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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 uint8_t justNoise(uint8_t *BitStream, size_t size)
29 {
30 static const uint8_t THRESHOLD = 123;
31 //test samples are not just noise
32 uint8_t justNoise1 = 1;
33 for(size_t idx=0; idx < size && justNoise1 ;idx++){
34 justNoise1 = BitStream[idx] < THRESHOLD;
35 }
36 return justNoise1;
37 }
38
39 //by marshmellow
40 //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
41 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
42 {
43 *high=0;
44 *low=255;
45 // get high and low thresholds
46 for (size_t i=0; i < size; i++){
47 if (BitStream[i] > *high) *high = BitStream[i];
48 if (BitStream[i] < *low) *low = BitStream[i];
49 }
50 if (*high < 123) return -1; // just noise
51 *high = ((*high-128)*fuzzHi + 12800)/100;
52 *low = ((*low-128)*fuzzLo + 12800)/100;
53 return 1;
54 }
55
56 // by marshmellow
57 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
58 // returns 1 if passed
59 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
60 {
61 uint8_t ans = 0;
62 for (uint8_t i = 0; i < bitLen; i++){
63 ans ^= ((bits >> i) & 1);
64 }
65 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
66 return (ans == pType);
67 }
68
69 //by marshmellow
70 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
71 // Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
72 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
73 {
74 uint32_t parityWd = 0;
75 size_t j = 0, bitCnt = 0;
76 for (int word = 0; word < (bLen); word+=pLen){
77 for (int bit=0; bit < pLen; bit++){
78 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
79 BitStream[j++] = (BitStream[startIdx+word+bit]);
80 }
81 j--; // overwrite parity with next data
82 // if parity fails then return 0
83 switch (pType) {
84 case 3: if (BitStream[j]==1) { return 0; } break; //should be 0 spacer bit
85 case 2: if (BitStream[j]==0) { return 0; } break; //should be 1 spacer bit
86 default: if (parityTest(parityWd, pLen, pType) == 0) { return 0; } break; //test parity
87 }
88 bitCnt+=(pLen-1);
89 parityWd = 0;
90 }
91 // if we got here then all the parities passed
92 //return ID start index and size
93 return bitCnt;
94 }
95
96 // by marshmellow
97 // takes a array of binary values, length of bits per parity (includes parity bit),
98 // Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
99 // Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
100 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
101 {
102 uint32_t parityWd = 0;
103 size_t j = 0, bitCnt = 0;
104 for (int word = 0; word < sourceLen; word+=pLen-1) {
105 for (int bit=0; bit < pLen-1; bit++){
106 parityWd = (parityWd << 1) | BitSource[word+bit];
107 dest[j++] = (BitSource[word+bit]);
108 }
109
110 // if parity fails then return 0
111 switch (pType) {
112 case 3: dest[j++]=0; break; // marker bit which should be a 0
113 case 2: dest[j++]=1; break; // marker bit which should be a 1
114 default:
115 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
116 break;
117 }
118 bitCnt += pLen;
119 parityWd = 0;
120 }
121 // if we got here then all the parities passed
122 //return ID start index and size
123 return bitCnt;
124 }
125
126 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
127 {
128 uint32_t num = 0;
129 for(int i = 0 ; i < numbits ; i++) {
130 num = (num << 1) | (*src);
131 src++;
132 }
133 return num;
134 }
135
136 //least significant bit first
137 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
138 {
139 uint32_t num = 0;
140 for(int i = 0 ; i < numbits ; i++) {
141 num = (num << 1) | *(src + (numbits-(i+1)));
142 }
143 return num;
144 }
145
146 //by marshmellow
147 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
148 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
149 {
150 // Sanity check. If preamble length is bigger than bitstream length.
151 if ( *size <= pLen ) return 0;
152
153 uint8_t foundCnt = 0;
154 for (int idx = 0; idx < *size - pLen; idx++){
155 if (memcmp(BitStream+idx, preamble, pLen) == 0){
156 //first index found
157 foundCnt++;
158 if (foundCnt == 1){
159 *startIdx = idx;
160 }
161 if (foundCnt == 2){
162 *size = idx - *startIdx;
163 return 1;
164 }
165 }
166 }
167 return 0;
168 }
169
170 //by marshmellow
171 //takes 1s and 0s and searches for EM410x format - output EM ID
172 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
173 {
174 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
175 // otherwise could be a void with no arguments
176 //set defaults
177 uint32_t i = 0;
178 if (BitStream[1]>1) return 0; //allow only 1s and 0s
179
180 // 111111111 bit pattern represent start of frame
181 // include 0 in front to help get start pos
182 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
183 uint32_t idx = 0;
184 uint32_t parityBits = 0;
185 uint8_t errChk = 0;
186 uint8_t FmtLen = 10;
187 *startIdx = 0;
188 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
189 if (errChk == 0 || *size < 64) return 0;
190 if (*size > 64) FmtLen = 22;
191 *startIdx += 1; //get rid of 0 from preamble
192 idx = *startIdx + 9;
193 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
194 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
195 //check even parity - quit if failed
196 if (parityTest(parityBits, 5, 0) == 0) return 0;
197 //set uint64 with ID from BitStream
198 for (uint8_t ii=0; ii<4; ii++){
199 *hi = (*hi << 1) | (*lo >> 63);
200 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
201 }
202 }
203 if (errChk != 0) return 1;
204 //skip last 5 bit parity test for simplicity.
