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FIX: lets see if this fixes the pyramid clone crash on OSX
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1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // Low frequency demod/decode commands
9 //-----------------------------------------------------------------------------
10
11 #include <stdlib.h>
12 #include "lfdemod.h"
13 #include <string.h>
14
15 //un_comment to allow debug print calls when used not on device
16 void dummy(char *fmt, ...){}
17
18 #ifndef ON_DEVICE
19 #include "ui.h"
20 #include "cmdparser.h"
21 #include "cmddata.h"
22 #define prnt PrintAndLog
23 #else
24 uint8_t g_debugMode=0;
25 #define prnt dummy
26 #endif
27
28 uint8_t justNoise(uint8_t *BitStream, size_t size)
29 {
30 static const uint8_t THRESHOLD = 123;
31 //test samples are not just noise
32 uint8_t justNoise1 = 1;
33 for(size_t idx=0; idx < size && justNoise1 ;idx++){
34 justNoise1 = BitStream[idx] < THRESHOLD;
35 }
36 return justNoise1;
37 }
38
39 //by marshmellow
40 //get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
41 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
42 {
43 *high=0;
44 *low=255;
45 // get high and low thresholds
46 for (size_t i=0; i < size; i++){
47 if (BitStream[i] > *high) *high = BitStream[i];
48 if (BitStream[i] < *low) *low = BitStream[i];
49 }
50 if (*high < 123) return -1; // just noise
51 *high = ((*high-128)*fuzzHi + 12800)/100;
52 *low = ((*low-128)*fuzzLo + 12800)/100;
53 return 1;
54 }
55
56 // by marshmellow
57 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
58 // returns 1 if passed
59 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
60 {
61 uint8_t ans = 0;
62 for (uint8_t i = 0; i < bitLen; i++){
63 ans ^= ((bits >> i) & 1);
64 }
65 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
66 return (ans == pType);
67 }
68
69 //by marshmellow
70 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
71 // Parity Type (1 for odd; 0 for even; 2 Always 1'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 if (pType == 2) { // then marker bit which should be a 1
84 if (!BitStream[j]) return 0;
85 } else {
86 if (parityTest(parityWd, pLen, pType) == 0) return 0;
87 }
88 bitCnt+=(pLen-1);
89 parityWd = 0;
90 }
91 // if we got here then all the parities passed
92 //return ID start index and size
93 return bitCnt;
94 }
95
96 // by marshmellow
97 // takes a array of binary values, length of bits per parity (includes parity bit),
98 // Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
99 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
100 {
101 uint32_t parityWd = 0;
102 size_t j = 0, bitCnt = 0;
103 for (int word = 0; word < sourceLen; word+=pLen-1) {
104 for (int bit=0; bit < pLen-1; bit++){
105 parityWd = (parityWd << 1) | BitSource[word+bit];
106 dest[j++] = (BitSource[word+bit]);
107 }
108 // if parity fails then return 0
109 if (pType == 2) { // then marker bit which should be a 1
110 dest[j++]=1;
111 } else {
112 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
113 }
114 bitCnt += pLen;
115 parityWd = 0;
116 }
117 // if we got here then all the parities passed
118 //return ID start index and size
119 return bitCnt;
120 }
121
122 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
123 {
124 uint32_t num = 0;
125 for(int i = 0 ; i < numbits ; i++)
126 {
127 num = (num << 1) | (*src);
128 src++;
129 }
130 return num;
131 }
132
133 //least significant bit first
134 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
135 {
136 uint32_t num = 0;
137 for(int i = 0 ; i < numbits ; i++) {
138 num = (num << 1) | *(src + (numbits-(i+1)));
139 }
140 return num;
141 }
142
143 //by marshmellow
144 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
145 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
146 {
147 uint8_t foundCnt=0;
148 for (int idx=0; idx < *size - pLen; idx++){
149 if (memcmp(BitStream+idx, preamble, pLen) == 0){
150 //first index found
151 foundCnt++;
152 if (foundCnt == 1){
153 *startIdx = idx;
154 }
155 if (foundCnt == 2){
156 *size = idx - *startIdx;
157 return 1;
158 }
159 }
160 }
161 return 0;
162 }
163
164 //by marshmellow
165 //takes 1s and 0s and searches for EM410x format - output EM ID
166 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
167 {
168 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
169 // otherwise could be a void with no arguments
170 //set defaults
171 uint32_t i = 0;
172 if (BitStream[1]>1) return 0; //allow only 1s and 0s
173
174 // 111111111 bit pattern represent start of frame
175 // include 0 in front to help get start pos
176 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
177 uint32_t idx = 0;
178 uint32_t parityBits = 0;
179 uint8_t errChk = 0;
180 uint8_t FmtLen = 10;
181 *startIdx = 0;
182 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
183 if (errChk == 0 || *size < 64) return 0;
184 if (*size > 64) FmtLen = 22;
185 *startIdx += 1; //get rid of 0 from preamble
186 idx = *startIdx + 9;
187 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
188 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
189 //check even parity - quit if failed
190 if (parityTest(parityBits, 5, 0) == 0) return 0;
191 //set uint64 with ID from BitStream
192 for (uint8_t ii=0; ii<4; ii++){
193 *hi = (*hi << 1) | (*lo >> 63);
194 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
195 }
196 }
197 if (errChk != 0) return 1;
198 //skip last 5 bit parity test for simplicity.
