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1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // Low frequency demod/decode commands
9 //-----------------------------------------------------------------------------
10
11 #include <stdlib.h>
12 #include "lfdemod.h"
13 #include <string.h>
14
15 //to allow debug print calls when used not on device
16 void dummy(char *fmt, ...){}
17
18 #ifndef ON_DEVICE
19 #include "ui.h"
20 #include "cmdparser.h"
21 #include "cmddata.h"
22 #define prnt PrintAndLog
23 #else
24 uint8_t g_debugMode=0;
25 #define prnt dummy
26 #endif
27
28 uint8_t justNoise(uint8_t *BitStream, size_t size)
29 {
30 static const uint8_t THRESHOLD = 123;
31 //test samples are not just noise
32 uint8_t justNoise1 = 1;
33 for(size_t idx=0; idx < size && justNoise1 ;idx++){
34 justNoise1 = BitStream[idx] < THRESHOLD;
35 }
36 return justNoise1;
37 }
38
39 //by marshmellow
40 //get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
41 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
42 {
43 *high=0;
44 *low=255;
45 // get high and low thresholds
46 for (size_t i=0; i < size; i++){
47 if (BitStream[i] > *high) *high = BitStream[i];
48 if (BitStream[i] < *low) *low = BitStream[i];
49 }
50 if (*high < 123) return -1; // just noise
51 *high = ((*high-128)*fuzzHi + 12800)/100;
52 *low = ((*low-128)*fuzzLo + 12800)/100;
53 return 1;
54 }
55
56 // by marshmellow
57 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
58 // returns 1 if passed
59 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
60 {
61 uint8_t ans = 0;
62 for (uint8_t i = 0; i < bitLen; i++){
63 ans ^= ((bits >> i) & 1);
64 }
65 if (g_debugMode) prnt("DEBUG: ans: %d, ptype: %d, bits: %08X",ans,pType,bits);
66 return (ans == pType);
67 }
68
69 // by marshmellow
70 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
71 // Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
72 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
73 {
74 uint32_t parityWd = 0;
75 size_t j = 0, bitCnt = 0;
76 for (int word = 0; word < (bLen); word+=pLen) {
77 for (int bit=0; bit < pLen; bit++) {
78 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
79 BitStream[j++] = (BitStream[startIdx+word+bit]);
80 }
81 if (word+pLen > bLen) break;
82
83 j--; // overwrite parity with next data
84 // if parity fails then return 0
85 switch (pType) {
86 case 3: if (BitStream[j]==1) {return 0;} break; //should be 0 spacer bit
87 case 2: if (BitStream[j]==0) {return 0;} break; //should be 1 spacer bit
88 default: if (parityTest(parityWd, pLen, pType) == 0) {return 0;} break; //test parity
89 }
90 bitCnt+=(pLen-1);
91 parityWd = 0;
92 }
93 // if we got here then all the parities passed
94 //return ID start index and size
95 return bitCnt;
96 }
97
98 // by marshmellow
99 // takes a array of binary values, length of bits per parity (includes parity bit),
100 // Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
101 // Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
102 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
103 {
104 uint32_t parityWd = 0;
105 size_t j = 0, bitCnt = 0;
106 for (int word = 0; word < sourceLen; word+=pLen-1) {
107 for (int bit=0; bit < pLen-1; bit++){
108 parityWd = (parityWd << 1) | BitSource[word+bit];
109 dest[j++] = (BitSource[word+bit]);
110 }
111 // if parity fails then return 0
112 switch (pType) {
113 case 3: dest[j++]=0; break; // marker bit which should be a 0
114 case 2: dest[j++]=1; break; // marker bit which should be a 1
115 default:
116 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
117 break;
118 }
119 bitCnt += pLen;
120 parityWd = 0;
121 }
122 // if we got here then all the parities passed
123 //return ID start index and size
124 return bitCnt;
125 }
126
127 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
128 {
129 uint32_t num = 0;
130 for(int i = 0 ; i < numbits ; i++)
131 {
132 num = (num << 1) | (*src);
133 src++;
134 }
135 return num;
136 }
137
138 //least significant bit first
139 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
140 {
141 uint32_t num = 0;
142 for(int i = 0 ; i < numbits ; i++)
143 {
144 num = (num << 1) | *(src + (numbits-(i+1)));
145 }
146 return num;
147 }
148
149 //by marshmellow
150 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
151 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
152 {
153 return (preambleSearchEx(BitStream, preamble, pLen, size, startIdx, false)) ? 1 : 0;
154 }
155
156 // search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found) and length if not fineone
157 // fineone does not look for a repeating preamble for em4x05/4x69 sends preamble once, so look for it once in the first pLen bits
158 bool preambleSearchEx(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx, bool findone) {
159 // Sanity check. If preamble length is bigger than bitstream length.
160 if ( *size <= pLen ) return false;
161
162 uint8_t foundCnt = 0;
163 for (size_t idx = 0; idx < *size - pLen; idx++) {
164 if (memcmp(BitStream+idx, preamble, pLen) == 0) {
165 //first index found
166 foundCnt++;
167 if (foundCnt == 1) {
168 if (g_debugMode) prnt("DEBUG: preamble found at %u", idx);
169 *startIdx = idx;
170 if (findone) return true;
171 } else if (foundCnt == 2) {
172 *size = idx - *startIdx;
173 return true;
174 }
175 }
176 }
177 return false;
178 }
179
180 // find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
181 size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_t expWaveSize) {
182 size_t i = 0;
183 size_t waveSizeCnt = 0;
184 uint8_t thresholdCnt = 0;
185 bool isAboveThreshold = dest[i++] >= threshold_value;
186 for (; i < size-20; i++ ) {
187 if(dest[i] < threshold_value && isAboveThreshold) {
188 thresholdCnt++;
189 if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
190 isAboveThreshold = false;
191 waveSizeCnt = 0;
192 } else if (dest[i] >= threshold_value && !isAboveThreshold) {
193 thresholdCnt++;
194 if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;
195 isAboveThreshold = true;
196 waveSizeCnt = 0;
197 } else {
198 waveSizeCnt++;
199 }
200 if (thresholdCnt > 10) break;
201 }
202 if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at %u, count: %u",i, thresholdCnt);
203 return i;
204 }
205
206 //by marshmellow
207 //takes 1s and 0s and searches for EM410x format - output EM ID
208 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
209 {
210 //sanity checks
211 if (*size < 64) return 0;
212 if (BitStream[1]>1) return 0; //allow only 1s and 0s
213
214 // 111111111 bit pattern represent start of frame
215 // include 0 in front to help get start pos
216 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
217 uint8_t errChk = 0;
218 uint8_t FmtLen = 10; // sets of 4 bits = end data
219 *startIdx = 0;
220 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
221 if (errChk == 0 || *size < 64) return 0;
222 if (*size == 110) FmtLen = 22; // 22 sets of 4 bits
223
224 //skip last 4bit parity row for simplicity
225 *size = removeParity(BitStream, *startIdx + sizeof(preamble), 5, 0, FmtLen * 5);
226 if (*size == 40) { // std em410x format
227 *hi = 0;