205 // *size = 64 | 128;
206 return 0;
207 }
208
209 //by marshmellow
210 //demodulates strong heavily clipped samples
211 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
212 {
213 size_t bitCnt=0, smplCnt=0, errCnt=0;
214 uint8_t waveHigh = 0;
215 for (size_t i=0; i < *size; i++){
216 if (BinStream[i] >= high && waveHigh){
217 smplCnt++;
218 } else if (BinStream[i] <= low && !waveHigh){
219 smplCnt++;
220 } else { //transition
221 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
222 if (smplCnt > clk-(clk/4)-1) { //full clock
223 if (smplCnt > clk + (clk/4)+1) { //too many samples
224 errCnt++;
225 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
226 BinStream[bitCnt++]=7;
227 } else if (waveHigh) {
228 BinStream[bitCnt++] = invert;
229 BinStream[bitCnt++] = invert;
230 } else if (!waveHigh) {
231 BinStream[bitCnt++] = invert ^ 1;
232 BinStream[bitCnt++] = invert ^ 1;
233 }
234 waveHigh ^= 1;
235 smplCnt = 0;
236 } else if (smplCnt > (clk/2) - (clk/4)-1) {
237 if (waveHigh) {
238 BinStream[bitCnt++] = invert;
239 } else if (!waveHigh) {
240 BinStream[bitCnt++] = invert ^ 1;
241 }
242 waveHigh ^= 1;
243 smplCnt = 0;
244 } else if (!bitCnt) {
245 //first bit
246 waveHigh = (BinStream[i] >= high);
247 smplCnt = 1;
248 } else {
249 smplCnt++;
250 //transition bit oops
251 }
252 } else { //haven't hit new high or new low yet
253 smplCnt++;
254 }
255 }
256 }
257 *size = bitCnt;
258 return errCnt;
259 }
260
261 //by marshmellow
262 void askAmp(uint8_t *BitStream, size_t size)
263 {
264 uint8_t last = 128;
265 for(size_t i = 1; i < size; ++i){
266 if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
267 last = 255;
268 else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
269 last = 0;
270
271 BitStream[i] = last;
272 }
273 }
274
275 //by marshmellow
276 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
277 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
278 {
279 if (*size==0) return -1;
280 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
281 if (*clk==0 || start < 0) return -3;
282 if (*invert != 1) *invert = 0;
283 if (amp==1) askAmp(BinStream, *size);
284 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
285
286 uint8_t initLoopMax = 255;
287 if (initLoopMax > *size) initLoopMax = *size;
288 // Detect high and lows
289 //25% clip in case highs and lows aren't clipped [marshmellow]
290 int high, low;
291 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
292 return -2; //just noise
293
294 size_t errCnt = 0;
295 // if clean clipped waves detected run alternate demod
296 if (DetectCleanAskWave(BinStream, *size, high, low)) {
297 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
298 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
299 if (askType) //askman
300 return manrawdecode(BinStream, size, 0);
301 else //askraw
302 return errCnt;
303 }
304 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
305
306 int lastBit; //set first clock check - can go negative
307 size_t i, bitnum = 0; //output counter
308 uint8_t midBit = 0;
309 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
310 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
311 size_t MaxBits = 3072; //max bits to collect
312 lastBit = start - *clk;
313
314 for (i = start; i < *size; ++i) {
315 if (i-lastBit >= *clk-tol){
316 if (BinStream[i] >= high) {
317 BinStream[bitnum++] = *invert;
318 } else if (BinStream[i] <= low) {
319 BinStream[bitnum++] = *invert ^ 1;
320 } else if (i-lastBit >= *clk+tol) {
321 if (bitnum > 0) {
322 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
323 BinStream[bitnum++]=7;
324 errCnt++;
325 }
326 } else { //in tolerance - looking for peak
327 continue;
328 }
329 midBit = 0;
330 lastBit += *clk;
331 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
332 if (BinStream[i] >= high) {
333 BinStream[bitnum++] = *invert;
334 } else if (BinStream[i] <= low) {
335 BinStream[bitnum++] = *invert ^ 1;
336 } else if (i-lastBit >= *clk/2+tol) {
337 BinStream[bitnum] = BinStream[bitnum-1];
338 bitnum++;
339 } else { //in tolerance - looking for peak
340 continue;
341 }
342 midBit = 1;
343 }
344 if (bitnum >= MaxBits) break;
345 }
346 *size = bitnum;
347 return errCnt;
348 }
349
350 //by marshmellow
351 //take 10 and 01 and manchester decode
352 //run through 2 times and take least errCnt
353 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
354 {
355 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
356 size_t i, ii;
357 uint16_t bestErr = 1000, bestRun = 0;
358 if (*size < 16) return -1;
359 //find correct start position [alignment]
360 for (ii=0;ii<2;++ii){
361 for (i=ii; i<*size-3; i+=2)
362 if (BitStream[i]==BitStream[i+1])
363 errCnt++;
364
365 if (bestErr>errCnt){
366 bestErr=errCnt;
367 bestRun=ii;
368 }
369 errCnt=0;
370 }
371 //decode
372 for (i=bestRun; i < *size-3; i+=2){
373 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
374 BitStream[bitnum++]=invert;
375 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
376 BitStream[bitnum++]=invert^1;
377 } else {
378 BitStream[bitnum++]=7;
379 }
380 if(bitnum>MaxBits) break;
381 }
382 *size=bitnum;
383 return bestErr;
384 }
385
386 uint32_t manchesterEncode2Bytes(uint16_t datain) {
387 uint32_t output = 0;
388 uint8_t curBit = 0;
389 for (uint8_t i=0; i<16; i++) {
390 curBit = (datain >> (15-i) & 1);
391 output |= (1<<(((15-i)*2)+curBit));
392 }
393 return output;
394 }
395
396 //by marshmellow
397 //encode binary data into binary manchester
398 int ManchesterEncode(uint8_t *BitStream, size_t size)
399 {
400 size_t modIdx=20000, i=0;
401 if (size>modIdx) return -1;
402 for (size_t idx=0; idx < size; idx++){
403 BitStream[idx+modIdx++] = BitStream[idx];
404 BitStream[idx+modIdx++] = BitStream[idx]^1;
405 }
406 for (; i<(size*2); i++){
407 BitStream[i] = BitStream[i+20000];
408 }
409 return i;
410 }
411
412 //by marshmellow
413 //take 01 or 10 = 1 and 11 or 00 = 0
414 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
415 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
416 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
417 {
418 uint16_t bitnum = 0;
419 uint16_t errCnt = 0;
420 size_t i = offset;
421 uint16_t MaxBits=512;
422 //if not enough samples - error
423 if (*size < 51) return -1;
424 //check for phase change faults - skip one sample if faulty
425 uint8_t offsetA = 1, offsetB = 1;
426 for (; i<48; i+=2){
427 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
428 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
429 }
430 if (!offsetA && offsetB) offset++;
431 for (i=offset; i<*size-3; i+=2){
432 //check for phase error
433 if (BitStream[i+1]==BitStream[i+2]) {
434 BitStream[bitnum++]=7;
435 errCnt++;
436 }
437 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
438 BitStream[bitnum++]=1^invert;
439 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