199 // *size = 64 | 128;
200 return 0;
201 }
202
203 //by marshmellow
204 //demodulates strong heavily clipped samples
205 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
206 {
207 size_t bitCnt=0, smplCnt=0, errCnt=0;
208 uint8_t waveHigh = 0;
209 for (size_t i=0; i < *size; i++){
210 if (BinStream[i] >= high && waveHigh){
211 smplCnt++;
212 } else if (BinStream[i] <= low && !waveHigh){
213 smplCnt++;
214 } else { //transition
215 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
216 if (smplCnt > clk-(clk/4)-1) { //full clock
217 if (smplCnt > clk + (clk/4)+1) { //too many samples
218 errCnt++;
219 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
220 BinStream[bitCnt++]=7;
221 } else if (waveHigh) {
222 BinStream[bitCnt++] = invert;
223 BinStream[bitCnt++] = invert;
224 } else if (!waveHigh) {
225 BinStream[bitCnt++] = invert ^ 1;
226 BinStream[bitCnt++] = invert ^ 1;
227 }
228 waveHigh ^= 1;
229 smplCnt = 0;
230 } else if (smplCnt > (clk/2) - (clk/4)-1) {
231 if (waveHigh) {
232 BinStream[bitCnt++] = invert;
233 } else if (!waveHigh) {
234 BinStream[bitCnt++] = invert ^ 1;
235 }
236 waveHigh ^= 1;
237 smplCnt = 0;
238 } else if (!bitCnt) {
239 //first bit
240 waveHigh = (BinStream[i] >= high);
241 smplCnt = 1;
242 } else {
243 smplCnt++;
244 //transition bit oops
245 }
246 } else { //haven't hit new high or new low yet
247 smplCnt++;
248 }
249 }
250 }
251 *size = bitCnt;
252 return errCnt;
253 }
254
255 //by marshmellow
256 void askAmp(uint8_t *BitStream, size_t size)
257 {
258 for(size_t i = 1; i<size; i++){
259 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
260 BitStream[i]=127;
261 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
262 BitStream[i]=-127;
263 }
264 return;
265 }
266
267 //by marshmellow
268 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
269 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
270 {
271 if (*size==0) return -1;
272 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
273 if (*clk==0 || start < 0) return -3;
274 if (*invert != 1) *invert = 0;
275 if (amp==1) askAmp(BinStream, *size);
276 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
277
278 uint8_t initLoopMax = 255;
279 if (initLoopMax > *size) initLoopMax = *size;
280 // Detect high and lows
281 //25% clip in case highs and lows aren't clipped [marshmellow]
282 int high, low;
283 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
284 return -2; //just noise
285
286 size_t errCnt = 0;
287 // if clean clipped waves detected run alternate demod
288 if (DetectCleanAskWave(BinStream, *size, high, low)) {
289 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
290 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
291 if (askType) //askman
292 return manrawdecode(BinStream, size, 0);
293 else //askraw
294 return errCnt;
295 }
296 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
297
298 int lastBit; //set first clock check - can go negative
299 size_t i, bitnum = 0; //output counter
300 uint8_t midBit = 0;
301 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
302 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
303 size_t MaxBits = 3072; //max bits to collect
304 lastBit = start - *clk;
305
306 for (i = start; i < *size; ++i) {
307 if (i-lastBit >= *clk-tol){
308 if (BinStream[i] >= high) {
309 BinStream[bitnum++] = *invert;
310 } else if (BinStream[i] <= low) {
311 BinStream[bitnum++] = *invert ^ 1;
312 } else if (i-lastBit >= *clk+tol) {
313 if (bitnum > 0) {
314 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
315 BinStream[bitnum++]=7;
316 errCnt++;
317 }
318 } else { //in tolerance - looking for peak
319 continue;
320 }
321 midBit = 0;
322 lastBit += *clk;
323 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
324 if (BinStream[i] >= high) {
325 BinStream[bitnum++] = *invert;
326 } else if (BinStream[i] <= low) {
327 BinStream[bitnum++] = *invert ^ 1;
328 } else if (i-lastBit >= *clk/2+tol) {
329 BinStream[bitnum] = BinStream[bitnum-1];
330 bitnum++;
331 } else { //in tolerance - looking for peak
332 continue;
333 }
334 midBit = 1;
335 }
336 if (bitnum >= MaxBits) break;
337 }
338 *size = bitnum;
339 return errCnt;
340 }
341
342 //by marshmellow
343 //take 10 and 01 and manchester decode
344 //run through 2 times and take least errCnt
345 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
346 {
347 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
348 size_t i, ii;
349 uint16_t bestErr = 1000, bestRun = 0;
350 if (*size < 16) return -1;
351 //find correct start position [alignment]
352 for (ii=0;ii<2;++ii){
353 for (i=ii; i<*size-3; i+=2)
354 if (BitStream[i]==BitStream[i+1])
355 errCnt++;
356
357 if (bestErr>errCnt){
358 bestErr=errCnt;
359 bestRun=ii;
360 }
361 errCnt=0;
362 }
363 //decode
364 for (i=bestRun; i < *size-3; i+=2){
365 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
366 BitStream[bitnum++]=invert;
367 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
368 BitStream[bitnum++]=invert^1;
369 } else {
370 BitStream[bitnum++]=7;
371 }
372 if(bitnum>MaxBits) break;
373 }
374 *size=bitnum;
375 return bestErr;
376 }
377
378 uint32_t manchesterEncode2Bytes(uint16_t datain) {
379 uint32_t output = 0;
380 uint8_t curBit = 0;
381 for (uint8_t i=0; i<16; i++) {
382 curBit = (datain >> (15-i) & 1);
383 output |= (1<<(((15-i)*2)+curBit));
384 }
385 return output;
386 }
387
388 //by marshmellow
389 //encode binary data into binary manchester
390 int ManchesterEncode(uint8_t *BitStream, size_t size)
391 {
392 size_t modIdx=20000, i=0;
393 if (size>modIdx) return -1;
394 for (size_t idx=0; idx < size; idx++){
395 BitStream[idx+modIdx++] = BitStream[idx];
396 BitStream[idx+modIdx++] = BitStream[idx]^1;
397 }
398 for (; i<(size*2); i++){
399 BitStream[i] = BitStream[i+20000];
400 }
401 return i;
402 }
403
404 //by marshmellow
405 //take 01 or 10 = 1 and 11 or 00 = 0
406 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
407 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
408 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
409 {
410 uint16_t bitnum = 0;
411 uint16_t errCnt = 0;
412 size_t i = offset;
413 uint16_t MaxBits=512;
414 //if not enough samples - error
415 if (*size < 51) return -1;
416 //check for phase change faults - skip one sample if faulty
417 uint8_t offsetA = 1, offsetB = 1;
418 for (; i<48; i+=2){
419 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
420 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
421 }
422 if (!offsetA && offsetB) offset++;
423 for (i=offset; i<*size-3; i+=2){
424 //check for phase error
425 if (BitStream[i+1]==BitStream[i+2]) {
426 BitStream[bitnum++]=7;
427 errCnt++;
428 }
429 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