228 *lo = ((uint64_t)(bytebits_to_byte(BitStream, 8)) << 32) | (bytebits_to_byte(BitStream + 8, 32));
229 } else if (*size == 88) { // long em format
230 *hi = (bytebits_to_byte(BitStream, 24));
231 *lo = ((uint64_t)(bytebits_to_byte(BitStream + 24, 32)) << 32) | (bytebits_to_byte(BitStream + 24 + 32, 32));
232 } else {
233 return 0;
234 }
235 return 1;
236 }
237
238 //by marshmellow
239 //demodulates strong heavily clipped samples
240 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
241 {
242 size_t bitCnt=0, smplCnt=0, errCnt=0;
243 uint8_t waveHigh = 0;
244 for (size_t i=0; i < *size; i++){
245 if (BinStream[i] >= high && waveHigh){
246 smplCnt++;
247 } else if (BinStream[i] <= low && !waveHigh){
248 smplCnt++;
249 } else { //transition
250 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
251 if (smplCnt > clk-(clk/4)-1) { //full clock
252 if (smplCnt > clk + (clk/4)+1) { //too many samples
253 errCnt++;
254 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
255 BinStream[bitCnt++]=7;
256 } else if (waveHigh) {
257 BinStream[bitCnt++] = invert;
258 BinStream[bitCnt++] = invert;
259 } else if (!waveHigh) {
260 BinStream[bitCnt++] = invert ^ 1;
261 BinStream[bitCnt++] = invert ^ 1;
262 }
263 waveHigh ^= 1;
264 smplCnt = 0;
265 } else if (smplCnt > (clk/2) - (clk/4)-1) {
266 if (waveHigh) {
267 BinStream[bitCnt++] = invert;
268 } else if (!waveHigh) {
269 BinStream[bitCnt++] = invert ^ 1;
270 }
271 waveHigh ^= 1;
272 smplCnt = 0;
273 } else if (!bitCnt) {
274 //first bit
275 waveHigh = (BinStream[i] >= high);
276 smplCnt = 1;
277 } else {
278 smplCnt++;
279 //transition bit oops
280 }
281 } else { //haven't hit new high or new low yet
282 smplCnt++;
283 }
284 }
285 }
286 *size = bitCnt;
287 return errCnt;
288 }
289
290 //by marshmellow
291 //amplify based on ask edge detection
292 void askAmp(uint8_t *BitStream, size_t size)
293 {
294 uint8_t Last = 128;
295 for(size_t i = 1; i<size; i++){
296 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
297 Last = 255;
298 else if(BitStream[i-1]-BitStream[i]>=20) //large jump down
299 Last = 0;
300
301 BitStream[i-1] = Last;
302 }
303 return;
304 }
305
306 //by marshmellow
307 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
308 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
309 {
310 if (*size==0) return -1;
311 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
312 if (*clk==0 || start < 0) return -3;
313 if (*invert != 1) *invert = 0;
314 if (amp==1) askAmp(BinStream, *size);
315 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d, amp %d", *clk, start, amp);
316
317 uint8_t initLoopMax = 255;
318 if (initLoopMax > *size) initLoopMax = *size;
319 // Detect high and lows
320 //25% clip in case highs and lows aren't clipped [marshmellow]
321 int high, low;
322 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
323 return -2; //just noise
324
325 size_t errCnt = 0;
326 // if clean clipped waves detected run alternate demod
327 if (DetectCleanAskWave(BinStream, *size, high, low)) {
328 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
329 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
330 if (askType) //askman
331 return manrawdecode(BinStream, size, 0);
332 else //askraw
333 return errCnt;
334 }
335 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
336
337 int lastBit; //set first clock check - can go negative
338 size_t i, bitnum = 0; //output counter
339 uint8_t midBit = 0;
340 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
341 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
342 size_t MaxBits = 3072; //max bits to collect
343 lastBit = start - *clk;
344
345 for (i = start; i < *size; ++i) {
346 if (i-lastBit >= *clk-tol){
347 if (BinStream[i] >= high) {
348 BinStream[bitnum++] = *invert;
349 } else if (BinStream[i] <= low) {
350 BinStream[bitnum++] = *invert ^ 1;
351 } else if (i-lastBit >= *clk+tol) {
352 if (bitnum > 0) {
353 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
354 BinStream[bitnum++]=7;
355 errCnt++;
356 }
357 } else { //in tolerance - looking for peak
358 continue;
359 }
360 midBit = 0;
361 lastBit += *clk;
362 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
363 if (BinStream[i] >= high) {
364 BinStream[bitnum++] = *invert;
365 } else if (BinStream[i] <= low) {
366 BinStream[bitnum++] = *invert ^ 1;
367 } else if (i-lastBit >= *clk/2+tol) {
368 BinStream[bitnum] = BinStream[bitnum-1];
369 bitnum++;
370 } else { //in tolerance - looking for peak
371 continue;
372 }
373 midBit = 1;
374 }
375 if (bitnum >= MaxBits) break;
376 }
377 *size = bitnum;
378 return errCnt;
379 }
380
381 //by marshmellow
382 //take 10 and 01 and manchester decode
383 //run through 2 times and take least errCnt
384 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
385 {
386 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
387 size_t i, ii;
388 uint16_t bestErr = 1000, bestRun = 0;
389 if (*size < 16) return -1;
390 //find correct start position [alignment]
391 for (ii=0;ii<2;++ii){
392 for (i=ii; i<*size-3; i+=2)
393 if (BitStream[i]==BitStream[i+1])
394 errCnt++;
395
396 if (bestErr>errCnt){
397 bestErr=errCnt;
398 bestRun=ii;
399 }
400 errCnt=0;
401 }
402 //decode
403 for (i=bestRun; i < *size-3; i+=2){
404 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
405 BitStream[bitnum++]=invert;
406 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
407 BitStream[bitnum++]=invert^1;
408 } else {
409 BitStream[bitnum++]=7;
410 }
411 if(bitnum>MaxBits) break;
412 }
413 *size=bitnum;
414 return bestErr;
415 }
416
417 uint32_t manchesterEncode2Bytes(uint16_t datain) {
418 uint32_t output = 0;
419 uint8_t curBit = 0;
420 for (uint8_t i=0; i<16; i++) {
421 curBit = (datain >> (15-i) & 1);
422 output |= (1<<(((15-i)*2)+curBit));
423 }
424 return output;
425 }
426
427 //by marshmellow
428 //encode binary data into binary manchester
429 int ManchesterEncode(uint8_t *BitStream, size_t size)
430 {
431 size_t modIdx=20000, i=0;
432 if (size>modIdx) return -1;
433 for (size_t idx=0; idx < size; idx++){
434 BitStream[idx+modIdx++] = BitStream[idx];
435 BitStream[idx+modIdx++] = BitStream[idx]^1;
436 }
437 for (; i<(size*2); i++){
438 BitStream[i] = BitStream[i+20000];
439 }
440 return i;
441 }
442
443 //by marshmellow
444 //take 01 or 10 = 1 and 11 or 00 = 0
445 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
446 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
447 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
448 {
449 uint16_t bitnum = 0;
450 uint16_t errCnt = 0;
451 size_t i = offset;
452 uint16_t MaxBits=512;
453 //if not enough samples - error
454 if (*size < 51) return -1;
455 //check for phase change faults - skip one sample if faulty
456 uint8_t offsetA = 1, offsetB = 1;
457 for (; i<48; i+=2){
458 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
459 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
460 }
461 if (!offsetA && offsetB) offset++;
462 for (i=offset; i<*size-3; i+=2){
463 //check for phase error
464 if (BitStream[i+1]==BitStream[i+2]) {
465 BitStream[bitnum++]=7;
466 errCnt++;
467 }
468 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
