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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)
88 return 0;
89 break;
90 }
91 bitCnt+=(pLen-1);
92 parityWd = 0;
93 }
94 // if we got here then all the parities passed
95 //return ID start index and size
96 return bitCnt;
97 }
98
99 // by marshmellow
100 // takes a array of binary values, length of bits per parity (includes parity bit),
101 // Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
102 // Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
103 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
104 {
105 uint32_t parityWd = 0;
106 size_t j = 0, bitCnt = 0;
107 for (int word = 0; word < sourceLen; word+=pLen-1) {
108 for (int bit=0; bit < pLen-1; bit++){
109 parityWd = (parityWd << 1) | BitSource[word+bit];
110 dest[j++] = (BitSource[word+bit]);
111 }
112
113 // if parity fails then return 0
114 switch (pType) {
115 case 3: dest[j++]=0; break; // marker bit which should be a 0
116 case 2: dest[j++]=1; break; // marker bit which should be a 1
117 default:
118 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
119 break;
120 }
121 bitCnt += pLen;
122 parityWd = 0;
123 }
124 // if we got here then all the parities passed
125 //return ID start index and size
126 return bitCnt;
127 }
128
129 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
130 {
131 uint32_t num = 0;
132 for(int i = 0 ; i < numbits ; i++) {
133 num = (num << 1) | (*src);
134 src++;
135 }
136 return num;
137 }
138
139 //least significant bit first
140 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
141 {
142 uint32_t num = 0;
143 for(int i = 0 ; i < numbits ; i++) {
144 num = (num << 1) | *(src + (numbits-(i+1)));
145 }
146 return num;
147 }
148
149 //by marshmellow
150 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
151 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
152 {
153 // Sanity check. If preamble length is bigger than bitstream length.
154 if ( *size <= pLen ) return 0;
155
156 uint8_t foundCnt = 0;
157 for (int idx = 0; idx < *size - pLen; idx++){
158 if (memcmp(BitStream+idx, preamble, pLen) == 0){
159 //first index found
160 foundCnt++;
161 if (foundCnt == 1){
162 *startIdx = idx;
163 }
164 if (foundCnt == 2){
165 *size = idx - *startIdx;
166 return 1;
167 }
168 }
169 }
170 return 0;
171 }
172
173 //by marshmellow
174 //takes 1s and 0s and searches for EM410x format - output EM ID
175 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
176 {
177 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
178 // otherwise could be a void with no arguments
179 //set defaults
180 uint32_t i = 0;
181 if (BitStream[1]>1) return 0; //allow only 1s and 0s
182
183 // 111111111 bit pattern represent start of frame
184 // include 0 in front to help get start pos
185 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
186 uint32_t idx = 0;
187 uint32_t parityBits = 0;
188 uint8_t errChk = 0;
189 uint8_t FmtLen = 10;
190 *startIdx = 0;
191 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
192 if (errChk == 0 || *size < 64) return 0;
193 if (*size > 64) FmtLen = 22;
194 *startIdx += 1; //get rid of 0 from preamble
195 idx = *startIdx + 9;
196 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
197 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
198 //check even parity - quit if failed
199 if (parityTest(parityBits, 5, 0) == 0) return 0;
200 //set uint64 with ID from BitStream
201 for (uint8_t ii=0; ii<4; ii++){
202 *hi = (*hi << 1) | (*lo >> 63);
203 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
204 }
205 }
206 if (errChk != 0) return 1;
207 //skip last 5 bit parity test for simplicity.
208 // *size = 64 | 128;
209 return 0;
210 }
211
212 //by marshmellow
213 //demodulates strong heavily clipped samples
214 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
215 {
216 size_t bitCnt=0, smplCnt=0, errCnt=0;
217 uint8_t waveHigh = 0;
218 for (size_t i=0; i < *size; i++){
219 if (BinStream[i] >= high && waveHigh){
220 smplCnt++;
221 } else if (BinStream[i] <= low && !waveHigh){
222 smplCnt++;
223 } else { //transition
224 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
225 if (smplCnt > clk-(clk/4)-1) { //full clock
226 if (smplCnt > clk + (clk/4)+1) { //too many samples
227 errCnt++;
228 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
229 BinStream[bitCnt++]=7;
230 } else if (waveHigh) {
231 BinStream[bitCnt++] = invert;
232 BinStream[bitCnt++] = invert;
233 } else if (!waveHigh) {
234 BinStream[bitCnt++] = invert ^ 1;
235 BinStream[bitCnt++] = invert ^ 1;
236 }
237 waveHigh ^= 1;
238 smplCnt = 0;
239 } else if (smplCnt > (clk/2) - (clk/4)-1) {
240 if (waveHigh) {
241 BinStream[bitCnt++] = invert;
242 } else if (!waveHigh) {
243 BinStream[bitCnt++] = invert ^ 1;
244 }
245 waveHigh ^= 1;
246 smplCnt = 0;
247 } else if (!bitCnt) {
248 //first bit
249 waveHigh = (BinStream[i] >= high);
250 smplCnt = 1;
251 } else {
252 smplCnt++;
253 //transition bit oops
254 }
255 } else { //haven't hit new high or new low yet
256 smplCnt++;
257 }
258 }
259 }
260 *size = bitCnt;
261 return errCnt;
262 }
263
264 //by marshmellow
265 void askAmp(uint8_t *BitStream, size_t size)
266 {
267 uint8_t last = 128;
268 for(size_t i = 1; i < size; ++i){
269 if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
270 last = 255;
271 else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
272 last = 0;
273
274 BitStream[i] = last;
275 }
276 }
277
278 //by marshmellow
279 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
280 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
281 {
282 if (*size==0) return -1;
283 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
284 if (*clk==0 || start < 0) return -3;
285 if (*invert != 1) *invert = 0;
286 if (amp==1) askAmp(BinStream, *size);
