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