469 BitStream[bitnum++]=1^invert;
470 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
471 BitStream[bitnum++]=invert;
472 } else {
473 BitStream[bitnum++]=7;
474 errCnt++;
475 }
476 if(bitnum>MaxBits) break;
477 }
478 *size=bitnum;
479 return errCnt;
480 }
481
482 // by marshmellow
483 // demod gProxIIDemod
484 // error returns as -x
485 // success returns start position in BitStream
486 // BitStream must contain previously askrawdemod and biphasedemoded data
487 int gProxII_Demod(uint8_t BitStream[], size_t *size)
488 {
489 size_t startIdx=0;
490 uint8_t preamble[] = {1,1,1,1,1,0};
491
492 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
493 if (errChk == 0) return -3; //preamble not found
494 if (*size != 96) return -2; //should have found 96 bits
495 //check first 6 spacer bits to verify format
496 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
497 //confirmed proper separator bits found
498 //return start position
499 return (int) startIdx;
500 }
501 return -5; //spacer bits not found - not a valid gproxII
502 }
503
504 //translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
505 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
506 {
507 size_t last_transition = 0;
508 size_t idx = 1;
509 if (fchigh==0) fchigh=10;
510 if (fclow==0) fclow=8;
511 //set the threshold close to 0 (graph) or 128 std to avoid static
512 uint8_t threshold_value = 123;
513 size_t preLastSample = 0;
514 size_t LastSample = 0;
515 size_t currSample = 0;
516 if ( size < 1024 ) return 0; // not enough samples
517
518 //find start of modulating data in trace
519 idx = findModStart(dest, size, threshold_value, fchigh);
520
521 // Need to threshold first sample
522 if(dest[idx] < threshold_value) dest[0] = 0;
523 else dest[0] = 1;
524 idx++;
525
526 size_t numBits = 0;
527 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
528 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
529 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
530 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
531 for(; idx < size-20; idx++) {
532 // threshold current value
533
534 if (dest[idx] < threshold_value) dest[idx] = 0;
535 else dest[idx] = 1;
536
537 // Check for 0->1 transition
538 if (dest[idx-1] < dest[idx]) {
539 preLastSample = LastSample;
540 LastSample = currSample;
541 currSample = idx-last_transition;
542 if (currSample < (fclow-2)) { //0-5 = garbage noise (or 0-3)
543 //do nothing with extra garbage
544 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
545 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
546 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1))){
547 dest[numBits-1]=1;
548 }
549 dest[numBits++]=1;
550
551 } else if (currSample > (fchigh+1) && numBits < 3) { //12 + and first two bit = unusable garbage
552 //do nothing with beginning garbage and reset.. should be rare..
553 numBits = 0;
554 } 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)
555 dest[numBits++]=1;
556 } else { //9+ = 10 sample waves (or 6+ = 7)
557 dest[numBits++]=0;
558 }
559 last_transition = idx;
560 }
561 }
562 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
563 }
564
565 //translate 11111100000 to 10
566 //rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
567 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
568 uint8_t invert, uint8_t fchigh, uint8_t fclow)
569 {
570 uint8_t lastval=dest[0];
571 size_t idx=0;
572 size_t numBits=0;
573 uint32_t n=1;
574 for( idx=1; idx < size; idx++) {
575 n++;
576 if (dest[idx]==lastval) continue; //skip until we hit a transition
577
578 //find out how many bits (n) we collected
579 //if lastval was 1, we have a 1->0 crossing
580 if (dest[idx-1]==1) {
581 n = (n * fclow + rfLen/2) / rfLen;
582 } else {// 0->1 crossing
583 n = (n * fchigh + rfLen/2) / rfLen;
584 }
585 if (n == 0) n = 1;
586
587 //add to our destination the bits we collected
588 memset(dest+numBits, dest[idx-1]^invert , n);
589 numBits += n;
590 n=0;
591 lastval=dest[idx];
592 }//end for
593 // if valid extra bits at the end were all the same frequency - add them in
594 if (n > rfLen/fchigh) {
595 if (dest[idx-2]==1) {
596 n = (n * fclow + rfLen/2) / rfLen;
597 } else {
598 n = (n * fchigh + rfLen/2) / rfLen;
599 }
600 memset(dest+numBits, dest[idx-1]^invert , n);
601 numBits += n;
602 }
603 return numBits;
604 }
605
606 //by marshmellow (from holiman's base)
607 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
608 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
609 {
610 // FSK demodulator
611 size = fsk_wave_demod(dest, size, fchigh, fclow);
612 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
613 return size;
614 }
615
616 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
617 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
618 {
619 if (justNoise(dest, *size)) return -1;
620
621 size_t numStart=0, size2=*size, startIdx=0;
622 // FSK demodulator
623 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
624 if (*size < 96*2) return -2;
625 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
626 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
627 // find bitstring in array
628 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
629 if (errChk == 0) return -3; //preamble not found
630
631 numStart = startIdx + sizeof(preamble);
632 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
633 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
634 if (dest[idx] == dest[idx+1]){
635 return -4; //not manchester data
636 }
637 *hi2 = (*hi2<<1)|(*hi>>31);
638 *hi = (*hi<<1)|(*lo>>31);
639 //Then, shift in a 0 or one into low
640 if (dest[idx] && !dest[idx+1]) // 1 0
641 *lo=(*lo<<1)|1;
642 else // 0 1
643 *lo=(*lo<<1)|0;
644 }
645 return (int)startIdx;
646 }
647
648 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
649 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
650 {
651 if (justNoise(dest, *size)) return -1;
652
653 size_t numStart=0, size2=*size, startIdx=0;
654 // FSK demodulator
655 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
656 if (*size < 96) return -2;
657
658 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
659 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
660
661 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
662 if (errChk == 0) return -3; //preamble not found
663
664 numStart = startIdx + sizeof(preamble);
665 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
666 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
667 if (dest[idx] == dest[idx+1])
668 return -4; //not manchester data
669 *hi2 = (*hi2<<1)|(*hi>>31);
670 *hi = (*hi<<1)|(*lo>>31);
671 //Then, shift in a 0 or one into low
672 if (dest[idx] && !dest[idx+1]) // 1 0
673 *lo=(*lo<<1)|1;
674 else // 0 1
675 *lo=(*lo<<1)|0;
676 }
677 return (int)startIdx;
678 }
679
680 int IOdemodFSK(uint8_t *dest, size_t size)
681 {
682 if (justNoise(dest, size)) return -1;
683 //make sure buffer has data
684 if (size < 66*64) return -2;
685 // FSK demodulator
686 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
687 if (size < 65) return -3; //did we get a good demod?