440 BitStream[bitnum++]=invert;
441 } else {
442 BitStream[bitnum++]=7;
443 errCnt++;
444 }
445 if(bitnum>MaxBits) break;
446 }
447 *size=bitnum;
448 return errCnt;
449 }
450
451 // by marshmellow
452 // demod gProxIIDemod
453 // error returns as -x
454 // success returns start position in BitStream
455 // BitStream must contain previously askrawdemod and biphasedemoded data
456 int gProxII_Demod(uint8_t BitStream[], size_t *size)
457 {
458 size_t startIdx=0;
459 uint8_t preamble[] = {1,1,1,1,1,0};
460
461 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
462 if (errChk == 0) return -3; //preamble not found
463 if (*size != 96) return -2; //should have found 96 bits
464 //check first 6 spacer bits to verify format
465 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
466 //confirmed proper separator bits found
467 //return start position
468 return (int) startIdx;
469 }
470 return -5; //spacer bits not found - not a valid gproxII
471 }
472
473 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
474 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
475 {
476 size_t last_transition = 0;
477 size_t idx = 1;
478 //uint32_t maxVal=0;
479 if (fchigh==0) fchigh=10;
480 if (fclow==0) fclow=8;
481 //set the threshold close to 0 (graph) or 128 std to avoid static
482 uint8_t threshold_value = 123;
483 size_t preLastSample = 0;
484 size_t LastSample = 0;
485 size_t currSample = 0;
486 // sync to first lo-hi transition, and threshold
487
488 // Need to threshold first sample
489 // skip 160 samples to allow antenna/samples to settle
490 if(dest[160] < threshold_value) dest[0] = 0;
491 else dest[0] = 1;
492
493 size_t numBits = 0;
494 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
495 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
496 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
497 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
498 for(idx = 161; idx < size-20; idx++) {
499 // threshold current value
500
501 if (dest[idx] < threshold_value) dest[idx] = 0;
502 else dest[idx] = 1;
503
504 // Check for 0->1 transition
505 if (dest[idx-1] < dest[idx]) {
506 preLastSample = LastSample;
507 LastSample = currSample;
508 currSample = idx-last_transition;
509 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
510 //do nothing with extra garbage
511 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
512 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
513 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
514 dest[numBits-1]=1;
515 }
516 dest[numBits++]=1;
517
518 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
519 //do nothing with beginning garbage
520 } 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)
521 dest[numBits++]=1;
522 } else { //9+ = 10 sample waves (or 6+ = 7)
523 dest[numBits++]=0;
524 }
525 last_transition = idx;
526 }
527 }
528 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
529 }
530
531 //translate 11111100000 to 10
532 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
533 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
534 uint8_t invert, uint8_t fchigh, uint8_t fclow)
535 {
536 uint8_t lastval=dest[0];
537 size_t idx=0;
538 size_t numBits=0;
539 uint32_t n=1;
540 for( idx=1; idx < size; idx++) {
541 n++;
542 if (dest[idx]==lastval) continue;
543
544 //find out how many bits (n) we collected
545 //if lastval was 1, we have a 1->0 crossing
546 if (dest[idx-1]==1) {
547 n = (n * fclow + rfLen/2) / rfLen;
548 } else {// 0->1 crossing
549 n = (n * fchigh + rfLen/2) / rfLen;
550 }
551 if (n == 0) n = 1;
552
553 //add to our destination the bits we collected
554 memset(dest+numBits, dest[idx-1]^invert , n);
555 numBits += n;
556 n=0;
557 lastval=dest[idx];
558 }//end for
559 // if valid extra bits at the end were all the same frequency - add them in
560 if (n > rfLen/fchigh) {
561 if (dest[idx-2]==1) {
562 n = (n * fclow + rfLen/2) / rfLen;
563 } else {
564 n = (n * fchigh + rfLen/2) / rfLen;
565 }
566 memset(dest+numBits, dest[idx-1]^invert , n);
567 numBits += n;
568 }
569 return numBits;
570 }
571
572 //by marshmellow (from holiman's base)
573 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
574 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
575 {
576 // FSK demodulator
577 size = fsk_wave_demod(dest, size, fchigh, fclow);
578 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
579 return size;
580 }
581
582 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
583 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
584 {
585 if (justNoise(dest, *size)) return -1;
586
587 size_t numStart=0, size2 = *size, startIdx=0;
588 // FSK demodulator
589 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
590 if (*size < 96*2) return -2;
591 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
592 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
593 // find bitstring in array
594 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
595 if (errChk == 0) return -3; //preamble not found
596
597 numStart = startIdx + sizeof(preamble);
598 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
599 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
600 if (dest[idx] == dest[idx+1]){
601 return -4; //not manchester data
602 }
603 *hi2 = (*hi2<<1)|(*hi>>31);
604 *hi = (*hi<<1)|(*lo>>31);
605 //Then, shift in a 0 or one into low
606 if (dest[idx] && !dest[idx+1]) // 1 0
607 *lo=(*lo<<1)|1;
608 else // 0 1
609 *lo=(*lo<<1)|0;
610 }
611 return (int)startIdx;
612 }
613
614 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
615 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
616 {
617 if (justNoise(dest, *size)) return -1;
618
619 size_t numStart=0, size2 = *size, startIdx=0;
620 // FSK demodulator
621 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
622 if (*size < 96) return -2;
623
624 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
625 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
626
627 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
628 if (errChk == 0) return -3; //preamble not found
629
630 numStart = startIdx + sizeof(preamble);
631 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
632 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
633 if (dest[idx] == dest[idx+1])
634 return -4; //not manchester data
635 *hi2 = (*hi2<<1)|(*hi>>31);
636 *hi = (*hi<<1)|(*lo>>31);
637 //Then, shift in a 0 or one into low
638 if (dest[idx] && !dest[idx+1]) // 1 0
639 *lo=(*lo<<1)|1;
640 else // 0 1
641 *lo=(*lo<<1)|0;
642 }
643 return (int)startIdx;
644 }
645
646 int IOdemodFSK(uint8_t *dest, size_t size)
647 {
648 if (justNoise(dest, size)) return -1;
649 //make sure buffer has data
650 if (size < 66*64) return -2;
651 // FSK demodulator
652 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
653 if (size < 65) return -3; //did we get a good demod?
