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