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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
16void 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
28uint8_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
41int 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
59uint8_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)
72size_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
101size_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
126uint32_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
138uint32_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
150uint8_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
171uint8_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
210int 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
261void askAmp(uint8_t *BitStream, size_t size)
262{
263 uint8_t Last = 128;
264 for(size_t i = 1; i<size; i++){
265 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
266 Last = 255;
267 else if(BitStream[i-1]-BitStream[i]>=20) //large jump down
268 Last = 0;
269
270 BitStream[i-1] = Last;
271 }
272 return;
273}
274
275//by marshmellow
276//attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
277int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
278{
279 if (*size==0) return -1;
280 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
281 if (*clk==0 || start < 0) return -3;
282 if (*invert != 1) *invert = 0;
283 if (amp==1) askAmp(BinStream, *size);
284 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
285
286 uint8_t initLoopMax = 255;
287 if (initLoopMax > *size) initLoopMax = *size;
288 // Detect high and lows
289 //25% clip in case highs and lows aren't clipped [marshmellow]
290 int high, low;
291 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
292 return -2; //just noise
293
294 size_t errCnt = 0;
295 // if clean clipped waves detected run alternate demod
296 if (DetectCleanAskWave(BinStream, *size, high, low)) {
297 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
298 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
299 if (askType) //askman
300 return manrawdecode(BinStream, size, 0);
301 else //askraw
302 return errCnt;
303 }
304 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
305
306 int lastBit; //set first clock check - can go negative
307 size_t i, bitnum = 0; //output counter
308 uint8_t midBit = 0;
309 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
310 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
311 size_t MaxBits = 3072; //max bits to collect
312 lastBit = start - *clk;
313
314 for (i = start; i < *size; ++i) {
315 if (i-lastBit >= *clk-tol){
316 if (BinStream[i] >= high) {
317 BinStream[bitnum++] = *invert;
318 } else if (BinStream[i] <= low) {
319 BinStream[bitnum++] = *invert ^ 1;
320 } else if (i-lastBit >= *clk+tol) {
321 if (bitnum > 0) {
322 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
323 BinStream[bitnum++]=7;
324 errCnt++;
325 }
326 } else { //in tolerance - looking for peak
327 continue;
328 }
329 midBit = 0;
330 lastBit += *clk;
331 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
332 if (BinStream[i] >= high) {
333 BinStream[bitnum++] = *invert;
334 } else if (BinStream[i] <= low) {
335 BinStream[bitnum++] = *invert ^ 1;
336 } else if (i-lastBit >= *clk/2+tol) {
337 BinStream[bitnum] = BinStream[bitnum-1];
338 bitnum++;
339 } else { //in tolerance - looking for peak
340 continue;
341 }
342 midBit = 1;
343 }
344 if (bitnum >= MaxBits) break;
345 }
346 *size = bitnum;
347 return errCnt;
348}
349
350//by marshmellow
351//take 10 and 01 and manchester decode
352//run through 2 times and take least errCnt
353int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
354{
355 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
356 size_t i, ii;
357 uint16_t bestErr = 1000, bestRun = 0;
358 if (*size < 16) return -1;
359 //find correct start position [alignment]
360 for (ii=0;ii<2;++ii){
361 for (i=ii; i<*size-3; i+=2)
362 if (BitStream[i]==BitStream[i+1])
363 errCnt++;
364
365 if (bestErr>errCnt){
366 bestErr=errCnt;
367 bestRun=ii;
368 }
369 errCnt=0;
370 }
371 //decode
372 for (i=bestRun; i < *size-3; i+=2){
373 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
374 BitStream[bitnum++]=invert;
375 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
376 BitStream[bitnum++]=invert^1;
377 } else {
378 BitStream[bitnum++]=7;
379 }
380 if(bitnum>MaxBits) break;
381 }
382 *size=bitnum;
383 return bestErr;
384}
385
386uint32_t manchesterEncode2Bytes(uint16_t datain) {
387 uint32_t output = 0;
388 uint8_t curBit = 0;
389 for (uint8_t i=0; i<16; i++) {
390 curBit = (datain >> (15-i) & 1);
391 output |= (1<<(((15-i)*2)+curBit));
392 }
393 return output;
394}
395
396//by marshmellow
397//encode binary data into binary manchester
398int ManchesterEncode(uint8_t *BitStream, size_t size)
399{
400 size_t modIdx=20000, i=0;
401 if (size>modIdx) return -1;
402 for (size_t idx=0; idx < size; idx++){
403 BitStream[idx+modIdx++] = BitStream[idx];
404 BitStream[idx+modIdx++] = BitStream[idx]^1;
405 }
406 for (; i<(size*2); i++){
407 BitStream[i] = BitStream[i+20000];
408 }
409 return i;
410}
411
412//by marshmellow
413//take 01 or 10 = 1 and 11 or 00 = 0
414//check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
415//decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
416int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
417{
418 uint16_t bitnum = 0;
419 uint16_t errCnt = 0;
420 size_t i = offset;
421 uint16_t MaxBits=512;
422 //if not enough samples - error
423 if (*size < 51) return -1;
424 //check for phase change faults - skip one sample if faulty
425 uint8_t offsetA = 1, offsetB = 1;
426 for (; i<48; i+=2){
427 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
428 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
429 }
430 if (!offsetA && offsetB) offset++;
431 for (i=offset; i<*size-3; i+=2){
432 //check for phase error
433 if (BitStream[i+1]==BitStream[i+2]) {
434 BitStream[bitnum++]=7;
435 errCnt++;
436 }
437 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
438 BitStream[bitnum++]=1^invert;
439 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
440 BitStream[bitnum++]=invert;
441 } else {
442 BitStream[bitnum++]=7;
443 errCnt++;
444 }
445 if(bitnum>MaxBits) break;
446 }
447 *size=bitnum;
448 return errCnt;
449}
450
451// by marshmellow
452// demod gProxIIDemod
453// error returns as -x
454// success returns start position in BitStream
455// BitStream must contain previously askrawdemod and biphasedemoded data