287 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
288
289 uint8_t initLoopMax = 255;
290 if (initLoopMax > *size) initLoopMax = *size;
291 // Detect high and lows
292 //25% clip in case highs and lows aren't clipped [marshmellow]
293 int high, low;
294 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
295 return -2; //just noise
296
297 size_t errCnt = 0;
298 // if clean clipped waves detected run alternate demod
299 if (DetectCleanAskWave(BinStream, *size, high, low)) {
300 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
301 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
302 if (askType) //askman
303 return manrawdecode(BinStream, size, 0);
304 else //askraw
305 return errCnt;
306 }
307 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
308
309 int lastBit; //set first clock check - can go negative
310 size_t i, bitnum = 0; //output counter
311 uint8_t midBit = 0;
312 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
313 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
314 size_t MaxBits = 3072; //max bits to collect
315 lastBit = start - *clk;
316
317 for (i = start; i < *size; ++i) {
318 if (i-lastBit >= *clk-tol){
319 if (BinStream[i] >= high) {
320 BinStream[bitnum++] = *invert;
321 } else if (BinStream[i] <= low) {
322 BinStream[bitnum++] = *invert ^ 1;
323 } else if (i-lastBit >= *clk+tol) {
324 if (bitnum > 0) {
325 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
326 BinStream[bitnum++]=7;
327 errCnt++;
328 }
329 } else { //in tolerance - looking for peak
330 continue;
331 }
332 midBit = 0;
333 lastBit += *clk;
334 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
335 if (BinStream[i] >= high) {
336 BinStream[bitnum++] = *invert;
337 } else if (BinStream[i] <= low) {
338 BinStream[bitnum++] = *invert ^ 1;
339 } else if (i-lastBit >= *clk/2+tol) {
340 BinStream[bitnum] = BinStream[bitnum-1];
341 bitnum++;
342 } else { //in tolerance - looking for peak
343 continue;
344 }
345 midBit = 1;
346 }
347 if (bitnum >= MaxBits) break;
348 }
349 *size = bitnum;
350 return errCnt;
351 }
352
353 //by marshmellow
354 //take 10 and 01 and manchester decode
355 //run through 2 times and take least errCnt
356 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
357 {
358 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
359 size_t i, ii;
360 uint16_t bestErr = 1000, bestRun = 0;
361 if (*size < 16) return -1;
362 //find correct start position [alignment]
363 for (ii=0;ii<2;++ii){
364 for (i=ii; i<*size-3; i+=2)
365 if (BitStream[i]==BitStream[i+1])
366 errCnt++;
367
368 if (bestErr>errCnt){
369 bestErr=errCnt;
370 bestRun=ii;
371 }
372 errCnt=0;
373 }
374 //decode
375 for (i=bestRun; i < *size-3; i+=2){
376 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
377 BitStream[bitnum++]=invert;
378 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
379 BitStream[bitnum++]=invert^1;
380 } else {
381 BitStream[bitnum++]=7;
382 }
383 if(bitnum>MaxBits) break;
384 }
385 *size=bitnum;
386 return bestErr;
387 }
388
389 uint32_t manchesterEncode2Bytes(uint16_t datain) {
390 uint32_t output = 0;
391 uint8_t curBit = 0;
392 for (uint8_t i=0; i<16; i++) {
393 curBit = (datain >> (15-i) & 1);
394 output |= (1<<(((15-i)*2)+curBit));
395 }
396 return output;
397 }
398
399 //by marshmellow
400 //encode binary data into binary manchester
401 int ManchesterEncode(uint8_t *BitStream, size_t size)
402 {
403 size_t modIdx=20000, i=0;
404 if (size>modIdx) return -1;
405 for (size_t idx=0; idx < size; idx++){
406 BitStream[idx+modIdx++] = BitStream[idx];
407 BitStream[idx+modIdx++] = BitStream[idx]^1;
408 }
409 for (; i<(size*2); i++){
410 BitStream[i] = BitStream[i+20000];
411 }
412 return i;
413 }
414
415 //by marshmellow
416 //take 01 or 10 = 1 and 11 or 00 = 0
417 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
418 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
419 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
420 {
421 uint16_t bitnum = 0;
422 uint16_t errCnt = 0;
423 size_t i = offset;
424 uint16_t MaxBits=512;
425 //if not enough samples - error
426 if (*size < 51) return -1;
427 //check for phase change faults - skip one sample if faulty
428 uint8_t offsetA = 1, offsetB = 1;
429 for (; i<48; i+=2){
430 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
431 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
432 }
433 if (!offsetA && offsetB) offset++;
434 for (i=offset; i<*size-3; i+=2){
435 //check for phase error
436 if (BitStream[i+1]==BitStream[i+2]) {
437 BitStream[bitnum++]=7;
438 errCnt++;
439 }
440 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
441 BitStream[bitnum++]=1^invert;
442 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
443 BitStream[bitnum++]=invert;
444 } else {
445 BitStream[bitnum++]=7;
446 errCnt++;
447 }
448 if(bitnum>MaxBits) break;
449 }
450 *size=bitnum;
451 return errCnt;
452 }
453
454 // by marshmellow
455 // demod gProxIIDemod
456 // error returns as -x
457 // success returns start position in BitStream
458 // BitStream must contain previously askrawdemod and biphasedemoded data
459 int gProxII_Demod(uint8_t BitStream[], size_t *size)
460 {
461 size_t startIdx=0;
462 uint8_t preamble[] = {1,1,1,1,1,0};
463
464 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
465 if (errChk == 0) return -3; //preamble not found
466 if (*size != 96) return -2; //should have found 96 bits
467 //check first 6 spacer bits to verify format
468 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
469 //confirmed proper separator bits found
470 //return start position
471 return (int) startIdx;
472 }
473 return -5; //spacer bits not found - not a valid gproxII
474 }
475
476 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
