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eb191de6 1//-----------------------------------------------------------------------------
ba1a299c 2// Copyright (C) 2014
eb191de6 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//-----------------------------------------------------------------------------
1e090a61 8// Low frequency demod/decode commands
eb191de6 9//-----------------------------------------------------------------------------
10
eb191de6 11#include <stdlib.h>
12#include <string.h>
eb191de6 13#include "lfdemod.h"
6426f6ba 14#include "common.h"
15
16/* //un_comment to allow debug print calls when used not on device
17void 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
a1d17964 28uint8_t justNoise(uint8_t *BitStream, size_t size)
29{
30 static const uint8_t THRESHOLD = 123;
31 //test samples are not just noise
32 uint8_t justNoise1 = 1;
33 for(size_t idx=0; idx < size && justNoise1 ;idx++){
34 justNoise1 = BitStream[idx] < THRESHOLD;
35 }
36 return justNoise1;
37}
38
1e090a61 39//by marshmellow
872e3d4d 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
1e090a61 41int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
42{
43 *high=0;
44 *low=255;
45 // get high and low thresholds
2eec55c8 46 for (size_t i=0; i < size; i++){
1e090a61 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
75cbbe9a 51 *high = ((*high-128)*fuzzHi + 12800)/100;
52 *low = ((*low-128)*fuzzLo + 12800)/100;
1e090a61 53 return 1;
54}
55
a1d17964 56// by marshmellow
57// pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
58// returns 1 if passed
59uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
60{
61 uint8_t ans = 0;
62 for (uint8_t i = 0; i < bitLen; i++){
63 ans ^= ((bits >> i) & 1);
64 }
f3bf15e4 65 //PrintAndLog("DEBUG: ans: %d, ptype: %d",ans,pType);
a1d17964 66 return (ans == pType);
67}
68
69//by marshmellow
2147c307 70//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
a1d17964 71uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
72{
e0165dcf 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;
a1d17964 88}
89
2147c307 90//by marshmellow
91//takes 1s and 0s and searches for EM410x format - output EM ID
92uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
93{
e0165dcf 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;
2767fc02 98 if (BitStream[1]>1) return 0; //allow only 1s and 0s
99
e0165dcf 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);
2eec55c8 115 //check even parity - quit if failed
116 if (parityTest(parityBits, 5, 0) == 0) return 0;
e0165dcf 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;
2147c307 127}
128
fef74fdc 129//by marshmellow
130//demodulates strong heavily clipped samples
23f0a7d8 131int 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;
23f0a7d8 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++;
2767fc02 145 BinStream[bitCnt++]=7;
23f0a7d8 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
eb191de6 180//by marshmellow
fef74fdc 181void 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
194int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
eb191de6 195{
fef74fdc 196 if (*size==0) return -1;
6e984446 197 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
2eec55c8 198 if (*clk==0 || start < 0) return -3;
fef74fdc 199 if (*invert != 1) *invert = 0;
200 if (amp==1) askAmp(BinStream, *size);
201
2eec55c8 202 uint8_t initLoopMax = 255;
203 if (initLoopMax > *size) initLoopMax = *size;
ba1a299c 204 // Detect high and lows
fef74fdc 205 //25% clip in case highs and lows aren't clipped [marshmellow]
2eec55c8 206 int high, low;
fef74fdc 207 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
208 return -2; //just noise
ba1a299c 209
fef74fdc 210 size_t errCnt = 0;
23f0a7d8 211 // if clean clipped waves detected run alternate demod
212 if (DetectCleanAskWave(BinStream, *size, high, low)) {
fef74fdc 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;
23f0a7d8 218 }
219
fef74fdc 220 int lastBit; //set first clock check - can go negative
221 size_t i, bitnum = 0; //output counter
222 uint8_t midBit = 0;
2eec55c8 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
fef74fdc 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;
6e984446 226 lastBit = start - *clk;
fef74fdc 227
6e984446 228 for (i = start; i < *size; ++i) {
fef74fdc 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;
2eec55c8 243 lastBit += *clk;
fef74fdc 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;
2eec55c8 256 }
257 if (bitnum >= MaxBits) break;
ba1a299c 258 }
2eec55c8 259 *size = bitnum;
6e984446 260 return errCnt;
eb191de6 261}
262
263//by marshmellow
264//take 10 and 01 and manchester decode
265//run through 2 times and take least errCnt
fef74fdc 266int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
eb191de6 267{
13d77ef9 268 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
269 size_t i, ii;