430 BitStream[bitnum++]=1^invert;
431 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
432 BitStream[bitnum++]=invert;
433 } else {
434 BitStream[bitnum++]=7;
435 errCnt++;
436 }
437 if(bitnum>MaxBits) break;
438 }
439 *size=bitnum;
440 return errCnt;
441 }
442
443 // by marshmellow
444 // demod gProxIIDemod
445 // error returns as -x
446 // success returns start position in BitStream
447 // BitStream must contain previously askrawdemod and biphasedemoded data
448 int gProxII_Demod(uint8_t BitStream[], size_t *size)
449 {
450 size_t startIdx=0;
451 uint8_t preamble[] = {1,1,1,1,1,0};
452
453 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
454 if (errChk == 0) return -3; //preamble not found
455 if (*size != 96) return -2; //should have found 96 bits
456 //check first 6 spacer bits to verify format
457 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
458 //confirmed proper separator bits found
459 //return start position
460 return (int) startIdx;
461 }
462 return -5;
463 }
464
465 //translate wave to 11111100000 (1 for each short wave 0 for each long wave)
466 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
467 {
468 size_t last_transition = 0;
469 size_t idx = 1;
470 //uint32_t maxVal=0;
471 if (fchigh==0) fchigh=10;
472 if (fclow==0) fclow=8;
473 //set the threshold close to 0 (graph) or 128 std to avoid static
474 uint8_t threshold_value = 123;
475 size_t preLastSample = 0;
476 size_t LastSample = 0;
477 size_t currSample = 0;
478 // sync to first lo-hi transition, and threshold
479
480 // Need to threshold first sample
481 // skip 160 samples to allow antenna/samples to settle
482 if(dest[160] < threshold_value) dest[0] = 0;
483 else dest[0] = 1;
484
485 size_t numBits = 0;
486 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
487 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
488 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
489 for(idx = 161; idx < size-20; idx++) {
490 // threshold current value
491
492 if (dest[idx] < threshold_value) dest[idx] = 0;
493 else dest[idx] = 1;
494
495 // Check for 0->1 transition
496 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
497 preLastSample = LastSample;
498 LastSample = currSample;
499 currSample = idx-last_transition;
500 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
501 //do nothing with extra garbage
502 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves or 3-6 = 5
503 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
504 dest[numBits-1]=1; //correct previous 9 wave surrounded by 8 waves
505 }
506 dest[numBits++]=1;
507
508 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage
509 //do nothing with beginning garbage
510 } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
511 dest[numBits++]=1;
512 } else { //9+ = 10 sample waves
513 dest[numBits++]=0;
514 }
515 last_transition = idx;
516 }
517 }
518 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
519 }
520
521 //translate 11111100000 to 10
522 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
523 uint8_t invert, uint8_t fchigh, uint8_t fclow)
524 {
525 uint8_t lastval=dest[0];
526 size_t idx=0;
527 size_t numBits=0;
528 uint32_t n=1;
529 for( idx=1; idx < size; idx++) {
530 n++;
531 if (dest[idx]==lastval) continue;
532
533 //if lastval was 1, we have a 1->0 crossing
534 if (dest[idx-1]==1) {
535 n = (n * fclow + rfLen/2) / rfLen;
536 } else {// 0->1 crossing
537 n = (n * fchigh + rfLen/2) / rfLen;
538 }
539 if (n == 0) n = 1;
540
541 memset(dest+numBits, dest[idx-1]^invert , n);
542 numBits += n;
543 n=0;
544 lastval=dest[idx];
545 }//end for
546 // if valid extra bits at the end were all the same frequency - add them in
547 if (n > rfLen/fchigh) {
548 if (dest[idx-2]==1) {
549 n = (n * fclow + rfLen/2) / rfLen;
550 } else {
551 n = (n * fchigh + rfLen/2) / rfLen;
552 }
553 memset(dest+numBits, dest[idx-1]^invert , n);
554 numBits += n;
555 }
556 return numBits;
557 }
558
559 //by marshmellow (from holiman's base)
560 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
561 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
562 {
563 // FSK demodulator
564 size = fsk_wave_demod(dest, size, fchigh, fclow);
565 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
566 return size;
567 }
568
569 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
570 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
571 {
572 if (justNoise(dest, *size)) return -1;
573
574 size_t numStart=0, size2=*size, startIdx=0;
575 // FSK demodulator
576 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
577 if (*size < 96*2) return -2;
578 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
579 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
580 // find bitstring in array
581 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
582 if (errChk == 0) return -3; //preamble not found
583
584 numStart = startIdx + sizeof(preamble);
585 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
586 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
587 if (dest[idx] == dest[idx+1]){
588 return -4; //not manchester data
589 }
590 *hi2 = (*hi2<<1)|(*hi>>31);
591 *hi = (*hi<<1)|(*lo>>31);
592 //Then, shift in a 0 or one into low
593 if (dest[idx] && !dest[idx+1]) // 1 0
594 *lo=(*lo<<1)|1;
595 else // 0 1
596 *lo=(*lo<<1)|0;
597 }
598 return (int)startIdx;
599 }
600
601 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
602 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
603 {
604 if (justNoise(dest, *size)) return -1;
605
606 size_t numStart=0, size2=*size, startIdx=0;
607 // FSK demodulator
608 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
609 if (*size < 96) return -2;
610
611 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
612 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
613
614 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
615 if (errChk == 0) return -3; //preamble not found
616
617 numStart = startIdx + sizeof(preamble);
618 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
619 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
620 if (dest[idx] == dest[idx+1])
621 return -4; //not manchester data
622 *hi2 = (*hi2<<1)|(*hi>>31);
623 *hi = (*hi<<1)|(*lo>>31);
624 //Then, shift in a 0 or one into low
625 if (dest[idx] && !dest[idx+1]) // 1 0
626 *lo=(*lo<<1)|1;
627 else // 0 1
628 *lo=(*lo<<1)|0;
629 }
630 return (int)startIdx;
631 }
632
633 int IOdemodFSK(uint8_t *dest, size_t size)
634 {
635 if (justNoise(dest, size)) return -1;
636 //make sure buffer has data
637 if (size < 66*64) return -2;
638 // FSK demodulator
639 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
640 if (size < 65) return -3; //did we get a good demod?
