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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 <string.h>
13 #include "lfdemod.h"
14 #include "common.h"
15
16 /* //un_comment to allow debug print calls when used not on device
17 void dummy(char *fmt, ...){}
18
19 #ifndef ON_DEVICE
20 #include "ui.h"
21 #define prnt PrintAndLog
22 #else
23
24 #define prnt dummy
25 #endif
26 */
27
28 uint8_t justNoise(uint8_t *BitStream, size_t size)
29 {
30 static const uint8_t THRESHOLD = 123;
31 //test samples are not just noise
32 uint8_t justNoise1 = 1;
33 for(size_t idx=0; idx < size && justNoise1 ;idx++){
34 justNoise1 = BitStream[idx] < THRESHOLD;
35 }
36 return justNoise1;
37 }
38
39 //by marshmellow
40 //get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
41 int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
42 {
43 *high=0;
44 *low=255;
45 // get high and low thresholds
46 for (size_t i=0; i < size; i++){
47 if (BitStream[i] > *high) *high = BitStream[i];
48 if (BitStream[i] < *low) *low = BitStream[i];
49 }
50 if (*high < 123) return -1; // just noise
51 *high = ((*high-128)*fuzzHi + 12800)/100;
52 *low = ((*low-128)*fuzzLo + 12800)/100;
53 return 1;
54 }
55
56 // by marshmellow
57 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
58 // returns 1 if passed
59 uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
60 {
61 uint8_t ans = 0;
62 for (uint8_t i = 0; i < bitLen; i++){
63 ans ^= ((bits >> i) & 1);
64 }
65 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
66 return (ans == pType);
67 }
68
69 //by marshmellow
70 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
71 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
72 {
73 uint8_t foundCnt=0;
74 for (int idx=0; idx < *size - pLen; idx++){
75 if (memcmp(BitStream+idx, preamble, pLen) == 0){
76 //first index found
77 foundCnt++;
78 if (foundCnt == 1){
79 *startIdx = idx;
80 }
81 if (foundCnt == 2){
82 *size = idx - *startIdx;
83 return 1;
84 }
85 }
86 }
87 return 0;
88 }
89
90 //by marshmellow
91 //takes 1s and 0s and searches for EM410x format - output EM ID
92 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
93 {
94 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
95 // otherwise could be a void with no arguments
96 //set defaults
97 uint32_t i = 0;
98 if (BitStream[1]>1) return 0; //allow only 1s and 0s
99
100 // 111111111 bit pattern represent start of frame
101 // include 0 in front to help get start pos
102 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
103 uint32_t idx = 0;
104 uint32_t parityBits = 0;
105 uint8_t errChk = 0;
106 uint8_t FmtLen = 10;
107 *startIdx = 0;
108 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
109 if (errChk == 0 || *size < 64) return 0;
110 if (*size > 64) FmtLen = 22;
111 *startIdx += 1; //get rid of 0 from preamble
112 idx = *startIdx + 9;
113 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
114 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
115 //check even parity - quit if failed
116 if (parityTest(parityBits, 5, 0) == 0) return 0;
117 //set uint64 with ID from BitStream
118 for (uint8_t ii=0; ii<4; ii++){
119 *hi = (*hi << 1) | (*lo >> 63);
120 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
121 }
122 }
123 if (errChk != 0) return 1;
124 //skip last 5 bit parity test for simplicity.
125 // *size = 64 | 128;
126 return 0;
127 }
128
129 //by marshmellow
130 //demodulates strong heavily clipped samples
131 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
132 {
133 size_t bitCnt=0, smplCnt=0, errCnt=0;
134 uint8_t waveHigh = 0;
135 for (size_t i=0; i < *size; i++){
136 if (BinStream[i] >= high && waveHigh){
137 smplCnt++;
138 } else if (BinStream[i] <= low && !waveHigh){
139 smplCnt++;
140 } else { //transition
141 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
142 if (smplCnt > clk-(clk/4)-1) { //full clock
143 if (smplCnt > clk + (clk/4)+1) { //too many samples
144 errCnt++;
145 BinStream[bitCnt++]=7;
146 } else if (waveHigh) {
147 BinStream[bitCnt++] = invert;
148 BinStream[bitCnt++] = invert;
149 } else if (!waveHigh) {
150 BinStream[bitCnt++] = invert ^ 1;
151 BinStream[bitCnt++] = invert ^ 1;
152 }
153 waveHigh ^= 1;
154 smplCnt = 0;
155 } else if (smplCnt > (clk/2) - (clk/4)-1) {
156 if (waveHigh) {
157 BinStream[bitCnt++] = invert;
158 } else if (!waveHigh) {
159 BinStream[bitCnt++] = invert ^ 1;
160 }
161 waveHigh ^= 1;
162 smplCnt = 0;
163 } else if (!bitCnt) {
164 //first bit
165 waveHigh = (BinStream[i] >= high);
166 smplCnt = 1;
167 } else {
168 smplCnt++;
169 //transition bit oops
170 }
171 } else { //haven't hit new high or new low yet
172 smplCnt++;
173 }
174 }
175 }
176 *size = bitCnt;
177 return errCnt;
178 }
179
180 //by marshmellow
181 void askAmp(uint8_t *BitStream, size_t size)
182 {
183 for(size_t i = 1; i<size; i++){
184 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
185 BitStream[i]=127;
186 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
187 BitStream[i]=-127;
188 }
189 return;
190 }
191
192 //by marshmellow
193 //attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
194 int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
195 {
196 if (*size==0) return -1;
197 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
198 if (*clk==0 || start < 0) return -3;
199 if (*invert != 1) *invert = 0;
200 if (amp==1) askAmp(BinStream, *size);
201
202 uint8_t initLoopMax = 255;
203 if (initLoopMax > *size) initLoopMax = *size;
204 // Detect high and lows
205 //25% clip in case highs and lows aren't clipped [marshmellow]
206 int high, low;
207 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
208 return -2; //just noise