456int gProxII_Demod(uint8_t BitStream[], size_t *size)
457{
458 size_t startIdx=0;
459 uint8_t preamble[] = {1,1,1,1,1,0};
460
461 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
462 if (errChk == 0) return -3; //preamble not found
463 if (*size != 96) return -2; //should have found 96 bits
464 //check first 6 spacer bits to verify format
465 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
466 //confirmed proper separator bits found
467 //return start position
468 return (int) startIdx;
469 }
470 return -5; //spacer bits not found - not a valid gproxII
471}
472
473//translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
474size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
475{
476 size_t last_transition = 0;
477 size_t idx = 1;
478 //uint32_t maxVal=0;
479 if (fchigh==0) fchigh=10;
480 if (fclow==0) fclow=8;
481 //set the threshold close to 0 (graph) or 128 std to avoid static
482 uint8_t threshold_value = 123;
483 size_t preLastSample = 0;
484 size_t LastSample = 0;
485 size_t currSample = 0;
486 // sync to first lo-hi transition, and threshold
487
488 // Need to threshold first sample
489 // skip 160 samples to allow antenna/samples to settle
490 if(dest[160] < threshold_value) dest[0] = 0;
491 else dest[0] = 1;
492
493 size_t numBits = 0;
494 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
495 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
496 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
497 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
498 for(idx = 161; idx < size-20; idx++) {
499 // threshold current value
500
501 if (dest[idx] < threshold_value) dest[idx] = 0;
502 else dest[idx] = 1;
503
504 // Check for 0->1 transition
505 if (dest[idx-1] < dest[idx]) {
506 preLastSample = LastSample;
507 LastSample = currSample;
508 currSample = idx-last_transition;
509 if (currSample < (fclow-2)) { //0-5 = garbage noise (or 0-3)
510 //do nothing with extra garbage
511 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
512 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
513 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
514 dest[numBits-1]=1;
515 }
516 dest[numBits++]=1;
517
518 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
519 //do nothing with beginning garbage
520 } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
521 dest[numBits++]=1;
522 } else { //9+ = 10 sample waves (or 6+ = 7)
523 dest[numBits++]=0;
524 }
525 last_transition = idx;
526 }
527 }
528 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
529}
530
531//translate 11111100000 to 10
532//rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
533size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
534 uint8_t invert, uint8_t fchigh, uint8_t fclow)
535{
536 uint8_t lastval=dest[0];
537 size_t idx=0;
538 size_t numBits=0;
539 uint32_t n=1;
540 for( idx=1; idx < size; idx++) {
541 n++;
542 if (dest[idx]==lastval) continue; //skip until we hit a transition
543
544 //find out how many bits (n) we collected
545 //if lastval was 1, we have a 1->0 crossing
546 if (dest[idx-1]==1) {
547 n = (n * fclow + rfLen/2) / rfLen;
548 } else {// 0->1 crossing
549 n = (n * fchigh + rfLen/2) / rfLen;
550 }
551 if (n == 0) n = 1;
552
553 //add to our destination the bits we collected
554 memset(dest+numBits, dest[idx-1]^invert , n);
555 numBits += n;
556 n=0;
557 lastval=dest[idx];
558 }//end for
559 // if valid extra bits at the end were all the same frequency - add them in
560 if (n > rfLen/fchigh) {
561 if (dest[idx-2]==1) {
562 n = (n * fclow + rfLen/2) / rfLen;
563 } else {
564 n = (n * fchigh + rfLen/2) / rfLen;
565 }
566 memset(dest+numBits, dest[idx-1]^invert , n);
567 numBits += n;
568 }
569 return numBits;
570}
571
572//by marshmellow (from holiman's base)
573// full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
574int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
575{
576 // FSK demodulator
577 size = fsk_wave_demod(dest, size, fchigh, fclow);
578 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
579 return size;
580}
581
582// loop to get raw HID waveform then FSK demodulate the TAG ID from it
583int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
584{
585 if (justNoise(dest, *size)) return -1;
586
587 size_t numStart=0, size2=*size, startIdx=0;
588 // FSK demodulator
589 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
590 if (*size < 96*2) return -2;
591 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
592 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
593 // find bitstring in array
594 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
595 if (errChk == 0) return -3; //preamble not found
596
597 numStart = startIdx + sizeof(preamble);
598 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
599 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
600 if (dest[idx] == dest[idx+1]){
601 return -4; //not manchester data
602 }
603 *hi2 = (*hi2<<1)|(*hi>>31);
604 *hi = (*hi<<1)|(*lo>>31);
605 //Then, shift in a 0 or one into low
606 if (dest[idx] && !dest[idx+1]) // 1 0
607 *lo=(*lo<<1)|1;
608 else // 0 1
609 *lo=(*lo<<1)|0;
610 }
611 return (int)startIdx;
612}
613
614// loop to get raw paradox waveform then FSK demodulate the TAG ID from it
615int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
616{
617 if (justNoise(dest, *size)) return -1;
618
619 size_t numStart=0, size2=*size, startIdx=0;
620 // FSK demodulator
621 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
622 if (*size < 96) return -2;
623
624 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
625 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
626
627 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
628 if (errChk == 0) return -3; //preamble not found
629
630 numStart = startIdx + sizeof(preamble);
631 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
632 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
633 if (dest[idx] == dest[idx+1])
634 return -4; //not manchester data
635 *hi2 = (*hi2<<1)|(*hi>>31);
636 *hi = (*hi<<1)|(*lo>>31);
637 //Then, shift in a 0 or one into low
638 if (dest[idx] && !dest[idx+1]) // 1 0
639 *lo=(*lo<<1)|1;
640 else // 0 1
641 *lo=(*lo<<1)|0;
642 }
643 return (int)startIdx;
644}
645
646int IOdemodFSK(uint8_t *dest, size_t size)
647{
648 if (justNoise(dest, size)) return -1;
649 //make sure buffer has data
650 if (size < 66*64) return -2;
651 // FSK demodulator
652 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
653 if (size < 65) return -3; //did we get a good demod?