641 //Index map
642 //0 10 20 30 40 50 60
643 //| | | | | | |
644 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
645 //-----------------------------------------------------------------------------
646 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
647 //
648 //XSF(version)facility:codeone+codetwo
649 //Handle the data
650 size_t startIdx = 0;
651 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
652 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
653 if (errChk == 0) return -4; //preamble not found
654
655 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
656 //confirmed proper separator bits found
657 //return start position
658 return (int) startIdx;
659 }
660 return -5;
661 }
662
663 // by marshmellow
664 // find viking preamble 0xF200 in already demoded data
665 int VikingDemod_AM(uint8_t *dest, size_t *size) {
666 //make sure buffer has data
667 if (*size < 64*2) return -2;
668
669 size_t startIdx = 0;
670 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};
671 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
672 if (errChk == 0) return -4; //preamble not found
673 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
674 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
675 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
676 if ( checkCalc != 0xA8 ) return -5;
677 if (*size != 64) return -6;
678 //return start position
679 return (int) startIdx;
680 }
681
682 // find presco preamble 0x10D in already demoded data
683 int PrescoDemod(uint8_t *dest, size_t *size) {
684 //make sure buffer has data
685 if (*size < 64*2) return -2;
686
687 size_t startIdx = 0;
688 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
689 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
690 if (errChk == 0) return -4; //preamble not found
691 //return start position
692 return (int) startIdx;
693 }
694
695
696 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
697 // BitStream must contain previously askrawdemod and biphasedemoded data
698 int FDXBdemodBI(uint8_t *dest, size_t *size)
699 {
700 //make sure buffer has enough data
701 if (*size < 128) return -1;
702
703 size_t startIdx = 0;
704 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
705
706 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
707 if (errChk == 0) return -2; //preamble not found
708 return (int)startIdx;
709 }
710
711 // by marshmellow
712 // FSK Demod then try to locate an AWID ID
713 int AWIDdemodFSK(uint8_t *dest, size_t *size)
714 {
715 //make sure buffer has enough data
716 if (*size < 96*50) return -1;
717
718 if (justNoise(dest, *size)) return -2;
719
720 // FSK demodulator
721 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
722 if (*size < 96) return -3; //did we get a good demod?
723
724 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
725 size_t startIdx = 0;
726 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
727 if (errChk == 0) return -4; //preamble not found
728 if (*size != 96) return -5;
729 return (int)startIdx;
730 }
731
732 // by marshmellow
733 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
734 int PyramiddemodFSK(uint8_t *dest, size_t *size)
735 {
736 //make sure buffer has data
737 if (*size < 128*50) return -5;
738
739 //test samples are not just noise
740 if (justNoise(dest, *size)) return -1;
741
742 // FSK demodulator
743 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
744 if (*size < 128) return -2; //did we get a good demod?
745
746 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
747 size_t startIdx = 0;
748 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
749 if (errChk == 0) return -4; //preamble not found
750 if (*size != 128) return -3;
751 return (int)startIdx;
752 }
753
754 // by marshmellow
755 // to detect a wave that has heavily clipped (clean) samples
756 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
757 {
758 bool allArePeaks = true;
759 uint16_t cntPeaks=0;
760 size_t loopEnd = 512+160;
761 if (loopEnd > size) loopEnd = size;
762 for (size_t i=160; i<loopEnd; i++){
763 if (dest[i]>low && dest[i]<high)
764 allArePeaks = false;
765 else
766 cntPeaks++;
767 }
768 if (!allArePeaks){
769 if (cntPeaks > 300) return true;
770 }
771 return allArePeaks;
772 }
773 // by marshmellow
774 // to help detect clocks on heavily clipped samples
775 // based on count of low to low
776 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
777 {
778 uint8_t fndClk[] = {8,16,32,40,50,64,128};
779 size_t startwave;
780 size_t i = 100;
781 size_t minClk = 255;
782 // get to first full low to prime loop and skip incomplete first pulse
783 while ((dest[i] < high) && (i < size))
784 ++i;
785 while ((dest[i] > low) && (i < size))
786 ++i;
787
788 // loop through all samples
789 while (i < size) {
790 // measure from low to low
791 while ((dest[i] > low) && (i < size))
792 ++i;
793 startwave= i;
794 while ((dest[i] < high) && (i < size))
795 ++i;
796 while ((dest[i] > low) && (i < size))
797 ++i;
798 //get minimum measured distance
799 if (i-startwave < minClk && i < size)
800 minClk = i - startwave;
801 }
802 // set clock
803 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
804 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
805 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
806 return fndClk[clkCnt];
807 }
808 return 0;
809 }
810
811 // by marshmellow
812 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
813 // maybe somehow adjust peak trimming value based on samples to fix?
814 // return start index of best starting position for that clock and return clock (by reference)
815 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
816 {
817 size_t i=1;
818 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
819 uint8_t clkEnd = 9;
820 uint8_t loopCnt = 255; //don't need to loop through entire array...
821 if (size <= loopCnt+60) return -1; //not enough samples
822 size -= 60; //sometimes there is a strange end wave - filter out this....
823 //if we already have a valid clock
824 uint8_t clockFnd=0;
825 for (;i<clkEnd;++i)
826 if (clk[i] == *clock) clockFnd = i;
827 //clock found but continue to find best startpos
828
829 //get high and low peak
830 int peak, low;
831 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
832
833 //test for large clean peaks
834 if (!clockFnd){
835 if (DetectCleanAskWave(dest, size, peak, low)==1){
836 int ans = DetectStrongAskClock(dest, size, peak, low);
837 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
838 for (i=clkEnd-1; i>0; i--){
839 if (clk[i] == ans) {
840 *clock = ans;
841 //clockFnd = i;
842 return 0; // for strong waves i don't use the 'best start position' yet...