477 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
478 {
479 size_t last_transition = 0;
480 size_t idx = 1;
481 //uint32_t maxVal=0;
482 if (fchigh==0) fchigh=10;
483 if (fclow==0) fclow=8;
484 //set the threshold close to 0 (graph) or 128 std to avoid static
485 uint8_t threshold_value = 123;
486 size_t preLastSample = 0;
487 size_t LastSample = 0;
488 size_t currSample = 0;
489 // sync to first lo-hi transition, and threshold
490
491 // Need to threshold first sample
492 // skip 160 samples to allow antenna/samples to settle
493 if(dest[160] < threshold_value) dest[0] = 0;
494 else dest[0] = 1;
495
496 size_t numBits = 0;
497 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
498 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
499 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
500 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
501 for(idx = 161; idx < size-20; idx++) {
502 // threshold current value
503
504 if (dest[idx] < threshold_value) dest[idx] = 0;
505 else dest[idx] = 1;
506
507 // Check for 0->1 transition
508 if (dest[idx-1] < dest[idx]) {
509 preLastSample = LastSample;
510 LastSample = currSample;
511 currSample = idx-last_transition;
512 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
513 //do nothing with extra garbage
514 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
515 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
516 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
517 dest[numBits-1]=1;
518 }
519 dest[numBits++]=1;
520
521 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
522 //do nothing with beginning garbage
523 } 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)
524 dest[numBits++]=1;
525 } else { //9+ = 10 sample waves (or 6+ = 7)
526 dest[numBits++]=0;
527 }
528 last_transition = idx;
529 }
530 }
531 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
532 }
533
534 //translate 11111100000 to 10
535 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
536 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
537 uint8_t invert, uint8_t fchigh, uint8_t fclow)
538 {
539 uint8_t lastval=dest[0];
540 size_t idx=0;
541 size_t numBits=0;
542 uint32_t n=1;
543 for( idx=1; idx < size; idx++) {
544 n++;
545 if (dest[idx]==lastval) continue;
546
547 //find out how many bits (n) we collected
548 //if lastval was 1, we have a 1->0 crossing
549 if (dest[idx-1]==1) {
550 n = (n * fclow + rfLen/2) / rfLen;
551 } else {// 0->1 crossing
552 n = (n * fchigh + rfLen/2) / rfLen;
553 }
554 if (n == 0) n = 1;
555
556 //add to our destination the bits we collected
557 memset(dest+numBits, dest[idx-1]^invert , n);
558 numBits += n;
559 n=0;
560 lastval=dest[idx];
561 }//end for
562 // if valid extra bits at the end were all the same frequency - add them in
563 if (n > rfLen/fchigh) {
564 if (dest[idx-2]==1) {
565 n = (n * fclow + rfLen/2) / rfLen;
566 } else {
567 n = (n * fchigh + rfLen/2) / rfLen;
568 }
569 memset(dest+numBits, dest[idx-1]^invert , n);
570 numBits += n;
571 }
572 return numBits;
573 }
574
575 //by marshmellow (from holiman's base)
576 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
577 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
578 {
579 // FSK demodulator
580 size = fsk_wave_demod(dest, size, fchigh, fclow);
581 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
582 return size;
583 }
584
585 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
586 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
587 {
588 if (justNoise(dest, *size)) return -1;
589
590 size_t numStart=0, size2 = *size, startIdx=0;
591 // FSK demodulator
592 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
593 if (*size < 96*2) return -2;
594 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
595 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
596 // find bitstring in array
597 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
598 if (errChk == 0) return -3; //preamble not found
599
600 numStart = startIdx + sizeof(preamble);
601 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
602 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
603 if (dest[idx] == dest[idx+1]){
604 return -4; //not manchester data
605 }
606 *hi2 = (*hi2<<1)|(*hi>>31);
607 *hi = (*hi<<1)|(*lo>>31);
608 //Then, shift in a 0 or one into low
609 if (dest[idx] && !dest[idx+1]) // 1 0
610 *lo=(*lo<<1)|1;
611 else // 0 1
612 *lo=(*lo<<1)|0;
613 }
614 return (int)startIdx;
615 }
616
617 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
618 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
619 {
620 if (justNoise(dest, *size)) return -1;
621
622 size_t numStart=0, size2 = *size, startIdx=0;
623 // FSK demodulator
624 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
625 if (*size < 96) return -2;
626
627 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
628 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
629
630 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
631 if (errChk == 0) return -3; //preamble not found
632
633 numStart = startIdx + sizeof(preamble);
634 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
635 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
636 if (dest[idx] == dest[idx+1])
637 return -4; //not manchester data
638 *hi2 = (*hi2<<1)|(*hi>>31);
639 *hi = (*hi<<1)|(*lo>>31);
640 //Then, shift in a 0 or one into low
641 if (dest[idx] && !dest[idx+1]) // 1 0
642 *lo=(*lo<<1)|1;
643 else // 0 1
644 *lo=(*lo<<1)|0;
645 }
646 return (int)startIdx;
647 }
648
649 int IOdemodFSK(uint8_t *dest, size_t size)
650 {
651 if (justNoise(dest, size)) return -1;
652 //make sure buffer has data
653 if (size < 66*64) return -2;
654 // FSK demodulator
655 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
656 if (size < 65) return -3; //did we get a good demod?