209
210 size_t errCnt = 0;
211 // if clean clipped waves detected run alternate demod
212 if (DetectCleanAskWave(BinStream, *size, high, low)) {
213 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
214 if (askType) //askman
215 return manrawdecode(BinStream, size, 0);
216 else //askraw
217 return errCnt;
218 }
219
220 int lastBit; //set first clock check - can go negative
221 size_t i, bitnum = 0; //output counter
222 uint8_t midBit = 0;
223 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
224 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
225 size_t MaxBits = 1024;
226 lastBit = start - *clk;
227
228 for (i = start; i < *size; ++i) {
229 if (i-lastBit >= *clk-tol){
230 if (BinStream[i] >= high) {
231 BinStream[bitnum++] = *invert;
232 } else if (BinStream[i] <= low) {
233 BinStream[bitnum++] = *invert ^ 1;
234 } else if (i-lastBit >= *clk+tol) {
235 if (bitnum > 0) {
236 BinStream[bitnum++]=7;
237 errCnt++;
238 }
239 } else { //in tolerance - looking for peak
240 continue;
241 }
242 midBit = 0;
243 lastBit += *clk;
244 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
245 if (BinStream[i] >= high) {
246 BinStream[bitnum++] = *invert;
247 } else if (BinStream[i] <= low) {
248 BinStream[bitnum++] = *invert ^ 1;
249 } else if (i-lastBit >= *clk/2+tol) {
250 BinStream[bitnum] = BinStream[bitnum-1];
251 bitnum++;
252 } else { //in tolerance - looking for peak
253 continue;
254 }
255 midBit = 1;
256 }
257 if (bitnum >= MaxBits) break;
258 }
259 *size = bitnum;
260 return errCnt;
261 }
262
263 //by marshmellow
264 //take 10 and 01 and manchester decode
265 //run through 2 times and take least errCnt
266 int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
267 {
268 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
269 size_t i, ii;
270 uint16_t bestErr = 1000, bestRun = 0;
271 if (*size < 16) return -1;
272 //find correct start position [alignment]
273 for (ii=0;ii<2;++ii){
274 for (i=ii; i<*size-3; i+=2)
275 if (BitStream[i]==BitStream[i+1])
276 errCnt++;
277
278 if (bestErr>errCnt){
279 bestErr=errCnt;
280 bestRun=ii;
281 }
282 errCnt=0;
283 }
284 //decode
285 for (i=bestRun; i < *size-3; i+=2){
286 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
287 BitStream[bitnum++]=invert;
288 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
289 BitStream[bitnum++]=invert^1;
290 } else {
291 BitStream[bitnum++]=7;
292 }
293 if(bitnum>MaxBits) break;
294 }
295 *size=bitnum;
296 return bestErr;
297 }
298
299 uint32_t manchesterEncode2Bytes(uint16_t datain) {
300 uint32_t output = 0;
301 uint8_t curBit = 0;
302 for (uint8_t i=0; i<16; i++) {
303 curBit = (datain >> (15-i) & 1);
304 output |= (1<<(((15-i)*2)+curBit));
305 }
306 return output;
307 }
308
309 //by marshmellow
310 //encode binary data into binary manchester
311 int ManchesterEncode(uint8_t *BitStream, size_t size)
312 {
313 size_t modIdx=20000, i=0;
314 if (size>modIdx) return -1;
315 for (size_t idx=0; idx < size; idx++){
316 BitStream[idx+modIdx++] = BitStream[idx];
317 BitStream[idx+modIdx++] = BitStream[idx]^1;
318 }
319 for (; i<(size*2); i++){
320 BitStream[i] = BitStream[i+20000];
321 }
322 return i;
323 }
324
325 //by marshmellow
326 //take 01 or 10 = 1 and 11 or 00 = 0
327 //check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
328 //decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
329 int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
330 {
331 uint16_t bitnum = 0;
332 uint16_t errCnt = 0;
333 size_t i = offset;
334 uint16_t MaxBits=512;
335 //if not enough samples - error
336 if (*size < 51) return -1;
337 //check for phase change faults - skip one sample if faulty
338 uint8_t offsetA = 1, offsetB = 1;
339 for (; i<48; i+=2){
340 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
341 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
342 }
343 if (!offsetA && offsetB) offset++;
344 for (i=offset; i<*size-3; i+=2){
345 //check for phase error
346 if (BitStream[i+1]==BitStream[i+2]) {
347 BitStream[bitnum++]=7;
348 errCnt++;
349 }
350 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
351 BitStream[bitnum++]=1^invert;
352 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
353 BitStream[bitnum++]=invert;
354 } else {
355 BitStream[bitnum++]=7;
356 errCnt++;
357 }
358 if(bitnum>MaxBits) break;
359 }
360 *size=bitnum;
361 return errCnt;
362 }
363
364 // by marshmellow
365 // demod gProxIIDemod
366 // error returns as -x
367 // success returns start position in BitStream
368 // BitStream must contain previously askrawdemod and biphasedemoded data
369 int gProxII_Demod(uint8_t BitStream[], size_t *size)
370 {
371 size_t startIdx=0;
372 uint8_t preamble[] = {1,1,1,1,1,0};
373
374 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
375 if (errChk == 0) return -3; //preamble not found
376 if (*size != 96) return -2; //should have found 96 bits
377 //check first 6 spacer bits to verify format
378 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
379 //confirmed proper separator bits found
380 //return start position
381 return (int) startIdx;
382 }
383 return -5;
384 }
385
386 //translate wave to 11111100000 (1 for each short wave 0 for each long wave)
387 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
388 {
389 size_t last_transition = 0;
390 size_t idx = 1;
391 //uint32_t maxVal=0;
392 if (fchigh==0) fchigh=10;
393 if (fclow==0) fclow=8;
394 //set the threshold close to 0 (graph) or 128 std to avoid static
395 uint8_t threshold_value = 123;
396 size_t preLastSample = 0;
397 size_t LastSample = 0;
398 size_t currSample = 0;
399 // sync to first lo-hi transition, and threshold
400