843 //break; //clock found but continue to find best startpos [not yet]
844 }
845 }
846 }
847 }
848 uint8_t ii;
849 uint8_t clkCnt, tol = 0;
850 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
851 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
852 size_t errCnt = 0;
853 size_t arrLoc, loopEnd;
854
855 if (clockFnd>0) {
856 clkCnt = clockFnd;
857 clkEnd = clockFnd+1;
858 }
859 else clkCnt=1;
860
861 //test each valid clock from smallest to greatest to see which lines up
862 for(; clkCnt < clkEnd; clkCnt++){
863 if (clk[clkCnt] <= 32){
864 tol=1;
865 }else{
866 tol=0;
867 }
868 //if no errors allowed - keep start within the first clock
869 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
870 bestErr[clkCnt]=1000;
871 //try lining up the peaks by moving starting point (try first few clocks)
872 for (ii=0; ii < loopCnt; ii++){
873 if (dest[ii] < peak && dest[ii] > low) continue;
874
875 errCnt=0;
876 // now that we have the first one lined up test rest of wave array
877 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
878 for (i=0; i < loopEnd; ++i){
879 arrLoc = ii + (i * clk[clkCnt]);
880 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
881 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
882 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
883 }else{ //error no peak detected
884 errCnt++;
885 }
886 }
887 //if we found no errors then we can stop here and a low clock (common clocks)
888 // this is correct one - return this clock
889 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
890 if(errCnt==0 && clkCnt<7) {
891 if (!clockFnd) *clock = clk[clkCnt];
892 return ii;
893 }
894 //if we found errors see if it is lowest so far and save it as best run
895 if(errCnt<bestErr[clkCnt]){
896 bestErr[clkCnt]=errCnt;
897 bestStart[clkCnt]=ii;
898 }
899 }
900 }
901 uint8_t iii;
902 uint8_t best=0;
903 for (iii=1; iii<clkEnd; ++iii){
904 if (bestErr[iii] < bestErr[best]){
905 if (bestErr[iii] == 0) bestErr[iii]=1;
906 // current best bit to error ratio vs new bit to error ratio
907 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
908 best = iii;
909 }
910 }
911 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]);
912 }
913 if (!clockFnd) *clock = clk[best];
914 return bestStart[best];
915 }
916
917 //by marshmellow
918 //detect psk clock by reading each phase shift
919 // a phase shift is determined by measuring the sample length of each wave
920 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
921 {
922 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
923 uint16_t loopCnt = 4096; //don't need to loop through entire array...
924 if (size == 0) return 0;
925 if (size<loopCnt) loopCnt = size-20;
926
927 //if we already have a valid clock quit
928 size_t i=1;
929 for (; i < 8; ++i)
930 if (clk[i] == clock) return clock;
931
932 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
933 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
934 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
935 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
936 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
937 fc = countFC(dest, size, 0);
938 if (fc!=2 && fc!=4 && fc!=8) return -1;
939 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
940
941 //find first full wave
942 for (i=160; i<loopCnt; i++){
943 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
944 if (waveStart == 0) {
945 waveStart = i+1;
946 //prnt("DEBUG: waveStart: %d",waveStart);
947 } else {
948 waveEnd = i+1;
949 //prnt("DEBUG: waveEnd: %d",waveEnd);
950 waveLenCnt = waveEnd-waveStart;
951 if (waveLenCnt > fc){
952 firstFullWave = waveStart;
953 fullWaveLen=waveLenCnt;
954 break;
955 }
956 waveStart=0;
957 }
958 }
959 }
960 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
961
962 //test each valid clock from greatest to smallest to see which lines up
963 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
964 lastClkBit = firstFullWave; //set end of wave as clock align
965 waveStart = 0;
966 errCnt=0;
967 peakcnt=0;
968 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
969
970 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
971 //top edge of wave = start of new wave
972 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
973 if (waveStart == 0) {
974 waveStart = i+1;
975 waveLenCnt=0;
976 } else { //waveEnd
977 waveEnd = i+1;
978 waveLenCnt = waveEnd-waveStart;
979 if (waveLenCnt > fc){
980 //if this wave is a phase shift
981 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);
982 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
983 peakcnt++;
984 lastClkBit+=clk[clkCnt];
985 } else if (i<lastClkBit+8){
986 //noise after a phase shift - ignore
987 } else { //phase shift before supposed to based on clock
988 errCnt++;
989 }
990 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
991 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
992 }
993 waveStart=i+1;
994 }
995 }
996 }
997 if (errCnt == 0){
998 return clk[clkCnt];
999 }
1000 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1001 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1002 }
1003 //all tested with errors
1004 //return the highest clk with the most peaks found
1005 uint8_t best=7;
1006 for (i=7; i>=1; i--){
1007 if (peaksdet[i] > peaksdet[best]) {
1008 best = i;
1009 }
1010 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1011 }
1012 return clk[best];
1013 }
1014
1015 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1016 //find shortest transition from high to low
1017 size_t i = 0;
1018 size_t transition1 = 0;
1019 int lowestTransition = 255;
1020 bool lastWasHigh = false;
1021
1022 //find first valid beginning of a high or low wave
1023 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1024 ++i;
1025 while ((dest[i] < peak && dest[i] > low) && (i < size))
1026 ++i;
1027 lastWasHigh = (dest[i] >= peak);
1028
1029 if (i==size) return 0;
1030 transition1 = i;
1031
1032 for (;i < size; i++) {
1033 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1034 lastWasHigh = (dest[i] >= peak);
1035 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1036 transition1 = i;
1037 }
1038 }
1039 if (lowestTransition == 255) lowestTransition = 0;
1040 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1041 return lowestTransition;
1042 }
1043
1044 //by marshmellow
1045 //detect nrz clock by reading #peaks vs no peaks(or errors)
1046 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1047 {
1048 size_t i=0;
1049 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1050 size_t loopCnt = 4096; //don't need to loop through entire array...
