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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 //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 if (g_debugMode) prnt("DEBUG: ans: %d, ptype: %d, bits: %08X",ans,pType,bits);
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 if (word+pLen >= bLen) break;
82
83 j--; // overwrite parity with next data
84 // if parity fails then return 0
85 switch (pType) {
86 case 3: if (BitStream[j]==1) {return 0;} break; //should be 0 spacer bit
87 case 2: if (BitStream[j]==0) {return 0;} break; //should be 1 spacer bit
88 default: if (parityTest(parityWd, pLen, pType) == 0) {return 0;} break; //test parity
89 }
90 bitCnt+=(pLen-1);
91 parityWd = 0;
92 }
93 // if we got here then all the parities passed
94 //return ID start index and size
95 return bitCnt;
96 }
97
98 // by marshmellow
99 // takes a array of binary values, length of bits per parity (includes parity bit),
100 // Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
101 // Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
102 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
103 {
104 uint32_t parityWd = 0;
105 size_t j = 0, bitCnt = 0;
106 for (int word = 0; word < sourceLen; word+=pLen-1) {
107 for (int bit=0; bit < pLen-1; bit++){
108 parityWd = (parityWd << 1) | BitSource[word+bit];
109 dest[j++] = (BitSource[word+bit]);
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 {
132 num = (num << 1) | (*src);
133 src++;
134 }
135 return num;
136 }
137
138 //least significant bit first
139 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
140 {
141 uint32_t num = 0;
142 for(int i = 0 ; i < numbits ; i++)
143 {
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 // search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found)
174 // does not look for a repeating preamble
175 // em4x05/4x69 only sends preamble once, so look for it once in the first pLen bits
176 // leave it generic so it could be reused later...
177 bool onePreambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t size, size_t *startIdx) {
178 // Sanity check. If preamble length is bigger than bitstream length.
179 if ( size <= pLen ) return false;
180 for (size_t idx = 0; idx < size - pLen; idx++) {
181 if (memcmp(BitStream+idx, preamble, pLen) == 0) {
182 if (g_debugMode) prnt("DEBUG: preamble found at %u", idx);
183 *startIdx = idx;
184 return true;
185 }
186 }
187 return false;
188 }
189
190 // find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
191 size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_t expWaveSize) {
192 size_t i = 0;
193 size_t waveSizeCnt = 0;
194 uint8_t thresholdCnt = 0;
195 bool isAboveThreshold = dest[i++] >= threshold_value;
196 for (; i < size-20; i++ ) {
197 if(dest[i] < threshold_value && isAboveThreshold) {
198 thresholdCnt++;
199 if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
200 isAboveThreshold = false;
201 waveSizeCnt = 0;
202 } else if (dest[i] >= threshold_value && !isAboveThreshold) {
203 thresholdCnt++;
204 if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
205 isAboveThreshold = true;
206 waveSizeCnt = 0;
207 } else {
208 waveSizeCnt++;
209 }
210 if (thresholdCnt > 10) break;
211 }
212 if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at %u, count: %u",i, thresholdCnt);
213 return i;
214 }
215
216 //by marshmellow
217 //takes 1s and 0s and searches for EM410x format - output EM ID
218 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
219 {
220 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
221 // otherwise could be a void with no arguments
222 //set defaults
223 uint32_t i = 0;
224 if (BitStream[1]>1) return 0; //allow only 1s and 0s
225
226 // 111111111 bit pattern represent start of frame
227 // include 0 in front to help get start pos
228 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
229 uint32_t idx = 0;
230 uint32_t parityBits = 0;
231 uint8_t errChk = 0;
232 uint8_t FmtLen = 10;
233 *startIdx = 0;
234 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
235 if (errChk == 0 || *size < 64) return 0;
236 if (*size > 64) FmtLen = 22;
237 *startIdx += 1; //get rid of 0 from preamble
238 idx = *startIdx + 9;
239 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
240 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
241 //check even parity - quit if failed
242 if (parityTest(parityBits, 5, 0) == 0) return 0;
243 //set uint64 with ID from BitStream
244 for (uint8_t ii=0; ii<4; ii++){
245 *hi = (*hi << 1) | (*lo >> 63);
246 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
247 }
248 }
249 if (errChk != 0) return 1;
250 //skip last 5 bit parity test for simplicity.
251 // *size = 64 | 128;
252 return 0;
253 }
254
255 //by marshmellow
256 //demodulates strong heavily clipped samples
257 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
258 {
259 size_t bitCnt=0, smplCnt=0, errCnt=0;
260 uint8_t waveHigh = 0;
261 for (size_t i=0; i < *size; i++){
262 if (BinStream[i] >= high && waveHigh){
263 smplCnt++;
264 } else if (BinStream[i] <= low && !waveHigh){
265 smplCnt++;
266 } else { //transition
267 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
268 if (smplCnt > clk-(clk/4)-1) { //full clock
269 if (smplCnt > clk + (clk/4)+1) { //too many samples
270 errCnt++;
271 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
272 BinStream[bitCnt++]=7;
273 } else if (waveHigh) {
274 BinStream[bitCnt++] = invert;
275 BinStream[bitCnt++] = invert;
276 } else if (!waveHigh) {
277 BinStream[bitCnt++] = invert ^ 1;
278 BinStream[bitCnt++] = invert ^ 1;
279 }
280 waveHigh ^= 1;
281 smplCnt = 0;
282 } else if (smplCnt > (clk/2) - (clk/4)-1) {
283 if (waveHigh) {
284 BinStream[bitCnt++] = invert;
285 } else if (!waveHigh) {
286 BinStream[bitCnt++] = invert ^ 1;
287 }
288 waveHigh ^= 1;
289 smplCnt = 0;
290 } else if (!bitCnt) {
291 //first bit
292 waveHigh = (BinStream[i] >= high);
293 smplCnt = 1;
294 } else {
295 smplCnt++;
296 //transition bit oops
297 }
298 } else { //haven't hit new high or new low yet
299 smplCnt++;
300 }
301 }
302 }
303 *size = bitCnt;
304 return errCnt;
305 }
306
307 //by marshmellow
308 void askAmp(uint8_t *BitStream, size_t size)
309 {
310 uint8_t Last = 128;
311 for(size_t i = 1; i<size; i++){
312 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
313 Last = 255;
314 else if(BitStream[i-1]-BitStream[i]>=20) //large jump down
315 Last = 0;
316
317 BitStream[i-1] = Last;
318 }
319 return;
320 }
321
322 //by marshmellow
323 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
324 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
325 {
326 if (*size==0) return -1;
327 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
328 if (*clk==0 || start < 0) return -3;
329 if (*invert != 1) *invert = 0;
330 if (amp==1) askAmp(BinStream, *size);
331 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d, amp %d", *clk, start, amp);
332
333 uint8_t initLoopMax = 255;
334 if (initLoopMax > *size) initLoopMax = *size;
335 // Detect high and lows
336 //25% clip in case highs and lows aren't clipped [marshmellow]
337 int high, low;
338 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