654 //Index map
655 //0 10 20 30 40 50 60
656 //| | | | | | |
657 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
658 //-----------------------------------------------------------------------------
659 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
660 //
661 //XSF(version)facility:codeone+codetwo
662 //Handle the data
663 size_t startIdx = 0;
664 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
665 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
666 if (errChk == 0) return -4; //preamble not found
667
668 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
669 //confirmed proper separator bits found
670 //return start position
671 return (int) startIdx;
672 }
673 return -5;
674}
675
676// by marshmellow
677// find viking preamble 0xF200 in already demoded data
678int VikingDemod_AM(uint8_t *dest, size_t *size) {
679 //make sure buffer has data
680 if (*size < 64*2) return -2;
681
682 size_t startIdx = 0;
683 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};
684 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
685 if (errChk == 0) return -4; //preamble not found
686 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
687 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
688 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
689 if ( checkCalc != 0xA8 ) return -5;
690 if (*size != 64) return -6;
691 //return start position
692 return (int) startIdx;
693}
694
695// find presco preamble 0x10D in already demoded data
696int PrescoDemod(uint8_t *dest, size_t *size) {
697 //make sure buffer has data
698 if (*size < 64*2) return -2;
699
700 size_t startIdx = 0;
701 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
702 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
703 if (errChk == 0) return -4; //preamble not found
704 //return start position
705 return (int) startIdx;
706}
707
708// Ask/Biphase Demod then try to locate an ISO 11784/85 ID
709// BitStream must contain previously askrawdemod and biphasedemoded data
710int FDXBdemodBI(uint8_t *dest, size_t *size)
711{
712 //make sure buffer has enough data
713 if (*size < 128) return -1;
714
715 size_t startIdx = 0;
716 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
717
718 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
719 if (errChk == 0) return -2; //preamble not found
720 return (int)startIdx;
721}
722
723// by marshmellow
724// FSK Demod then try to locate an AWID ID
725int AWIDdemodFSK(uint8_t *dest, size_t *size)
726{
727 //make sure buffer has enough data
728 if (*size < 96*50) return -1;
729
730 if (justNoise(dest, *size)) return -2;
731
732 // FSK demodulator
733 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
734 if (*size < 96) return -3; //did we get a good demod?
735
736 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
737 size_t startIdx = 0;
738 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
739 if (errChk == 0) return -4; //preamble not found
740 if (*size != 96) return -5;
741 return (int)startIdx;
742}
743
744// by marshmellow
745// FSK Demod then try to locate a Farpointe Data (pyramid) ID
746int PyramiddemodFSK(uint8_t *dest, size_t *size)
747{
748 //make sure buffer has data
749 if (*size < 128*50) return -5;
750
751 //test samples are not just noise
752 if (justNoise(dest, *size)) return -1;
753
754 // FSK demodulator
755 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
756 if (*size < 128) return -2; //did we get a good demod?
757
758 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
759 size_t startIdx = 0;
760 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
761 if (errChk == 0) return -4; //preamble not found
762 if (*size != 128) return -3;
763 return (int)startIdx;
764}
765
766// by marshmellow
767// to detect a wave that has heavily clipped (clean) samples
768uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
769{
770 bool allArePeaks = true;
771 uint16_t cntPeaks=0;
772 size_t loopEnd = 512+160;
773 if (loopEnd > size) loopEnd = size;
774 for (size_t i=160; i<loopEnd; i++){
775 if (dest[i]>low && dest[i]<high)
776 allArePeaks = false;
777 else
778 cntPeaks++;
779 }
780 if (!allArePeaks){
781 if (cntPeaks > 300) return true;
782 }
783 return allArePeaks;
784}
785// by marshmellow
786// to help detect clocks on heavily clipped samples
787// based on count of low to low
788int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
789{
790 uint8_t fndClk[] = {8,16,32,40,50,64,128};
791 size_t startwave;
792 size_t i = 100;
793 size_t minClk = 255;
794 // get to first full low to prime loop and skip incomplete first pulse
795 while ((dest[i] < high) && (i < size))
796 ++i;
797 while ((dest[i] > low) && (i < size))
798 ++i;
799
800 // loop through all samples
801 while (i < size) {
802 // measure from low to low
803 while ((dest[i] > low) && (i < size))
804 ++i;
805 startwave= i;
806 while ((dest[i] < high) && (i < size))
807 ++i;
808 while ((dest[i] > low) && (i < size))
809 ++i;
810 //get minimum measured distance
811 if (i-startwave < minClk && i < size)
812 minClk = i - startwave;
813 }
814 // set clock
815 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
816 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
817 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
818 return fndClk[clkCnt];
819 }
820 return 0;
821}
822
823// by marshmellow
824// not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
825// maybe somehow adjust peak trimming value based on samples to fix?