270 uint16_t bestErr = 1000, bestRun = 0;
fef74fdc 271 if (*size < 16) return -1;
2767fc02 272 //find correct start position [alignment]
13d77ef9 273 for (ii=0;ii<2;++ii){
fef74fdc 274 for (i=ii; i<*size-3; i+=2)
2eec55c8 275 if (BitStream[i]==BitStream[i+1])
ba1a299c 276 errCnt++;
2eec55c8 277
ba1a299c 278 if (bestErr>errCnt){
279 bestErr=errCnt;
280 bestRun=ii;
281 }
282 errCnt=0;
283 }
2767fc02 284 //decode
fef74fdc 285 for (i=bestRun; i < *size-3; i+=2){
23f0a7d8 286 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
fef74fdc 287 BitStream[bitnum++]=invert;
23f0a7d8 288 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
fef74fdc 289 BitStream[bitnum++]=invert^1;
23f0a7d8 290 } else {
2767fc02 291 BitStream[bitnum++]=7;
ba1a299c 292 }
23f0a7d8 293 if(bitnum>MaxBits) break;
ba1a299c 294 }
23f0a7d8 295 *size=bitnum;
2eec55c8 296 return bestErr;
f822a063 297}
298
1d0ccbe0 299uint32_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
fef74fdc 309//by marshmellow
310//encode binary data into binary manchester
311int 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
f822a063 325//by marshmellow
2147c307 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
13d77ef9 328//decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
1e090a61 329int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
f822a063 330{
2eec55c8 331 uint16_t bitnum = 0;
332 uint16_t errCnt = 0;
333 size_t i = offset;
2147c307 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
13d77ef9 346 if (BitStream[i+1]==BitStream[i+2]) {
2767fc02 347 BitStream[bitnum++]=7;
2147c307 348 errCnt++;
349 }
ba1a299c 350 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
1e090a61 351 BitStream[bitnum++]=1^invert;
ba1a299c 352 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
1e090a61 353 BitStream[bitnum++]=invert;
ba1a299c 354 } else {
2767fc02 355 BitStream[bitnum++]=7;
ba1a299c 356 errCnt++;
357 }
6de43508 358 if(bitnum>MaxBits) break;
ba1a299c 359 }
360 *size=bitnum;
361 return errCnt;
eb191de6 362}
363
fef74fdc 364// by marshmellow
11081e04 365// demod gProxIIDemod
366// error returns as -x
367// success returns start position in BitStream
368// BitStream must contain previously askrawdemod and biphasedemoded data
369int 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
ba1a299c 386//translate wave to 11111100000 (1 for each short wave 0 for each long wave)
f822a063 387size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
eb191de6 388{
2eec55c8 389 size_t last_transition = 0;
390 size_t idx = 1;
ac3ba7ee 391 //uint32_t maxVal=0;
ba1a299c 392 if (fchigh==0) fchigh=10;
393 if (fclow==0) fclow=8;
84871873 394 //set the threshold close to 0 (graph) or 128 std to avoid static
395 uint8_t threshold_value = 123;
ac2df346 396 size_t preLastSample = 0;
397 size_t LastSample = 0;
398 size_t currSample = 0;
ba1a299c 399 // sync to first lo-hi transition, and threshold
400
401 // Need to threshold first sample
6426f6ba 402 // skip 160 samples to allow antenna/samples to settle
403 if(dest[160] < threshold_value) dest[0] = 0;
ba1a299c 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
6426f6ba 410 for(idx = 161; idx < size-20; idx++) {
ba1a299c 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
ac2df346 418 preLastSample = LastSample;
419 LastSample = currSample;
420 currSample = idx-last_transition;
6426f6ba 421 if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
ba1a299c 422 //do nothing with extra garbage
6426f6ba 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
ac2df346 426 }
2eec55c8 427 dest[numBits++]=1;
ac2df346 428
6426f6ba 429 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage
13d77ef9 430 //do nothing with beginning garbage
ac2df346 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
2eec55c8 434 dest[numBits++]=0;
ba1a299c 435 }
436 last_transition = idx;
ba1a299c 437 }
438 }
439 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
eb191de6 440}
441
ba1a299c 442//translate 11111100000 to 10
2eec55c8 443size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
e0165dcf 444 uint8_t invert, uint8_t fchigh, uint8_t fclow)
eb191de6 445{
ba1a299c 446 uint8_t lastval=dest[0];
2eec55c8 447 size_t idx=0;
ba1a299c 448 size_t numBits=0;
449 uint32_t n=1;
ba1a299c 450 for( idx=1; idx < size; idx++) {
13d77ef9 451 n++;
2eec55c8 452 if (dest[idx]==lastval) continue;
453
ba1a299c 454 //if lastval was 1, we have a 1->0 crossing
13d77ef9 455 if (dest[idx-1]==1) {
75cbbe9a 456 n = (n * fclow + rfLen/2) / rfLen;
13d77ef9 457 } else {// 0->1 crossing
75cbbe9a 458 n = (n * fchigh + rfLen/2) / rfLen;
ba1a299c 459 }
460 if (n == 0) n = 1;
461
2eec55c8 462 memset(dest+numBits, dest[idx-1]^invert , n);
463 numBits += n;
ba1a299c 464 n=0;
465 lastval=dest[idx];
466 }//end for
13d77ef9 467 // if valid extra bits at the end were all the same frequency - add them in
75cbbe9a 468 if (n > rfLen/fchigh) {