657 //Index map
658 //0 10 20 30 40 50 60
659 //| | | | | | |
660 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
661 //-----------------------------------------------------------------------------
662 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
663 //
664 //XSF(version)facility:codeone+codetwo
665 //Handle the data
666 size_t startIdx = 0;
667 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
668 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
669 if (errChk == 0) return -4; //preamble not found
670
671 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
672 //confirmed proper separator bits found
673 //return start position
674 return (int) startIdx;
675 }
676 return -5;
677 }
678
679 // by marshmellow
680 // find viking preamble 0xF200 in already demoded data
681 int VikingDemod_AM(uint8_t *dest, size_t *size) {
682 //make sure buffer has data
683 if (*size < 64*2) return -2;
684
685 size_t startIdx = 0;
686 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};
687 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
688 if (errChk == 0) return -4; //preamble not found
689 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^
690 bytebits_to_byte(dest+startIdx+8,8) ^
691 bytebits_to_byte(dest+startIdx+16,8) ^
692 bytebits_to_byte(dest+startIdx+24,8) ^
693 bytebits_to_byte(dest+startIdx+32,8) ^
694 bytebits_to_byte(dest+startIdx+40,8) ^
695 bytebits_to_byte(dest+startIdx+48,8) ^
696 bytebits_to_byte(dest+startIdx+56,8);
697 if ( checkCalc != 0xA8 ) return -5;
698 if (*size != 64) return -6;
699 //return start position
700 return (int) startIdx;
701 }
702
703 // find presco preamble 0x10D in already demoded data
704 int PrescoDemod(uint8_t *dest, size_t *size) {
705 //make sure buffer has data
706 if (*size < 64*2) return -2;
707
708 size_t startIdx = 0;
709 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
710 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
711 if (errChk == 0) return -4; //preamble not found
712 //return start position
713 return (int) startIdx;
714 }
715
716 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
717 // BitStream must contain previously askrawdemod and biphasedemoded data
718 int FDXBdemodBI(uint8_t *dest, size_t *size)
719 {
720 //make sure buffer has enough data
721 if (*size < 128) return -1;
722
723 size_t startIdx = 0;
724 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
725
726 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
727 if (errChk == 0) return -2; //preamble not found
728 return (int)startIdx;
729 }
730
731 // ASK/Diphase fc/64 (inverted Biphase)
732 // Note: this i s not a demod, this is only a detection
733 // the parameter *dest needs to be demoded before call
734 int JablotronDemod(uint8_t *dest, size_t *size){
735 //make sure buffer has enough data
736 if (*size < 64) return -1;
737
738 size_t startIdx = 0;
739 // 0xFFFF preamble, 64bits
740 uint8_t preamble[] = {
741 1,1,1,1,
742 1,1,1,1,
743 1,1,1,1,
744 1,1,1,1,
745 0
746 };
747
748 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
749 if (errChk == 0) return -4; //preamble not found
750 if (*size != 64) return -3;
751
752 uint8_t checkchksum = 0;
753 for (int i=16; i < 56; i += 8) {
754 checkchksum += bytebits_to_byte(dest+startIdx+i,8);
755 }
756 checkchksum ^= 0x3A;
757
758 uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
759
760 if ( checkchksum != crc ) return -5;
761 return (int)startIdx;
762 }
763
764 // by marshmellow
765 // FSK Demod then try to locate an AWID ID
766 int AWIDdemodFSK(uint8_t *dest, size_t *size)
767 {
768 //make sure buffer has enough data
769 if (*size < 96*50) return -1;
770
771 if (justNoise(dest, *size)) return -2;
772
773 // FSK demodulator
774 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
775 if (*size < 96) return -3; //did we get a good demod?
776
777 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
778 size_t startIdx = 0;
779 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
780 if (errChk == 0) return -4; //preamble not found
781 if (*size != 96) return -5;
782 return (int)startIdx;
783 }
784
785 // by marshmellow
786 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
787 int PyramiddemodFSK(uint8_t *dest, size_t *size)
788 {
789 //make sure buffer has data
790 if (*size < 128*50) return -5;
791
792 //test samples are not just noise
793 if (justNoise(dest, *size)) return -1;
794
795 // FSK demodulator
796 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
797 if (*size < 128) return -2; //did we get a good demod?
798
799 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
800 size_t startIdx = 0;
801 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
802 if (errChk == 0) return -4; //preamble not found
803 if (*size != 128) return -3;
804 return (int)startIdx;
805 }
806
807 // find nedap preamble in already demoded data
808 int NedapDemod(uint8_t *dest, size_t *size) {
809 //make sure buffer has data
810 if (*size < 128) return -3;
811
812 size_t startIdx = 0;
813 //uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
814 uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
815 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
816 if (errChk == 0) return -4; //preamble not found
817 return (int) startIdx;
818 }
819
820 // by marshmellow
821 // to detect a wave that has heavily clipped (clean) samples
822 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
823 {
824 bool allArePeaks = true;
825 uint16_t cntPeaks=0;
826 size_t loopEnd = 512+160;
827 if (loopEnd > size) loopEnd = size;
828 for (size_t i=160; i<loopEnd; i++){
829 if (dest[i]>low && dest[i]<high)
830 allArePeaks = false;
831 else
832 cntPeaks++;
833 }
834 if (!allArePeaks){
835 if (cntPeaks > 300) return true;
836 }
837 return allArePeaks;
838 }
839 // by marshmellow
840 // to help detect clocks on heavily clipped samples
841 // based on count of low to low
842 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
843 {
844 uint8_t fndClk[] = {8,16,32,40,50,64,128};
845 size_t startwave;
846 size_t i = 100;
847 size_t minClk = 255;
848 // get to first full low to prime loop and skip incomplete first pulse
849 while ((dest[i] < high) && (i < size))
850 ++i;
851 while ((dest[i] > low) && (i < size))
852 ++i;
853
854 // loop through all samples
855 while (i < size) {
856 // measure from low to low
857 while ((dest[i] > low) && (i < size))
858 ++i;
859 startwave= i;
860 while ((dest[i] < high) && (i < size))
861 ++i;
862 while ((dest[i] > low) && (i < size))
863 ++i;
864 //get minimum measured distance
865 if (i-startwave < minClk && i < size)
866 minClk = i - startwave;
867 }
868 // set clock
869 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
870 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
871 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
872 return fndClk[clkCnt];
873 }
874 return 0;
875 }
876
877 // by marshmellow
878 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
879 // maybe somehow adjust peak trimming value based on samples to fix?
880 // return start index of best starting position for that clock and return clock (by reference)
881 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
882 {
883 size_t i=1;
884 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
885 uint8_t clkEnd = 9;
886 uint8_t loopCnt = 255; //don't need to loop through entire array...
887 if (size <= loopCnt+60) return -1; //not enough samples
888 size -= 60; //sometimes there is a strange end wave - filter out this....
889 //if we already have a valid clock
890 uint8_t clockFnd=0;
891 for (;i<clkEnd;++i)
892 if (clk[i] == *clock) clockFnd = i;
893 //clock found but continue to find best startpos
894
895 //get high and low peak
896 int peak, low;
897 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
898
899 //test for large clean peaks
900 if (!clockFnd){
901 if (DetectCleanAskWave(dest, size, peak, low)==1){
902 int ans = DetectStrongAskClock(dest, size, peak, low);
903 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
904 for (i=clkEnd-1; i>0; i--){
905 if (clk[i] == ans) {
906 *clock = ans;
907 //clockFnd = i;
908 return 0; // for strong waves i don't use the 'best start position' yet...