826// return start index of best starting position for that clock and return clock (by reference)
827int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
828{
829 size_t i=1;
830 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
831 uint8_t clkEnd = 9;
832 uint8_t loopCnt = 255; //don't need to loop through entire array...
833 if (size <= loopCnt+60) return -1; //not enough samples
834 size -= 60; //sometimes there is a strange end wave - filter out this....
835 //if we already have a valid clock
836 uint8_t clockFnd=0;
837 for (;i<clkEnd;++i)
838 if (clk[i] == *clock) clockFnd = i;
839 //clock found but continue to find best startpos
840
841 //get high and low peak
842 int peak, low;
843 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
844
845 //test for large clean peaks
846 if (!clockFnd){
847 if (DetectCleanAskWave(dest, size, peak, low)==1){
848 int ans = DetectStrongAskClock(dest, size, peak, low);
849 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
850 for (i=clkEnd-1; i>0; i--){
851 if (clk[i] == ans) {
852 *clock = ans;
853 //clockFnd = i;
854 return 0; // for strong waves i don't use the 'best start position' yet...
855 //break; //clock found but continue to find best startpos [not yet]
856 }
857 }
858 }
859 }
860 uint8_t ii;
861 uint8_t clkCnt, tol = 0;
862 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
863 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
864 size_t errCnt = 0;
865 size_t arrLoc, loopEnd;
866
867 if (clockFnd>0) {
868 clkCnt = clockFnd;
869 clkEnd = clockFnd+1;
870 }
871 else clkCnt=1;
872
873 //test each valid clock from smallest to greatest to see which lines up
874 for(; clkCnt < clkEnd; clkCnt++){
875 if (clk[clkCnt] <= 32){
876 tol=1;
877 }else{
878 tol=0;
879 }
880 //if no errors allowed - keep start within the first clock
881 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
882 bestErr[clkCnt]=1000;
883 //try lining up the peaks by moving starting point (try first few clocks)
884 for (ii=0; ii < loopCnt; ii++){
885 if (dest[ii] < peak && dest[ii] > low) continue;
886
887 errCnt=0;
888 // now that we have the first one lined up test rest of wave array
889 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
890 for (i=0; i < loopEnd; ++i){
891 arrLoc = ii + (i * clk[clkCnt]);
892 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
893 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
894 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
895 }else{ //error no peak detected
896 errCnt++;
897 }
898 }
899 //if we found no errors then we can stop here and a low clock (common clocks)
900 // this is correct one - return this clock
901 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
902 if(errCnt==0 && clkCnt<7) {
903 if (!clockFnd) *clock = clk[clkCnt];
904 return ii;
905 }
906 //if we found errors see if it is lowest so far and save it as best run
907 if(errCnt<bestErr[clkCnt]){
908 bestErr[clkCnt]=errCnt;
909 bestStart[clkCnt]=ii;
910 }
911 }
912 }
913 uint8_t iii;
914 uint8_t best=0;
915 for (iii=1; iii<clkEnd; ++iii){
916 if (bestErr[iii] < bestErr[best]){
917 if (bestErr[iii] == 0) bestErr[iii]=1;
918 // current best bit to error ratio vs new bit to error ratio
919 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
920 best = iii;
921 }
922 }
923 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]);
924 }
925 if (!clockFnd) *clock = clk[best];
926 return bestStart[best];
927}
928
929//by marshmellow
930//detect psk clock by reading each phase shift
931// a phase shift is determined by measuring the sample length of each wave
932int DetectPSKClock(uint8_t dest[], size_t size, int clock)
933{
934 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
935 uint16_t loopCnt = 4096; //don't need to loop through entire array...