13d77ef9 469 if (dest[idx-2]==1) {
75cbbe9a 470 n = (n * fclow + rfLen/2) / rfLen;
13d77ef9 471 } else {
75cbbe9a 472 n = (n * fchigh + rfLen/2) / rfLen;
13d77ef9 473 }
2eec55c8 474 memset(dest+numBits, dest[idx-1]^invert , n);
13d77ef9 475 numBits += n;
476 }
ba1a299c 477 return numBits;
eb191de6 478}
6426f6ba 479
eb191de6 480//by marshmellow (from holiman's base)
481// full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
f822a063 482int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
eb191de6 483{
ba1a299c 484 // FSK demodulator
485 size = fsk_wave_demod(dest, size, fchigh, fclow);
2eec55c8 486 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
ba1a299c 487 return size;
eb191de6 488}
a1d17964 489
eb191de6 490// loop to get raw HID waveform then FSK demodulate the TAG ID from it
ec75f5c1 491int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
eb191de6 492{
e0165dcf 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
2eec55c8 498 if (*size < 96*2) return -2;
e0165dcf 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;
eb191de6 520}
521
ec75f5c1 522// loop to get raw paradox waveform then FSK demodulate the TAG ID from it
a1d17964 523int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
ec75f5c1 524{
a1d17964 525 if (justNoise(dest, *size)) return -1;
526
527 size_t numStart=0, size2=*size, startIdx=0;
ec75f5c1 528 // FSK demodulator
a1d17964 529 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
530 if (*size < 96) return -2;
ec75f5c1 531
a1d17964 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;
ec75f5c1 550 }
a1d17964 551 return (int)startIdx;
ec75f5c1 552}
553
ba1a299c 554uint32_t bytebits_to_byte(uint8_t* src, size_t numbits)
eb191de6 555{
ba1a299c 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;
eb191de6 563}
564
ad6219fc 565//least significant bit first
566uint32_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
eb191de6 576int IOdemodFSK(uint8_t *dest, size_t size)
577{
a1d17964 578 if (justNoise(dest, size)) return -1;
ba1a299c 579 //make sure buffer has data
a1d17964 580 if (size < 66*64) return -2;
ba1a299c 581 // FSK demodulator
a1d17964 582 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
583 if (size < 65) return -3; //did we get a good demod?
ba1a299c 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
a1d17964 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
eb191de6 597
a1d17964 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;
1e090a61 602 }
a1d17964 603 return -5;
1e090a61 604}
605
70459879 606// by marshmellow
607// find viking preamble 0xF200 in already demoded data
608int VikingDemod_AM(uint8_t *dest, size_t *size) {
70459879 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;
57c7b44b 620 if (*size != 64) return -6;
70459879 621 //return start position
622 return (int) startIdx;
623}
624
1e090a61 625// by marshmellow
626// takes a array of binary values, start position, length of bits per parity (includes parity bit),
ac2df346 627// Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
1e090a61 628size_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];
f3bf15e4 635 BitStream[j++] = (BitStream[startIdx+word+bit]);
1e090a61 636 }
ac2df346 637 j--; // overwrite parity with next data
1e090a61 638 // if parity fails then return 0
ac2df346 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;
ad6219fc 643 }
1e090a61 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}
ad6219fc 651
615f21dd 652// Ask/Biphase Demod then try to locate an ISO 11784/85 ID
0df669a2 653// BitStream must contain previously askrawdemod and biphasedemoded data
ad6219fc 654int FDXBdemodBI(uint8_t *dest, size_t *size)
615f21dd 655{
656 //make sure buffer has enough data
0df669a2 657 if (*size < 128) return -1;
615f21dd 658
615f21dd 659 size_t startIdx = 0;
0df669a2 660 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
661
615f21dd 662 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
0df669a2 663 if (errChk == 0) return -2; //preamble not found
615f21dd 664 return (int)startIdx;
665}
1e090a61 666
667// by marshmellow
668// FSK Demod then try to locate an AWID ID
a1d17964 669int AWIDdemodFSK(uint8_t *dest, size_t *size)
1e090a61 670{
a1d17964 671 //make sure buffer has enough data
672 if (*size < 96*50) return -1;
673
674 if (justNoise(dest, *size)) return -2;
1e090a61 675
676 // FSK demodulator
a1d17964 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;
1e090a61 686}
687
688// by marshmellow
6426f6ba 689// FSK Demod then try to locate a Farpointe Data (pyramid) ID
a1d17964 690int PyramiddemodFSK(uint8_t *dest, size_t *size)
1e090a61 691{
f3bf15e4 692 //make sure buffer has data
693 if (*size < 128*50) return -5;
a1d17964 694
f3bf15e4 695 //test samples are not just noise
696 if (justNoise(dest, *size)) return -1;
1e090a61 697
f3bf15e4 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?