1051 if (size == 0) return 0;
1052 if (size<loopCnt) loopCnt = size-20;
1053 //if we already have a valid clock quit
1054 for (; i < 8; ++i)
1055 if (clk[i] == clock) return clock;
1056
1057 //get high and low peak
1058 int peak, low;
1059 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1060
1061 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1062 size_t ii;
1063 uint8_t clkCnt;
1064 uint8_t tol = 0;
1065 uint16_t smplCnt = 0;
1066 int16_t peakcnt = 0;
1067 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1068 uint16_t maxPeak = 255;
1069 bool firstpeak = false;
1070 //test for large clipped waves
1071 for (i=0; i<loopCnt; i++){
1072 if (dest[i] >= peak || dest[i] <= low){
1073 if (!firstpeak) continue;
1074 smplCnt++;
1075 } else {
1076 firstpeak=true;
1077 if (smplCnt > 6 ){
1078 if (maxPeak > smplCnt){
1079 maxPeak = smplCnt;
1080 //prnt("maxPk: %d",maxPeak);
1081 }
1082 peakcnt++;
1083 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1084 smplCnt=0;
1085 }
1086 }
1087 }
1088 bool errBitHigh = 0;
1089 bool bitHigh = 0;
1090 uint8_t ignoreCnt = 0;
1091 uint8_t ignoreWindow = 4;
1092 bool lastPeakHigh = 0;
1093 int lastBit = 0;
1094 peakcnt=0;
1095 //test each valid clock from smallest to greatest to see which lines up
1096 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1097 //ignore clocks smaller than smallest peak
1098 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1099 //try lining up the peaks by moving starting point (try first 256)
1100 for (ii=20; ii < loopCnt; ++ii){
1101 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1102 peakcnt=0;
1103 bitHigh = false;
1104 ignoreCnt = 0;
1105 lastBit = ii-clk[clkCnt];
1106 //loop through to see if this start location works
1107 for (i = ii; i < size-20; ++i) {
1108 //if we are at a clock bit
1109 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1110 //test high/low
1111 if (dest[i] >= peak || dest[i] <= low) {
1112 //if same peak don't count it
1113 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1114 peakcnt++;
1115 }
1116 lastPeakHigh = (dest[i] >= peak);
1117 bitHigh = true;
1118 errBitHigh = false;
1119 ignoreCnt = ignoreWindow;
1120 lastBit += clk[clkCnt];
1121 } else if (i == lastBit + clk[clkCnt] + tol) {
1122 lastBit += clk[clkCnt];
1123 }
1124 //else if not a clock bit and no peaks
1125 } else if (dest[i] < peak && dest[i] > low){
1126 if (ignoreCnt==0){
1127 bitHigh=false;
1128 if (errBitHigh==true) peakcnt--;
1129 errBitHigh=false;
1130 } else {
1131 ignoreCnt--;
1132 }
1133 // else if not a clock bit but we have a peak
1134 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1135 //error bar found no clock...
1136 errBitHigh=true;
1137 }
1138 }
1139 if(peakcnt>peaksdet[clkCnt]) {
1140 peaksdet[clkCnt]=peakcnt;
1141 }
1142 }
1143 }
1144 }
1145 int iii=7;
1146 uint8_t best=0;
1147 for (iii=7; iii > 0; iii--){
1148 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1149 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1150 best = iii;
1151 }
1152 } else if (peaksdet[iii] > peaksdet[best]){
1153 best = iii;
1154 }
1155 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);
1156 }
1157
1158 return clk[best];
1159 }
1160
1161 // by marshmellow
1162 // convert psk1 demod to psk2 demod
1163 // only transition waves are 1s
1164 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1165 {
1166 size_t i=1;
1167 uint8_t lastBit=BitStream[0];
1168 for (; i<size; i++){
1169 if (BitStream[i]==7){
1170 //ignore errors
1171 } else if (lastBit!=BitStream[i]){
1172 lastBit=BitStream[i];
1173 BitStream[i]=1;
1174 } else {
1175 BitStream[i]=0;
1176 }
1177 }
1178 return;
1179 }
1180
1181 // by marshmellow
1182 // convert psk2 demod to psk1 demod
1183 // from only transition waves are 1s to phase shifts change bit
1184 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1185 {
1186 uint8_t phase=0;
1187 for (size_t i=0; i<size; i++){
1188 if (BitStream[i]==1){
1189 phase ^=1;
1190 }
1191 BitStream[i]=phase;
1192 }
1193 return;
1194 }
1195
1196 // redesigned by marshmellow adjusted from existing decode functions
1197 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1198 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1199 {
1200 //26 bit 40134 format (don't know other formats)
1201 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};
1202 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};
1203 size_t startidx = 0;
1204 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1205 // if didn't find preamble try again inverting
1206 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1207 *invert ^= 1;
1208 }
1209 if (*size != 64 && *size != 224) return -2;
1210 if (*invert==1)
1211 for (size_t i = startidx; i < *size; i++)
1212 bitStream[i] ^= 1;
1213
1214 return (int) startidx;
1215 }
1216
1217 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1218 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1219 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1220 if (justNoise(dest, *size)) return -1;
1221 *clk = DetectNRZClock(dest, *size, *clk);
1222 if (*clk==0) return -2;
1223 size_t i, gLen = 4096;
1224 if (gLen>*size) gLen = *size-20;
1225 int high, low;
1226 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1227
1228 uint8_t bit=0;
1229 //convert wave samples to 1's and 0's
1230 for(i=20; i < *size-20; i++){
1231 if (dest[i] >= high) bit = 1;
1232 if (dest[i] <= low) bit = 0;
1233 dest[i] = bit;
1234 }
1235 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1236 size_t lastBit = 0;
1237 size_t numBits = 0;
1238 for(i=21; i < *size-20; i++) {
1239 //if transition detected or large number of same bits - store the passed bits
1240 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1241 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1242 numBits += (i - lastBit + (*clk/4)) / *clk;
1243 lastBit = i-1;
1244 }
1245 }
1246 *size = numBits;
1247 return 0;
1248 }
1249
1250 //by marshmellow
1251 //detects the bit clock for FSK given the high and low Field Clocks
1252 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1253 {
1254 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1255 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1256 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1257 uint8_t rfLensFnd = 0;
1258 uint8_t lastFCcnt = 0;
1259 uint16_t fcCounter = 0;
1260 uint16_t rfCounter = 0;
1261 uint8_t firstBitFnd = 0;
1262 size_t i;
1263 if (size == 0) return 0;
1264
1265 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1266 rfLensFnd=0;
1267 fcCounter=0;
1268 rfCounter=0;
1269 firstBitFnd=0;
1270 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1271 // prime i to first peak / up transition
1272 for (i = 160; i < size-20; i++)
1273 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1274 break;
1275
1276 for (; i < size-20; i++){
1277 fcCounter++;
1278 rfCounter++;
1279
1280 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1281 continue;
1282 // else new peak
1283 // if we got less than the small fc + tolerance then set it to the small fc
1284 if (fcCounter < fcLow+fcTol)
1285 fcCounter = fcLow;
1286 else //set it to the large fc
1287 fcCounter = fcHigh;
1288
1289 //look for bit clock (rf/xx)
1290 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1291 //not the same size as the last wave - start of new bit sequence
1292 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1293 for (int ii=0; ii<15; ii++){
1294 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1295 rfCnts[ii]++;
1296 rfCounter = 0;
1297 break;
1298 }
1299 }
1300 if (rfCounter > 0 && rfLensFnd < 15){
1301 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1302 rfCnts[rfLensFnd]++;
1303 rfLens[rfLensFnd++] = rfCounter;
1304 }
1305 } else {
1306 firstBitFnd++;
1307 }
1308 rfCounter=0;
1309 lastFCcnt=fcCounter;
1310 }
1311 fcCounter=0;
1312 }
1313 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1314
1315 for (i=0; i<15; i++){
1316 //get highest 2 RF values (might need to get more values to compare or compare all?)