909 //break; //clock found but continue to find best startpos [not yet]
910 }
911 }
912 }
913 }
914 uint8_t ii;
915 uint8_t clkCnt, tol = 0;
916 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
917 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
918 size_t errCnt = 0;
919 size_t arrLoc, loopEnd;
920
921 if (clockFnd>0) {
922 clkCnt = clockFnd;
923 clkEnd = clockFnd+1;
924 }
925 else clkCnt=1;
926
927 //test each valid clock from smallest to greatest to see which lines up
928 for(; clkCnt < clkEnd; clkCnt++){
929 if (clk[clkCnt] <= 32){
930 tol=1;
931 }else{
932 tol=0;
933 }
934 //if no errors allowed - keep start within the first clock
935 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
936 bestErr[clkCnt]=1000;
937 //try lining up the peaks by moving starting point (try first few clocks)
938 for (ii=0; ii < loopCnt; ii++){
939 if (dest[ii] < peak && dest[ii] > low) continue;
940
941 errCnt=0;
942 // now that we have the first one lined up test rest of wave array
943 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
944 for (i=0; i < loopEnd; ++i){
945 arrLoc = ii + (i * clk[clkCnt]);
946 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
947 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
948 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
949 }else{ //error no peak detected
950 errCnt++;
951 }
952 }
953 //if we found no errors then we can stop here and a low clock (common clocks)
954 // this is correct one - return this clock
955 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
956 if(errCnt==0 && clkCnt<7) {
957 if (!clockFnd) *clock = clk[clkCnt];
958 return ii;
959 }
960 //if we found errors see if it is lowest so far and save it as best run
961 if(errCnt<bestErr[clkCnt]){
962 bestErr[clkCnt]=errCnt;
963 bestStart[clkCnt]=ii;
964 }
965 }
966 }
967 uint8_t iii;
968 uint8_t best=0;
969 for (iii=1; iii<clkEnd; ++iii){
970 if (bestErr[iii] < bestErr[best]){
971 if (bestErr[iii] == 0) bestErr[iii]=1;
972 // current best bit to error ratio vs new bit to error ratio
973 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
974 best = iii;
975 }
976 }
977 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]);
978 }
979 if (!clockFnd) *clock = clk[best];
980 return bestStart[best];
981 }
982
983 //by marshmellow
984 //detect psk clock by reading each phase shift
985 // a phase shift is determined by measuring the sample length of each wave
986 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
987 {
988 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
989 uint16_t loopCnt = 4096; //don't need to loop through entire array...
990 if (size == 0) return 0;
991 if (size<loopCnt) loopCnt = size-20;
992
993 //if we already have a valid clock quit
994 size_t i=1;
995 for (; i < 8; ++i)
996 if (clk[i] == clock) return clock;
997
998 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
999 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
1000 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
1001 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
1002 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
1003 fc = countFC(dest, size, 0);
1004 if (fc!=2 && fc!=4 && fc!=8) return -1;
1005 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
1006
1007 //find first full wave
1008 for (i=160; i<loopCnt; i++){
1009 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1010 if (waveStart == 0) {
1011 waveStart = i+1;
1012 //prnt("DEBUG: waveStart: %d",waveStart);
1013 } else {
1014 waveEnd = i+1;
1015 //prnt("DEBUG: waveEnd: %d",waveEnd);
1016 waveLenCnt = waveEnd-waveStart;
1017 if (waveLenCnt > fc){
1018 firstFullWave = waveStart;
1019 fullWaveLen=waveLenCnt;
1020 break;
1021 }
1022 waveStart=0;
1023 }
1024 }
1025 }
1026 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1027
1028 //test each valid clock from greatest to smallest to see which lines up
1029 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1030 lastClkBit = firstFullWave; //set end of wave as clock align
1031 waveStart = 0;
1032 errCnt=0;
1033 peakcnt=0;
1034 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1035
1036 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1037 //top edge of wave = start of new wave
1038 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1039 if (waveStart == 0) {
1040 waveStart = i+1;
1041 waveLenCnt=0;
1042 } else { //waveEnd
1043 waveEnd = i+1;
1044 waveLenCnt = waveEnd-waveStart;
1045 if (waveLenCnt > fc){
1046 //if this wave is a phase shift
1047 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);
1048 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1049 peakcnt++;
1050 lastClkBit+=clk[clkCnt];
1051 } else if (i<lastClkBit+8){
1052 //noise after a phase shift - ignore
1053 } else { //phase shift before supposed to based on clock
1054 errCnt++;
1055 }
1056 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1057 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1058 }
1059 waveStart=i+1;
1060 }
1061 }
1062 }
1063 if (errCnt == 0){
1064 return clk[clkCnt];
1065 }
1066 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1067 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1068 }
1069 //all tested with errors
1070 //return the highest clk with the most peaks found
1071 uint8_t best=7;
1072 for (i=7; i>=1; i--){
1073 if (peaksdet[i] > peaksdet[best]) {
1074 best = i;
1075 }
1076 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1077 }
1078 return clk[best];
1079 }
1080
1081 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1082 //find shortest transition from high to low
1083 size_t i = 0;
1084 size_t transition1 = 0;
1085 int lowestTransition = 255;
1086 bool lastWasHigh = false;
1087
1088 //find first valid beginning of a high or low wave
1089 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1090 ++i;
1091 while ((dest[i] < peak && dest[i] > low) && (i < size))
1092 ++i;
1093 lastWasHigh = (dest[i] >= peak);
1094
1095 if (i==size) return 0;
1096 transition1 = i;
1097
1098 for (;i < size; i++) {
1099 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1100 lastWasHigh = (dest[i] >= peak);
1101 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1102 transition1 = i;
1103 }
1104 }
1105 if (lowestTransition == 255) lowestTransition = 0;
1106 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1107 return lowestTransition;
1108 }
1109
1110 //by marshmellow
1111 //detect nrz clock by reading #peaks vs no peaks(or errors)
1112 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1113 {
1114 size_t i=0;
1115 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1116 size_t loopCnt = 4096; //don't need to loop through entire array...