a1d17964 701
f3bf15e4 702 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
a1d17964 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;
1e090a61 708}
709
fef74fdc 710// by marshmellow
711// to detect a wave that has heavily clipped (clean) samples
cc15a118 712uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
6de43508 713{
6426f6ba 714 bool allArePeaks = true;
6de43508 715 uint16_t cntPeaks=0;
6426f6ba 716 size_t loopEnd = 512+160;
1fbf8956 717 if (loopEnd > size) loopEnd = size;
6426f6ba 718 for (size_t i=160; i<loopEnd; i++){
6de43508 719 if (dest[i]>low && dest[i]<high)
6426f6ba 720 allArePeaks = false;
6de43508 721 else
722 cntPeaks++;
723 }
6426f6ba 724 if (!allArePeaks){
725 if (cntPeaks > 300) return true;
6de43508 726 }
6426f6ba 727 return allArePeaks;
6de43508 728}
2eec55c8 729// by marshmellow
730// to help detect clocks on heavily clipped samples
cc15a118 731// based on count of low to low
732int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
13d77ef9 733{
cc15a118 734 uint8_t fndClk[] = {8,16,32,40,50,64,128};
735 size_t startwave;
6426f6ba 736 size_t i = 100;
cc15a118 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;
13d77ef9 757 }
cc15a118 758 // set clock
6426f6ba 759 //prnt("minClk: %d",minClk);
cc15a118 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];
13d77ef9 763 }
cc15a118 764 return 0;
13d77ef9 765}
766
eb191de6 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?
6de43508 770// return start index of best starting position for that clock and return clock (by reference)
771int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
eb191de6 772{
6e984446 773 size_t i=1;
cc15a118 774 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
775 uint8_t clkEnd = 9;
2eec55c8 776 uint8_t loopCnt = 255; //don't need to loop through entire array...
6426f6ba 777 if (size <= loopCnt+60) return -1; //not enough samples
778 size -= 60; //sometimes there is a strange end wave - filter out this....
6e984446 779 //if we already have a valid clock
780 uint8_t clockFnd=0;
cc15a118 781 for (;i<clkEnd;++i)
782 if (clk[i] == *clock) clockFnd = i;
6e984446 783 //clock found but continue to find best startpos
e0165dcf 784
785 //get high and low peak
786 int peak, low;
2eec55c8 787 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
e0165dcf 788
789 //test for large clean peaks
cc15a118 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 }
e0165dcf 800 }
801 }
802 }
cc15a118 803
2eec55c8 804 uint8_t ii;
805 uint8_t clkCnt, tol = 0;
806 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
807 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
808 size_t errCnt = 0;
809 size_t arrLoc, loopEnd;
6e984446 810
cc15a118 811 if (clockFnd>0) {
812 clkCnt = clockFnd;
813 clkEnd = clockFnd+1;
814 }
815 else clkCnt=1;
816
817 //test each valid clock from smallest to greatest to see which lines up
818 for(; clkCnt < clkEnd; clkCnt++){
fef74fdc 819 if (clk[clkCnt] <= 32){
e0165dcf 820 tol=1;
821 }else{
822 tol=0;
823 }
2767fc02 824 //if no errors allowed - keep start within the first clock
cc15a118 825 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
e0165dcf 826 bestErr[clkCnt]=1000;
6e984446 827 //try lining up the peaks by moving starting point (try first few clocks)
cc15a118 828 for (ii=0; ii < loopCnt; ii++){
2eec55c8 829 if (dest[ii] < peak && dest[ii] > low) continue;
830
831 errCnt=0;
832 // now that we have the first one lined up test rest of wave array
833 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
834 for (i=0; i < loopEnd; ++i){
835 arrLoc = ii + (i * clk[clkCnt]);
836 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
837 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
838 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
839 }else{ //error no peak detected
840 errCnt++;
e0165dcf 841 }
842 }
cc15a118 843 //if we found no errors then we can stop here and a low clock (common clocks)
2eec55c8 844 // this is correct one - return this clock
6426f6ba 845 //prnt("DEBUG: clk %d, err %d, ii %d, i %d",clk[clkCnt],errCnt,ii,i);
cc15a118 846 if(errCnt==0 && clkCnt<7) {
847 if (!clockFnd) *clock = clk[clkCnt];
2eec55c8 848 return ii;
849 }
850 //if we found errors see if it is lowest so far and save it as best run
851 if(errCnt<bestErr[clkCnt]){
852 bestErr[clkCnt]=errCnt;
853 bestStart[clkCnt]=ii;
854 }
e0165dcf 855 }
856 }
cc15a118 857 uint8_t iii;
e0165dcf 858 uint8_t best=0;
cc15a118 859 for (iii=1; iii<clkEnd; ++iii){
2eec55c8 860 if (bestErr[iii] < bestErr[best]){
861 if (bestErr[iii] == 0) bestErr[iii]=1;
e0165dcf 862 // current best bit to error ratio vs new bit to error ratio
2eec55c8 863 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
e0165dcf 864 best = iii;
865 }
866 }
867 }
2767fc02 868 //if (bestErr[best] > maxErr) return -1;
cc15a118 869 if (!clockFnd) *clock = clk[best];
e0165dcf 870 return bestStart[best];
eb191de6 871}
ba1a299c 872
873//by marshmellow
6de43508 874//detect psk clock by reading each phase shift
875// a phase shift is determined by measuring the sample length of each wave
876int DetectPSKClock(uint8_t dest[], size_t size, int clock)
ba1a299c 877{
e0165dcf 878 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
879 uint16_t loopCnt = 4096; //don't need to loop through entire array...