1317 if (rfCnts[i]>rfCnts[rfHighest]){
1318 rfHighest3=rfHighest2;
1319 rfHighest2=rfHighest;
1320 rfHighest=i;
1321 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1322 rfHighest3=rfHighest2;
1323 rfHighest2=i;
1324 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1325 rfHighest3=i;
1326 }
1327 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1328 }
1329 // set allowed clock remainder tolerance to be 1 large field clock length+1
1330 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1331 uint8_t tol1 = fcHigh+1;
1332
1333 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1334
1335 // loop to find the highest clock that has a remainder less than the tolerance
1336 // compare samples counted divided by
1337 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1338 int ii=7;
1339 for (; ii>=2; ii--){
1340 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1341 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1342 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1343 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1344 break;
1345 }
1346 }
1347 }
1348 }
1349
1350 if (ii<0) return 0; // oops we went too far
1351
1352 return clk[ii];
1353 }
1354
1355 //by marshmellow
1356 //countFC is to detect the field clock lengths.
1357 //counts and returns the 2 most common wave lengths
1358 //mainly used for FSK field clock detection
1359 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1360 {
1361 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1362 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1363 uint8_t fcLensFnd = 0;
1364 uint8_t lastFCcnt=0;
1365 uint8_t fcCounter = 0;
1366 size_t i;
1367 if (size == 0) return 0;
1368
1369 // prime i to first up transition
1370 for (i = 160; i < size-20; i++)
1371 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1372 break;
1373
1374 for (; i < size-20; i++){
1375 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1376 // new up transition
1377 fcCounter++;
1378 if (fskAdj){
1379 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1380 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1381 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1382 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1383 // save last field clock count (fc/xx)
1384 lastFCcnt = fcCounter;
1385 }
1386 // find which fcLens to save it to:
1387 for (int ii=0; ii<15; ii++){
1388 if (fcLens[ii]==fcCounter){
1389 fcCnts[ii]++;
1390 fcCounter=0;
1391 break;
1392 }
1393 }
1394 if (fcCounter>0 && fcLensFnd<15){
1395 //add new fc length
1396 fcCnts[fcLensFnd]++;
1397 fcLens[fcLensFnd++]=fcCounter;
1398 }
1399 fcCounter=0;
1400 } else {
1401 // count sample
1402 fcCounter++;
1403 }
1404 }
1405
1406 uint8_t best1=14, best2=14, best3=14;
1407 uint16_t maxCnt1=0;
1408 // go through fclens and find which ones are bigest 2
1409 for (i=0; i<15; i++){
1410 // get the 3 best FC values
1411 if (fcCnts[i]>maxCnt1) {
1412 best3=best2;
1413 best2=best1;
1414 maxCnt1=fcCnts[i];
1415 best1=i;
1416 } else if(fcCnts[i]>fcCnts[best2]){
1417 best3=best2;
1418 best2=i;
1419 } else if(fcCnts[i]>fcCnts[best3]){
1420 best3=i;
1421 }
1422 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]);
1423 }
1424 if (fcLens[best1]==0) return 0;
1425 uint8_t fcH=0, fcL=0;
1426 if (fcLens[best1]>fcLens[best2]){
1427 fcH=fcLens[best1];
1428 fcL=fcLens[best2];
1429 } else{
1430 fcH=fcLens[best2];
1431 fcL=fcLens[best1];
1432 }
1433 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1434 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]);
1435 return 0; //lots of waves not psk or fsk
1436 }
1437 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1438
1439 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1440 if (fskAdj) return fcs;
1441 return fcLens[best1];
1442 }
1443
1444 //by marshmellow - demodulate PSK1 wave
1445 //uses wave lengths (# Samples)
1446 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1447 {
1448 if (size == 0) return -1;
1449 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1450 if (*size<loopCnt) loopCnt = *size;
1451
1452 size_t numBits=0;
1453 uint8_t curPhase = *invert;
1454 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1455 uint8_t fc=0, fullWaveLen=0, tol=1;
1456 uint16_t errCnt=0, waveLenCnt=0;
1457 fc = countFC(dest, *size, 0);
1458 if (fc!=2 && fc!=4 && fc!=8) return -1;
1459 //PrintAndLog("DEBUG: FC: %d",fc);
1460 *clock = DetectPSKClock(dest, *size, *clock);
1461 if (*clock == 0) return -1;
1462 int avgWaveVal=0, lastAvgWaveVal=0;
1463 //find first phase shift
1464 for (i=0; i<loopCnt; i++){
1465 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1466 waveEnd = i+1;
1467 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1468 waveLenCnt = waveEnd-waveStart;
1469 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1470 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1471 firstFullWave = waveStart;
1472 fullWaveLen=waveLenCnt;
1473 //if average wave value is > graph 0 then it is an up wave or a 1
1474 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1475 break;
1476 }
1477 waveStart = i+1;
1478 avgWaveVal = 0;
1479 }
1480 avgWaveVal += dest[i+2];
1481 }
1482 if (firstFullWave == 0) {
1483 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1484 // so skip a little to ensure we are past any Start Signal
1485 firstFullWave = 160;
1486 memset(dest, curPhase, firstFullWave / *clock);
1487 } else {
1488 memset(dest, curPhase^1, firstFullWave / *clock);
1489 }
1490 //advance bits
1491 numBits += (firstFullWave / *clock);
1492 //set start of wave as clock align
1493 lastClkBit = firstFullWave;
1494 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1495 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1496 waveStart = 0;
1497 dest[numBits++] = curPhase; //set first read bit
1498 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1499 //top edge of wave = start of new wave
1500 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1501 if (waveStart == 0) {