339 return -2; //just noise
340
341 size_t errCnt = 0;
342 // if clean clipped waves detected run alternate demod
343 if (DetectCleanAskWave(BinStream, *size, high, low)) {
344 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
345 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
346 if (askType) //askman
347 return manrawdecode(BinStream, size, 0);
348 else //askraw
349 return errCnt;
350 }
351 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
352
353 int lastBit; //set first clock check - can go negative
354 size_t i, bitnum = 0; //output counter
355 uint8_t midBit = 0;
356 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
357 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
358 size_t MaxBits = 3072; //max bits to collect
359 lastBit = start - *clk;
360
361 for (i = start; i < *size; ++i) {
362 if (i-lastBit >= *clk-tol){
363 if (BinStream[i] >= high) {
364 BinStream[bitnum++] = *invert;
365 } else if (BinStream[i] <= low) {
366 BinStream[bitnum++] = *invert ^ 1;
367 } else if (i-lastBit >= *clk+tol) {
368 if (bitnum > 0) {
369 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
370 BinStream[bitnum++]=7;
371 errCnt++;
372 }
373 } else { //in tolerance - looking for peak
374 continue;
375 }
376 midBit = 0;
377 lastBit += *clk;
378 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
379 if (BinStream[i] >= high) {
380 BinStream[bitnum++] = *invert;
381 } else if (BinStream[i] <= low) {
382 BinStream[bitnum++] = *invert ^ 1;
383 } else if (i-lastBit >= *clk/2+tol) {
384 BinStream[bitnum] = BinStream[bitnum-1];
385 bitnum++;
386 } else { //in tolerance - looking for peak
387 continue;
388 }
389 midBit = 1;
390 }
391 if (bitnum >= MaxBits) break;
392 }
393 *size = bitnum;
394 return errCnt;
395 }
396
397 //by marshmellow
398 //take 10 and 01 and manchester decode
399 //run through 2 times and take least errCnt
400 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
401 {
402 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
403 size_t i, ii;
404 uint16_t bestErr = 1000, bestRun = 0;
405 if (*size < 16) return -1;
406 //find correct start position [alignment]
407 for (ii=0;ii<2;++ii){
408 for (i=ii; i<*size-3; i+=2)
409 if (BitStream[i]==BitStream[i+1])
410 errCnt++;
411
412 if (bestErr>errCnt){
413 bestErr=errCnt;
414 bestRun=ii;
415 }
416 errCnt=0;
417 }
418 //decode
419 for (i=bestRun; i < *size-3; i+=2){
420 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
421 BitStream[bitnum++]=invert;
422 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
423 BitStream[bitnum++]=invert^1;
424 } else {
425 BitStream[bitnum++]=7;
426 }
427 if(bitnum>MaxBits) break;
428 }
429 *size=bitnum;
430 return bestErr;
431 }
432
433 uint32_t manchesterEncode2Bytes(uint16_t datain) {
434 uint32_t output = 0;
435 uint8_t curBit = 0;
436 for (uint8_t i=0; i<16; i++) {
437 curBit = (datain >> (15-i) & 1);
438 output |= (1<<(((15-i)*2)+curBit));
439 }
440 return output;
441 }
442
443 //by marshmellow
444 //encode binary data into binary manchester
445 int ManchesterEncode(uint8_t *BitStream, size_t size)
446 {
447 size_t modIdx=20000, i=0;
448 if (size>modIdx) return -1;
449 for (size_t idx=0; idx < size; idx++){
450 BitStream[idx+modIdx++] = BitStream[idx];
451 BitStream[idx+modIdx++] = BitStream[idx]^1;
452 }
453 for (; i<(size*2); i++){
454 BitStream[i] = BitStream[i+20000];
455 }
456 return i;
457 }
458
459 //by marshmellow
460 //take 01 or 10 = 1 and 11 or 00 = 0
461 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
462 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
463 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
464 {
465 uint16_t bitnum = 0;
466 uint16_t errCnt = 0;
467 size_t i = offset;
468 uint16_t MaxBits=512;
469 //if not enough samples - error
470 if (*size < 51) return -1;
471 //check for phase change faults - skip one sample if faulty
472 uint8_t offsetA = 1, offsetB = 1;
473 for (; i<48; i+=2){
474 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
475 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
476 }
477 if (!offsetA && offsetB) offset++;
478 for (i=offset; i<*size-3; i+=2){
479 //check for phase error
480 if (BitStream[i+1]==BitStream[i+2]) {
481 BitStream[bitnum++]=7;
482 errCnt++;
483 }
484 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
485 BitStream[bitnum++]=1^invert;
486 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
487 BitStream[bitnum++]=invert;
488 } else {
489 BitStream[bitnum++]=7;
490 errCnt++;
491 }
492 if(bitnum>MaxBits) break;
493 }
494 *size=bitnum;
495 return errCnt;
496 }
497
498 // by marshmellow
499 // demod gProxIIDemod
500 // error returns as -x
501 // success returns start position in BitStream
502 // BitStream must contain previously askrawdemod and biphasedemoded data
503 int gProxII_Demod(uint8_t BitStream[], size_t *size)
504 {
505 size_t startIdx=0;
506 uint8_t preamble[] = {1,1,1,1,1,0};
507
508 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
509 if (errChk == 0) return -3; //preamble not found
510 if (*size != 96) return -2; //should have found 96 bits
511 //check first 6 spacer bits to verify format
512 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
513 //confirmed proper separator bits found
514 //return start position
515 return (int) startIdx;
516 }
517 return -5; //spacer bits not found - not a valid gproxII
518 }
519
520 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
521 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
522 {
523 size_t last_transition = 0;
524 size_t idx = 1;
525 if (fchigh==0) fchigh=10;
526 if (fclow==0) fclow=8;
527 //set the threshold close to 0 (graph) or 128 std to avoid static
528 uint8_t threshold_value = 123;
529 size_t preLastSample = 0;
530 size_t LastSample = 0;
531 size_t currSample = 0;
532 if ( size < 1024 ) return 0; // not enough samples
533
534 //find start of modulating data in trace
535 idx = findModStart(dest, size, threshold_value, fchigh);
536
537 // Need to threshold first sample
538 if(dest[idx] < threshold_value) dest[0] = 0;
539 else dest[0] = 1;
540 idx++;
541
542 size_t numBits = 0;
543 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
544 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
545 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
546 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
547 for(; idx < size-20; idx++) {
548 // threshold current value
549
550 if (dest[idx] < threshold_value) dest[idx] = 0;
551 else dest[idx] = 1;
552
553 // Check for 0->1 transition
554 if (dest[idx-1] < dest[idx]) {
555 preLastSample = LastSample;
556 LastSample = currSample;
557 currSample = idx-last_transition;
558 if (currSample < (fclow-2)) { //0-5 = garbage noise (or 0-3)
559 //do nothing with extra garbage
560 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
561 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
562 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1))){
563 dest[numBits-1]=1;
564 }
565 dest[numBits++]=1;
566
567 } else if (currSample > (fchigh+1) && numBits < 3) { //12 + and first two bit = unusable garbage
568 //do nothing with beginning garbage and reset.. should be rare..