1117 if (size == 0) return 0;
1118 if (size<loopCnt) loopCnt = size-20;
1119 //if we already have a valid clock quit
1120 for (; i < 8; ++i)
1121 if (clk[i] == clock) return clock;
1122
1123 //get high and low peak
1124 int peak, low;
1125 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1126
1127 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1128 size_t ii;
1129 uint8_t clkCnt;
1130 uint8_t tol = 0;
1131 uint16_t smplCnt = 0;
1132 int16_t peakcnt = 0;
1133 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1134 uint16_t maxPeak = 255;
1135 bool firstpeak = false;
1136 //test for large clipped waves
1137 for (i=0; i<loopCnt; i++){
1138 if (dest[i] >= peak || dest[i] <= low){
1139 if (!firstpeak) continue;
1140 smplCnt++;
1141 } else {
1142 firstpeak=true;
1143 if (smplCnt > 6 ){
1144 if (maxPeak > smplCnt){
1145 maxPeak = smplCnt;
1146 //prnt("maxPk: %d",maxPeak);
1147 }
1148 peakcnt++;
1149 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1150 smplCnt=0;
1151 }
1152 }
1153 }
1154 bool errBitHigh = 0;
1155 bool bitHigh = 0;
1156 uint8_t ignoreCnt = 0;
1157 uint8_t ignoreWindow = 4;
1158 bool lastPeakHigh = 0;
1159 int lastBit = 0;
1160 peakcnt=0;
1161 //test each valid clock from smallest to greatest to see which lines up
1162 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1163 //ignore clocks smaller than smallest peak
1164 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1165 //try lining up the peaks by moving starting point (try first 256)
1166 for (ii=20; ii < loopCnt; ++ii){
1167 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1168 peakcnt=0;
1169 bitHigh = false;
1170 ignoreCnt = 0;
1171 lastBit = ii-clk[clkCnt];
1172 //loop through to see if this start location works
1173 for (i = ii; i < size-20; ++i) {
1174 //if we are at a clock bit
1175 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1176 //test high/low
1177 if (dest[i] >= peak || dest[i] <= low) {
1178 //if same peak don't count it
1179 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1180 peakcnt++;
1181 }
1182 lastPeakHigh = (dest[i] >= peak);
1183 bitHigh = true;
1184 errBitHigh = false;
1185 ignoreCnt = ignoreWindow;
1186 lastBit += clk[clkCnt];
1187 } else if (i == lastBit + clk[clkCnt] + tol) {
1188 lastBit += clk[clkCnt];
1189 }
1190 //else if not a clock bit and no peaks
1191 } else if (dest[i] < peak && dest[i] > low){
1192 if (ignoreCnt==0){
1193 bitHigh=false;
1194 if (errBitHigh==true) peakcnt--;
1195 errBitHigh=false;
1196 } else {
1197 ignoreCnt--;
1198 }
1199 // else if not a clock bit but we have a peak
1200 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1201 //error bar found no clock...
1202 errBitHigh=true;
1203 }
1204 }
1205 if(peakcnt>peaksdet[clkCnt]) {
1206 peaksdet[clkCnt]=peakcnt;
1207 }
1208 }
1209 }
1210 }
1211 int iii=7;
1212 uint8_t best=0;
1213 for (iii=7; iii > 0; iii--){
1214 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1215 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1216 best = iii;
1217 }
1218 } else if (peaksdet[iii] > peaksdet[best]){
1219 best = iii;
1220 }
1221 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);
1222 }
1223
1224 return clk[best];
1225 }
1226
1227 // by marshmellow
1228 // convert psk1 demod to psk2 demod
1229 // only transition waves are 1s
1230 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1231 {
1232 size_t i=1;
1233 uint8_t lastBit=BitStream[0];
1234 for (; i<size; i++){
1235 if (BitStream[i]==7){
1236 //ignore errors
1237 } else if (lastBit!=BitStream[i]){
1238 lastBit=BitStream[i];
1239 BitStream[i]=1;
1240 } else {
1241 BitStream[i]=0;
1242 }
1243 }
1244 return;
1245 }
1246
1247 // by marshmellow
1248 // convert psk2 demod to psk1 demod
1249 // from only transition waves are 1s to phase shifts change bit
1250 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1251 {
1252 uint8_t phase=0;
1253 for (size_t i=0; i<size; i++){
1254 if (BitStream[i]==1){
1255 phase ^=1;
1256 }
1257 BitStream[i]=phase;
1258 }
1259 return;
1260 }
1261
1262 // redesigned by marshmellow adjusted from existing decode functions
1263 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1264 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1265 {
1266 //26 bit 40134 format (don't know other formats)
1267 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};
1268 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};
1269 size_t startidx = 0;
1270 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1271 // if didn't find preamble try again inverting
1272 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1273 *invert ^= 1;
1274 }
1275 if (*size != 64 && *size != 224) return -2;
1276 if (*invert==1)
1277 for (size_t i = startidx; i < *size; i++)
1278 bitStream[i] ^= 1;
1279
1280 return (int) startidx;
1281 }
1282
1283 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1284 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1285 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1286 if (justNoise(dest, *size)) return -1;
1287 *clk = DetectNRZClock(dest, *size, *clk);
1288 if (*clk==0) return -2;
1289 size_t i, gLen = 4096;
1290 if (gLen>*size) gLen = *size-20;
1291 int high, low;
1292 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1293
1294 uint8_t bit=0;
1295 //convert wave samples to 1's and 0's
1296 for(i=20; i < *size-20; i++){
1297 if (dest[i] >= high) bit = 1;
1298 if (dest[i] <= low) bit = 0;
1299 dest[i] = bit;
1300 }
1301 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1302 size_t lastBit = 0;
1303 size_t numBits = 0;
1304 for(i=21; i < *size-20; i++) {
1305 //if transition detected or large number of same bits - store the passed bits
1306 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1307 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1308 numBits += (i - lastBit + (*clk/4)) / *clk;
1309 lastBit = i-1;
1310 }
1311 }
1312 *size = numBits;
1313 return 0;
1314 }
1315
1316 //by marshmellow
1317 //detects the bit clock for FSK given the high and low Field Clocks
1318 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1319 {
1320 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1321 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1322 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1323 uint8_t rfLensFnd = 0;
1324 uint8_t lastFCcnt = 0;
1325 uint16_t fcCounter = 0;
1326 uint16_t rfCounter = 0;
1327 uint8_t firstBitFnd = 0;
1328 size_t i;
1329 if (size == 0) return 0;
1330
1331 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1332 rfLensFnd=0;
1333 fcCounter=0;
1334 rfCounter=0;
1335 firstBitFnd=0;
1336 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1337 // prime i to first peak / up transition
1338 for (i = 160; i < size-20; i++)
1339 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1340 break;
1341
1342 for (; i < size-20; i++){
1343 fcCounter++;
1344 rfCounter++;
1345
1346 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1347 continue;
1348 // else new peak
1349 // if we got less than the small fc + tolerance then set it to the small fc
1350 if (fcCounter < fcLow+fcTol)
1351 fcCounter = fcLow;
1352 else //set it to the large fc
1353 fcCounter = fcHigh;
1354
1355 //look for bit clock (rf/xx)
1356 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1357 //not the same size as the last wave - start of new bit sequence
1358 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1359 for (int ii=0; ii<15; ii++){
1360 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1361 rfCnts[ii]++;
1362 rfCounter = 0;
1363 break;
1364 }
1365 }
1366 if (rfCounter > 0 && rfLensFnd < 15){
1367 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1368 rfCnts[rfLensFnd]++;
1369 rfLens[rfLensFnd++] = rfCounter;
1370 }
1371 } else {
1372 firstBitFnd++;
1373 }
1374 rfCounter=0;
1375 lastFCcnt=fcCounter;
1376 }
1377 fcCounter=0;
1378 }
1379 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1380
1381 for (i=0; i<15; i++){
1382 //get highest 2 RF values (might need to get more values to compare or compare all?)