1502 waveStart = i+1;
1503 waveLenCnt = 0;
1504 avgWaveVal = dest[i+1];
1505 } else { //waveEnd
1506 waveEnd = i+1;
1507 waveLenCnt = waveEnd-waveStart;
1508 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1509 if (waveLenCnt > fc){
1510 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1511 //this wave is a phase shift
1512 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1513 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1514 curPhase ^= 1;
1515 dest[numBits++] = curPhase;
1516 lastClkBit += *clock;
1517 } else if (i < lastClkBit+10+fc){
1518 //noise after a phase shift - ignore
1519 } else { //phase shift before supposed to based on clock
1520 errCnt++;
1521 dest[numBits++] = 7;
1522 }
1523 } else if (i+1 > lastClkBit + *clock + tol + fc){
1524 lastClkBit += *clock; //no phase shift but clock bit
1525 dest[numBits++] = curPhase;
1526 }
1527 avgWaveVal = 0;
1528 waveStart = i+1;
1529 }
1530 }
1531 avgWaveVal += dest[i+1];
1532 }
1533 *size = numBits;
1534 return errCnt;
1535 }
1536
1537 //by marshmellow
1538 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1539 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1540 size_t bufsize = *size;
1541 //need to loop through all samples and identify our clock, look for the ST pattern
1542 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1543 int clk = 0;
1544 int tol = 0;
1545 int i, j, skip, start, end, low, high, minClk, waveStart;
1546 bool complete = false;
1547 int tmpbuff[bufsize / 64];
1548 int waveLen[bufsize / 64];
1549 size_t testsize = (bufsize < 512) ? bufsize : 512;
1550 int phaseoff = 0;
1551 high = low = 128;
1552 memset(tmpbuff, 0, sizeof(tmpbuff));
1553
1554 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1555 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1556 return false; //just noise
1557 }
1558 i = 0;
1559 j = 0;
1560 minClk = 255;
1561 // get to first full low to prime loop and skip incomplete first pulse
1562 while ((buffer[i] < high) && (i < bufsize))
1563 ++i;
1564 while ((buffer[i] > low) && (i < bufsize))
1565 ++i;
1566 skip = i;
1567
1568 // populate tmpbuff buffer with pulse lengths
1569 while (i < bufsize) {
1570 // measure from low to low
1571 while ((buffer[i] > low) && (i < bufsize))
1572 ++i;
1573 start= i;
1574 while ((buffer[i] < high) && (i < bufsize))
1575 ++i;
1576 //first high point for this wave
1577 waveStart = i;
1578 while ((buffer[i] > low) && (i < bufsize))
1579 ++i;
1580 if (j >= (bufsize/64)) {
1581 break;
1582 }
1583 waveLen[j] = i - waveStart; //first high to first low
1584 tmpbuff[j++] = i - start;
1585 if (i-start < minClk && i < bufsize) {
1586 minClk = i - start;
1587 }
1588 }
1589 // set clock - might be able to get this externally and remove this work...
1590 if (!clk) {
1591 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1592 tol = fndClk[clkCnt]/8;
1593 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1594 clk=fndClk[clkCnt];
1595 break;
1596 }
1597 }
1598 // clock not found - ERROR
1599 if (!clk) {
1600 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1601 return false;
1602 }
1603 } else tol = clk/8;
1604
1605 *foundclock = clk;
1606
1607 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1608 start = -1;
1609 for (i = 0; i < j - 4; ++i) {
1610 skip += tmpbuff[i];
1611 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1612 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
1613 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
1614 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1615 start = i + 3;
1616 break;
1617 }
1618 }
1619 }
1620 }
1621 }
1622 // first ST not found - ERROR
1623 if (start < 0) {
1624 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1625 return false;
1626 }
1627 if (waveLen[i+2] > clk*1+tol)
1628 phaseoff = 0;
1629 else
1630 phaseoff = clk/2;
1631
1632 // skip over the remainder of ST
1633 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1634
1635 // now do it again to find the end
1636 end = skip;
1637 for (i += 3; i < j - 4; ++i) {
1638 end += tmpbuff[i];
1639 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) { //1 to 2 clocks depending on 2 bits prior
1640 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
1641 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
1642 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1643 complete = true;
1644 break;
1645 }
1646 }
1647 }
1648 }
1649 }
1650 end -= phaseoff;
1651 //didn't find second ST - ERROR
1652 if (!complete) {
1653 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1654 return false;
1655 }
1656 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);
1657 //now begin to trim out ST so we can use normal demod cmds
1658 start = skip;
1659 size_t datalen = end - start;
1660 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1661 if (datalen % clk > clk/8) {
1662 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1663 return false;
1664 } else {
1665 // padd the amount off - could be problematic... but shouldn't happen often
1666 datalen += datalen % clk;
1667 }
1668 // if datalen is less than one t55xx block - ERROR
1669 if (datalen/clk < 8*4) {
1670 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1671 return false;
1672 }
1673 size_t dataloc = start;
1674 size_t newloc = 0;
1675 i=0;
1676 // warning - overwriting buffer given with raw wave data with ST removed...
1677 while ( dataloc < bufsize-(clk/2) ) {
1678 //compensate for long high at end of ST not being high... (we cut out the high part)
1679 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1680 for(i=0; i < clk/2-tol; ++i) {
1681 buffer[dataloc+i] = high+5;
1682 }
1683 }
1684 for (i=0; i<datalen; ++i) {
1685 if (i+newloc < bufsize) {
1686 if (i+newloc < dataloc)
1687 buffer[i+newloc] = buffer[dataloc];
1688
1689 dataloc++;
1690 }
1691 }
1692 newloc += i;
1693 //skip next ST
1694 dataloc += clk*4;
1695 }
1696 *size = newloc;
1697 return true;
1698 }
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