654 //Index map
655 //0 10 20 30 40 50 60
656 //| | | | | | |
657 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
658 //-----------------------------------------------------------------------------
659 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
660 //
661 //XSF(version)facility:codeone+codetwo
662 //Handle the data
663 size_t startIdx = 0;
664 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
665 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
666 if (errChk == 0) return -4; //preamble not found
667
668 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
669 //confirmed proper separator bits found
670 //return start position
671 return (int) startIdx;
672 }
673 return -5;
674 }
675
676 // by marshmellow
677 // find viking preamble 0xF200 in already demoded data
678 int VikingDemod_AM(uint8_t *dest, size_t *size) {
679 //make sure buffer has data
680 if (*size < 64*2) return -2;
681
682 size_t startIdx = 0;
683 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};
684 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
685 if (errChk == 0) return -4; //preamble not found
686 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^
687 bytebits_to_byte(dest+startIdx+8,8) ^
688 bytebits_to_byte(dest+startIdx+16,8) ^
689 bytebits_to_byte(dest+startIdx+24,8) ^
690 bytebits_to_byte(dest+startIdx+32,8) ^
691 bytebits_to_byte(dest+startIdx+40,8) ^
692 bytebits_to_byte(dest+startIdx+48,8) ^
693 bytebits_to_byte(dest+startIdx+56,8);
694 if ( checkCalc != 0xA8 ) return -5;
695 if (*size != 64) return -6;
696 //return start position
697 return (int) startIdx;
698 }
699
700 // find presco preamble 0x10D in already demoded data
701 int PrescoDemod(uint8_t *dest, size_t *size) {
702 //make sure buffer has data
703 if (*size < 64*2) return -2;
704
705 size_t startIdx = 0;
706 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
707 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
708 if (errChk == 0) return -4; //preamble not found
709 //return start position
710 return (int) startIdx;
711 }
712
713 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
714 // BitStream must contain previously askrawdemod and biphasedemoded data
715 int FDXBdemodBI(uint8_t *dest, size_t *size)
716 {
717 //make sure buffer has enough data
718 if (*size < 128) return -1;
719
720 size_t startIdx = 0;
721 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
722
723 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
724 if (errChk == 0) return -2; //preamble not found
725 return (int)startIdx;
726 }
727
728 // ASK/Diphase fc/64 (inverted Biphase)
729 // Note: this i s not a demod, this is only a detection
730 // the parameter *dest needs to be demoded before call
731 int JablotronDemod(uint8_t *dest, size_t *size){
732 //make sure buffer has enough data
733 if (*size < 64) return -1;
734
735 size_t startIdx = 0;
736 // 0xFFFF preamble, 64bits
737 uint8_t preamble[] = {
738 1,1,1,1,
739 1,1,1,1,
740 1,1,1,1,
741 1,1,1,1,
742 0
743 };
744
745 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
746 if (errChk == 0) return -4; //preamble not found
747 if (*size != 64) return -3;
748
749 uint8_t checkchksum = 0;
750 for (int i=16; i < 56; i += 8) {
751 checkchksum += bytebits_to_byte(dest+startIdx+i,8);
752 }
753 checkchksum ^= 0x3A;
754
755 uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
756
757 if ( checkchksum != crc ) return -5;
758 return (int)startIdx;
759 }
760
761 // by marshmellow
762 // FSK Demod then try to locate an AWID ID
763 int AWIDdemodFSK(uint8_t *dest, size_t *size)
764 {
765 //make sure buffer has enough data
766 if (*size < 96*50) return -1;
767
768 if (justNoise(dest, *size)) return -2;
769
770 // FSK demodulator
771 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
772 if (*size < 96) return -3; //did we get a good demod?
773
774 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
775 size_t startIdx = 0;
776 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
777 if (errChk == 0) return -4; //preamble not found
778 if (*size != 96) return -5;
779 return (int)startIdx;
780 }
781
782 // by marshmellow
783 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
784 int PyramiddemodFSK(uint8_t *dest, size_t *size)
785 {
786 //make sure buffer has data
787 if (*size < 128*50) return -5;
788
789 //test samples are not just noise
790 if (justNoise(dest, *size)) return -1;
791
792 // FSK demodulator
793 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
794 if (*size < 128) return -2; //did we get a good demod?
795
796 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
797 size_t startIdx = 0;
798 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
799 if (errChk == 0) return -4; //preamble not found
800 if (*size != 128) return -3;
801 return (int)startIdx;
802 }
803
804 // find nedap preamble in already demoded data
805 int NedapDemod(uint8_t *dest, size_t *size) {
806 //make sure buffer has data
807 if (*size < 128) return -3;
808
809 size_t startIdx = 0;
810 //uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
811 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
812 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
813 if (errChk == 0) return -4; //preamble not found
814 return (int) startIdx;
815 }
816
817 // by marshmellow
818 // to detect a wave that has heavily clipped (clean) samples
819 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
820 {
821 bool allArePeaks = true;
822 uint16_t cntPeaks=0;
823 size_t loopEnd = 512+160;
824 if (loopEnd > size) loopEnd = size;
825 for (size_t i=160; i<loopEnd; i++){
826 if (dest[i]>low && dest[i]<high)
827 allArePeaks = false;
828 else
829 cntPeaks++;
830 }
831 if (!allArePeaks){
832 if (cntPeaks > 300) return true;
833 }
834 return allArePeaks;
835 }
836 // by marshmellow
837 // to help detect clocks on heavily clipped samples
838 // based on count of low to low
839 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
840 {
841 uint8_t fndClk[] = {8,16,32,40,50,64,128};
842 size_t startwave;
843 size_t i = 100;
844 size_t minClk = 255;
845 // get to first full low to prime loop and skip incomplete first pulse
846 while ((dest[i] < high) && (i < size))
847 ++i;
848 while ((dest[i] > low) && (i < size))
849 ++i;
850
851 // loop through all samples
852 while (i < size) {
853 // measure from low to low
854 while ((dest[i] > low) && (i < size))
855 ++i;
856 startwave= i;
857 while ((dest[i] < high) && (i < size))
858 ++i;
859 while ((dest[i] > low) && (i < size))
860 ++i;
861 //get minimum measured distance
862 if (i-startwave < minClk && i < size)
863 minClk = i - startwave;
864 }
865 // set clock
866 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
867 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
868 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
869 return fndClk[clkCnt];
870 }
871 return 0;
872 }
873
874 // by marshmellow
875 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
876 // maybe somehow adjust peak trimming value based on samples to fix?
877 // return start index of best starting position for that clock and return clock (by reference)
878 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
879 {
880 size_t i=1;
881 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
882 uint8_t clkEnd = 9;
883 uint8_t loopCnt = 255; //don't need to loop through entire array...
884 if (size <= loopCnt+60) return -1; //not enough samples
885 size -= 60; //sometimes there is a strange end wave - filter out this....