401 // Need to threshold first sample
402 // skip 160 samples to allow antenna/samples to settle
403 if(dest[160] < threshold_value) dest[0] = 0;
404 else dest[0] = 1;
405
406 size_t numBits = 0;
407 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
408 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
409 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
410 for(idx = 161; idx < size-20; idx++) {
411 // threshold current value
412
413 if (dest[idx] < threshold_value) dest[idx] = 0;
414 else dest[idx] = 1;
415
416 // Check for 0->1 transition
417 if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
418 preLastSample = LastSample;
419 LastSample = currSample;
420 currSample = idx-last_transition;
421 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
422 //do nothing with extra garbage
423 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves or 3-6 = 5
424 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
425 dest[numBits-1]=1; //correct previous 9 wave surrounded by 8 waves
426 }
427 dest[numBits++]=1;
428
429 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage
430 //do nothing with beginning garbage
431 } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
432 dest[numBits++]=1;
433 } else { //9+ = 10 sample waves
434 dest[numBits++]=0;
435 }
436 last_transition = idx;
437 }
438 }
439 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
440 }
441
442 //translate 11111100000 to 10
443 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
444 uint8_t invert, uint8_t fchigh, uint8_t fclow)
445 {
446 uint8_t lastval=dest[0];
447 size_t idx=0;
448 size_t numBits=0;
449 uint32_t n=1;
450 for( idx=1; idx < size; idx++) {
451 n++;
452 if (dest[idx]==lastval) continue;
453
454 //if lastval was 1, we have a 1->0 crossing
455 if (dest[idx-1]==1) {
456 n = (n * fclow + rfLen/2) / rfLen;
457 } else {// 0->1 crossing
458 n = (n * fchigh + rfLen/2) / rfLen;
459 }
460 if (n == 0) n = 1;
461
462 memset(dest+numBits, dest[idx-1]^invert , n);
463 numBits += n;
464 n=0;
465 lastval=dest[idx];
466 }//end for
467 // if valid extra bits at the end were all the same frequency - add them in
468 if (n > rfLen/fchigh) {
469 if (dest[idx-2]==1) {
470 n = (n * fclow + rfLen/2) / rfLen;
471 } else {
472 n = (n * fchigh + rfLen/2) / rfLen;
473 }
474 memset(dest+numBits, dest[idx-1]^invert , n);
475 numBits += n;
476 }
477 return numBits;
478 }
479
480 //by marshmellow (from holiman's base)
481 // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
482 int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
483 {
484 // FSK demodulator
485 size = fsk_wave_demod(dest, size, fchigh, fclow);
486 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
487 return size;
488 }
489
490 // loop to get raw HID waveform then FSK demodulate the TAG ID from it
491 int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
492 {
493 if (justNoise(dest, *size)) return -1;
494
495 size_t numStart=0, size2=*size, startIdx=0;
496 // FSK demodulator
497 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
498 if (*size < 96*2) return -2;
499 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
500 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
501 // find bitstring in array
502 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
503 if (errChk == 0) return -3; //preamble not found
504
505 numStart = startIdx + sizeof(preamble);
506 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
507 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
508 if (dest[idx] == dest[idx+1]){
509 return -4; //not manchester data
510 }
511 *hi2 = (*hi2<<1)|(*hi>>31);
512 *hi = (*hi<<1)|(*lo>>31);
513 //Then, shift in a 0 or one into low
514 if (dest[idx] && !dest[idx+1]) // 1 0
515 *lo=(*lo<<1)|1;
516 else // 0 1
517 *lo=(*lo<<1)|0;
518 }
519 return (int)startIdx;
520 }
521
522 // loop to get raw paradox waveform then FSK demodulate the TAG ID from it
523 int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
524 {
525 if (justNoise(dest, *size)) return -1;
526
527 size_t numStart=0, size2=*size, startIdx=0;
528 // FSK demodulator
529 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
530 if (*size < 96) return -2;
531
532 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
533 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
534
535 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
536 if (errChk == 0) return -3; //preamble not found
537
538 numStart = startIdx + sizeof(preamble);
539 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
540 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
541 if (dest[idx] == dest[idx+1])
542 return -4; //not manchester data
543 *hi2 = (*hi2<<1)|(*hi>>31);
544 *hi = (*hi<<1)|(*lo>>31);
545 //Then, shift in a 0 or one into low
546 if (dest[idx] && !dest[idx+1]) // 1 0
547 *lo=(*lo<<1)|1;
548 else // 0 1
549 *lo=(*lo<<1)|0;
550 }
551 return (int)startIdx;
552 }
553
554 uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
555 {
556 uint32_t num = 0;
557 for(int i = 0 ; i < numbits ; i++)
558 {
559 num = (num << 1) | (*src);
560 src++;
561 }
562 return num;
563 }
564
565 //least significant bit first
566 uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
567 {
568 uint32_t num = 0;
569 for(int i = 0 ; i < numbits ; i++)
570 {
571 num = (num << 1) | *(src + (numbits-(i+1)));
572 }
573 return num;
574 }
575
576 int IOdemodFSK(uint8_t *dest, size_t size)
577 {
578 if (justNoise(dest, size)) return -1;
579 //make sure buffer has data
580 if (size < 66*64) return -2;
581 // FSK demodulator
582 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
583 if (size < 65) return -3; //did we get a good demod?