1383 if (rfCnts[i]>rfCnts[rfHighest]){
1384 rfHighest3=rfHighest2;
1385 rfHighest2=rfHighest;
1386 rfHighest=i;
1387 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1388 rfHighest3=rfHighest2;
1389 rfHighest2=i;
1390 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1391 rfHighest3=i;
1392 }
1393 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1394 }
1395 // set allowed clock remainder tolerance to be 1 large field clock length+1
1396 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1397 uint8_t tol1 = fcHigh+1;
1398
1399 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1400
1401 // loop to find the highest clock that has a remainder less than the tolerance
1402 // compare samples counted divided by
1403 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1404 int ii=7;
1405 for (; ii>=2; ii--){
1406 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1407 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1408 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1409 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1410 break;
1411 }
1412 }
1413 }
1414 }
1415
1416 if (ii<0) return 0; // oops we went too far
1417
1418 return clk[ii];
1419 }
1420
1421 //by marshmellow
1422 //countFC is to detect the field clock lengths.
1423 //counts and returns the 2 most common wave lengths
1424 //mainly used for FSK field clock detection
1425 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1426 {
1427 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1428 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1429 uint8_t fcLensFnd = 0;
1430 uint8_t lastFCcnt=0;
1431 uint8_t fcCounter = 0;
1432 size_t i;
1433 if (size == 0) return 0;
1434
1435 // prime i to first up transition
1436 for (i = 160; i < size-20; i++)
1437 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1438 break;
1439
1440 for (; i < size-20; i++){
1441 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1442 // new up transition
1443 fcCounter++;
1444 if (fskAdj){
1445 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1446 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1447 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1448 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1449 // save last field clock count (fc/xx)
1450 lastFCcnt = fcCounter;
1451 }
1452 // find which fcLens to save it to:
1453 for (int ii=0; ii<15; ii++){
1454 if (fcLens[ii]==fcCounter){
1455 fcCnts[ii]++;
1456 fcCounter=0;
1457 break;
1458 }
1459 }
1460 if (fcCounter>0 && fcLensFnd<15){
1461 //add new fc length
1462 fcCnts[fcLensFnd]++;
1463 fcLens[fcLensFnd++]=fcCounter;
1464 }
1465 fcCounter=0;
1466 } else {
1467 // count sample
1468 fcCounter++;
1469 }
1470 }
1471
1472 uint8_t best1=14, best2=14, best3=14;
1473 uint16_t maxCnt1=0;
1474 // go through fclens and find which ones are bigest 2
1475 for (i=0; i<15; i++){
1476 // get the 3 best FC values
1477 if (fcCnts[i]>maxCnt1) {
1478 best3=best2;
1479 best2=best1;
1480 maxCnt1=fcCnts[i];
1481 best1=i;
1482 } else if(fcCnts[i]>fcCnts[best2]){
1483 best3=best2;
1484 best2=i;
1485 } else if(fcCnts[i]>fcCnts[best3]){
1486 best3=i;
1487 }
1488 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]);
1489 }
1490 if (fcLens[best1]==0) return 0;
1491 uint8_t fcH=0, fcL=0;
1492 if (fcLens[best1]>fcLens[best2]){
1493 fcH=fcLens[best1];
1494 fcL=fcLens[best2];
1495 } else{
1496 fcH=fcLens[best2];
1497 fcL=fcLens[best1];
1498 }
1499 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1500 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]);
1501 return 0; //lots of waves not psk or fsk
1502 }
1503 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1504
1505 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1506 if (fskAdj) return fcs;
1507 return fcLens[best1];
1508 }
1509
1510 //by marshmellow - demodulate PSK1 wave
1511 //uses wave lengths (# Samples)
1512 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1513 {
1514 if (size == 0) return -1;
1515 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1516 if (*size<loopCnt) loopCnt = *size;
1517
1518 size_t numBits=0;
1519 uint8_t curPhase = *invert;
1520 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1521 uint8_t fc=0, fullWaveLen=0, tol=1;
1522 uint16_t errCnt=0, waveLenCnt=0;
1523 fc = countFC(dest, *size, 0);
1524 if (fc!=2 && fc!=4 && fc!=8) return -1;
1525 //PrintAndLog("DEBUG: FC: %d",fc);
1526 *clock = DetectPSKClock(dest, *size, *clock);
1527 if (*clock == 0) return -1;
1528 int avgWaveVal=0, lastAvgWaveVal=0;
1529 //find first phase shift
1530 for (i=0; i<loopCnt; i++){
1531 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1532 waveEnd = i+1;
1533 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1534 waveLenCnt = waveEnd-waveStart;
1535 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1536 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1537 firstFullWave = waveStart;
1538 fullWaveLen=waveLenCnt;
1539 //if average wave value is > graph 0 then it is an up wave or a 1
1540 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1541 break;
1542 }
1543 waveStart = i+1;
1544 avgWaveVal = 0;
1545 }
1546 avgWaveVal += dest[i+2];
1547 }
1548 if (firstFullWave == 0) {
1549 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1550 // so skip a little to ensure we are past any Start Signal
1551 firstFullWave = 160;
1552 memset(dest, curPhase, firstFullWave / *clock);
1553 } else {
1554 memset(dest, curPhase^1, firstFullWave / *clock);
1555 }
1556 //advance bits
1557 numBits += (firstFullWave / *clock);
1558 //set start of wave as clock align
1559 lastClkBit = firstFullWave;
1560 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1561 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1562 waveStart = 0;
1563 dest[numBits++] = curPhase; //set first read bit
1564 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1565 //top edge of wave = start of new wave
1566 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1567 if (waveStart == 0) {