880 if (size == 0) return 0;
6426f6ba 881 if (size<loopCnt) loopCnt = size-20;
e0165dcf 882
883 //if we already have a valid clock quit
884 size_t i=1;
885 for (; i < 8; ++i)
886 if (clk[i] == clock) return clock;
887
888 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
889 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
890 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
891 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
892 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
2eec55c8 893 fc = countFC(dest, size, 0);
894 if (fc!=2 && fc!=4 && fc!=8) return -1;
6426f6ba 895 //prnt("DEBUG: FC: %d",fc);
e0165dcf 896
897 //find first full wave
6426f6ba 898 for (i=160; i<loopCnt; i++){
e0165dcf 899 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
900 if (waveStart == 0) {
901 waveStart = i+1;
6426f6ba 902 //prnt("DEBUG: waveStart: %d",waveStart);
e0165dcf 903 } else {
904 waveEnd = i+1;
6426f6ba 905 //prnt("DEBUG: waveEnd: %d",waveEnd);
e0165dcf 906 waveLenCnt = waveEnd-waveStart;
907 if (waveLenCnt > fc){
908 firstFullWave = waveStart;
909 fullWaveLen=waveLenCnt;
910 break;
911 }
912 waveStart=0;
913 }
914 }
915 }
6426f6ba 916 //prnt("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
e0165dcf 917
918 //test each valid clock from greatest to smallest to see which lines up
919 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
920 lastClkBit = firstFullWave; //set end of wave as clock align
921 waveStart = 0;
922 errCnt=0;
923 peakcnt=0;
6426f6ba 924 //prnt("DEBUG: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
e0165dcf 925
926 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
927 //top edge of wave = start of new wave
928 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
929 if (waveStart == 0) {
930 waveStart = i+1;
931 waveLenCnt=0;
932 } else { //waveEnd
933 waveEnd = i+1;
934 waveLenCnt = waveEnd-waveStart;
935 if (waveLenCnt > fc){
936 //if this wave is a phase shift
6426f6ba 937 //prnt("DEBUG: phase shift at: %d, len: %d, nextClk: %d, ii: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,ii+1,fc);
e0165dcf 938 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
939 peakcnt++;
940 lastClkBit+=clk[clkCnt];
941 } else if (i<lastClkBit+8){
942 //noise after a phase shift - ignore
943 } else { //phase shift before supposed to based on clock
944 errCnt++;
945 }
946 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
947 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
948 }
949 waveStart=i+1;
950 }
951 }
952 }
953 if (errCnt == 0){
954 return clk[clkCnt];
955 }
956 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
957 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
958 }
959 //all tested with errors
960 //return the highest clk with the most peaks found
961 uint8_t best=7;
962 for (i=7; i>=1; i--){
963 if (peaksdet[i] > peaksdet[best]) {
964 best = i;
965 }
6426f6ba 966 //prnt("DEBUG: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[iii],peaksdet[iii],bestErr[iii],clk[best]);
e0165dcf 967 }
968 return clk[best];
ba1a299c 969}
970
6426f6ba 971int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
972 //find shortest transition from high to low
973 size_t i = 0;
974 size_t transition1 = 0;
975 int lowestTransition = 255;
976 bool lastWasHigh = false;
977
978 //find first valid beginning of a high or low wave
979 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
980 ++i;
981 while ((dest[i] < peak && dest[i] > low) && (i < size))
982 ++i;
983 lastWasHigh = (dest[i] >= peak);
984
985 if (i==size) return 0;
986 transition1 = i;
987
988 for (;i < size; i++) {
989 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
990 lastWasHigh = (dest[i] >= peak);
991 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
992 transition1 = i;
993 }
994 }
995 //prnt("DEBUG: LowestTrs: %d",lowestTransition);
996 if (lowestTransition == 255) lowestTransition = 0;
997 return lowestTransition;
998}
999
6de43508 1000//by marshmellow
1001//detect nrz clock by reading #peaks vs no peaks(or errors)
1002int DetectNRZClock(uint8_t dest[], size_t size, int clock)
ba1a299c 1003{
2eec55c8 1004 size_t i=0;
1005 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1006 size_t loopCnt = 4096; //don't need to loop through entire array...