584 //Index map
585 //0 10 20 30 40 50 60
586 //| | | | | | |
587 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
588 //-----------------------------------------------------------------------------
589 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
590 //
591 //XSF(version)facility:codeone+codetwo
592 //Handle the data
593 size_t startIdx = 0;
594 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
595 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
596 if (errChk == 0) return -4; //preamble not found
597
598 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
599 //confirmed proper separator bits found
600 //return start position
601 return (int) startIdx;
602 }
603 return -5;
604 }
605
606 // by marshmellow
607 // find viking preamble 0xF200 in already demoded data
608 int VikingDemod_AM(uint8_t *dest, size_t *size) {
609 //make sure buffer has data
610 if (*size < 64*2) return -2;
611
612 size_t startIdx = 0;
613 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};
614 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
615 if (errChk == 0) return -4; //preamble not found
616 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
617 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
618 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
619 if ( checkCalc != 0xA8 ) return -5;
620 if (*size != 64) return -6;
621 //return start position
622 return (int) startIdx;
623 }
624
625 // by marshmellow
626 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
627 // Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
628 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
629 {
630 uint32_t parityWd = 0;
631 size_t j = 0, bitCnt = 0;
632 for (int word = 0; word < (bLen); word+=pLen){
633 for (int bit=0; bit < pLen; bit++){
634 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
635 BitStream[j++] = (BitStream[startIdx+word+bit]);
636 }
637 j--; // overwrite parity with next data
638 // if parity fails then return 0
639 if (pType == 2) { // then marker bit which should be a 1
640 if (!BitStream[j]) return 0;
641 } else {
642 if (parityTest(parityWd, pLen, pType) == 0) return 0;
643 }
644 bitCnt+=(pLen-1);
645 parityWd = 0;
646 }
647 // if we got here then all the parities passed
648 //return ID start index and size
649 return bitCnt;
650 }
651
652 // Ask/Biphase Demod then try to locate an ISO 11784/85 ID
653 // BitStream must contain previously askrawdemod and biphasedemoded data
654 int FDXBdemodBI(uint8_t *dest, size_t *size)
655 {
656 //make sure buffer has enough data
657 if (*size < 128) return -1;
658
659 size_t startIdx = 0;
660 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
661
662 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
663 if (errChk == 0) return -2; //preamble not found
664 return (int)startIdx;
665 }
666
667 // by marshmellow
668 // FSK Demod then try to locate an AWID ID
669 int AWIDdemodFSK(uint8_t *dest, size_t *size)
670 {
671 //make sure buffer has enough data
672 if (*size < 96*50) return -1;
673
674 if (justNoise(dest, *size)) return -2;
675
676 // FSK demodulator
677 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
678 if (*size < 96) return -3; //did we get a good demod?
679
680 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
681 size_t startIdx = 0;
682 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
683 if (errChk == 0) return -4; //preamble not found
684 if (*size != 96) return -5;
685 return (int)startIdx;
686 }
687
688 // by marshmellow
689 // FSK Demod then try to locate a Farpointe Data (pyramid) ID
690 int PyramiddemodFSK(uint8_t *dest, size_t *size)
691 {
692 //make sure buffer has data
693 if (*size < 128*50) return -5;
694
695 //test samples are not just noise
696 if (justNoise(dest, *size)) return -1;
697
698 // FSK demodulator
699 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
700 if (*size < 128) return -2; //did we get a good demod?
701
702 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
703 size_t startIdx = 0;
704 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
705 if (errChk == 0) return -4; //preamble not found
706 if (*size != 128) return -3;
707 return (int)startIdx;
708 }
709
710 // by marshmellow
711 // to detect a wave that has heavily clipped (clean) samples
712 uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
713 {
714 bool allArePeaks = true;
715 uint16_t cntPeaks=0;
716 size_t loopEnd = 512+160;
717 if (loopEnd > size) loopEnd = size;
718 for (size_t i=160; i<loopEnd; i++){
719 if (dest[i]>low && dest[i]<high)
720 allArePeaks = false;
721 else
722 cntPeaks++;
723 }
724 if (!allArePeaks){
725 if (cntPeaks > 300) return true;
726 }
727 return allArePeaks;
728 }
729 // by marshmellow
730 // to help detect clocks on heavily clipped samples
731 // based on count of low to low
732 int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
733 {
734 uint8_t fndClk[] = {8,16,32,40,50,64,128};
735 size_t startwave;
736 size_t i = 100;
737 size_t minClk = 255;
738 // get to first full low to prime loop and skip incomplete first pulse
739 while ((dest[i] < high) && (i < size))
740 ++i;
741 while ((dest[i] > low) && (i < size))
742 ++i;
743
744 // loop through all samples
745 while (i < size) {
746 // measure from low to low
747 while ((dest[i] > low) && (i < size))
748 ++i;
749 startwave= i;
750 while ((dest[i] < high) && (i < size))
751 ++i;
752 while ((dest[i] > low) && (i < size))
753 ++i;
754 //get minimum measured distance
755 if (i-startwave < minClk && i < size)
756 minClk = i - startwave;
757 }
758 // set clock
759 //prnt("minClk: %d",minClk);
760 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
761 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
762 return fndClk[clkCnt];
763 }
764 return 0;
765 }
766
767 // by marshmellow
768 // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
769 // maybe somehow adjust peak trimming value based on samples to fix?
770 // return start index of best starting position for that clock and return clock (by reference)
771 int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
772 {
773 size_t i=1;
774 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
775 uint8_t clkEnd = 9;
776 uint8_t loopCnt = 255; //don't need to loop through entire array...