1568 waveStart = i+1;
1569 waveLenCnt = 0;
1570 avgWaveVal = dest[i+1];
1571 } else { //waveEnd
1572 waveEnd = i+1;
1573 waveLenCnt = waveEnd-waveStart;
1574 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1575 if (waveLenCnt > fc){
1576 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1577 //this wave is a phase shift
1578 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1579 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1580 curPhase ^= 1;
1581 dest[numBits++] = curPhase;
1582 lastClkBit += *clock;
1583 } else if (i < lastClkBit+10+fc){
1584 //noise after a phase shift - ignore
1585 } else { //phase shift before supposed to based on clock
1586 errCnt++;
1587 dest[numBits++] = 7;
1588 }
1589 } else if (i+1 > lastClkBit + *clock + tol + fc){
1590 lastClkBit += *clock; //no phase shift but clock bit
1591 dest[numBits++] = curPhase;
1592 }
1593 avgWaveVal = 0;
1594 waveStart = i+1;
1595 }
1596 }
1597 avgWaveVal += dest[i+1];
1598 }
1599 *size = numBits;
1600 return errCnt;
1601 }
1602
1603 //by marshmellow
1604 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1605 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1606 size_t bufsize = *size;
1607 //need to loop through all samples and identify our clock, look for the ST pattern
1608 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1609 int clk = 0;
1610 int tol = 0;
1611 int i, j, skip, start, end, low, high, minClk, waveStart;
1612 bool complete = false;
1613 int tmpbuff[bufsize / 64];
1614 int waveLen[bufsize / 64];
1615 size_t testsize = (bufsize < 512) ? bufsize : 512;
1616 int phaseoff = 0;
1617 high = low = 128;
1618 memset(tmpbuff, 0, sizeof(tmpbuff));
1619
1620 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1621 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1622 return false; //just noise
1623 }
1624 i = 0;
1625 j = 0;
1626 minClk = 255;
1627 // get to first full low to prime loop and skip incomplete first pulse
1628 while ((buffer[i] < high) && (i < bufsize))
1629 ++i;
1630 while ((buffer[i] > low) && (i < bufsize))
1631 ++i;
1632 skip = i;
1633
1634 // populate tmpbuff buffer with pulse lengths
1635 while (i < bufsize) {
1636 // measure from low to low
1637 while ((buffer[i] > low) && (i < bufsize))
1638 ++i;
1639 start= i;
1640 while ((buffer[i] < high) && (i < bufsize))
1641 ++i;
1642 //first high point for this wave
1643 waveStart = i;
1644 while ((buffer[i] > low) && (i < bufsize))
1645 ++i;
1646 if (j >= (bufsize/64)) {
1647 break;
1648 }
1649 waveLen[j] = i - waveStart; //first high to first low
1650 tmpbuff[j++] = i - start;
1651 if (i-start < minClk && i < bufsize) {
1652 minClk = i - start;
1653 }
1654 }
1655 // set clock - might be able to get this externally and remove this work...
1656 if (!clk) {
1657 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1658 tol = fndClk[clkCnt]/8;
1659 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1660 clk=fndClk[clkCnt];
1661 break;
1662 }
1663 }
1664 // clock not found - ERROR
1665 if (!clk) {
1666 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1667 return false;
1668 }
1669 } else tol = clk/8;
1670
1671 *foundclock = clk;
1672
1673 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1674 start = -1;
1675 for (i = 0; i < j - 4; ++i) {
1676 skip += tmpbuff[i];
1677 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1678 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
1679 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
1680 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1681 start = i + 3;
1682 break;
1683 }
1684 }
1685 }
1686 }
1687 }
1688 // first ST not found - ERROR
1689 if (start < 0) {
1690 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1691 return false;
1692 }
1693 if (waveLen[i+2] > clk*1+tol)
1694 phaseoff = 0;
1695 else
1696 phaseoff = clk/2;
1697
1698 // skip over the remainder of ST
1699 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1700
1701 // now do it again to find the end
1702 end = skip;
1703 for (i += 3; i < j - 4; ++i) {
1704 end += tmpbuff[i];
1705 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) { //1 to 2 clocks depending on 2 bits prior
1706 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
1707 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
1708 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1709 complete = true;
1710 break;
1711 }
1712 }
1713 }
1714 }
1715 }
1716 end -= phaseoff;
1717 //didn't find second ST - ERROR
1718 if (!complete) {
1719 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1720 return false;
1721 }
1722 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);
1723 //now begin to trim out ST so we can use normal demod cmds
1724 start = skip;
1725 size_t datalen = end - start;
1726 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1727 if (datalen % clk > clk/8) {
1728 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1729 return false;
1730 } else {
1731 // padd the amount off - could be problematic... but shouldn't happen often
1732 datalen += datalen % clk;
1733 }
1734 // if datalen is less than one t55xx block - ERROR
1735 if (datalen/clk < 8*4) {
1736 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1737 return false;
1738 }
1739 size_t dataloc = start;
1740 size_t newloc = 0;
1741 i=0;
1742 // warning - overwriting buffer given with raw wave data with ST removed...
1743 while ( dataloc < bufsize-(clk/2) ) {
1744 //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)
1745 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1746 for(i=0; i < clk/2-tol; ++i) {
1747 buffer[dataloc+i] = high+5;
1748 }
1749 }
1750 for (i=0; i<datalen; ++i) {
1751 if (i+newloc < bufsize) {
1752 if (i+newloc < dataloc)
1753 buffer[i+newloc] = buffer[dataloc];
1754
1755 dataloc++;
1756 }
1757 }
1758 newloc += i;
1759 //skip next ST - we just assume it will be there from now on...
1760 dataloc += clk*4;
1761 }
1762 *size = newloc;
1763 return true;
1764 }
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