936 if (size == 0) return 0;
937 if (size<loopCnt) loopCnt = size-20;
938
939 //if we already have a valid clock quit
940 size_t i=1;
941 for (; i < 8; ++i)
942 if (clk[i] == clock) return clock;
943
944 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
945 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
946 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
947 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
948 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
949 fc = countFC(dest, size, 0);
950 if (fc!=2 && fc!=4 && fc!=8) return -1;
951 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
952
953 //find first full wave
954 for (i=160; i<loopCnt; i++){
955 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
956 if (waveStart == 0) {
957 waveStart = i+1;
958 //prnt("DEBUG: waveStart: %d",waveStart);
959 } else {
960 waveEnd = i+1;
961 //prnt("DEBUG: waveEnd: %d",waveEnd);
962 waveLenCnt = waveEnd-waveStart;
963 if (waveLenCnt > fc){
964 firstFullWave = waveStart;
965 fullWaveLen=waveLenCnt;
966 break;
967 }
968 waveStart=0;
969 }
970 }
971 }
972 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
973
974 //test each valid clock from greatest to smallest to see which lines up
975 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
976 lastClkBit = firstFullWave; //set end of wave as clock align
977 waveStart = 0;
978 errCnt=0;
979 peakcnt=0;
980 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
981
982 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
983 //top edge of wave = start of new wave
984 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
985 if (waveStart == 0) {
986 waveStart = i+1;
987 waveLenCnt=0;
988 } else { //waveEnd
989 waveEnd = i+1;
990 waveLenCnt = waveEnd-waveStart;
991 if (waveLenCnt > fc){
992 //if this wave is a phase shift
993 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);
994 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
995 peakcnt++;
996 lastClkBit+=clk[clkCnt];
997 } else if (i<lastClkBit+8){
998 //noise after a phase shift - ignore
999 } else { //phase shift before supposed to based on clock
1000 errCnt++;
1001 }
1002 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1003 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1004 }
1005 waveStart=i+1;
1006 }
1007 }
1008 }
1009 if (errCnt == 0){
1010 return clk[clkCnt];
1011 }
1012 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1013 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1014 }
1015 //all tested with errors
1016 //return the highest clk with the most peaks found
1017 uint8_t best=7;
1018 for (i=7; i>=1; i--){
1019 if (peaksdet[i] > peaksdet[best]) {
1020 best = i;
1021 }
1022 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1023 }
1024 return clk[best];
1025}
1026
1027int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1028 //find shortest transition from high to low
1029 size_t i = 0;
1030 size_t transition1 = 0;
1031 int lowestTransition = 255;
1032 bool lastWasHigh = false;
1033
1034 //find first valid beginning of a high or low wave
1035 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1036 ++i;
1037 while ((dest[i] < peak && dest[i] > low) && (i < size))
1038 ++i;
1039 lastWasHigh = (dest[i] >= peak);
1040
1041 if (i==size) return 0;
1042 transition1 = i;
1043
1044 for (;i < size; i++) {
1045 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1046 lastWasHigh = (dest[i] >= peak);
1047 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1048 transition1 = i;
1049 }
1050 }
1051 if (lowestTransition == 255) lowestTransition = 0;
1052 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1053 return lowestTransition;
1054}
1055
1056//by marshmellow
1057//detect nrz clock by reading #peaks vs no peaks(or errors)
1058int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1059{
1060 size_t i=0;
1061 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1062 size_t loopCnt = 4096; //don't need to loop through entire array...
1063 if (size == 0) return 0;
1064 if (size<loopCnt) loopCnt = size-20;
1065 //if we already have a valid clock quit
1066 for (; i < 8; ++i)
1067 if (clk[i] == clock) return clock;
1068
1069 //get high and low peak
1070 int peak, low;
1071 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1072
1073 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1074 size_t ii;
1075 uint8_t clkCnt;
1076 uint8_t tol = 0;
1077 uint16_t smplCnt = 0;
1078 int16_t peakcnt = 0;
1079 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1080 uint16_t maxPeak = 255;
1081 bool firstpeak = false;
1082 //test for large clipped waves
1083 for (i=0; i<loopCnt; i++){
1084 if (dest[i] >= peak || dest[i] <= low){
1085 if (!firstpeak) continue;
1086 smplCnt++;
1087 } else {
1088 firstpeak=true;
1089 if (smplCnt > 6 ){
1090 if (maxPeak > smplCnt){
1091 maxPeak = smplCnt;
1092 //prnt("maxPk: %d",maxPeak);
1093 }
1094 peakcnt++;
1095 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1096 smplCnt=0;
1097 }
1098 }
1099 }
1100 bool errBitHigh = 0;
1101 bool bitHigh = 0;
1102 uint8_t ignoreCnt = 0;
1103 uint8_t ignoreWindow = 4;
1104 bool lastPeakHigh = 0;
1105 int lastBit = 0;
1106 peakcnt=0;
1107 //test each valid clock from smallest to greatest to see which lines up
1108 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1109 //ignore clocks smaller than smallest peak
1110 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1111 //try lining up the peaks by moving starting point (try first 256)
1112 for (ii=20; ii < loopCnt; ++ii){
1113 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1114 peakcnt = 0;
1115 bitHigh = false;
1116 ignoreCnt = 0;
1117 lastBit = ii-clk[clkCnt];
1118 //loop through to see if this start location works
1119 for (i = ii; i < size-20; ++i) {
1120 //if we are at a clock bit
1121 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1122 //test high/low
1123 if (dest[i] >= peak || dest[i] <= low) {
1124 //if same peak don't count it
1125 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1126 peakcnt++;
1127 }
1128 lastPeakHigh = (dest[i] >= peak);
1129 bitHigh = true;
1130 errBitHigh = false;
1131 ignoreCnt = ignoreWindow;
1132 lastBit += clk[clkCnt];
1133 } else if (i == lastBit + clk[clkCnt] + tol) {
1134 lastBit += clk[clkCnt];
1135 }
1136 //else if not a clock bit and no peaks
1137 } else if (dest[i] < peak && dest[i] > low){
1138 if (ignoreCnt==0){
1139 bitHigh=false;
1140 if (errBitHigh==true) peakcnt--;
1141 errBitHigh=false;
1142 } else {
1143 ignoreCnt--;
1144 }
1145 // else if not a clock bit but we have a peak
1146 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1147 //error bar found no clock...