569 numBits = 0;
570 } 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)
571 dest[numBits++]=1;
572 } else { //9+ = 10 sample waves (or 6+ = 7)
573 dest[numBits++]=0;
574 }
575 last_transition = idx;
576 }
577 }
578 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
579 }
580
581 //translate 11111100000 to 10
582 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
583 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
584 uint8_t invert, uint8_t fchigh, uint8_t fclow)
585 {
586 uint8_t lastval=dest[0];
587 size_t idx=0;
588 size_t numBits=0;
589 uint32_t n=1;
590 for( idx=1; idx < size; idx++) {
591 n++;
592 if (dest[idx]==lastval) continue; //skip until we hit a transition
593
594 //find out how many bits (n) we collected
595 //if lastval was 1, we have a 1->0 crossing
596 if (dest[idx-1]==1) {
597 n = (n * fclow + rfLen/2) / rfLen;
598 } else {// 0->1 crossing
599 n = (n * fchigh + rfLen/2) / rfLen;
600 }
601 if (n == 0) n = 1;
602
603 //add to our destination the bits we collected
604 memset(dest+numBits, dest[idx-1]^invert , n);
605 numBits += n;
606 n=0;
607 lastval=dest[idx];
608 }//end for
609 // if valid extra bits at the end were all the same frequency - add them in
610 if (n > rfLen/fchigh) {
611 if (dest[idx-2]==1) {
612 n = (n * fclow + rfLen/2) / rfLen;
613 } else {
614 n = (n * fchigh + rfLen/2) / rfLen;
615 }
616 memset(dest+numBits, dest[idx-1]^invert , n);
617 numBits += n;
618 }
619 return numBits;
620 }
621
622 //by marshmellow (from holiman's base)
623 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
624 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
625 {
626 // FSK demodulator
627 size = fsk_wave_demod(dest, size, fchigh, fclow);
628 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
629 return size;
630 }
631
632 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
633 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
634 {
635 if (justNoise(dest, *size)) return -1;
636
637 size_t numStart=0, size2=*size, startIdx=0;
638 // FSK demodulator
639 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
640 if (*size < 96*2) return -2;
641 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
642 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
643 // find bitstring in array
644 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
645 if (errChk == 0) return -3; //preamble not found
646
647 numStart = startIdx + sizeof(preamble);
648 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
649 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
650 if (dest[idx] == dest[idx+1]){
651 return -4; //not manchester data
652 }
653 *hi2 = (*hi2<<1)|(*hi>>31);
654 *hi = (*hi<<1)|(*lo>>31);
655 //Then, shift in a 0 or one into low
656 if (dest[idx] && !dest[idx+1]) // 1 0
657 *lo=(*lo<<1)|1;
658 else // 0 1
659 *lo=(*lo<<1)|0;
660 }
661 return (int)startIdx;
662 }
663
664 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
665 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
666 {
667 if (justNoise(dest, *size)) return -1;
668
669 size_t numStart=0, size2=*size, startIdx=0;
670 // FSK demodulator
671 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
672 if (*size < 96) return -2;
673
674 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
675 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
676
677 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
678 if (errChk == 0) return -3; //preamble not found
679
680 numStart = startIdx + sizeof(preamble);
681 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
682 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
683 if (dest[idx] == dest[idx+1])
684 return -4; //not manchester data
685 *hi2 = (*hi2<<1)|(*hi>>31);
686 *hi = (*hi<<1)|(*lo>>31);
687 //Then, shift in a 0 or one into low
688 if (dest[idx] && !dest[idx+1]) // 1 0
689 *lo=(*lo<<1)|1;
690 else // 0 1
691 *lo=(*lo<<1)|0;
692 }
693 return (int)startIdx;
694 }
695
696 int IOdemodFSK(uint8_t *dest, size_t size)
697 {
698 if (justNoise(dest, size)) return -1;
699 //make sure buffer has data
700 if (size < 66*64) return -2;
701 // FSK demodulator
702 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
703 if (size < 65) return -3; //did we get a good demod?
704 //Index map
705 //0 10 20 30 40 50 60
706 //| | | | | | |
707 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
708 //-----------------------------------------------------------------------------
709 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
710 //
711 //XSF(version)facility:codeone+codetwo
712 //Handle the data
713 size_t startIdx = 0;
714 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
715 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
716 if (errChk == 0) return -4; //preamble not found
717
718 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
719 //confirmed proper separator bits found
720 //return start position
721 return (int) startIdx;
722 }
723 return -5;
724 }
725
726 // by marshmellow
727 // find viking preamble 0xF200 in already demoded data
728 int VikingDemod_AM(uint8_t *dest, size_t *size) {
729 //make sure buffer has data
730 if (*size < 64*2) return -2;
731
732 size_t startIdx = 0;
733 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};
734 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
735 if (errChk == 0) return -4; //preamble not found
736 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
737 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
738 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
739 if ( checkCalc != 0xA8 ) return -5;
740 if (*size != 64) return -6;
741 //return start position
742 return (int) startIdx;
743 }
744
745 // find presco preamble 0x10D in already demoded data
746 int PrescoDemod(uint8_t *dest, size_t *size) {
747 //make sure buffer has data
748 if (*size < 64*2) return -2;
749
750 size_t startIdx = 0;
751 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
752 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
753 if (errChk == 0) return -4; //preamble not found
754 //return start position
755 return (int) startIdx;
756 }
757
758 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
759 // BitStream must contain previously askrawdemod and biphasedemoded data
760 int FDXBdemodBI(uint8_t *dest, size_t *size)
761 {
762 //make sure buffer has enough data
763 if (*size < 128) return -1;
764
765 size_t startIdx = 0;
766 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
767
768 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
769 if (errChk == 0) return -2; //preamble not found
770 return (int)startIdx;
771 }
772
773 // by marshmellow
774 // FSK Demod then try to locate an AWID ID
775 int AWIDdemodFSK(uint8_t *dest, size_t *size)
776 {
777 //make sure buffer has enough data
778 if (*size < 96*50) return -1;
779
780 if (justNoise(dest, *size)) return -2;
781
782 // FSK demodulator
783 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
784 if (*size < 96) return -3; //did we get a good demod?