688 //Index map
689 //0 10 20 30 40 50 60
690 //| | | | | | |
691 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
692 //-----------------------------------------------------------------------------
693 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
694 //
695 //XSF(version)facility:codeone+codetwo
696 //Handle the data
697 size_t startIdx = 0;
698 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
699 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
700 if (errChk == 0) return -4; //preamble not found
701
702 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
703 //confirmed proper separator bits found
704 //return start position
705 return (int) startIdx;
706 }
707 return -5;
708 }
709
710 // by marshmellow
711 // find viking preamble 0xF200 in already demoded data
712 int VikingDemod_AM(uint8_t *dest, size_t *size) {
713 //make sure buffer has data
714 if (*size < 64*2) return -2;
715
716 size_t startIdx = 0;
717 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};
718 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
719 if (errChk == 0) return -4; //preamble not found
720 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
721 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
722 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
723 if ( checkCalc != 0xA8 ) return -5;
724 if (*size != 64) return -6;
725 //return start position
726 return (int) startIdx;
727 }
728
729 // find presco preamble 0x10D in already demoded data
730 int PrescoDemod(uint8_t *dest, size_t *size) {
731 //make sure buffer has data
732 if (*size < 64*2) return -2;
733
734 size_t startIdx = 0;
735 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
736 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
737 if (errChk == 0) return -4; //preamble not found
738 //return start position
739 return (int) startIdx;
740 }
741
742 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
743 // BitStream must contain previously askrawdemod and biphasedemoded data
744 int FDXBdemodBI(uint8_t *dest, size_t *size)
745 {
746 //make sure buffer has enough data
747 if (*size < 128) return -1;
748
749 size_t startIdx = 0;
750 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
751
752 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
753 if (errChk == 0) return -2; //preamble not found
754 return (int)startIdx;
755 }
756
757 // by marshmellow
758 // FSK Demod then try to locate an AWID ID
759 int AWIDdemodFSK(uint8_t *dest, size_t *size)
760 {
761 //make sure buffer has enough data
762 if (*size < 96*50) return -1;
763
764 if (justNoise(dest, *size)) return -2;
765
766 // FSK demodulator
767 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
768 if (*size < 96) return -3; //did we get a good demod?
769
770 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
771 size_t startIdx = 0;
772 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
773 if (errChk == 0) return -4; //preamble not found
774 if (*size != 96) return -5;
775 return (int)startIdx;
776 }
777
778 // by marshmellow
779 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
780 int PyramiddemodFSK(uint8_t *dest, size_t *size)
781 {
782 //make sure buffer has data
783 if (*size < 128*50) return -5;
784
785 //test samples are not just noise
786 if (justNoise(dest, *size)) return -1;
787
788 // FSK demodulator
789 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
790 if (*size < 128) return -2; //did we get a good demod?
791
792 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
793 size_t startIdx = 0;
794 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
795 if (errChk == 0) return -4; //preamble not found
796 if (*size != 128) return -3;
797 return (int)startIdx;
798 }
799
800 // by marshmellow
801 // to detect a wave that has heavily clipped (clean) samples
802 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
803 {
804 bool allArePeaks = true;
805 uint16_t cntPeaks=0;
806 size_t loopEnd = 512+160;
807 if (loopEnd > size) loopEnd = size;
808 for (size_t i=160; i<loopEnd; i++){
809 if (dest[i]>low && dest[i]<high)
810 allArePeaks = false;
811 else
812 cntPeaks++;
813 }
814 if (!allArePeaks){
815 if (cntPeaks > 300) return true;
816 }
817 return allArePeaks;
818 }
819 // by marshmellow
820 // to help detect clocks on heavily clipped samples
821 // based on count of low to low
822 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
823 {
824 uint8_t fndClk[] = {8,16,32,40,50,64,128};
825 size_t startwave;
826 size_t i = 100;
827 size_t minClk = 255;
828 // get to first full low to prime loop and skip incomplete first pulse
829 while ((dest[i] < high) && (i < size))
830 ++i;
831 while ((dest[i] > low) && (i < size))
832 ++i;
833
834 // loop through all samples
835 while (i < size) {
836 // measure from low to low
837 while ((dest[i] > low) && (i < size))
838 ++i;
839 startwave= i;
840 while ((dest[i] < high) && (i < size))
841 ++i;
842 while ((dest[i] > low) && (i < size))
843 ++i;
844 //get minimum measured distance
845 if (i-startwave < minClk && i < size)
846 minClk = i - startwave;
847 }
848 // set clock
849 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
850 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
851 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
852 return fndClk[clkCnt];
853 }
854 return 0;
855 }
856
857 // by marshmellow
858 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
859 // maybe somehow adjust peak trimming value based on samples to fix?
860 // return start index of best starting position for that clock and return clock (by reference)
861 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
862 {
863 size_t i=1;
864 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
865 uint8_t clkEnd = 9;
866 uint8_t loopCnt = 255; //don't need to loop through entire array...
867 if (size <= loopCnt+60) return -1; //not enough samples
868 size -= 60; //sometimes there is a strange end wave - filter out this....
869 //if we already have a valid clock
870 uint8_t clockFnd=0;
871 for (;i<clkEnd;++i)
872 if (clk[i] == *clock) clockFnd = i;
873 //clock found but continue to find best startpos
874
875 //get high and low peak
876 int peak, low;
877 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
878
879 //test for large clean peaks
880 if (!clockFnd){
881 if (DetectCleanAskWave(dest, size, peak, low)==1){
882 int ans = DetectStrongAskClock(dest, size, peak, low);
883 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
884 for (i=clkEnd-1; i>0; i--){
885 if (clk[i] == ans) {
886 *clock = ans;
887 //clockFnd = i;
888 return 0; // for strong waves i don't use the 'best start position' yet...