1148 errBitHigh=true;
1149 }
1150 }
1151 if(peakcnt>peaksdet[clkCnt]) {
1152 peaksdet[clkCnt]=peakcnt;
1153 }
1154 }
1155 }
1156 }
1157 int iii=7;
1158 uint8_t best=0;
1159 for (iii=7; iii > 0; iii--){
1160 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1161 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1162 best = iii;
1163 }
1164 } else if (peaksdet[iii] > peaksdet[best]){
1165 best = iii;
1166 }
1167 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);
1168 }
1169
1170 return clk[best];
1171}
1172
1173// by marshmellow
1174// convert psk1 demod to psk2 demod
1175// only transition waves are 1s
1176void psk1TOpsk2(uint8_t *BitStream, size_t size)
1177{
1178 size_t i=1;
1179 uint8_t lastBit=BitStream[0];
1180 for (; i<size; i++){
1181 if (BitStream[i]==7){
1182 //ignore errors
1183 } else if (lastBit!=BitStream[i]){
1184 lastBit=BitStream[i];
1185 BitStream[i]=1;
1186 } else {
1187 BitStream[i]=0;
1188 }
1189 }
1190 return;
1191}
1192
1193// by marshmellow
1194// convert psk2 demod to psk1 demod
1195// from only transition waves are 1s to phase shifts change bit
1196void psk2TOpsk1(uint8_t *BitStream, size_t size)
1197{
1198 uint8_t phase=0;
1199 for (size_t i=0; i<size; i++){
1200 if (BitStream[i]==1){
1201 phase ^=1;
1202 }
1203 BitStream[i]=phase;
1204 }
1205 return;
1206}
1207
1208// redesigned by marshmellow adjusted from existing decode functions
1209// indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1210int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1211{
1212 //26 bit 40134 format (don't know other formats)
1213 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};
1214 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};
1215 size_t startidx = 0;
1216 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1217 // if didn't find preamble try again inverting
1218 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1219 *invert ^= 1;
1220 }
1221 if (*size != 64 && *size != 224) return -2;
1222 if (*invert==1)
1223 for (size_t i = startidx; i < *size; i++)
1224 bitStream[i] ^= 1;
1225
1226 return (int) startidx;
1227}
1228
1229// by marshmellow - demodulate NRZ wave - requires a read with strong signal
1230// peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1231int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1232 if (justNoise(dest, *size)) return -1;
1233 *clk = DetectNRZClock(dest, *size, *clk);
1234 if (*clk==0) return -2;
1235 size_t i, gLen = 4096;
1236 if (gLen>*size) gLen = *size-20;
1237 int high, low;
1238 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1239
1240 uint8_t bit=0;
1241 //convert wave samples to 1's and 0's
1242 for(i=20; i < *size-20; i++){
1243 if (dest[i] >= high) bit = 1;
1244 if (dest[i] <= low) bit = 0;
1245 dest[i] = bit;
1246 }
1247 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1248 size_t lastBit = 0;
1249 size_t numBits = 0;
1250 for(i=21; i < *size-20; i++) {
1251 //if transition detected or large number of same bits - store the passed bits
1252 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1253 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1254 numBits += (i - lastBit + (*clk/4)) / *clk;
1255 lastBit = i-1;
1256 }
1257 }
1258 *size = numBits;
1259 return 0;
1260}
1261
1262//by marshmellow
1263//detects the bit clock for FSK given the high and low Field Clocks
1264uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1265{
1266 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1267 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1268 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1269 uint8_t rfLensFnd = 0;
1270 uint8_t lastFCcnt = 0;
1271 uint16_t fcCounter = 0;
1272 uint16_t rfCounter = 0;
1273 uint8_t firstBitFnd = 0;
1274 size_t i;
1275 if (size == 0) return 0;
1276
1277 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1278 rfLensFnd=0;
1279 fcCounter=0;
1280 rfCounter=0;
1281 firstBitFnd=0;
1282 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1283 // prime i to first peak / up transition
1284 for (i = 160; i < size-20; i++)
1285 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1286 break;
1287
1288 for (; i < size-20; i++){
1289 fcCounter++;
1290 rfCounter++;
1291
1292 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1293 continue;
1294 // else new peak
1295 // if we got less than the small fc + tolerance then set it to the small fc
1296 if (fcCounter < fcLow+fcTol)
1297 fcCounter = fcLow;
1298 else //set it to the large fc
1299 fcCounter = fcHigh;
1300
1301 //look for bit clock (rf/xx)
1302 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1303 //not the same size as the last wave - start of new bit sequence
1304 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1305 for (int ii=0; ii<15; ii++){
1306 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1307 rfCnts[ii]++;
1308 rfCounter = 0;
1309 break;
1310 }
1311 }
1312 if (rfCounter > 0 && rfLensFnd < 15){
1313 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1314 rfCnts[rfLensFnd]++;
1315 rfLens[rfLensFnd++] = rfCounter;
1316 }
1317 } else {
1318 firstBitFnd++;
1319 }
1320 rfCounter=0;
1321 lastFCcnt=fcCounter;
1322 }
1323 fcCounter=0;
1324 }
1325 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1326
1327 for (i=0; i<15; i++){
1328 //get highest 2 RF values (might need to get more values to compare or compare all?)
1329 if (rfCnts[i]>rfCnts[rfHighest]){
1330 rfHighest3=rfHighest2;
1331 rfHighest2=rfHighest;
1332 rfHighest=i;
1333 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1334 rfHighest3=rfHighest2;
1335 rfHighest2=i;
1336 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1337 rfHighest3=i;
1338 }
1339 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1340 }
1341 // set allowed clock remainder tolerance to be 1 large field clock length+1
1342 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1343 uint8_t tol1 = fcHigh+1;
1344
1345 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1346
1347 // loop to find the highest clock that has a remainder less than the tolerance
1348 // compare samples counted divided by
1349 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1350 int ii=7;
1351 for (; ii>=2; ii--){
1352 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1353 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1354 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1355 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1356 break;
1357 }
1358 }
1359 }
1360 }
1361
1362 if (ii<0) return 0; // oops we went too far
1363
1364 return clk[ii];
1365}
1366
1367//by marshmellow
1368//countFC is to detect the field clock lengths.