785
786 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
787 size_t startIdx = 0;
788 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
789 if (errChk == 0) return -4; //preamble not found
790 if (*size != 96) return -5;
791 return (int)startIdx;
792 }
793
794 // by marshmellow
795 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
796 int PyramiddemodFSK(uint8_t *dest, size_t *size)
797 {
798 //make sure buffer has data
799 if (*size < 128*50) return -5;
800
801 //test samples are not just noise
802 if (justNoise(dest, *size)) return -1;
803
804 // FSK demodulator
805 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
806 if (*size < 128) return -2; //did we get a good demod?
807
808 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
809 size_t startIdx = 0;
810 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
811 if (errChk == 0) return -4; //preamble not found
812 if (*size != 128) return -3;
813 return (int)startIdx;
814 }
815
816 // by marshmellow
817 // to detect a wave that has heavily clipped (clean) samples
818 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
819 {
820 bool allArePeaks = true;
821 uint16_t cntPeaks=0;
822 size_t loopEnd = 512+160;
823 if (loopEnd > size) loopEnd = size;
824 for (size_t i=160; i<loopEnd; i++){
825 if (dest[i]>low && dest[i]<high)
826 allArePeaks = false;
827 else
828 cntPeaks++;
829 }
830 if (!allArePeaks){
831 if (cntPeaks > 300) return true;
832 }
833 return allArePeaks;
834 }
835 // by marshmellow
836 // to help detect clocks on heavily clipped samples
837 // based on count of low to low
838 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
839 {
840 uint8_t fndClk[] = {8,16,32,40,50,64,128};
841 size_t startwave;
842 size_t i = 100;
843 size_t minClk = 255;
844 // get to first full low to prime loop and skip incomplete first pulse
845 while ((dest[i] < high) && (i < size))
846 ++i;
847 while ((dest[i] > low) && (i < size))
848 ++i;
849
850 // loop through all samples
851 while (i < size) {
852 // measure from low to low
853 while ((dest[i] > low) && (i < size))
854 ++i;
855 startwave= i;
856 while ((dest[i] < high) && (i < size))
857 ++i;
858 while ((dest[i] > low) && (i < size))
859 ++i;
860 //get minimum measured distance
861 if (i-startwave < minClk && i < size)
862 minClk = i - startwave;
863 }
864 // set clock
865 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
866 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
867 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
868 return fndClk[clkCnt];
869 }
870 return 0;
871 }
872
873 // by marshmellow
874 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
875 // maybe somehow adjust peak trimming value based on samples to fix?
876 // return start index of best starting position for that clock and return clock (by reference)
877 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
878 {
879 size_t i=1;
880 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
881 uint8_t clkEnd = 9;
882 uint8_t loopCnt = 255; //don't need to loop through entire array...
883 if (size <= loopCnt+60) return -1; //not enough samples
884 size -= 60; //sometimes there is a strange end wave - filter out this....
885 //if we already have a valid clock
886 uint8_t clockFnd=0;
887 for (;i<clkEnd;++i)
888 if (clk[i] == *clock) clockFnd = i;
889 //clock found but continue to find best startpos
890
891 //get high and low peak
892 int peak, low;
893 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
894
895 //test for large clean peaks
896 if (!clockFnd){
897 if (DetectCleanAskWave(dest, size, peak, low)==1){
898 int ans = DetectStrongAskClock(dest, size, peak, low);
899 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
900 for (i=clkEnd-1; i>0; i--){
901 if (clk[i] == ans) {
902 *clock = ans;
903 //clockFnd = i;
904 return 0; // for strong waves i don't use the 'best start position' yet...
905 //break; //clock found but continue to find best startpos [not yet]
906 }
907 }
908 }
909 }
910 uint8_t ii;
911 uint8_t clkCnt, tol = 0;
912 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
913 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
914 size_t errCnt = 0;
915 size_t arrLoc, loopEnd;
916
917 if (clockFnd>0) {
918 clkCnt = clockFnd;
919 clkEnd = clockFnd+1;
920 }
921 else clkCnt=1;
922
923 //test each valid clock from smallest to greatest to see which lines up
924 for(; clkCnt < clkEnd; clkCnt++){
925 if (clk[clkCnt] <= 32){
926 tol=1;
927 }else{
928 tol=0;
929 }
930 //if no errors allowed - keep start within the first clock
931 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
932 bestErr[clkCnt]=1000;
933 //try lining up the peaks by moving starting point (try first few clocks)
934 for (ii=0; ii < loopCnt; ii++){
935 if (dest[ii] < peak && dest[ii] > low) continue;
936
937 errCnt=0;
938 // now that we have the first one lined up test rest of wave array
939 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
940 for (i=0; i < loopEnd; ++i){
941 arrLoc = ii + (i * clk[clkCnt]);
942 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
943 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
944 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
945 }else{ //error no peak detected
946 errCnt++;
947 }
948 }
949 //if we found no errors then we can stop here and a low clock (common clocks)
950 // this is correct one - return this clock
951 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
952 if(errCnt==0 && clkCnt<7) {
953 if (!clockFnd) *clock = clk[clkCnt];
954 return ii;
955 }
956 //if we found errors see if it is lowest so far and save it as best run
957 if(errCnt<bestErr[clkCnt]){
958 bestErr[clkCnt]=errCnt;
959 bestStart[clkCnt]=ii;
960 }
961 }
962 }
963 uint8_t iii;
964 uint8_t best=0;
965 for (iii=1; iii<clkEnd; ++iii){
966 if (bestErr[iii] < bestErr[best]){
967 if (bestErr[iii] == 0) bestErr[iii]=1;
968 // current best bit to error ratio vs new bit to error ratio
969 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
970 best = iii;
971 }
972 }
973 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d",clk[iii],bestErr[iii],clk[best],bestStart[best]);
974 }
975 if (!clockFnd) *clock = clk[best];
976 return bestStart[best];
977 }
978
979 //by marshmellow
980 //detect psk clock by reading each phase shift
981 // a phase shift is determined by measuring the sample length of each wave
982 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
983 {
984 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
985 uint16_t loopCnt = 4096; //don't need to loop through entire array...