886 //if we already have a valid clock
887 uint8_t clockFnd=0;
888 for (;i<clkEnd;++i)
889 if (clk[i] == *clock) clockFnd = i;
890 //clock found but continue to find best startpos
891
892 //get high and low peak
893 int peak, low;
894 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
895
896 //test for large clean peaks
897 if (!clockFnd){
898 if (DetectCleanAskWave(dest, size, peak, low)==1){
899 int ans = DetectStrongAskClock(dest, size, peak, low);
900 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
901 for (i=clkEnd-1; i>0; i--){
902 if (clk[i] == ans) {
903 *clock = ans;
904 //clockFnd = i;
905 return 0; // for strong waves i don't use the 'best start position' yet...
906 //break; //clock found but continue to find best startpos [not yet]
907 }
908 }
909 }
910 }
911 uint8_t ii;
912 uint8_t clkCnt, tol = 0;
913 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
914 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
915 size_t errCnt = 0;
916 size_t arrLoc, loopEnd;
917
918 if (clockFnd>0) {
919 clkCnt = clockFnd;
920 clkEnd = clockFnd+1;
921 }
922 else clkCnt=1;
923
924 //test each valid clock from smallest to greatest to see which lines up
925 for(; clkCnt < clkEnd; clkCnt++){
926 if (clk[clkCnt] <= 32){
927 tol=1;
928 }else{
929 tol=0;
930 }
931 //if no errors allowed - keep start within the first clock
932 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
933 bestErr[clkCnt]=1000;
934 //try lining up the peaks by moving starting point (try first few clocks)
935 for (ii=0; ii < loopCnt; ii++){
936 if (dest[ii] < peak && dest[ii] > low) continue;
937
938 errCnt=0;
939 // now that we have the first one lined up test rest of wave array
940 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
941 for (i=0; i < loopEnd; ++i){
942 arrLoc = ii + (i * clk[clkCnt]);
943 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
944 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
945 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
946 }else{ //error no peak detected
947 errCnt++;
948 }
949 }
950 //if we found no errors then we can stop here and a low clock (common clocks)
951 // this is correct one - return this clock
952 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
953 if(errCnt==0 && clkCnt<7) {
954 if (!clockFnd) *clock = clk[clkCnt];
955 return ii;
956 }
957 //if we found errors see if it is lowest so far and save it as best run
958 if(errCnt<bestErr[clkCnt]){
959 bestErr[clkCnt]=errCnt;
960 bestStart[clkCnt]=ii;
961 }
962 }
963 }
964 uint8_t iii;
965 uint8_t best=0;
966 for (iii=1; iii<clkEnd; ++iii){
967 if (bestErr[iii] < bestErr[best]){
968 if (bestErr[iii] == 0) bestErr[iii]=1;
969 // current best bit to error ratio vs new bit to error ratio
970 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
971 best = iii;
972 }
973 }
974 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]);
975 }
976 if (!clockFnd) *clock = clk[best];
977 return bestStart[best];
978 }
979
980 //by marshmellow
981 //detect psk clock by reading each phase shift
982 // a phase shift is determined by measuring the sample length of each wave
983 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
984 {
985 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
986 uint16_t loopCnt = 4096; //don't need to loop through entire array...
987 if (size == 0) return 0;
988 if (size<loopCnt) loopCnt = size-20;
989
990 //if we already have a valid clock quit
991 size_t i=1;
992 for (; i < 8; ++i)
993 if (clk[i] == clock) return clock;
994
995 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
996 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
997 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
998 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
999 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
1000 fc = countFC(dest, size, 0);
1001 if (fc!=2 && fc!=4 && fc!=8) return -1;
1002 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
1003
1004 //find first full wave
1005 for (i=160; i<loopCnt; i++){
1006 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1007 if (waveStart == 0) {
1008 waveStart = i+1;
1009 //prnt("DEBUG: waveStart: %d",waveStart);
1010 } else {
1011 waveEnd = i+1;
1012 //prnt("DEBUG: waveEnd: %d",waveEnd);
1013 waveLenCnt = waveEnd-waveStart;
1014 if (waveLenCnt > fc){
1015 firstFullWave = waveStart;
1016 fullWaveLen=waveLenCnt;
1017 break;
1018 }
1019 waveStart=0;
1020 }
1021 }
1022 }
1023 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1024
1025 //test each valid clock from greatest to smallest to see which lines up
1026 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1027 lastClkBit = firstFullWave; //set end of wave as clock align
1028 waveStart = 0;
1029 errCnt=0;
1030 peakcnt=0;
1031 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1032
1033 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1034 //top edge of wave = start of new wave
1035 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1036 if (waveStart == 0) {
1037 waveStart = i+1;
1038 waveLenCnt=0;
1039 } else { //waveEnd
1040 waveEnd = i+1;
1041 waveLenCnt = waveEnd-waveStart;
1042 if (waveLenCnt > fc){
1043 //if this wave is a phase shift
1044 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);
1045 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1046 peakcnt++;
1047 lastClkBit+=clk[clkCnt];
1048 } else if (i<lastClkBit+8){
1049 //noise after a phase shift - ignore
1050 } else { //phase shift before supposed to based on clock
1051 errCnt++;
1052 }
1053 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1054 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1055 }
1056 waveStart=i+1;
1057 }
1058 }
1059 }
1060 if (errCnt == 0){
1061 return clk[clkCnt];
1062 }
1063 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1064 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1065 }
1066 //all tested with errors
1067 //return the highest clk with the most peaks found
1068 uint8_t best=7;
1069 for (i=7; i>=1; i--){
1070 if (peaksdet[i] > peaksdet[best]) {
1071 best = i;
1072 }
1073 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1074 }
1075 return clk[best];
1076 }
1077
1078 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1079 //find shortest transition from high to low
1080 size_t i = 0;
1081 size_t transition1 = 0;
1082 int lowestTransition = 255;
1083 bool lastWasHigh = false;
1084
1085 //find first valid beginning of a high or low wave
1086 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1087 ++i;
1088 while ((dest[i] < peak && dest[i] > low) && (i < size))
1089 ++i;
1090 lastWasHigh = (dest[i] >= peak);
1091
1092 if (i==size) return 0;
1093 transition1 = i;
1094
1095 for (;i < size; i++) {
1096 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1097 lastWasHigh = (dest[i] >= peak);
1098 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1099 transition1 = i;
1100 }
1101 }
1102 if (lowestTransition == 255) lowestTransition = 0;
1103 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1104 return lowestTransition;
1105 }
1106
1107 //by marshmellow
1108 //detect nrz clock by reading #peaks vs no peaks(or errors)
1109 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1110 {
1111 size_t i=0;
1112 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1113 size_t loopCnt = 4096; //don't need to loop through entire array...