889 //break; //clock found but continue to find best startpos [not yet]
890 }
891 }
892 }
893 }
894 uint8_t ii;
895 uint8_t clkCnt, tol = 0;
896 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
897 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
898 size_t errCnt = 0;
899 size_t arrLoc, loopEnd;
900
901 if (clockFnd>0) {
902 clkCnt = clockFnd;
903 clkEnd = clockFnd+1;
904 }
905 else clkCnt=1;
906
907 //test each valid clock from smallest to greatest to see which lines up
908 for(; clkCnt < clkEnd; clkCnt++){
909 if (clk[clkCnt] <= 32){
910 tol=1;
911 }else{
912 tol=0;
913 }
914 //if no errors allowed - keep start within the first clock
915 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
916 bestErr[clkCnt]=1000;
917 //try lining up the peaks by moving starting point (try first few clocks)
918 for (ii=0; ii < loopCnt; ii++){
919 if (dest[ii] < peak && dest[ii] > low) continue;
920
921 errCnt=0;
922 // now that we have the first one lined up test rest of wave array
923 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
924 for (i=0; i < loopEnd; ++i){
925 arrLoc = ii + (i * clk[clkCnt]);
926 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
927 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
928 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
929 }else{ //error no peak detected
930 errCnt++;
931 }
932 }
933 //if we found no errors then we can stop here and a low clock (common clocks)
934 // this is correct one - return this clock
935 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
936 if(errCnt==0 && clkCnt<7) {
937 if (!clockFnd) *clock = clk[clkCnt];
938 return ii;
939 }
940 //if we found errors see if it is lowest so far and save it as best run
941 if(errCnt<bestErr[clkCnt]){
942 bestErr[clkCnt]=errCnt;
943 bestStart[clkCnt]=ii;
944 }
945 }
946 }
947 uint8_t iii;
948 uint8_t best=0;
949 for (iii=1; iii<clkEnd; ++iii){
950 if (bestErr[iii] < bestErr[best]){
951 if (bestErr[iii] == 0) bestErr[iii]=1;
952 // current best bit to error ratio vs new bit to error ratio
953 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
954 best = iii;
955 }
956 }
957 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]);
958 }
959 if (!clockFnd) *clock = clk[best];
960 return bestStart[best];
961 }
962
963 //by marshmellow
964 //detect psk clock by reading each phase shift
965 // a phase shift is determined by measuring the sample length of each wave
966 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
967 {
968 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
969 uint16_t loopCnt = 4096; //don't need to loop through entire array...
970 if (size == 0) return 0;
971 if (size<loopCnt) loopCnt = size-20;
972
973 //if we already have a valid clock quit
974 size_t i=1;
975 for (; i < 8; ++i)
976 if (clk[i] == clock) return clock;
977
978 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
979 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
980 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
981 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
982 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
983 fc = countFC(dest, size, 0);
984 if (fc!=2 && fc!=4 && fc!=8) return -1;
985 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
986
987 //find first full wave
988 for (i=160; i<loopCnt; i++){
989 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
990 if (waveStart == 0) {
991 waveStart = i+1;
992 //prnt("DEBUG: waveStart: %d",waveStart);
993 } else {
994 waveEnd = i+1;
995 //prnt("DEBUG: waveEnd: %d",waveEnd);
996 waveLenCnt = waveEnd-waveStart;
997 if (waveLenCnt > fc){
998 firstFullWave = waveStart;
999 fullWaveLen=waveLenCnt;
1000 break;
1001 }
1002 waveStart=0;
1003 }
1004 }
1005 }
1006 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1007
1008 //test each valid clock from greatest to smallest to see which lines up
1009 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
1010 lastClkBit = firstFullWave; //set end of wave as clock align
1011 waveStart = 0;
1012 errCnt=0;
1013 peakcnt=0;
1014 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
1015
1016 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
1017 //top edge of wave = start of new wave
1018 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
1019 if (waveStart == 0) {
1020 waveStart = i+1;
1021 waveLenCnt=0;
1022 } else { //waveEnd
1023 waveEnd = i+1;
1024 waveLenCnt = waveEnd-waveStart;
1025 if (waveLenCnt > fc){
1026 //if this wave is a phase shift
1027 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);
1028 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
1029 peakcnt++;
1030 lastClkBit+=clk[clkCnt];
1031 } else if (i<lastClkBit+8){
1032 //noise after a phase shift - ignore
1033 } else { //phase shift before supposed to based on clock
1034 errCnt++;
1035 }
1036 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1037 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1038 }
1039 waveStart=i+1;
1040 }
1041 }
1042 }
1043 if (errCnt == 0){
1044 return clk[clkCnt];
1045 }
1046 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1047 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1048 }
1049 //all tested with errors
1050 //return the highest clk with the most peaks found
1051 uint8_t best=7;
1052 for (i=7; i>=1; i--){
1053 if (peaksdet[i] > peaksdet[best]) {
1054 best = i;
1055 }
1056 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
1057 }
1058 return clk[best];
1059 }
1060
1061 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1062 //find shortest transition from high to low
1063 size_t i = 0;
1064 size_t transition1 = 0;
1065 int lowestTransition = 255;
1066 bool lastWasHigh = false;
1067
1068 //find first valid beginning of a high or low wave
1069 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1070 ++i;
1071 while ((dest[i] < peak && dest[i] > low) && (i < size))
1072 ++i;
1073 lastWasHigh = (dest[i] >= peak);
1074
1075 if (i==size) return 0;
1076 transition1 = i;
1077
1078 for (;i < size; i++) {
1079 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1080 lastWasHigh = (dest[i] >= peak);
1081 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1082 transition1 = i;
1083 }
1084 }
1085 if (lowestTransition == 255) lowestTransition = 0;
1086 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
1087 return lowestTransition;
1088 }
1089
1090 //by marshmellow
1091 //detect nrz clock by reading #peaks vs no peaks(or errors)
1092 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1093 {
1094 size_t i=0;
1095 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1096 size_t loopCnt = 4096; //don't need to loop through entire array...