777 if (size <= loopCnt+60) return -1; //not enough samples
778 size -= 60; //sometimes there is a strange end wave - filter out this....
779 //if we already have a valid clock
780 uint8_t clockFnd=0;
781 for (;i<clkEnd;++i)
782 if (clk[i] == *clock) clockFnd = i;
783 //clock found but continue to find best startpos
784
785 //get high and low peak
786 int peak, low;
787 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
788
789 //test for large clean peaks
790 if (!clockFnd){
791 if (DetectCleanAskWave(dest, size, peak, low)==1){
792 int ans = DetectStrongAskClock(dest, size, peak, low);
793 for (i=clkEnd-1; i>0; i--){
794 if (clk[i] == ans) {
795 *clock = ans;
796 //clockFnd = i;
797 return 0; // for strong waves i don't use the 'best start position' yet...
798 //break; //clock found but continue to find best startpos [not yet]
799 }
800 }
801 }
802 }
803 uint8_t ii;
804 uint8_t clkCnt, tol = 0;
805 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
806 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
807 size_t errCnt = 0;
808 size_t arrLoc, loopEnd;
809
810 if (clockFnd>0) {
811 clkCnt = clockFnd;
812 clkEnd = clockFnd+1;
813 }
814 else clkCnt=1;
815
816 //test each valid clock from smallest to greatest to see which lines up
817 for(; clkCnt < clkEnd; clkCnt++){
818 if (clk[clkCnt] <= 32){
819 tol=1;
820 }else{
821 tol=0;
822 }
823 //if no errors allowed - keep start within the first clock
824 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
825 bestErr[clkCnt]=1000;
826 //try lining up the peaks by moving starting point (try first few clocks)
827 for (ii=0; ii < loopCnt; ii++){
828 if (dest[ii] < peak && dest[ii] > low) continue;
829
830 errCnt=0;
831 // now that we have the first one lined up test rest of wave array
832 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
833 for (i=0; i < loopEnd; ++i){
834 arrLoc = ii + (i * clk[clkCnt]);
835 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
836 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
837 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
838 }else{ //error no peak detected
839 errCnt++;
840 }
841 }
842 //if we found no errors then we can stop here and a low clock (common clocks)
843 // this is correct one - return this clock
844 //prnt("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
845 if(errCnt==0 && clkCnt<7) {
846 if (!clockFnd) *clock = clk[clkCnt];
847 return ii;
848 }
849 //if we found errors see if it is lowest so far and save it as best run
850 if(errCnt<bestErr[clkCnt]){
851 bestErr[clkCnt]=errCnt;
852 bestStart[clkCnt]=ii;
853 }
854 }
855 }
856 uint8_t iii;
857 uint8_t best=0;
858 for (iii=1; iii<clkEnd; ++iii){
859 if (bestErr[iii] < bestErr[best]){
860 if (bestErr[iii] == 0) bestErr[iii]=1;
861 // current best bit to error ratio vs new bit to error ratio
862 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
863 best = iii;
864 }
865 }
866 }
867 //if (bestErr[best] > maxErr) return -1;
868 if (!clockFnd) *clock = clk[best];
869 return bestStart[best];
870 }
871
872 //by marshmellow
873 //detect psk clock by reading each phase shift
874 // a phase shift is determined by measuring the sample length of each wave
875 int DetectPSKClock(uint8_t dest[], size_t size, int clock)
876 {
877 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
878 uint16_t loopCnt = 4096; //don't need to loop through entire array...
879 if (size == 0) return 0;
880 if (size<loopCnt) loopCnt = size-20;
881
882 //if we already have a valid clock quit
883 size_t i=1;
884 for (; i < 8; ++i)
885 if (clk[i] == clock) return clock;
886
887 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
888 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
889 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
890 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
891 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
892 fc = countFC(dest, size, 0);
893 if (fc!=2 && fc!=4 && fc!=8) return -1;
894 //prnt("DEBUG: FC: %d",fc);
895
896 //find first full wave
897 for (i=160; i<loopCnt; i++){
898 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
899 if (waveStart == 0) {
900 waveStart = i+1;
901 //prnt("DEBUG: waveStart: %d",waveStart);
902 } else {
903 waveEnd = i+1;
904 //prnt("DEBUG: waveEnd: %d",waveEnd);
905 waveLenCnt = waveEnd-waveStart;
906 if (waveLenCnt > fc){
907 firstFullWave = waveStart;
908 fullWaveLen=waveLenCnt;
909 break;
910 }
911 waveStart=0;
912 }
913 }
914 }
915 //prnt("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
916
917 //test each valid clock from greatest to smallest to see which lines up
918 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
919 lastClkBit = firstFullWave; //set end of wave as clock align
920 waveStart = 0;
921 errCnt=0;
922 peakcnt=0;
923 //prnt("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
924
925 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
926 //top edge of wave = start of new wave
927 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
928 if (waveStart == 0) {
929 waveStart = i+1;
930 waveLenCnt=0;
931 } else { //waveEnd
932 waveEnd = i+1;
933 waveLenCnt = waveEnd-waveStart;
934 if (waveLenCnt > fc){
935 //if this wave is a phase shift
936 //prnt("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
937 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
938 peakcnt++;
939 lastClkBit+=clk[clkCnt];
940 } else if (i<lastClkBit+8){
941 //noise after a phase shift - ignore
942 } else { //phase shift before supposed to based on clock
943 errCnt++;
944 }
945 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
946 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
947 }
948 waveStart=i+1;
949 }
950 }
951 }
952 if (errCnt == 0){
953 return clk[clkCnt];
954 }
955 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
956 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
957 }
958 //all tested with errors
959 //return the highest clk with the most peaks found
960 uint8_t best=7;
961 for (i=7; i>=1; i--){
962 if (peaksdet[i] > peaksdet[best]) {
963 best = i;
964 }
965 //prnt("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
966 }
967 return clk[best];
968 }
969
970 int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
971 //find shortest transition from high to low
972 size_t i = 0;
973 size_t transition1 = 0;
974 int lowestTransition = 255;
975 bool lastWasHigh = false;
976
977 //find first valid beginning of a high or low wave
978 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
979 ++i;
980 while ((dest[i] < peak && dest[i] > low) && (i < size))
981 ++i;
982 lastWasHigh = (dest[i] >= peak);
983
984 if (i==size) return 0;
985 transition1 = i;
986
987 for (;i < size; i++) {
988 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
989 lastWasHigh = (dest[i] >= peak);
990 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
991 transition1 = i;
992 }
993 }
994 //prnt("DEBUG: LowestTrs: %d",lowestTransition);
995 if (lowestTransition == 255) lowestTransition = 0;
996 return lowestTransition;
997 }
998
999 //by marshmellow
1000 //detect nrz clock by reading #peaks vs no peaks(or errors)
1001 int DetectNRZClock(uint8_t dest[], size_t size, int clock)
1002 {
1003 size_t i=0;
1004 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1005 size_t loopCnt = 4096; //don't need to loop through entire array...