986 if (size == 0) return 0;
987 if (size<loopCnt) loopCnt = size-20;
988
989 //if we already have a valid clock quit
990 size_t i=1;
991 for (; i < 8; ++i)
992 if (clk[i] == clock) return clock;
993
994 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
995 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
996 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
997 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
998 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
999 fc = countFC(dest, size, 0);
1000 if (fc!=2 && fc!=4 && fc!=8) return -1;
1001 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
1002
1003 //find first full wave
1004 for (i=160; i<loopCnt; i++){
1005 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1006 if (waveStart == 0) {
1007 waveStart = i+1;
1008 //prnt("DEBUG: waveStart: %d",waveStart);
1009 } else {
1010 waveEnd = i+1;
1011 //prnt("DEBUG: waveEnd: %d",waveEnd);
1012 waveLenCnt = waveEnd-waveStart;
1013 if (waveLenCnt > fc){
1014 firstFullWave = waveStart;
1015 fullWaveLen=waveLenCnt;
1016 break;
1017 }
1018 waveStart=0;
1019 }
1020 }
1021 }
1022 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1023
1024 //test each valid clock from greatest to smallest to see which lines up
1025 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1026 lastClkBit = firstFullWave; //set end of wave as clock align
1027 waveStart = 0;
1028 errCnt=0;
1029 peakcnt=0;
1030 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1031
1032 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1033 //top edge of wave = start of new wave
1034 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1035 if (waveStart == 0) {
1036 waveStart = i+1;
1037 waveLenCnt=0;
1038 } else { //waveEnd
1039 waveEnd = i+1;
1040 waveLenCnt = waveEnd-waveStart;
1041 if (waveLenCnt > fc){
1042 //if this wave is a phase shift
1043 if (g_debugMode == 2) prnt("DEBUG PSK: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,i+1,fc);
1044 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1045 peakcnt++;
1046 lastClkBit+=clk[clkCnt];
1047 } else if (i<lastClkBit+8){
1048 //noise after a phase shift - ignore
1049 } else { //phase shift before supposed to based on clock
1050 errCnt++;
1051 }
1052 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1053 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1054 }
1055 waveStart=i+1;
1056 }
1057 }
1058 }
1059 if (errCnt == 0){
1060 return clk[clkCnt];
1061 }
1062 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1063 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1064 }
1065 //all tested with errors
1066 //return the highest clk with the most peaks found
1067 uint8_t best=7;
1068 for (i=7; i>=1; i--){
1069 if (peaksdet[i] > peaksdet[best]) {
1070 best = i;
1071 }
1072 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1073 }
1074 return clk[best];
1075 }
1076
1077 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1078 //find shortest transition from high to low
1079 size_t i = 0;
1080 size_t transition1 = 0;
1081 int lowestTransition = 255;
1082 bool lastWasHigh = false;
1083
1084 //find first valid beginning of a high or low wave
1085 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1086 ++i;
1087 while ((dest[i] < peak && dest[i] > low) && (i < size))
1088 ++i;
1089 lastWasHigh = (dest[i] >= peak);
1090
1091 if (i==size) return 0;
1092 transition1 = i;
1093
1094 for (;i < size; i++) {
1095 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1096 lastWasHigh = (dest[i] >= peak);
1097 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1098 transition1 = i;
1099 }
1100 }
1101 if (lowestTransition == 255) lowestTransition = 0;
1102 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1103 return lowestTransition;
1104 }
1105
1106 //by marshmellow
1107 //detect nrz clock by reading #peaks vs no peaks(or errors)
1108 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1109 {
1110 size_t i=0;
1111 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1112 size_t loopCnt = 4096; //don't need to loop through entire array...
1113 if (size == 0) return 0;
1114 if (size<loopCnt) loopCnt = size-20;
1115 //if we already have a valid clock quit
1116 for (; i < 8; ++i)
1117 if (clk[i] == clock) return clock;
1118
1119 //get high and low peak
1120 int peak, low;
1121 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1122
1123 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1124 size_t ii;
1125 uint8_t clkCnt;
1126 uint8_t tol = 0;
1127 uint16_t smplCnt = 0;
1128 int16_t peakcnt = 0;
1129 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1130 uint16_t maxPeak = 255;
1131 bool firstpeak = false;
1132 //test for large clipped waves
1133 for (i=0; i<loopCnt; i++){
1134 if (dest[i] >= peak || dest[i] <= low){
1135 if (!firstpeak) continue;
1136 smplCnt++;
1137 } else {
1138 firstpeak=true;
1139 if (smplCnt > 6 ){
1140 if (maxPeak > smplCnt){
1141 maxPeak = smplCnt;
1142 //prnt("maxPk: %d",maxPeak);
1143 }
1144 peakcnt++;
1145 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1146 smplCnt=0;
1147 }
1148 }
1149 }
1150 bool errBitHigh = 0;
1151 bool bitHigh = 0;
1152 uint8_t ignoreCnt = 0;
1153 uint8_t ignoreWindow = 4;
1154 bool lastPeakHigh = 0;
1155 int lastBit = 0;
1156 peakcnt=0;
1157 //test each valid clock from smallest to greatest to see which lines up
1158 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1159 //ignore clocks smaller than smallest peak
1160 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1161 //try lining up the peaks by moving starting point (try first 256)
1162 for (ii=20; ii < loopCnt; ++ii){
1163 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1164 peakcnt = 0;
1165 bitHigh = false;
1166 ignoreCnt = 0;
1167 lastBit = ii-clk[clkCnt];
1168 //loop through to see if this start location works
1169 for (i = ii; i < size-20; ++i) {
1170 //if we are at a clock bit
1171 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1172 //test high/low
1173 if (dest[i] >= peak || dest[i] <= low) {
1174 //if same peak don't count it
1175 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1176 peakcnt++;
1177 }
1178 lastPeakHigh = (dest[i] >= peak);
1179 bitHigh = true;
1180 errBitHigh = false;
1181 ignoreCnt = ignoreWindow;
1182 lastBit += clk[clkCnt];
1183 } else if (i == lastBit + clk[clkCnt] + tol) {
1184 lastBit += clk[clkCnt];
1185 }
1186 //else if not a clock bit and no peaks
1187 } else if (dest[i] < peak && dest[i] > low){
1188 if (ignoreCnt==0){
1189 bitHigh=false;
1190 if (errBitHigh==true) peakcnt--;
1191 errBitHigh=false;
1192 } else {
1193 ignoreCnt--;
1194 }
1195 // else if not a clock bit but we have a peak
1196 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1197 //error bar found no clock...
