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