e0165dcf 1007 if (size == 0) return 0;
6426f6ba 1008 if (size<loopCnt) loopCnt = size-20;
e0165dcf 1009 //if we already have a valid clock quit
1010 for (; i < 8; ++i)
1011 if (clk[i] == clock) return clock;
1012
1013 //get high and low peak
1014 int peak, low;
2eec55c8 1015 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
e0165dcf 1016
6426f6ba 1017 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
2eec55c8 1018 size_t ii;
e0165dcf 1019 uint8_t clkCnt;
1020 uint8_t tol = 0;
6426f6ba 1021 uint16_t smplCnt = 0;
1022 int16_t peakcnt = 0;
1023 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1024 uint16_t maxPeak = 255;
1025 bool firstpeak = false;
e0165dcf 1026 //test for large clipped waves
1027 for (i=0; i<loopCnt; i++){
1028 if (dest[i] >= peak || dest[i] <= low){
6426f6ba 1029 if (!firstpeak) continue;
1030 smplCnt++;
e0165dcf 1031 } else {
6426f6ba 1032 firstpeak=true;
1033 if (smplCnt > 6 ){
1034 if (maxPeak > smplCnt){
1035 maxPeak = smplCnt;
1036 //prnt("maxPk: %d",maxPeak);
1037 }
1038 peakcnt++;
1039 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1040 smplCnt=0;
e0165dcf 1041 }
e0165dcf 1042 }
1043 }
6426f6ba 1044 bool errBitHigh = 0;
1045 bool bitHigh = 0;
1046 uint8_t ignoreCnt = 0;
1047 uint8_t ignoreWindow = 4;
1048 bool lastPeakHigh = 0;
1049 int lastBit = 0;
e0165dcf 1050 peakcnt=0;
1051 //test each valid clock from smallest to greatest to see which lines up
1052 for(clkCnt=0; clkCnt < 8; ++clkCnt){
6426f6ba 1053 //ignore clocks smaller than smallest peak
1054 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
e0165dcf 1055 //try lining up the peaks by moving starting point (try first 256)
6426f6ba 1056 for (ii=20; ii < loopCnt; ++ii){
e0165dcf 1057 if ((dest[ii] >= peak) || (dest[ii] <= low)){
1058 peakcnt=0;
6426f6ba 1059 bitHigh = false;
1060 ignoreCnt = 0;
1061 lastBit = ii-clk[clkCnt];
1062 //loop through to see if this start location works
1063 for (i = ii; i < size-20; ++i) {
1064 //if we are at a clock bit
1065 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1066 //test high/low
1067 if (dest[i] >= peak || dest[i] <= low) {
1068 //if same peak don't count it
1069 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
e0165dcf 1070 peakcnt++;
6426f6ba 1071 }
1072 lastPeakHigh = (dest[i] >= peak);
1073 bitHigh = true;
1074 errBitHigh = false;
1075 ignoreCnt = ignoreWindow;
1076 lastBit += clk[clkCnt];
1077 } else if (i == lastBit + clk[clkCnt] + tol) {
1078 lastBit += clk[clkCnt];
1079 }
1080 //else if not a clock bit and no peaks
1081 } else if (dest[i] < peak && dest[i] > low){
1082 if (ignoreCnt==0){
1083 bitHigh=false;
1084 if (errBitHigh==true) peakcnt--;
1085 errBitHigh=false;
1086 } else {
1087 ignoreCnt--;
1088 }
1089 // else if not a clock bit but we have a peak
1090 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
1091 //error bar found no clock...