1198 errBitHigh=true;
1199 }
1200 }
1201 if(peakcnt>peaksdet[clkCnt]) {
1202 peaksdet[clkCnt]=peakcnt;
1203 }
1204 }
1205 }
1206 }
1207 int iii=7;
1208 uint8_t best=0;
1209 for (iii=7; iii > 0; iii--){
1210 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1211 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1212 best = iii;
1213 }
1214 } else if (peaksdet[iii] > peaksdet[best]){
1215 best = iii;
1216 }
1217 if (g_debugMode==2) prnt("DEBUG NRZ: Clk: %d, peaks: %d, maxPeak: %d, bestClk: %d, lowestTrs: %d",clk[iii],peaksdet[iii],maxPeak, clk[best], lowestTransition);
1218 }
1219
1220 return clk[best];
1221 }
1222
1223 // by marshmellow
1224 // convert psk1 demod to psk2 demod
1225 // only transition waves are 1s
1226 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1227 {
1228 size_t i=1;
1229 uint8_t lastBit=BitStream[0];
1230 for (; i<size; i++){
1231 if (BitStream[i]==7){
1232 //ignore errors
1233 } else if (lastBit!=BitStream[i]){
1234 lastBit=BitStream[i];
1235 BitStream[i]=1;
1236 } else {
1237 BitStream[i]=0;
1238 }
1239 }
1240 return;
1241 }
1242
1243 // by marshmellow
1244 // convert psk2 demod to psk1 demod
1245 // from only transition waves are 1s to phase shifts change bit
1246 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1247 {
1248 uint8_t phase=0;
1249 for (size_t i=0; i<size; i++){
1250 if (BitStream[i]==1){
1251 phase ^=1;
1252 }
1253 BitStream[i]=phase;
1254 }
1255 return;
1256 }
1257
1258 // redesigned by marshmellow adjusted from existing decode functions
1259 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1260 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1261 {
1262 //26 bit 40134 format (don't know other formats)
1263 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
1264 uint8_t preamble_i[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0};
1265 size_t startidx = 0;
1266 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1267 // if didn't find preamble try again inverting
1268 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1269 *invert ^= 1;
1270 }
1271 if (*size != 64 && *size != 224) return -2;
1272 if (*invert==1)
1273 for (size_t i = startidx; i < *size; i++)
1274 bitStream[i] ^= 1;
1275
1276 return (int) startidx;
1277 }
1278
1279 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1280 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1281 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1282 if (justNoise(dest, *size)) return -1;
1283 *clk = DetectNRZClock(dest, *size, *clk);
1284 if (*clk==0) return -2;
1285 size_t i, gLen = 4096;
1286 if (gLen>*size) gLen = *size-20;
1287 int high, low;
1288 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1289
1290 uint8_t bit=0;
1291 //convert wave samples to 1's and 0's
1292 for(i=20; i < *size-20; i++){
1293 if (dest[i] >= high) bit = 1;
1294 if (dest[i] <= low) bit = 0;
1295 dest[i] = bit;
1296 }
1297 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1298 size_t lastBit = 0;
1299 size_t numBits = 0;
1300 for(i=21; i < *size-20; i++) {
1301 //if transition detected or large number of same bits - store the passed bits
1302 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1303 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1304 numBits += (i - lastBit + (*clk/4)) / *clk;
1305 lastBit = i-1;
1306 }
1307 }
1308 *size = numBits;
1309 return 0;
1310 }
1311
1312 //by marshmellow
1313 //detects the bit clock for FSK given the high and low Field Clocks
1314 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1315 {
1316 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1317 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1318 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1319 uint8_t rfLensFnd = 0;
1320 uint8_t lastFCcnt = 0;
1321 uint16_t fcCounter = 0;
1322 uint16_t rfCounter = 0;
1323 uint8_t firstBitFnd = 0;
1324 size_t i;
1325 if (size == 0) return 0;
1326
1327 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1328 rfLensFnd=0;
1329 fcCounter=0;
1330 rfCounter=0;
1331 firstBitFnd=0;
1332 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1333 // prime i to first peak / up transition
1334 for (i = 160; i < size-20; i++)
1335 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1336 break;
1337
1338 for (; i < size-20; i++){
1339 fcCounter++;
1340 rfCounter++;
1341
1342 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1343 continue;
1344 // else new peak
1345 // if we got less than the small fc + tolerance then set it to the small fc
1346 // if it is inbetween set it to the last counter
1347 if (fcCounter < fcHigh && fcCounter > fcLow)
1348 fcCounter = lastFCcnt;
1349 else if (fcCounter < fcLow+fcTol)
1350 fcCounter = fcLow;
1351 else //set it to the large fc
1352 fcCounter = fcHigh;
1353
1354 //look for bit clock (rf/xx)
1355 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1356 //not the same size as the last wave - start of new bit sequence
1357 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1358 for (int ii=0; ii<15; ii++){
1359 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1360 rfCnts[ii]++;
1361 rfCounter = 0;
1362 break;
1363 }
1364 }
1365 if (rfCounter > 0 && rfLensFnd < 15){
1366 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1367 rfCnts[rfLensFnd]++;
1368 rfLens[rfLensFnd++] = rfCounter;
1369 }
1370 } else {
1371 firstBitFnd++;
1372 }
1373 rfCounter=0;
1374 lastFCcnt=fcCounter;
1375 }
1376 fcCounter=0;
1377 }
1378 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1379
1380 for (i=0; i<15; i++){
1381 //get highest 2 RF values (might need to get more values to compare or compare all?)
