkCnt]/8;
1682 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1683 clk=fndClk[clkCnt];
1684 break;
1685 }
1686 }
1687 // clock not found - ERROR
1688 if (!clk) {
1689 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1690 return false;
1691 }
1692 } else tol = clk/8;
1693
1694 *foundclock = clk;
1695
1696 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1697 start = -1;
1698 for (i = 0; i < j - 4; ++i) {
1699 skip += tmpbuff[i];
1700 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1701 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
1702 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
1703 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1704 start = i + 3;
1705 break;
1706 }
1707 }
1708 }
1709 }
1710 }
1711 // first ST not found - ERROR
1712 if (start < 0) {
1713 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1714 return false;
1715 } else {
1716 if (g_debugMode==2) prnt("DEBUG STT: first STT found at: %d, j=%d",start, j);
1717 }
1718 if (waveLen[i+2] > clk*1+tol)
1719 phaseoff = 0;
1720 else
1721 phaseoff = clk/2;
1722
1723 // skip over the remainder of ST
1724 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1725
1726 // now do it again to find the end
1727 end = skip;
1728 for (i += 3; i < j - 4; ++i) {
1729 end += tmpbuff[i];
1730 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1731 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
1732 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
1733 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1734 complete = true;
1735 break;
1736 }
1737 }
1738 }
1739 }
1740 }
1741 end -= phaseoff;
1742 //didn't find second ST - ERROR
1743 if (!complete) {
1744 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1745 return false;
1746 }
1747 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);
1748 //now begin to trim out ST so we can use normal demod cmds
1749 start = skip;
1750 size_t datalen = end - start;
1751 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1752 if ( clk - (datalen % clk) <= clk/8) {
1753 // padd the amount off - could be problematic... but shouldn't happen often
1754 datalen += clk - (datalen % clk);
1755 } else if ( (datalen % clk) <= clk/8 ) {
1756 // padd the amount off - could be problematic... but shouldn't happen often
1757 datalen -= datalen % clk;
1758 } else {
1759 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1760 return false;
1761 }
1762 // if datalen is less than one t55xx block - ERROR
1763 if (datalen/clk < 8*4) {
1764 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1765 return false;
1766 }
1767 size_t dataloc = start;
1768 if (buffer[dataloc-(clk*4)-(clk/8)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
1769 //we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start
1770 for ( i=0; i <= (clk/8); ++i ) {
1771 if ( buffer[dataloc - (clk*4) - i] <= low ) {
1772 dataloc -= i;
1773 break;
1774 }
1775 }
1776 }
1777
1778 size_t newloc = 0;
1779 i=0;
1780 if (g_debugMode==2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);
1781
1782 // warning - overwriting buffer given with raw wave data with ST removed...
1783 while ( dataloc < bufsize-(clk/2) ) {
1784 //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)
1785 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1786 for(i=0; i < clk/2-tol; ++i) {
1787 buffer[dataloc+i] = high+5;
1788 }
1789 }
1790 for (i=0; i<datalen; ++i) {
1791 if (i+newloc < bufsize) {
1792 if (i+newloc < dataloc)
1793 buffer[i+newloc] = buffer[dataloc];
1794
1795 dataloc++;
1796 }
1797 }
1798 newloc += i;
1799 //skip next ST - we just assume it will be there from now on...
1800 if (g_debugMode==2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
1801 dataloc += clk*4;
1802 }
1803 *size = newloc;
1804 return true;
1805 }
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