1114 if (size == 0) return 0;
1115 if (size<loopCnt) loopCnt = size-20;
1116 //if we already have a valid clock quit
1117 for (; i < 8; ++i)
1118 if (clk[i] == clock) return clock;
1119
1120 //get high and low peak
1121 int peak, low;
1122 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1123
1124 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1125 size_t ii;
1126 uint8_t clkCnt;
1127 uint8_t tol = 0;
1128 uint16_t smplCnt = 0;
1129 int16_t peakcnt = 0;
1130 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1131 uint16_t maxPeak = 255;
1132 bool firstpeak = false;
1133 //test for large clipped waves
1134 for (i=0; i<loopCnt; i++){
1135 if (dest[i] >= peak || dest[i] <= low){
1136 if (!firstpeak) continue;
1137 smplCnt++;
1138 } else {
1139 firstpeak=true;
1140 if (smplCnt > 6 ){
1141 if (maxPeak > smplCnt){
1142 maxPeak = smplCnt;
1143 //prnt("maxPk: %d",maxPeak);
1144 }
1145 peakcnt++;
1146 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1147 smplCnt=0;
1148 }
1149 }
1150 }
1151 bool errBitHigh = 0;
1152 bool bitHigh = 0;
1153 uint8_t ignoreCnt = 0;
1154 uint8_t ignoreWindow = 4;
1155 bool lastPeakHigh = 0;
1156 int lastBit = 0;
1157 peakcnt=0;
1158 //test each valid clock from smallest to greatest to see which lines up
1159 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1160 //ignore clocks smaller than smallest peak
1161 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1162 //try lining up the peaks by moving starting point (try first 256)
1163 for (ii=20; ii < loopCnt; ++ii){
1164 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1165 peakcnt=0;
1166 bitHigh = false;
1167 ignoreCnt = 0;
1168 lastBit = ii-clk[clkCnt];
1169 //loop through to see if this start location works
1170 for (i = ii; i < size-20; ++i) {
1171 //if we are at a clock bit
1172 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1173 //test high/low
1174 if (dest[i] >= peak || dest[i] <= low) {
1175 //if same peak don't count it
1176 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1177 peakcnt++;
1178 }
1179 lastPeakHigh = (dest[i] >= peak);
1180 bitHigh = true;
1181 errBitHigh = false;
1182 ignoreCnt = ignoreWindow;
1183 lastBit += clk[clkCnt];
1184 } else if (i == lastBit + clk[clkCnt] + tol) {
1185 lastBit += clk[clkCnt];
1186 }
1187 //else if not a clock bit and no peaks
1188 } else if (dest[i] < peak && dest[i] > low){
1189 if (ignoreCnt==0){
1190 bitHigh=false;
1191 if (errBitHigh==true) peakcnt--;
1192 errBitHigh=false;
1193 } else {
1194 ignoreCnt--;
1195 }
1196 // else if not a clock bit but we have a peak
1197 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1198 //error bar found no clock...
1199 errBitHigh=true;
1200 }
1201 }
1202 if(peakcnt>peaksdet[clkCnt]) {
1203 peaksdet[clkCnt]=peakcnt;
1204 }
1205 }
1206 }
1207 }
1208 int iii=7;
1209 uint8_t best=0;
1210 for (iii=7; iii > 0; iii--){
1211 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1212 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1213 best = iii;
1214 }
1215 } else if (peaksdet[iii] > peaksdet[best]){
1216 best = iii;
1217 }
1218 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);
1219 }
1220
1221 return clk[best];
1222 }
1223
1224 // by marshmellow
1225 // convert psk1 demod to psk2 demod
1226 // only transition waves are 1s
1227 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1228 {
1229 size_t i=1;
1230 uint8_t lastBit=BitStream[0];
1231 for (; i<size; i++){
1232 if (BitStream[i]==7){
1233 //ignore errors
1234 } else if (lastBit!=BitStream[i]){
1235 lastBit=BitStream[i];
1236 BitStream[i]=1;
1237 } else {
1238 BitStream[i]=0;
1239 }
1240 }
1241 return;
1242 }
1243
1244 // by marshmellow
1245 // convert psk2 demod to psk1 demod
1246 // from only transition waves are 1s to phase shifts change bit
1247 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1248 {
1249 uint8_t phase=0;
1250 for (size_t i=0; i<size; i++){
1251 if (BitStream[i]==1){
1252 phase ^=1;
1253 }
1254 BitStream[i]=phase;
1255 }
1256 return;
1257 }
1258
1259 // redesigned by marshmellow adjusted from existing decode functions
1260 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1261 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1262 {
1263 //26 bit 40134 format (don't know other formats)
1264 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};
1265 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};
1266 size_t startidx = 0;
1267 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1268 // if didn't find preamble try again inverting
1269 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1270 *invert ^= 1;
1271 }
1272 if (*size != 64 && *size != 224) return -2;
1273 if (*invert==1)
1274 for (size_t i = startidx; i < *size; i++)
1275 bitStream[i] ^= 1;
1276
1277 return (int) startidx;
1278 }
1279
1280 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1281 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1282 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1283 if (justNoise(dest, *size)) return -1;
1284 *clk = DetectNRZClock(dest, *size, *clk);
1285 if (*clk==0) return -2;
1286 size_t i, gLen = 4096;
1287 if (gLen>*size) gLen = *size-20;
1288 int high, low;
1289 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1290
1291 uint8_t bit=0;
1292 //convert wave samples to 1's and 0's
1293 for(i=20; i < *size-20; i++){
1294 if (dest[i] >= high) bit = 1;
1295 if (dest[i] <= low) bit = 0;
1296 dest[i] = bit;
1297 }
1298 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1299 size_t lastBit = 0;
1300 size_t numBits = 0;
1301 for(i=21; i < *size-20; i++) {
1302 //if transition detected or large number of same bits - store the passed bits
1303 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1304 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1305 numBits += (i - lastBit + (*clk/4)) / *clk;
1306 lastBit = i-1;
1307 }
1308 }
1309 *size = numBits;
1310 return 0;
1311 }
1312
1313 //by marshmellow
1314 //detects the bit clock for FSK given the high and low Field Clocks
1315 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1316 {
1317 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1318 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1319 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1320 uint8_t rfLensFnd = 0;
1321 uint8_t lastFCcnt = 0;
1322 uint16_t fcCounter = 0;
1323 uint16_t rfCounter = 0;
1324 uint8_t firstBitFnd = 0;
1325 size_t i;
1326 if (size == 0) return 0;
1327
1328 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1329 rfLensFnd=0;
1330 fcCounter=0;
1331 rfCounter=0;
1332 firstBitFnd=0;
1333 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1334 // prime i to first peak / up transition
1335 for (i = 160; i < size-20; i++)
1336 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1337 break;
1338
1339 for (; i < size-20; i++){
1340 fcCounter++;
1341 rfCounter++;
1342
1343 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1344 continue;
1345 // else new peak
1346 // if we got less than the small fc + tolerance then set it to the small fc
1347 if (fcCounter < fcLow+fcTol)
1348 fcCounter = fcLow;
1349 else //set it to the large fc
1350 fcCounter = fcHigh;
1351
1352 //look for bit clock (rf/xx)
1353 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1354 //not the same size as the last wave - start of new bit sequence
1355 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1356 for (int ii=0; ii<15; ii++){
1357 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1358 rfCnts[ii]++;
1359 rfCounter = 0;
1360 break;
1361 }
1362 }
1363 if (rfCounter > 0 && rfLensFnd < 15){
1364 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1365 rfCnts[rfLensFnd]++;
1366 rfLens[rfLensFnd++] = rfCounter;
1367 }
1368 } else {
1369 firstBitFnd++;
1370 }
1371 rfCounter=0;
1372 lastFCcnt=fcCounter;
1373 }
1374 fcCounter=0;
1375 }
1376 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1377
1378 for (i=0; i<15; i++){
1379 //get highest 2 RF values (might need to get more values to compare or compare all?)