1382 if (rfCnts[i]>rfCnts[rfHighest]){
1383 rfHighest3=rfHighest2;
1384 rfHighest2=rfHighest;
1385 rfHighest=i;
1386 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1387 rfHighest3=rfHighest2;
1388 rfHighest2=i;
1389 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1390 rfHighest3=i;
1391 }
1392 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1393 }
1394 // set allowed clock remainder tolerance to be 1 large field clock length+1
1395 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1396 uint8_t tol1 = fcHigh+1;
1397
1398 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1399
1400 // loop to find the highest clock that has a remainder less than the tolerance
1401 // compare samples counted divided by
1402 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1403 int ii=7;
1404 for (; ii>=2; ii--){
1405 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1406 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1407 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1408 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1409 break;
1410 }
1411 }
1412 }
1413 }
1414
1415 if (ii<2) return 0; // oops we went too far
1416
1417 return clk[ii];
1418 }
1419
1420 //by marshmellow
1421 //countFC is to detect the field clock lengths.
1422 //counts and returns the 2 most common wave lengths
1423 //mainly used for FSK field clock detection
1424 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1425 {
1426 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1427 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1428 uint8_t fcLensFnd = 0;
1429 uint8_t lastFCcnt = 0;
1430 uint8_t fcCounter = 0;
1431 size_t i;
1432 if (size < 180) return 0;
1433
1434 // prime i to first up transition
1435 for (i = 160; i < size-20; i++)
1436 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1437 break;
1438
1439 for (; i < size-20; i++){
1440 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1441 // new up transition
1442 fcCounter++;
1443 if (fskAdj){
1444 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1445 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1446 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1447 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1448 // save last field clock count (fc/xx)
1449 lastFCcnt = fcCounter;
1450 }
1451 // find which fcLens to save it to:
1452 for (int ii=0; ii<15; ii++){
1453 if (fcLens[ii]==fcCounter){
1454 fcCnts[ii]++;
1455 fcCounter=0;
1456 break;
1457 }
1458 }
1459 if (fcCounter>0 && fcLensFnd<15){
1460 //add new fc length
1461 fcCnts[fcLensFnd]++;
1462 fcLens[fcLensFnd++]=fcCounter;
1463 }
1464 fcCounter=0;
1465 } else {
1466 // count sample
1467 fcCounter++;
1468 }
1469 }
1470
1471 uint8_t best1=14, best2=14, best3=14;
1472 uint16_t maxCnt1=0;
1473 // go through fclens and find which ones are bigest 2
1474 for (i=0; i<15; i++){
1475 // get the 3 best FC values
1476 if (fcCnts[i]>maxCnt1) {
1477 best3=best2;
1478 best2=best1;
1479 maxCnt1=fcCnts[i];
1480 best1=i;
1481 } else if(fcCnts[i]>fcCnts[best2]){
1482 best3=best2;
1483 best2=i;
1484 } else if(fcCnts[i]>fcCnts[best3]){
1485 best3=i;
1486 }
1487 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]);
1488 }
1489 if (fcLens[best1]==0) return 0;
1490 uint8_t fcH=0, fcL=0;
1491 if (fcLens[best1]>fcLens[best2]){
1492 fcH=fcLens[best1];
1493 fcL=fcLens[best2];
1494 } else{
1495 fcH=fcLens[best2];
1496 fcL=fcLens[best1];
1497 }
1498 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1499 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]);
1500 return 0; //lots of waves not psk or fsk
1501 }
1502 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1503
1504 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1505 if (fskAdj) return fcs;
1506 return fcLens[best1];
1507 }
1508
1509 //by marshmellow - demodulate PSK1 wave
1510 //uses wave lengths (# Samples)
1511 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1512 {
1513 if (size == 0) return -1;
1514 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1515 if (*size<loopCnt) loopCnt = *size;
1516
1517 size_t numBits=0;
1518 uint8_t curPhase = *invert;
1519 size_t i=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1520 uint16_t fc=0, fullWaveLen=0, tol=1;
1521 uint16_t errCnt=0, waveLenCnt=0, errCnt2=0;
1522 fc = countFC(dest, *size, 1);
1523 uint8_t fc2 = fc >> 8;
1524 if (fc2 == 10) return -1; //fsk found - quit
1525 fc = fc & 0xFF;
1526 if (fc!=2 && fc!=4 && fc!=8) return -1;
1527 //PrintAndLog("DEBUG: FC: %d",fc);
1528 *clock = DetectPSKClock(dest, *size, *clock);
1529 if (*clock == 0) return -1;
1530
1531 //find start of modulating data in trace
1532 uint8_t threshold_value = 123; //-5
1533 i = findModStart(dest, *size, threshold_value, fc);
1534
1535 //find first phase shift
1536 int avgWaveVal=0, lastAvgWaveVal=0;
1537 waveStart = i;
1538 for (; i<loopCnt; i++) {
1539 // find peak
1540 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1541 waveEnd = i+1;
1542 if (g_debugMode == 2) prnt("DEBUG PSK: waveEnd: %u, waveStart: %u",waveEnd, waveStart);
1543 waveLenCnt = waveEnd-waveStart;
1544 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+3)){ //not first peak and is a large wave but not out of whack
1545 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1546 firstFullWave = waveStart;
1547 fullWaveLen=waveLenCnt;
1548 //if average wave value is > graph 0 then it is an up wave or a 1 (could cause inverting)
1549 if (lastAvgWaveVal > threshold_value) curPhase ^= 1;
1550 break;
1551 }
1552 waveStart = i+1;
1553 avgWaveVal = 0;
1554 }
1555 avgWaveVal += dest[i+2];
1556 }
1557 if (firstFullWave == 0) {
1558 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1559 // so skip a little to ensure we are past any Start Signal
1560 firstFullWave = 160;
1561 memset(dest, curPhase, firstFullWave / *clock);
1562 } else {
1563 memset(dest, curPhase^1, firstFullWave / *clock);
1564 }
1565 //advance bits
1566 numBits += (firstFullWave / *clock);
1567 //set start of wave as clock align
1568 lastClkBit = firstFullWave;
1569 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1570 if (g_debugMode==2) prnt("DEBUG PSK: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1571 waveStart = 0;
1572 dest[numBits++] = curPhase; //set first read bit
1573 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1574 //top edge of wave = start of new wave
1575 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1576 if (waveStart == 0) {
1577 waveStart = i+1;
1578 waveLenCnt = 0;
1579 avgWaveVal = dest[i+1];
1580 } else { //waveEnd
1581 waveEnd = i+1;
1582 waveLenCnt = waveEnd-waveStart;
1583 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1584 if (waveLenCnt > fc){
1585 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1586 //this wave is a phase shift
1587 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1588 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1589 curPhase ^= 1;
1590 dest[numBits++] = curPhase;
1591 lastClkBit += *clock;
1592 } else if (i < lastClkBit+10+fc){
1593 //noise after a phase shift - ignore
1594 } else { //phase shift before supposed to based on clock
1595 errCnt++;
1596 dest[numBits++] = 7;
1597 }
1598 } else if (i+1 > lastClkBit + *clock + tol + fc){
1599 lastClkBit += *clock; //no phase shift but clock bit
1600 dest[numBits++] = curPhase;
1601 } else if (waveLenCnt < fc - 1) { //wave is smaller than field clock (shouldn't happen often)
1602 errCnt2++;
1603 if(errCnt2 > 101) return errCnt2;
1604 }
1605 avgWaveVal = 0;
1606 waveStart = i+1;
1607 }
1608 }
1609 avgWaveVal += dest[i+1];
1610 }
1611 *size = numBits;
1612 return errCnt;
1613 }
1614
1615 //by marshmellow
1616 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1617 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1618 size_t bufsize = *size;
1619 //need to loop through all samples and identify our clock, look for the ST pattern
1620 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1621 int clk = 0;
1622 int tol = 0;
1623 int i, j, skip, start, end, low, high, minClk, waveStart;
1624 bool complete = false;
1625 int tmpbuff[bufsize / 32]; //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
1626 int waveLen[bufsize / 32]; // if clock is larger then we waste memory in array size that is not needed...