1097 if (size == 0) return 0;
1098 if (size<loopCnt) loopCnt = size-20;
1099 //if we already have a valid clock quit
1100 for (; i < 8; ++i)
1101 if (clk[i] == clock) return clock;
1102
1103 //get high and low peak
1104 int peak, low;
1105 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1106
1107 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1108 size_t ii;
1109 uint8_t clkCnt;
1110 uint8_t tol = 0;
1111 uint16_t smplCnt = 0;
1112 int16_t peakcnt = 0;
1113 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1114 uint16_t maxPeak = 255;
1115 bool firstpeak = false;
1116 //test for large clipped waves
1117 for (i=0; i<loopCnt; i++){
1118 if (dest[i] >= peak || dest[i] <= low){
1119 if (!firstpeak) continue;
1120 smplCnt++;
1121 } else {
1122 firstpeak=true;
1123 if (smplCnt > 6 ){
1124 if (maxPeak > smplCnt){
1125 maxPeak = smplCnt;
1126 //prnt("maxPk: %d",maxPeak);
1127 }
1128 peakcnt++;
1129 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1130 smplCnt=0;
1131 }
1132 }
1133 }
1134 bool errBitHigh = 0;
1135 bool bitHigh = 0;
1136 uint8_t ignoreCnt = 0;
1137 uint8_t ignoreWindow = 4;
1138 bool lastPeakHigh = 0;
1139 int lastBit = 0;
1140 peakcnt=0;
1141 //test each valid clock from smallest to greatest to see which lines up
1142 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1143 //ignore clocks smaller than smallest peak
1144 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1145 //try lining up the peaks by moving starting point (try first 256)
1146 for (ii=20; ii < loopCnt; ++ii){
1147 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1148 peakcnt = 0;
1149 bitHigh = false;
1150 ignoreCnt = 0;
1151 lastBit = ii-clk[clkCnt];
1152 //loop through to see if this start location works
1153 for (i = ii; i < size-20; ++i) {
1154 //if we are at a clock bit
1155 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1156 //test high/low
1157 if (dest[i] >= peak || dest[i] <= low) {
1158 //if same peak don't count it
1159 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1160 peakcnt++;
1161 }
1162 lastPeakHigh = (dest[i] >= peak);
1163 bitHigh = true;
1164 errBitHigh = false;
1165 ignoreCnt = ignoreWindow;
1166 lastBit += clk[clkCnt];
1167 } else if (i == lastBit + clk[clkCnt] + tol) {
1168 lastBit += clk[clkCnt];
1169 }
1170 //else if not a clock bit and no peaks
1171 } else if (dest[i] < peak && dest[i] > low){
1172 if (ignoreCnt==0){
1173 bitHigh=false;
1174 if (errBitHigh==true) peakcnt--;
1175 errBitHigh=false;
1176 } else {
1177 ignoreCnt--;
1178 }
1179 // else if not a clock bit but we have a peak
1180 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1181 //error bar found no clock...
1182 errBitHigh=true;
1183 }
1184 }
1185 if(peakcnt>peaksdet[clkCnt]) {
1186 peaksdet[clkCnt]=peakcnt;
1187 }
1188 }
1189 }
1190 }
1191 int iii=7;
1192 uint8_t best=0;
1193 for (iii=7; iii > 0; iii--){
1194 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1195 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1196 best = iii;
1197 }
1198 } else if (peaksdet[iii] > peaksdet[best]){
1199 best = iii;
1200 }
1201 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);
1202 }
1203
1204 return clk[best];
1205 }
1206
1207 // by marshmellow
1208 // convert psk1 demod to psk2 demod
1209 // only transition waves are 1s
1210 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1211 {
1212 size_t i=1;
1213 uint8_t lastBit=BitStream[0];
1214 for (; i<size; i++){
1215 if (BitStream[i]==7){
1216 //ignore errors
1217 } else if (lastBit!=BitStream[i]){
1218 lastBit=BitStream[i];
1219 BitStream[i]=1;
1220 } else {
1221 BitStream[i]=0;
1222 }
1223 }
1224 return;
1225 }
1226
1227 // by marshmellow
1228 // convert psk2 demod to psk1 demod
1229 // from only transition waves are 1s to phase shifts change bit
1230 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1231 {
1232 uint8_t phase=0;
1233 for (size_t i=0; i<size; i++){
1234 if (BitStream[i]==1){
1235 phase ^=1;
1236 }
1237 BitStream[i]=phase;
1238 }
1239 return;
1240 }
1241
1242 // redesigned by marshmellow adjusted from existing decode functions
1243 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1244 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1245 {
1246 //26 bit 40134 format (don't know other formats)
1247 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};
1248 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};
1249 size_t startidx = 0;
1250 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1251 // if didn't find preamble try again inverting
1252 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1253 *invert ^= 1;
1254 }
1255 if (*size != 64 && *size != 224) return -2;
1256 if (*invert==1)
1257 for (size_t i = startidx; i < *size; i++)
1258 bitStream[i] ^= 1;
1259
1260 return (int) startidx;
1261 }
1262
1263 // by marshmellow - demodulate NRZ wave - requires a read with strong signal
1264 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1265 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1266 if (justNoise(dest, *size)) return -1;
1267 *clk = DetectNRZClock(dest, *size, *clk);
1268 if (*clk==0) return -2;
1269 size_t i, gLen = 4096;
1270 if (gLen>*size) gLen = *size-20;
1271 int high, low;
1272 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1273
1274 uint8_t bit=0;
1275 //convert wave samples to 1's and 0's
1276 for(i=20; i < *size-20; i++){
1277 if (dest[i] >= high) bit = 1;
1278 if (dest[i] <= low) bit = 0;
1279 dest[i] = bit;
1280 }
1281 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1282 size_t lastBit = 0;
1283 size_t numBits = 0;
1284 for(i=21; i < *size-20; i++) {
1285 //if transition detected or large number of same bits - store the passed bits
1286 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1287 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1288 numBits += (i - lastBit + (*clk/4)) / *clk;
1289 lastBit = i-1;
1290 }
1291 }
1292 *size = numBits;
1293 return 0;
1294 }
1295
1296 //by marshmellow
1297 //detects the bit clock for FSK given the high and low Field Clocks
1298 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1299 {
1300 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1301 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1302 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1303 uint8_t rfLensFnd = 0;
1304 uint8_t lastFCcnt = 0;
1305 uint16_t fcCounter = 0;
1306 uint16_t rfCounter = 0;
1307 uint8_t firstBitFnd = 0;
1308 size_t i;
1309 if (size == 0) return 0;
1310
1311 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1312 rfLensFnd=0;
1313 fcCounter=0;
1314 rfCounter=0;
1315 firstBitFnd=0;
1316 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1317 // prime i to first peak / up transition
1318 for (i = 160; i < size-20; i++)
1319 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1320 break;
1321
1322 for (; i < size-20; i++){
1323 fcCounter++;
1324 rfCounter++;
1325
1326 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1327 continue;
1328 // else new peak
1329 // if we got less than the small fc + tolerance then set it to the small fc
1330 // if it is inbetween set it to the last counter
1331 if (fcCounter < fcHigh && fcCounter > fcLow)
1332 fcCounter = lastFCcnt;
1333 else if (fcCounter < fcLow+fcTol)
1334 fcCounter = fcLow;
1335 else //set it to the large fc
1336 fcCounter = fcHigh;
1337
1338 //look for bit clock (rf/xx)
1339 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1340 //not the same size as the last wave - start of new bit sequence
1341 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1342 for (int ii=0; ii<15; ii++){
1343 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1344 rfCnts[ii]++;
1345 rfCounter = 0;
1346 break;
1347 }
1348 }
1349 if (rfCounter > 0 && rfLensFnd < 15){
1350 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1351 rfCnts[rfLensFnd]++;
1352 rfLens[rfLensFnd++] = rfCounter;
1353 }
1354 } else {
1355 firstBitFnd++;
1356 }
1357 rfCounter=0;
1358 lastFCcnt=fcCounter;
1359 }
1360 fcCounter=0;
1361 }
1362 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1363
1364 for (i=0; i<15; i++){
1365 //get highest 2 RF values (might need to get more values to compare or compare all?)