1006 if (size == 0) return 0;
1007 if (size<loopCnt) loopCnt = size-20;
1008 //if we already have a valid clock quit
1009 for (; i < 8; ++i)
1010 if (clk[i] == clock) return clock;
1011
1012 //get high and low peak
1013 int peak, low;
1014 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
1015
1016 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
1017 size_t ii;
1018 uint8_t clkCnt;
1019 uint8_t tol = 0;
1020 uint16_t smplCnt = 0;
1021 int16_t peakcnt = 0;
1022 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1023 uint16_t maxPeak = 255;
1024 bool firstpeak = false;
1025 //test for large clipped waves
1026 for (i=0; i<loopCnt; i++){
1027 if (dest[i] >= peak || dest[i] <= low){
1028 if (!firstpeak) continue;
1029 smplCnt++;
1030 } else {
1031 firstpeak=true;
1032 if (smplCnt > 6 ){
1033 if (maxPeak > smplCnt){
1034 maxPeak = smplCnt;
1035 //prnt("maxPk: %d",maxPeak);
1036 }
1037 peakcnt++;
1038 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1039 smplCnt=0;
1040 }
1041 }
1042 }
1043 bool errBitHigh = 0;
1044 bool bitHigh = 0;
1045 uint8_t ignoreCnt = 0;
1046 uint8_t ignoreWindow = 4;
1047 bool lastPeakHigh = 0;
1048 int lastBit = 0;
1049 peakcnt=0;
1050 //test each valid clock from smallest to greatest to see which lines up
1051 for(clkCnt=0; clkCnt < 8; ++clkCnt){
1052 //ignore clocks smaller than smallest peak
1053 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
1054 //try lining up the peaks by moving starting point (try first 256)
1055 for (ii=20; ii < loopCnt; ++ii){
1056 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1057 peakcnt = 0;
1058 bitHigh = false;
1059 ignoreCnt = 0;
1060 lastBit = ii-clk[clkCnt];
1061 //loop through to see if this start location works
1062 for (i = ii; i < size-20; ++i) {
1063 //if we are at a clock bit
1064 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1065 //test high/low
1066 if (dest[i] >= peak || dest[i] <= low) {
1067 //if same peak don't count it
1068 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1069 peakcnt++;
1070 }
1071 lastPeakHigh = (dest[i] >= peak);
1072 bitHigh = true;
1073 errBitHigh = false;
1074 ignoreCnt = ignoreWindow;
1075 lastBit += clk[clkCnt];
1076 } else if (i == lastBit + clk[clkCnt] + tol) {
1077 lastBit += clk[clkCnt];
1078 }
1079 //else if not a clock bit and no peaks
1080 } else if (dest[i] < peak && dest[i] > low){
1081 if (ignoreCnt==0){
1082 bitHigh=false;
1083 if (errBitHigh==true) peakcnt--;
1084 errBitHigh=false;
1085 } else {
1086 ignoreCnt--;
1087 }
1088 // else if not a clock bit but we have a peak
1089 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1090 //error bar found no clock...