1627 size_t testsize = (bufsize < 512) ? bufsize : 512;
1628 int phaseoff = 0;
1629 high = low = 128;
1630 memset(tmpbuff, 0, sizeof(tmpbuff));
1631
1632 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1633 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1634 return false; //just noise
1635 }
1636 i = 0;
1637 j = 0;
1638 minClk = 255;
1639 // get to first full low to prime loop and skip incomplete first pulse
1640 while ((buffer[i] < high) && (i < bufsize))
1641 ++i;
1642 while ((buffer[i] > low) && (i < bufsize))
1643 ++i;
1644 skip = i;
1645
1646 // populate tmpbuff buffer with pulse lengths
1647 while (i < bufsize) {
1648 // measure from low to low
1649 while ((buffer[i] > low) && (i < bufsize))
1650 ++i;
1651 start= i;
1652 while ((buffer[i] < high) && (i < bufsize))
1653 ++i;
1654 //first high point for this wave
1655 waveStart = i;
1656 while ((buffer[i] > low) && (i < bufsize))
1657 ++i;
1658 if (j >= (bufsize/32)) {
1659 break;
1660 }
1661 waveLen[j] = i - waveStart; //first high to first low
1662 tmpbuff[j++] = i - start;
1663 if (i-start < minClk && i < bufsize) {
1664 minClk = i - start;
1665 }
1666 }
1667 // set clock - might be able to get this externally and remove this work...
1668 if (!clk) {
1669 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1670 tol = fndClk[clkCnt]/8;
1671 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1672 clk=fndClk[clkCnt];
1673 break;
1674 }
1675 }
1676 // clock not found - ERROR
1677 if (!clk) {
1678 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1679 return false;
1680 }
1681 } else tol = clk/8;
1682
1683 *foundclock = clk;
1684
1685 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1686 start = -1;
1687 for (i = 0; i < j - 4; ++i) {
1688 skip += tmpbuff[i];
1689 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1690 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
1691 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
1692 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1693 start = i + 3;
1694 break;
1695 }
1696 }
1697 }
1698 }
1699 }
1700 // first ST not found - ERROR
1701 if (start < 0) {
1702 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1703 return false;
1704 } else {
1705 if (g_debugMode==2) prnt("DEBUG STT: first STT found at: %d, j=%d",start, j);
1706 }
1707 if (waveLen[i+2] > clk*1+tol)
1708 phaseoff = 0;
1709 else
1710 phaseoff = clk/2;
1711
1712 // skip over the remainder of ST
1713 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1714
1715 // now do it again to find the end
1716 end = skip;
1717 for (i += 3; i < j - 4; ++i) {
1718 end += tmpbuff[i];
1719 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1720 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
1721 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
1722 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1723 complete = true;
1724 break;
1725 }
1726 }
1727 }
1728 }
1729 }
1730 end -= phaseoff;
1731 //didn't find second ST - ERROR
1732 if (!complete) {
1733 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1734 return false;
1735 }
1736 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);
1737 //now begin to trim out ST so we can use normal demod cmds
1738 start = skip;
1739 size_t datalen = end - start;
1740 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1741 if ( clk - (datalen % clk) <= clk/8) {
1742 // padd the amount off - could be problematic... but shouldn't happen often
1743 datalen += clk - (datalen % clk);
1744 } else if ( (datalen % clk) <= clk/8 ) {
1745 // padd the amount off - could be problematic... but shouldn't happen often
1746 datalen -= datalen % clk;
1747 } else {
1748 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1749 return false;
1750 }
1751 // if datalen is less than one t55xx block - ERROR
1752 if (datalen/clk < 8*4) {
1753 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1754 return false;
1755 }
1756 size_t dataloc = start;
1757 if (buffer[dataloc-(clk*4)-(clk/8)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
1758 //we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start
1759 for ( i=0; i <= (clk/8); ++i ) {
1760 if ( buffer[dataloc - (clk*4) - i] <= low ) {
1761 dataloc -= i;
1762 break;
1763 }
1764 }
1765 }
1766
1767 size_t newloc = 0;
1768 i=0;
1769 if (g_debugMode==2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);
1770
1771 // warning - overwriting buffer given with raw wave data with ST removed...
1772 while ( dataloc < bufsize-(clk/2) ) {
1773 //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)
1774 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1775 for(i=0; i < clk/2-tol; ++i) {
1776 buffer[dataloc+i] = high+5;
1777 }
1778 }
1779 for (i=0; i<datalen; ++i) {
1780 if (i+newloc < bufsize) {
1781 if (i+newloc < dataloc)
1782 buffer[i+newloc] = buffer[dataloc];
1783
1784 dataloc++;
1785 }
1786 }
1787 newloc += i;
1788 //skip next ST - we just assume it will be there from now on...
1789 if (g_debugMode==2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
1790 dataloc += clk*4;
1791 }
1792 *size = newloc;
1793 return true;
1794 }
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