1366 if (rfCnts[i]>rfCnts[rfHighest]){
1367 rfHighest3=rfHighest2;
1368 rfHighest2=rfHighest;
1369 rfHighest=i;
1370 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1371 rfHighest3=rfHighest2;
1372 rfHighest2=i;
1373 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1374 rfHighest3=i;
1375 }
1376 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1377 }
1378 // set allowed clock remainder tolerance to be 1 large field clock length+1
1379 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1380 uint8_t tol1 = fcHigh+1;
1381
1382 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1383
1384 // loop to find the highest clock that has a remainder less than the tolerance
1385 // compare samples counted divided by
1386 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1387 int ii=7;
1388 for (; ii>=2; ii--){
1389 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1390 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1391 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1392 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
1393 break;
1394 }
1395 }
1396 }
1397 }
1398
1399 if (ii<2) return 0; // oops we went too far
1400
1401 return clk[ii];
1402 }
1403
1404 //by marshmellow
1405 //countFC is to detect the field clock lengths.
1406 //counts and returns the 2 most common wave lengths
1407 //mainly used for FSK field clock detection
1408 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1409 {
1410 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1411 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1412 uint8_t fcLensFnd = 0;
1413 uint8_t lastFCcnt = 0;
1414 uint8_t fcCounter = 0;
1415 size_t i;
1416 if (size < 180) return 0;
1417
1418 // prime i to first up transition
1419 for (i = 160; i < size-20; i++)
1420 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1421 break;
1422
1423 for (; i < size-20; i++){
1424 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1425 // new up transition
1426 fcCounter++;
1427 if (fskAdj){
1428 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1429 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1430 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1431 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1432 // save last field clock count (fc/xx)
1433 lastFCcnt = fcCounter;
1434 }
1435 // find which fcLens to save it to:
1436 for (int ii=0; ii<15; ii++){
1437 if (fcLens[ii]==fcCounter){
1438 fcCnts[ii]++;
1439 fcCounter=0;
1440 break;
1441 }
1442 }
1443 if (fcCounter>0 && fcLensFnd<15){
1444 //add new fc length
1445 fcCnts[fcLensFnd]++;
1446 fcLens[fcLensFnd++]=fcCounter;
1447 }
1448 fcCounter=0;
1449 } else {
1450 // count sample
1451 fcCounter++;
1452 }
1453 }
1454
1455 uint8_t best1=14, best2=14, best3=14;
1456 uint16_t maxCnt1=0;
1457 // go through fclens and find which ones are bigest 2
1458 for (i=0; i<15; i++){
1459 // get the 3 best FC values
1460 if (fcCnts[i]>maxCnt1) {
1461 best3=best2;
1462 best2=best1;
1463 maxCnt1=fcCnts[i];
1464 best1=i;
1465 } else if(fcCnts[i]>fcCnts[best2]){
1466 best3=best2;
1467 best2=i;
1468 } else if(fcCnts[i]>fcCnts[best3]){
1469 best3=i;
1470 }
1471 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]);
1472 }
1473 if (fcLens[best1]==0) return 0;
1474 uint8_t fcH=0, fcL=0;
1475 if (fcLens[best1]>fcLens[best2]){
1476 fcH=fcLens[best1];
1477 fcL=fcLens[best2];
1478 } else{
1479 fcH=fcLens[best2];
1480 fcL=fcLens[best1];
1481 }
1482 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1483 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]);
1484 return 0; //lots of waves not psk or fsk
1485 }
1486 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1487
1488 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1489 if (fskAdj) return fcs;
1490 return fcLens[best1];
1491 }
1492
1493 //by marshmellow - demodulate PSK1 wave
1494 //uses wave lengths (# Samples)
1495 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1496 {
1497 if (size == 0) return -1;
1498 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1499 if (*size<loopCnt) loopCnt = *size;
1500
1501 size_t numBits=0;
1502 uint8_t curPhase = *invert;
1503 size_t i=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1504 uint16_t fc=0, fullWaveLen=0, tol=1;
1505 uint16_t errCnt=0, waveLenCnt=0, errCnt2=0;
1506 fc = countFC(dest, *size, 1);
1507 uint8_t fc2 = fc >> 8;
1508 if (fc2 == 10) return -1; //fsk found - quit
1509 fc = fc & 0xFF;
1510 if (fc!=2 && fc!=4 && fc!=8) return -1;
1511 //PrintAndLog("DEBUG: FC: %d",fc);
1512 *clock = DetectPSKClock(dest, *size, *clock);
1513 if (*clock == 0) return -1;
1514
1515 //find start of modulating data in trace
1516 uint8_t threshold_value = 123; //-5
1517 i = findModStart(dest, *size, threshold_value, fc);
1518
1519 //find first phase shift
1520 int avgWaveVal=0, lastAvgWaveVal=0;
1521 waveStart = i;
1522 for (; i<loopCnt; i++) {
1523 // find peak
1524 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1525 waveEnd = i+1;
1526 if (g_debugMode == 2) prnt("DEBUG PSK: waveEnd: %u, waveStart: %u",waveEnd, waveStart);
1527 waveLenCnt = waveEnd-waveStart;
1528 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+3)){ //not first peak and is a large wave but not out of whack
1529 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1530 firstFullWave = waveStart;
1531 fullWaveLen=waveLenCnt;
1532 //if average wave value is > graph 0 then it is an up wave or a 1 (could cause inverting)
1533 if (lastAvgWaveVal > threshold_value) curPhase ^= 1;
1534 break;
1535 }
1536 waveStart = i+1;
1537 avgWaveVal = 0;
1538 }
1539 avgWaveVal += dest[i+2];
1540 }
1541 if (firstFullWave == 0) {
1542 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1543 // so skip a little to ensure we are past any Start Signal
1544 firstFullWave = 160;
1545 memset(dest, curPhase, firstFullWave / *clock);
1546 } else {
1547 memset(dest, curPhase^1, firstFullWave / *clock);
1548 }
1549 //advance bits
1550 numBits += (firstFullWave / *clock);
1551 //set start of wave as clock align
1552 lastClkBit = firstFullWave;
1553 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1554 if (g_debugMode==2) prnt("DEBUG PSK: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
1555 waveStart = 0;
1556 dest[numBits++] = curPhase; //set first read bit
1557 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1558 //top edge of wave = start of new wave
1559 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1560 if (waveStart == 0) {
1561 waveStart = i+1;
1562 waveLenCnt = 0;
1563 avgWaveVal = dest[i+1];
1564 } else { //waveEnd
1565 waveEnd = i+1;
1566 waveLenCnt = waveEnd-waveStart;
1567 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1568 if (waveLenCnt > fc){
1569 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1570 //this wave is a phase shift
1571 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1572 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1573 curPhase ^= 1;
1574 dest[numBits++] = curPhase;
1575 lastClkBit += *clock;
1576 } else if (i < lastClkBit+10+fc){
1577 //noise after a phase shift - ignore
1578 } else { //phase shift before supposed to based on clock
1579 errCnt++;
1580 dest[numBits++] = 7;
1581 }
1582 } else if (i+1 > lastClkBit + *clock + tol + fc){
1583 lastClkBit += *clock; //no phase shift but clock bit
1584 dest[numBits++] = curPhase;
1585 } else if (waveLenCnt < fc - 1) { //wave is smaller than field clock (shouldn't happen often)
1586 errCnt2++;
1587 if(errCnt2 > 101) return errCnt2;
1588 }
1589 avgWaveVal = 0;
1590 waveStart = i+1;
1591 }
1592 }
1593 avgWaveVal += dest[i+1];
1594 }
1595 *size = numBits;
1596 return errCnt;
1597 }
1598
1599 //by marshmellow
1600 //attempt to identify a Sequence Terminator in ASK modulated raw wave
1601 bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1602 size_t bufsize = *size;
1603 //need to loop through all samples and identify our clock, look for the ST pattern
1604 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1605 int clk = 0;
1606 int tol = 0;
1607 int i, j, skip, start, end, low, high, minClk, waveStart;
1608 bool complete = false;
1609 int tmpbuff[bufsize / 32]; //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
1610 int waveLen[bufsize / 32]; // if clock is larger then we waste memory in array size that is not needed...