1369//counts and returns the 2 most common wave lengths
1370//mainly used for FSK field clock detection
1371uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1372{
1373 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1374 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1375 uint8_t fcLensFnd = 0;
1376 uint8_t lastFCcnt=0;
1377 uint8_t fcCounter = 0;
1378 size_t i;
1379 if (size == 0) return 0;
1380
1381 // prime i to first up transition
1382 for (i = 160; i < size-20; i++)
1383 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1384 break;
1385
1386 for (; i < size-20; i++){
1387 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1388 // new up transition
1389 fcCounter++;
1390 if (fskAdj){
1391 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1392 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1393 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1394 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1395 // save last field clock count (fc/xx)
1396 lastFCcnt = fcCounter;
1397 }
1398 // find which fcLens to save it to:
1399 for (int ii=0; ii<15; ii++){
1400 if (fcLens[ii]==fcCounter){
1401 fcCnts[ii]++;
1402 fcCounter=0;
1403 break;
1404 }
1405 }
1406 if (fcCounter>0 && fcLensFnd<15){
1407 //add new fc length
1408 fcCnts[fcLensFnd]++;
1409 fcLens[fcLensFnd++]=fcCounter;
1410 }
1411 fcCounter=0;
1412 } else {
1413 // count sample
1414 fcCounter++;
1415 }
1416 }
1417
1418 uint8_t best1=14, best2=14, best3=14;
1419 uint16_t maxCnt1=0;
1420 // go through fclens and find which ones are bigest 2
1421 for (i=0; i<15; i++){
1422 // get the 3 best FC values
1423 if (fcCnts[i]>maxCnt1) {
1424 best3=best2;
1425 best2=best1;
1426 maxCnt1=fcCnts[i];
1427 best1=i;
1428 } else if(fcCnts[i]>fcCnts[best2]){
1429 best3=best2;
1430 best2=i;
1431 } else if(fcCnts[i]>fcCnts[best3]){
1432 best3=i;
1433 }
1434 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]);
1435 }
1436 if (fcLens[best1]==0) return 0;
1437 uint8_t fcH=0, fcL=0;
1438 if (fcLens[best1]>fcLens[best2]){
1439 fcH=fcLens[best1];
1440 fcL=fcLens[best2];
1441 } else{
1442 fcH=fcLens[best2];
1443 fcL=fcLens[best1];
1444 }
1445 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1446 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]);
1447 return 0; //lots of waves not psk or fsk
1448 }
1449 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1450
1451 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1452 if (fskAdj) return fcs;
1453 return fcLens[best1];
1454}
1455
1456//by marshmellow - demodulate PSK1 wave
1457//uses wave lengths (# Samples)
1458int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1459{
1460 if (size == 0) return -1;
1461 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1462 if (*size<loopCnt) loopCnt = *size;
1463
1464 size_t numBits=0;
1465 uint8_t curPhase = *invert;
1466 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1467 uint8_t fc=0, fullWaveLen=0, tol=1;
1468 uint16_t errCnt=0, waveLenCnt=0;
1469 fc = countFC(dest, *size, 0);
1470 if (fc!=2 && fc!=4 && fc!=8) return -1;
1471 //PrintAndLog("DEBUG: FC: %d",fc);
1472 *clock = DetectPSKClock(dest, *size, *clock);
1473 if (*clock == 0) return -1;
1474 int avgWaveVal=0, lastAvgWaveVal=0;
1475 //find first phase shift
1476 for (i=0; i<loopCnt; i++){
1477 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1478 waveEnd = i+1;
1479 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1480 waveLenCnt = waveEnd-waveStart;
1481 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1482 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1483 firstFullWave = waveStart;
1484 fullWaveLen=waveLenCnt;
1485 //if average wave value is > graph 0 then it is an up wave or a 1
1486 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1487 break;
1488 }
1489 waveStart = i+1;
1490 avgWaveVal = 0;
1491 }
1492 avgWaveVal += dest[i+2];
1493 }
1494 if (firstFullWave == 0) {
1495 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1496 // so skip a little to ensure we are past any Start Signal
1497 firstFullWave = 160;
1498 memset(dest, curPhase, firstFullWave / *clock);
1499 } else {
1500 memset(dest, curPhase^1, firstFullWave / *clock);
1501 }
1502 //advance bits
1503 numBits += (firstFullWave / *clock);
1504 //set start of wave as clock align
1505 lastClkBit = firstFullWave;
1506 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1507 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1508 waveStart = 0;
1509 dest[numBits++] = curPhase; //set first read bit
1510 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1511 //top edge of wave = start of new wave
1512 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1513 if (waveStart == 0) {
1514 waveStart = i+1;
1515 waveLenCnt = 0;
1516 avgWaveVal = dest[i+1];
1517 } else { //waveEnd
1518 waveEnd = i+1;
1519 waveLenCnt = waveEnd-waveStart;
1520 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1521 if (waveLenCnt > fc){
1522 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1523 //this wave is a phase shift
1524 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1525 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1526 curPhase ^= 1;
1527 dest[numBits++] = curPhase;
1528 lastClkBit += *clock;
1529 } else if (i < lastClkBit+10+fc){
1530 //noise after a phase shift - ignore
1531 } else { //phase shift before supposed to based on clock
1532 errCnt++;