1091 errBitHigh=true;
1092 }
1093 }
1094 if(peakcnt>peaksdet[clkCnt]) {
1095 peaksdet[clkCnt]=peakcnt;
1096 }
1097 }
1098 }
1099 }
1100 int iii=7;
1101 uint8_t best=0;
1102 for (iii=7; iii > 0; iii--){
1103 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1104 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1105 best = iii;
1106 }
1107 } else if (peaksdet[iii] > peaksdet[best]){
1108 best = iii;
1109 }
1110 //prnt("DEBUG: Clk: %d, peaks: %d, maxPeak: %d, bestClk: %d, lowestTrs: %d",clk[iii],peaksdet[iii],maxPeak, clk[best], lowestTransition);
1111 }
1112
1113 return clk[best];
1114 }
1115
1116 // by marshmellow
1117 // convert psk1 demod to psk2 demod
1118 // only transition waves are 1s
1119 void psk1TOpsk2(uint8_t *BitStream, size_t size)
1120 {
1121 size_t i=1;
1122 uint8_t lastBit=BitStream[0];
1123 for (; i<size; i++){
1124 if (BitStream[i]==7){
1125 //ignore errors
1126 } else if (lastBit!=BitStream[i]){
1127 lastBit=BitStream[i];
1128 BitStream[i]=1;
1129 } else {
1130 BitStream[i]=0;
1131 }
1132 }
1133 return;
1134 }
1135
1136 // by marshmellow
1137 // convert psk2 demod to psk1 demod
1138 // from only transition waves are 1s to phase shifts change bit
1139 void psk2TOpsk1(uint8_t *BitStream, size_t size)
1140 {
1141 uint8_t phase=0;
1142 for (size_t i=0; i<size; i++){
1143 if (BitStream[i]==1){
1144 phase ^=1;
1145 }
1146 BitStream[i]=phase;
1147 }
1148 return;
1149 }
1150
1151 // redesigned by marshmellow adjusted from existing decode functions
1152 // indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
1153 int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1154 {
1155 //26 bit 40134 format (don't know other formats)
1156 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};
1157 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};
1158 size_t startidx = 0;
1159 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1160 // if didn't find preamble try again inverting
1161 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1162 *invert ^= 1;
1163 }
1164 if (*size != 64 && *size != 224) return -2;
1165 if (*invert==1)
1166 for (size_t i = startidx; i < *size; i++)
1167 bitStream[i] ^= 1;
1168
1169 return (int) startidx;
1170 }
1171
1172 // by marshmellow - demodulate NRZ wave
1173 // peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
1174 int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
1175 if (justNoise(dest, *size)) return -1;
1176 *clk = DetectNRZClock(dest, *size, *clk);
1177 if (*clk==0) return -2;
1178 size_t i, gLen = 4096;
1179 if (gLen>*size) gLen = *size-20;
1180 int high, low;
1181 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
1182
1183 uint8_t bit=0;
1184 //convert wave samples to 1's and 0's
1185 for(i=20; i < *size-20; i++){
1186 if (dest[i] >= high) bit = 1;
1187 if (dest[i] <= low) bit = 0;
1188 dest[i] = bit;
1189 }
1190 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1191 size_t lastBit = 0;
1192 size_t numBits = 0;
1193 for(i=21; i < *size-20; i++) {
1194 //if transition detected or large number of same bits - store the passed bits
1195 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1196 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1197 numBits += (i - lastBit + (*clk/4)) / *clk;
1198 lastBit = i-1;
1199 }
1200 }
1201 *size = numBits;
1202 return 0;
1203 }
1204
1205 //by marshmellow
1206 //detects the bit clock for FSK given the high and low Field Clocks
1207 uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1208 {
1209 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1210 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1211 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1212 uint8_t rfLensFnd = 0;
1213 uint8_t lastFCcnt = 0;
1214 uint16_t fcCounter = 0;
1215 uint16_t rfCounter = 0;
1216 uint8_t firstBitFnd = 0;
1217 size_t i;
1218 if (size == 0) return 0;
1219
1220 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
1221 rfLensFnd=0;
1222 fcCounter=0;
1223 rfCounter=0;
1224 firstBitFnd=0;
1225 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
1226 // prime i to first peak / up transition
1227 for (i = 160; i < size-20; i++)
1228 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1229 break;
1230
1231 for (; i < size-20; i++){
1232 fcCounter++;
1233 rfCounter++;
1234
1235 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1236 continue;
1237 // else new peak
1238 // if we got less than the small fc + tolerance then set it to the small fc
1239 if (fcCounter < fcLow+fcTol)
1240 fcCounter = fcLow;
1241 else //set it to the large fc
1242 fcCounter = fcHigh;
1243
1244 //look for bit clock (rf/xx)
1245 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1246 //not the same size as the last wave - start of new bit sequence
1247 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1248 for (int ii=0; ii<15; ii++){
1249 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
1250 rfCnts[ii]++;
1251 rfCounter = 0;
1252 break;
1253 }
1254 }
1255 if (rfCounter > 0 && rfLensFnd < 15){
1256 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1257 rfCnts[rfLensFnd]++;
1258 rfLens[rfLensFnd++] = rfCounter;
1259 }
1260 } else {
1261 firstBitFnd++;
1262 }
1263 rfCounter=0;
1264 lastFCcnt=fcCounter;
1265 }
1266 fcCounter=0;
1267 }
1268 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1269
1270 for (i=0; i<15; i++){
1271 //prnt("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
1272 //get highest 2 RF values (might need to get more values to compare or compare all?)
1273 if (rfCnts[i]>rfCnts[rfHighest]){
1274 rfHighest3=rfHighest2;
1275 rfHighest2=rfHighest;
1276 rfHighest=i;
1277 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1278 rfHighest3=rfHighest2;
1279 rfHighest2=i;
1280 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1281 rfHighest3=i;
1282 }
1283 }
1284 // set allowed clock remainder tolerance to be 1 large field clock length+1
1285 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1286 uint8_t tol1 = fcHigh+1;
1287
1288 //prnt("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
1289
1290 // loop to find the highest clock that has a remainder less than the tolerance
1291 // compare samples counted divided by
1292 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
1293 int ii=7;
1294 for (; ii>=2; ii--){
1295 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1296 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1297 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1298 break;
1299 }
1300 }
1301 }
1302 }
1303
1304 if (ii<0) return 0; // oops we went too far
1305
1306 return clk[ii];
1307 }
1308
1309 //by marshmellow
1310 //countFC is to detect the field clock lengths.