1380 if (rfCnts[i]>rfCnts[rfHighest]){
1381 rfHighest3=rfHighest2;
1382 rfHighest2=rfHighest;
1383 rfHighest=i;
1384 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1385 rfHighest3=rfHighest2;
1386 rfHighest2=i;
1387 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1388 rfHighest3=i;
1389 }
1390 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1391 }
1392 // set allowed clock remainder tolerance to be 1 large field clock length+1
1393 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1394 uint8_t tol1 = fcHigh+1;
1395
1396 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1397
1398 // loop to find the highest clock that has a remainder less than the tolerance
1399 // compare samples counted divided by
1400 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1401 int ii=7;
1402 for (; ii>=2; ii--){
1403 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1404 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1405 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1406 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1407 break;
1408 }
1409 }
1410 }
1411 }
1412
1413 if (ii<0) return 0; // oops we went too far
1414
1415 return clk[ii];
1416 }
1417
1418 //by marshmellow
1419 //countFC is to detect the field clock lengths.
1420 //counts and returns the 2 most common wave lengths
1421 //mainly used for FSK field clock detection
1422 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1423 {
1424 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1425 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1426 uint8_t fcLensFnd = 0;
1427 uint8_t lastFCcnt=0;
1428 uint8_t fcCounter = 0;
1429 size_t i;
1430 if (size == 0) return 0;
1431
1432 // prime i to first up transition
1433 for (i = 160; i < size-20; i++)
1434 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1435 break;
1436
1437 for (; i < size-20; i++){
1438 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1439 // new up transition
1440 fcCounter++;
1441 if (fskAdj){
1442 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1443 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1444 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1445 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1446 // save last field clock count (fc/xx)
1447 lastFCcnt = fcCounter;
1448 }
1449 // find which fcLens to save it to:
1450 for (int ii=0; ii<15; ii++){
1451 if (fcLens[ii]==fcCounter){
1452 fcCnts[ii]++;
1453 fcCounter=0;
1454 break;
1455 }
1456 }
1457 if (fcCounter>0 && fcLensFnd<15){
1458 //add new fc length
1459 fcCnts[fcLensFnd]++;
1460 fcLens[fcLensFnd++]=fcCounter;
1461 }
1462 fcCounter=0;
1463 } else {
1464 // count sample
1465 fcCounter++;
1466 }
1467 }
1468
1469 uint8_t best1=14, best2=14, best3=14;
1470 uint16_t maxCnt1=0;
1471 // go through fclens and find which ones are bigest 2
1472 for (i=0; i<15; i++){
1473 // get the 3 best FC values
1474 if (fcCnts[i]>maxCnt1) {
1475 best3=best2;
1476 best2=best1;
1477 maxCnt1=fcCnts[i];
1478 best1=i;
1479 } else if(fcCnts[i]>fcCnts[best2]){
1480 best3=best2;
1481 best2=i;
1482 } else if(fcCnts[i]>fcCnts[best3]){
1483 best3=i;
1484 }
1485 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]);
1486 }
1487 if (fcLens[best1]==0) return 0;
1488 uint8_t fcH=0, fcL=0;
1489 if (fcLens[best1]>fcLens[best2]){
1490 fcH=fcLens[best1];
1491 fcL=fcLens[best2];
1492 } else{
1493 fcH=fcLens[best2];
1494 fcL=fcLens[best1];
1495 }
1496 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1497 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]);
1498 return 0; //lots of waves not psk or fsk
1499 }
1500 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1501
1502 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1503 if (fskAdj) return fcs;
1504 return fcLens[best1];
1505 }
1506
1507 //by marshmellow - demodulate PSK1 wave
1508 //uses wave lengths (# Samples)
1509 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1510 {
1511 if (size == 0) return -1;
1512 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1513 if (*size<loopCnt) loopCnt = *size;
1514
1515 size_t numBits=0;
1516 uint8_t curPhase = *invert;
1517 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1518 uint8_t fc=0, fullWaveLen=0, tol=1;
1519 uint16_t errCnt=0, waveLenCnt=0;
1520 fc = countFC(dest, *size, 0);
1521 if (fc!=2 && fc!=4 && fc!=8) return -1;
1522 //PrintAndLog("DEBUG: FC: %d",fc);
1523 *clock = DetectPSKClock(dest, *size, *clock);
1524 if (*clock == 0) return -1;
1525 int avgWaveVal=0, lastAvgWaveVal=0;
1526 //find first phase shift
1527 for (i=0; i<loopCnt; i++){
1528 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1529 waveEnd = i+1;
1530 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1531 waveLenCnt = waveEnd-waveStart;
1532 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1533 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1534 firstFullWave = waveStart;
1535 fullWaveLen=waveLenCnt;
1536 //if average wave value is > graph 0 then it is an up wave or a 1
1537 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1538 break;
1539 }
1540 waveStart = i+1;
1541 avgWaveVal = 0;
1542 }
1543 avgWaveVal += dest[i+2];
1544 }
1545 if (firstFullWave == 0) {
1546 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1547 // so skip a little to ensure we are past any Start Signal
1548 firstFullWave = 160;
1549 memset(dest, curPhase, firstFullWave / *clock);
1550 } else {
1551 memset(dest, curPhase^1, firstFullWave / *clock);
1552 }
1553 //advance bits
1554 numBits += (firstFullWave / *clock);
1555 //set start of wave as clock align
1556 lastClkBit = firstFullWave;
1557 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1558 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1559 waveStart = 0;
1560 dest[numBits++] = curPhase; //set first read bit
1561 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1562 //top edge of wave = start of new wave
1563 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1564 if (waveStart == 0) {