1533 dest[numBits++] = 7;
1534 }
1535 } else if (i+1 > lastClkBit + *clock + tol + fc){
1536 lastClkBit += *clock; //no phase shift but clock bit
1537 dest[numBits++] = curPhase;
1538 }
1539 avgWaveVal = 0;
1540 waveStart = i+1;
1541 }
1542 }
1543 avgWaveVal += dest[i+1];
1544 }
1545 *size = numBits;
1546 return errCnt;
1547}
1548
1549//by marshmellow
1550//attempt to identify a Sequence Terminator in ASK modulated raw wave
1551bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1552 size_t bufsize = *size;
1553 //need to loop through all samples and identify our clock, look for the ST pattern
1554 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1555 int clk = 0;
1556 int tol = 0;
1557 int i, j, skip, start, end, low, high, minClk, waveStart;
1558 bool complete = false;
1559 int tmpbuff[bufsize / 64];
1560 int waveLen[bufsize / 64];
1561 size_t testsize = (bufsize < 512) ? bufsize : 512;
1562 int phaseoff = 0;
1563 high = low = 128;
1564 memset(tmpbuff, 0, sizeof(tmpbuff));
1565
1566 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1567 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1568 return false; //just noise
1569 }
1570 i = 0;
1571 j = 0;
1572 minClk = 255;
1573 // get to first full low to prime loop and skip incomplete first pulse
1574 while ((buffer[i] < high) && (i < bufsize))
1575 ++i;
1576 while ((buffer[i] > low) && (i < bufsize))
1577 ++i;
1578 skip = i;
1579
1580 // populate tmpbuff buffer with pulse lengths
1581 while (i < bufsize) {
1582 // measure from low to low
1583 while ((buffer[i] > low) && (i < bufsize))
1584 ++i;
1585 start= i;
1586 while ((buffer[i] < high) && (i < bufsize))
1587 ++i;
1588 //first high point for this wave
1589 waveStart = i;
1590 while ((buffer[i] > low) && (i < bufsize))
1591 ++i;
1592 if (j >= (bufsize/64)) {
1593 break;
1594 }
1595 waveLen[j] = i - waveStart; //first high to first low
1596 tmpbuff[j++] = i - start;
1597 if (i-start < minClk && i < bufsize) {
1598 minClk = i - start;
1599 }
1600 }
1601 // set clock - might be able to get this externally and remove this work...
1602 if (!clk) {
1603 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1604 tol = fndClk[clkCnt]/8;
1605 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1606 clk=fndClk[clkCnt];
1607 break;
1608 }
1609 }
1610 // clock not found - ERROR
1611 if (!clk) {
1612 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1613 return false;
1614 }
1615 } else tol = clk/8;
1616
1617 *foundclock = clk;
1618
1619 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1620 start = -1;
1621 for (i = 0; i < j - 4; ++i) {
1622 skip += tmpbuff[i];
1623 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1624 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
1625 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
1626 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1627 start = i + 3;
1628 break;
1629 }
1630 }
1631 }
1632 }
1633 }
1634 // first ST not found - ERROR
1635 if (start < 0) {
1636 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1637 return false;
1638 }
1639 if (waveLen[i+2] > clk*1+tol)
1640 phaseoff = 0;
1641 else
1642 phaseoff = clk/2;
1643
1644 // skip over the remainder of ST
1645 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1646
1647 // now do it again to find the end
1648 end = skip;
1649 for (i += 3; i < j - 4; ++i) {
1650 end += tmpbuff[i];
1651 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) { //1 to 2 clocks depending on 2 bits prior
1652 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
1653 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
1654 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1655 complete = true;
1656 break;
1657 }
1658 }
1659 }
1660 }
1661 }
1662 end -= phaseoff;
1663 //didn't find second ST - ERROR
1664 if (!complete) {
1665 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1666 return false;
1667 }
1668 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);
1669 //now begin to trim out ST so we can use normal demod cmds
1670 start = skip;
1671 size_t datalen = end - start;
1672 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1673 if (datalen % clk > clk/8) {
1674 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1675 return false;
1676 } else {
1677 // padd the amount off - could be problematic... but shouldn't happen often
1678 datalen += datalen % clk;
1679 }
1680 // if datalen is less than one t55xx block - ERROR
1681 if (datalen/clk < 8*4) {
1682 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1683 return false;
1684 }
1685 size_t dataloc = start;
1686 size_t newloc = 0;
1687 i=0;
1688 // warning - overwriting buffer given with raw wave data with ST removed...
1689 while ( dataloc < bufsize-(clk/2) ) {
1690 //compensate for long high at end of ST not being high due to signal loss... (and we cut out the start of wave high part)
1691 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1692 for(i=0; i < clk/2-tol; ++i) {
1693 buffer[dataloc+i] = high+5;
1694 }
1695 }
1696 for (i=0; i<datalen; ++i) {
1697 if (i+newloc < bufsize) {
1698 if (i+newloc < dataloc)
1699 buffer[i+newloc] = buffer[dataloc];
1700
1701 dataloc++;
1702 }
1703 }
1704 newloc += i;
1705 //skip next ST - we just assume it will be there from now on...
1706 dataloc += clk*4;
1707 }
1708 *size = newloc;
1709 return true;
1710}
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