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