1092 errBitHigh=true;
e0165dcf 1093 }
1094 }
1095 if(peakcnt>peaksdet[clkCnt]) {
1096 peaksdet[clkCnt]=peakcnt;
1097 }
1098 }
1099 }
1100 }
1101 int iii=7;
2eec55c8 1102 uint8_t best=0;
e0165dcf 1103 for (iii=7; iii > 0; iii--){
6426f6ba 1104 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1105 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
1106 best = iii;
1107 }
1108 } else if (peaksdet[iii] > peaksdet[best]){
e0165dcf 1109 best = iii;
1110 }
6426f6ba 1111 //prnt("DEBUG: Clk: %d, peaks: %d, maxPeak: %d, bestClk: %d, lowestTrs: %d",clk[iii],peaksdet[iii],maxPeak, clk[best], lowestTransition);
e0165dcf 1112 }
6426f6ba 1113
e0165dcf 1114 return clk[best];
ba1a299c 1115}
1116
04d2721b 1117// by marshmellow
1118// convert psk1 demod to psk2 demod
1119// only transition waves are 1s
1120void psk1TOpsk2(uint8_t *BitStream, size_t size)
1121{
1122 size_t i=1;
1123 uint8_t lastBit=BitStream[0];
1124 for (; i<size; i++){
2767fc02 1125 if (BitStream[i]==7){
7a8a982b 1126 //ignore errors
1127 } else if (lastBit!=BitStream[i]){
04d2721b 1128 lastBit=BitStream[i];
1129 BitStream[i]=1;
1130 } else {
1131 BitStream[i]=0;
1132 }
1133 }
1134 return;
1135}
ba1a299c 1136
3bc66a96 1137// by marshmellow
1138// convert psk2 demod to psk1 demod
1139// from only transition waves are 1s to phase shifts change bit
1140void psk2TOpsk1(uint8_t *BitStream, size_t size)
1141{
712ebfa6 1142 uint8_t phase=0;
1143 for (size_t i=0; i<size; i++){
1144 if (BitStream[i]==1){
3bc66a96 1145 phase ^=1;
1146 }
1147 BitStream[i]=phase;
1148 }
1149 return;
1150}
1151
04d2721b 1152// redesigned by marshmellow adjusted from existing decode functions
1153// indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
ba1a299c 1154int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1155{
1156 //26 bit 40134 format (don't know other formats)
57c7b44b 1157 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};
1158 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};
1159 size_t startidx = 0;
1160 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1161 // if didn't find preamble try again inverting
1162 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1163 *invert ^= 1;
1164 }
1165 if (*size != 64 && *size != 224) return -2;
1166 if (*invert==1)
1167 for (size_t i = startidx; i < *size; i++)
1168 bitStream[i] ^= 1;
ba1a299c 1169
57c7b44b 1170 return (int) startidx;
ba1a299c 1171}
1172
6426f6ba 1173// by marshmellow - demodulate NRZ wave
04d2721b 1174// peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
6426f6ba 1175int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
e0165dcf 1176 if (justNoise(dest, *size)) return -1;
1177 *clk = DetectNRZClock(dest, *size, *clk);
1178 if (*clk==0) return -2;
2eec55c8 1179 size_t i, gLen = 4096;
6426f6ba 1180 if (gLen>*size) gLen = *size-20;
e0165dcf 1181 int high, low;
1182 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
6426f6ba 1183
1184 uint8_t bit=0;
1185 //convert wave samples to 1's and 0's
1186 for(i=20; i < *size-20; i++){
1187 if (dest[i] >= high) bit = 1;
1188 if (dest[i] <= low) bit = 0;
1189 dest[i] = bit;
e0165dcf 1190 }
6426f6ba 1191 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1192 size_t lastBit = 0;
1193 size_t numBits = 0;
1194 for(i=21; i < *size-20; i++) {
1195 //if transition detected or large number of same bits - store the passed bits
1196 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1197 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1198 numBits += (i - lastBit + (*clk/4)) / *clk;
1199 lastBit = i-1;
e0165dcf 1200 }
e0165dcf 1201 }
6426f6ba 1202 *size = numBits;
1203 return 0;
ba1a299c 1204}
1205
1e090a61 1206//by marshmellow
03e6bb4a 1207//detects the bit clock for FSK given the high and low Field Clocks
1208uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1e090a61 1209{
e0165dcf 1210 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1211 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1212 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1213 uint8_t rfLensFnd = 0;
2eec55c8 1214 uint8_t lastFCcnt = 0;
1215 uint16_t fcCounter = 0;
e0165dcf 1216 uint16_t rfCounter = 0;
1217 uint8_t firstBitFnd = 0;
1218 size_t i;
1219 if (size == 0) return 0;
1220
6426f6ba 1221 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
e0165dcf 1222 rfLensFnd=0;
1223 fcCounter=0;
1224 rfCounter=0;
1225 firstBitFnd=0;
1226 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
6426f6ba 1227 // prime i to first peak / up transition
1228 for (i = 160; i < size-20; i++)
e0165dcf 1229 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1230 break;
1231
6426f6ba 1232 for (; i < size-20; i++){
2eec55c8 1233 fcCounter++;
1234 rfCounter++;
1235
1236 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1237 continue;
1238 // else new peak
1239 // if we got less than the small fc + tolerance then set it to the small fc
1240 if (fcCounter < fcLow+fcTol)
1241 fcCounter = fcLow;
1242 else //set it to the large fc
1243 fcCounter = fcHigh;
1244
1245 //look for bit clock (rf/xx)
1246 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1247 //not the same size as the last wave - start of new bit sequence
1248 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1249 for (int ii=0; ii<15; ii++){
6426f6ba 1250 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
2eec55c8 1251 rfCnts[ii]++;
1252 rfCounter = 0;
1253 break;
e0165dcf 1254 }
e0165dcf 1255 }
2eec55c8 1256 if (rfCounter > 0 && rfLensFnd < 15){
1257 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1258 rfCnts[rfLensFnd]++;
1259 rfLens[rfLensFnd++] = rfCounter;
1260 }
1261 } else {
1262 firstBitFnd++;
e0165dcf 1263 }
2eec55c8 1264 rfCounter=0;
1265 lastFCcnt=fcCounter;
e0165dcf 1266 }
2eec55c8 1267 fcCounter=0;
e0165dcf 1268 }
1269 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1270
1271 for (i=0; i<15; i++){
6426f6ba 1272 //prnt("DEBUG: RF %d, cnts %d",rfLens[i], rfCnts[i]);
e0165dcf 1273 //get highest 2 RF values (might need to get more values to compare or compare all?)