1565 waveStart = i+1;
1566 waveLenCnt = 0;
1567 avgWaveVal = dest[i+1];
1568 } else { //waveEnd
1569 waveEnd = i+1;
1570 waveLenCnt = waveEnd-waveStart;
1571 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1572 if (waveLenCnt > fc){
1573 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1574 //this wave is a phase shift
1575 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1576 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1577 curPhase ^= 1;
1578 dest[numBits++] = curPhase;
1579 lastClkBit += *clock;
1580 } else if (i < lastClkBit+10+fc){
1581 //noise after a phase shift - ignore
1582 } else { //phase shift before supposed to based on clock
1583 errCnt++;
1584 dest[numBits++] = 7;
1585 }
1586 } else if (i+1 > lastClkBit + *clock + tol + fc){
1587 lastClkBit += *clock; //no phase shift but clock bit
1588 dest[numBits++] = curPhase;
1589 }
1590 avgWaveVal = 0;
1591 waveStart = i+1;
1592 }
1593 }
1594 avgWaveVal += dest[i+1];
1595 }
1596 *size = numBits;
1597 return errCnt;
1598 }
1599
1600 //by marshmellow
1601 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1602 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1603 size_t bufsize = *size;
1604 //need to loop through all samples and identify our clock, look for the ST pattern
1605 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1606 int clk = 0;
1607 int tol = 0;
1608 int i, j, skip, start, end, low, high, minClk, waveStart;
1609 bool complete = false;
1610 int tmpbuff[bufsize / 64];
1611 int waveLen[bufsize / 64];
1612 size_t testsize = (bufsize < 512) ? bufsize : 512;
1613 int phaseoff = 0;
1614 high = low = 128;
1615 memset(tmpbuff, 0, sizeof(tmpbuff));
1616
1617 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1618 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1619 return false; //just noise
1620 }
1621 i = 0;
1622 j = 0;
1623 minClk = 255;
1624 // get to first full low to prime loop and skip incomplete first pulse
1625 while ((buffer[i] < high) && (i < bufsize))
1626 ++i;
1627 while ((buffer[i] > low) && (i < bufsize))
1628 ++i;
1629 skip = i;
1630
1631 // populate tmpbuff buffer with pulse lengths
1632 while (i < bufsize) {
1633 // measure from low to low
1634 while ((buffer[i] > low) && (i < bufsize))
1635 ++i;
1636 start= i;
1637 while ((buffer[i] < high) && (i < bufsize))
1638 ++i;
1639 //first high point for this wave
1640 waveStart = i;
1641 while ((buffer[i] > low) && (i < bufsize))
1642 ++i;
1643 if (j >= (bufsize/64)) {
1644 break;
1645 }
1646 waveLen[j] = i - waveStart; //first high to first low
1647 tmpbuff[j++] = i - start;
1648 if (i-start < minClk && i < bufsize) {
1649 minClk = i - start;
1650 }
1651 }
1652 // set clock - might be able to get this externally and remove this work...
1653 if (!clk) {
1654 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1655 tol = fndClk[clkCnt]/8;
1656 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1657 clk=fndClk[clkCnt];
1658 break;
1659 }
1660 }
1661 // clock not found - ERROR
1662 if (!clk) {
1663 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1664 return false;
1665 }
1666 } else tol = clk/8;
1667
1668 *foundclock = clk;
1669
1670 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1671 start = -1;
1672 for (i = 0; i < j - 4; ++i) {
1673 skip += tmpbuff[i];
1674 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1675 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
1676 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
1677 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1678 start = i + 3;
1679 break;
1680 }
1681 }
1682 }
1683 }
1684 }
1685 // first ST not found - ERROR
1686 if (start < 0) {
1687 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1688 return false;
1689 }
1690 if (waveLen[i+2] > clk*1+tol)
1691 phaseoff = 0;
1692 else
1693 phaseoff = clk/2;
1694
1695 // skip over the remainder of ST
1696 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1697
1698 // now do it again to find the end
1699 end = skip;
1700 for (i += 3; i < j - 4; ++i) {
1701 end += tmpbuff[i];
1702 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) { //1 to 2 clocks depending on 2 bits prior
1703 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
1704 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
1705 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1706 complete = true;
1707 break;
1708 }
1709 }
1710 }
1711 }
1712 }
1713 end -= phaseoff;
1714 //didn't find second ST - ERROR
1715 if (!complete) {
1716 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1717 return false;
1718 }
1719 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);
1720 //now begin to trim out ST so we can use normal demod cmds
1721 start = skip;
1722 size_t datalen = end - start;
1723 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1724 if (datalen % clk > clk/8) {
1725 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1726 return false;
1727 } else {
1728 // padd the amount off - could be problematic... but shouldn't happen often
1729 datalen += datalen % clk;
1730 }
1731 // if datalen is less than one t55xx block - ERROR
1732 if (datalen/clk < 8*4) {
1733 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1734 return false;
1735 }
1736 size_t dataloc = start;
1737 size_t newloc = 0;
1738 i=0;
1739 // warning - overwriting buffer given with raw wave data with ST removed...
1740 while ( dataloc < bufsize-(clk/2) ) {
1741 //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)
1742 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1743 for(i=0; i < clk/2-tol; ++i) {
1744 buffer[dataloc+i] = high+5;
1745 }
1746 }
1747 for (i=0; i<datalen; ++i) {
1748 if (i+newloc < bufsize) {
1749 if (i+newloc < dataloc)
1750 buffer[i+newloc] = buffer[dataloc];
1751
1752 dataloc++;
1753 }
1754 }
1755 newloc += i;
1756 //skip next ST - we just assume it will be there from now on...
1757 dataloc += clk*4;
1758 }
1759 *size = newloc;
1760 return true;
1761 }
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