1311 //counts and returns the 2 most common wave lengths
1312 //mainly used for FSK field clock detection
1313 uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
1314 {
1315 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1316 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1317 uint8_t fcLensFnd = 0;
1318 uint8_t lastFCcnt=0;
1319 uint8_t fcCounter = 0;
1320 size_t i;
1321 if (size == 0) return 0;
1322
1323 // prime i to first up transition
1324 for (i = 160; i < size-20; i++)
1325 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1326 break;
1327
1328 for (; i < size-20; i++){
1329 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1330 // new up transition
1331 fcCounter++;
1332 if (fskAdj){
1333 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1334 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1335 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1336 if ((fcCounter==9) || fcCounter==4) fcCounter++;
1337 // save last field clock count (fc/xx)
1338 lastFCcnt = fcCounter;
1339 }
1340 // find which fcLens to save it to:
1341 for (int ii=0; ii<15; ii++){
1342 if (fcLens[ii]==fcCounter){
1343 fcCnts[ii]++;
1344 fcCounter=0;
1345 break;
1346 }
1347 }
1348 if (fcCounter>0 && fcLensFnd<15){
1349 //add new fc length
1350 fcCnts[fcLensFnd]++;
1351 fcLens[fcLensFnd++]=fcCounter;
1352 }
1353 fcCounter=0;
1354 } else {
1355 // count sample
1356 fcCounter++;
1357 }
1358 }
1359
1360 uint8_t best1=14, best2=14, best3=14;
1361 uint16_t maxCnt1=0;
1362 // go through fclens and find which ones are bigest 2
1363 for (i=0; i<15; i++){
1364 //prnt("DEBUG: FC %d, Cnt %d",fcLens[i],fcCnts[i]);
1365 // get the 3 best FC values
1366 if (fcCnts[i]>maxCnt1) {
1367 best3=best2;
1368 best2=best1;
1369 maxCnt1=fcCnts[i];
1370 best1=i;
1371 } else if(fcCnts[i]>fcCnts[best2]){
1372 best3=best2;
1373 best2=i;
1374 } else if(fcCnts[i]>fcCnts[best3]){
1375 best3=i;
1376 }
1377 }
1378 if (fcLens[best1]==0) return 0;
1379 uint8_t fcH=0, fcL=0;
1380 if (fcLens[best1]>fcLens[best2]){
1381 fcH=fcLens[best1];
1382 fcL=fcLens[best2];
1383 } else{
1384 fcH=fcLens[best2];
1385 fcL=fcLens[best1];
1386 }
1387 //prnt("DEBUG: dd %d > %d",(size-180)/fcH/3,fcCnts[best1]+fcCnts[best2]);
1388 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) return 0; //lots of waves not psk or fsk
1389
1390 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1391
1392 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
1393 //prnt("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
1394 if (fskAdj) return fcs;
1395 return fcLens[best1];
1396 }
1397
1398 //by marshmellow - demodulate PSK1 wave
1399 //uses wave lengths (# Samples)
1400 int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1401 {
1402 if (size == 0) return -1;
1403 uint16_t loopCnt = 4096; //don't need to loop through entire array...
1404 if (*size<loopCnt) loopCnt = *size;
1405
1406 size_t numBits=0;
1407 uint8_t curPhase = *invert;
1408 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1409 uint8_t fc=0, fullWaveLen=0, tol=1;
1410 uint16_t errCnt=0, waveLenCnt=0;
1411 fc = countFC(dest, *size, 0);
1412 if (fc!=2 && fc!=4 && fc!=8) return -1;
1413 //PrintAndLog("DEBUG: FC: %d",fc);
1414 *clock = DetectPSKClock(dest, *size, *clock);
1415 if (*clock == 0) return -1;
1416 int avgWaveVal=0, lastAvgWaveVal=0;
1417 //find first phase shift
1418 for (i=0; i<loopCnt; i++){
1419 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1420 waveEnd = i+1;
1421 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1422 waveLenCnt = waveEnd-waveStart;
1423 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
1424 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1425 firstFullWave = waveStart;
1426 fullWaveLen=waveLenCnt;
1427 //if average wave value is > graph 0 then it is an up wave or a 1
1428 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
1429 break;
1430 }
1431 waveStart = i+1;
1432 avgWaveVal = 0;
1433 }
1434 avgWaveVal += dest[i+2];
1435 }
1436 if (firstFullWave == 0) {
1437 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1438 // so skip a little to ensure we are past any Start Signal
1439 firstFullWave = 160;
1440 memset(dest, curPhase, firstFullWave / *clock);
1441 } else {
1442 memset(dest, curPhase^1, firstFullWave / *clock);
1443 }
1444 //advance bits
1445 numBits += (firstFullWave / *clock);
1446 //set start of wave as clock align
1447 lastClkBit = firstFullWave;
1448 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
1449 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1450 waveStart = 0;
1451 dest[numBits++] = curPhase; //set first read bit
1452 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
1453 //top edge of wave = start of new wave
1454 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1455 if (waveStart == 0) {
1456 waveStart = i+1;
1457 waveLenCnt = 0;
1458 avgWaveVal = dest[i+1];
1459 } else { //waveEnd
1460 waveEnd = i+1;
1461 waveLenCnt = waveEnd-waveStart;
1462 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1463 if (waveLenCnt > fc){
1464 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
1465 //this wave is a phase shift
1466 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1467 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
1468 curPhase ^= 1;
1469 dest[numBits++] = curPhase;
1470 lastClkBit += *clock;
1471 } else if (i < lastClkBit+10+fc){
1472 //noise after a phase shift - ignore
1473 } else { //phase shift before supposed to based on clock
1474 errCnt++;
1475 dest[numBits++] = 7;
1476 }
1477 } else if (i+1 > lastClkBit + *clock + tol + fc){
1478 lastClkBit += *clock; //no phase shift but clock bit
1479 dest[numBits++] = curPhase;
1480 }
1481 avgWaveVal = 0;
1482 waveStart = i+1;
1483 }
1484 }
1485 avgWaveVal += dest[i+1];
1486 }
1487 *size = numBits;
1488 return errCnt;
1489 }
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