1611 size_t testsize = (bufsize < 512) ? bufsize : 512;
1612 int phaseoff = 0;
1613 high = low = 128;
1614 memset(tmpbuff, 0, sizeof(tmpbuff));
1615
1616 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1617 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1618 return false; //just noise
1619 }
1620 i = 0;
1621 j = 0;
1622 minClk = 255;
1623 // get to first full low to prime loop and skip incomplete first pulse
1624 while ((buffer[i] < high) && (i < bufsize))
1625 ++i;
1626 while ((buffer[i] > low) && (i < bufsize))
1627 ++i;
1628 skip = i;
1629
1630 // populate tmpbuff buffer with pulse lengths
1631 while (i < bufsize) {
1632 // measure from low to low
1633 while ((buffer[i] > low) && (i < bufsize))
1634 ++i;
1635 start= i;
1636 while ((buffer[i] < high) && (i < bufsize))
1637 ++i;
1638 //first high point for this wave
1639 waveStart = i;
1640 while ((buffer[i] > low) && (i < bufsize))
1641 ++i;
1642 if (j >= (bufsize/32)) {
1643 break;
1644 }
1645 waveLen[j] = i - waveStart; //first high to first low
1646 tmpbuff[j++] = i - start;
1647 if (i-start < minClk && i < bufsize) {
1648 minClk = i - start;
1649 }
1650 }
1651 // set clock - might be able to get this externally and remove this work...
1652 if (!clk) {
1653 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1654 tol = fndClk[clkCnt]/8;
1655 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1656 clk=fndClk[clkCnt];
1657 break;
1658 }
1659 }
1660 // clock not found - ERROR
1661 if (!clk) {
1662 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1663 return false;
1664 }
1665 } else tol = clk/8;
1666
1667 *foundclock = clk;
1668
1669 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1670 start = -1;
1671 for (i = 0; i < j - 4; ++i) {
1672 skip += tmpbuff[i];
1673 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1674 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
1675 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
1676 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1677 start = i + 3;
1678 break;
1679 }
1680 }
1681 }
1682 }
1683 }
1684 // first ST not found - ERROR
1685 if (start < 0) {
1686 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1687 return false;
1688 } else {
1689 if (g_debugMode==2) prnt("DEBUG STT: first STT found at: %d, j=%d",start, j);
1690 }
1691 if (waveLen[i+2] > clk*1+tol)
1692 phaseoff = 0;
1693 else
1694 phaseoff = clk/2;
1695
1696 // skip over the remainder of ST
1697 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1698
1699 // now do it again to find the end
1700 end = skip;
1701 for (i += 3; i < j - 4; ++i) {
1702 end += tmpbuff[i];
1703 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1704 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
1705 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
1706 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
1707 complete = true;
1708 break;
1709 }
1710 }
1711 }
1712 }
1713 }
1714 end -= phaseoff;
1715 //didn't find second ST - ERROR
1716 if (!complete) {
1717 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1718 return false;
1719 }
1720 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);
1721 //now begin to trim out ST so we can use normal demod cmds
1722 start = skip;
1723 size_t datalen = end - start;
1724 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1725 if ( clk - (datalen % clk) <= clk/8) {
1726 // padd the amount off - could be problematic... but shouldn't happen often
1727 datalen += clk - (datalen % clk);
1728 } else if ( (datalen % clk) <= clk/8 ) {
1729 // padd the amount off - could be problematic... but shouldn't happen often
1730 datalen -= datalen % clk;
1731 } else {
1732 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1733 return false;
1734 }
1735 // if datalen is less than one t55xx block - ERROR
1736 if (datalen/clk < 8*4) {
1737 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1738 return false;
1739 }
1740 size_t dataloc = start;
1741 if (buffer[dataloc-(clk*4)-(clk/8)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
1742 //we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start
1743 for ( i=0; i <= (clk/8); ++i ) {
1744 if ( buffer[dataloc - (clk*4) - i] <= low ) {
1745 dataloc -= i;
1746 break;
1747 }
1748 }
1749 }
1750
1751 size_t newloc = 0;
1752 i=0;
1753 if (g_debugMode==2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);
1754
1755 // warning - overwriting buffer given with raw wave data with ST removed...
1756 while ( dataloc < bufsize-(clk/2) ) {
1757 //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)
1758 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1759 for(i=0; i < clk/2-tol; ++i) {
1760 buffer[dataloc+i] = high+5;
1761 }
1762 } //test for single sample outlier (high between two lows) in the case of very strong waves
1763 if (buffer[dataloc] >= high && buffer[dataloc+2] <= low) {
1764 buffer[dataloc] = buffer[dataloc+2];
1765 buffer[dataloc+1] = buffer[dataloc+2];
1766 }
1767 for (i=0; i<datalen; ++i) {
1768 if (i+newloc < bufsize) {
1769 if (i+newloc < dataloc)
1770 buffer[i+newloc] = buffer[dataloc];
1771
1772 dataloc++;
1773 }
1774 }
1775 newloc += i;
1776 //skip next ST - we just assume it will be there from now on...
1777 if (g_debugMode==2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
1778 dataloc += clk*4;
1779 }
1780 *size = newloc;
1781 return true;
1782 }
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