1274 if (rfCnts[i]>rfCnts[rfHighest]){
1275 rfHighest3=rfHighest2;
1276 rfHighest2=rfHighest;
1277 rfHighest=i;
1278 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1279 rfHighest3=rfHighest2;
1280 rfHighest2=i;
1281 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1282 rfHighest3=i;
1283 }
1284 }
1285 // set allowed clock remainder tolerance to be 1 large field clock length+1
1286 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1287 uint8_t tol1 = fcHigh+1;
1288
6426f6ba 1289 //prnt("DEBUG: hightest: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
e0165dcf 1290
1291 // loop to find the highest clock that has a remainder less than the tolerance
1292 // compare samples counted divided by
6426f6ba 1293 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
e0165dcf 1294 int ii=7;
6426f6ba 1295 for (; ii>=2; ii--){
e0165dcf 1296 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1297 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1298 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
1299 break;
1300 }
1301 }
1302 }
1303 }
1304
1305 if (ii<0) return 0; // oops we went too far
1306
1307 return clk[ii];
03e6bb4a 1308}
1e090a61 1309
03e6bb4a 1310//by marshmellow
1311//countFC is to detect the field clock lengths.
1312//counts and returns the 2 most common wave lengths
6de43508 1313//mainly used for FSK field clock detection
2eec55c8 1314uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
03e6bb4a 1315{
6426f6ba 1316 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1317 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
e0165dcf 1318 uint8_t fcLensFnd = 0;
1319 uint8_t lastFCcnt=0;
2eec55c8 1320 uint8_t fcCounter = 0;
e0165dcf 1321 size_t i;
1322 if (size == 0) return 0;
1323
1324 // prime i to first up transition
6426f6ba 1325 for (i = 160; i < size-20; i++)
e0165dcf 1326 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1327 break;
1328
6426f6ba 1329 for (; i < size-20; i++){
e0165dcf 1330 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1331 // new up transition
1332 fcCounter++;
2eec55c8 1333 if (fskAdj){
1334 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1335 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1336 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1337 if ((fcCounter==9) || fcCounter==4) fcCounter++;
e0165dcf 1338 // save last field clock count (fc/xx)
2eec55c8 1339 lastFCcnt = fcCounter;
1340 }
e0165dcf 1341 // find which fcLens to save it to:
6426f6ba 1342 for (int ii=0; ii<15; ii++){
e0165dcf 1343 if (fcLens[ii]==fcCounter){
1344 fcCnts[ii]++;
1345 fcCounter=0;
1346 break;
1347 }
1348 }
6426f6ba 1349 if (fcCounter>0 && fcLensFnd<15){
e0165dcf 1350 //add new fc length
1351 fcCnts[fcLensFnd]++;
1352 fcLens[fcLensFnd++]=fcCounter;
1353 }
1354 fcCounter=0;
1355 } else {
1356 // count sample
1357 fcCounter++;
1358 }
1359 }
1360
6426f6ba 1361 uint8_t best1=14, best2=14, best3=14;
e0165dcf 1362 uint16_t maxCnt1=0;
1363 // go through fclens and find which ones are bigest 2
6426f6ba 1364 for (i=0; i<15; i++){
1365 //prnt("DEBUG: FC %d, Cnt %d",fcLens[i],fcCnts[i]);
e0165dcf 1366 // get the 3 best FC values
1367 if (fcCnts[i]>maxCnt1) {
1368 best3=best2;
1369 best2=best1;
1370 maxCnt1=fcCnts[i];
1371 best1=i;
1372 } else if(fcCnts[i]>fcCnts[best2]){
1373 best3=best2;
1374 best2=i;
1375 } else if(fcCnts[i]>fcCnts[best3]){
1376 best3=i;
1377 }
1378 }
6426f6ba 1379 if (fcLens[best1]==0) return 0;
e0165dcf 1380 uint8_t fcH=0, fcL=0;
1381 if (fcLens[best1]>fcLens[best2]){
1382 fcH=fcLens[best1];
1383 fcL=fcLens[best2];
1384 } else{
1385 fcH=fcLens[best2];
1386 fcL=fcLens[best1];
1387 }
6426f6ba 1388 //prnt("DEBUG: dd %d > %d",(size-180)/fcH/3,fcCnts[best1]+fcCnts[best2]);
1389 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) return 0; //lots of waves not psk or fsk
e0165dcf 1390
e0165dcf 1391 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1392
1393 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
6426f6ba 1394 //prnt("DEBUG: Best %d best2 %d best3 %d",fcLens[best1],fcLens[best2],fcLens[best3]);
2eec55c8 1395 if (fskAdj) return fcs;
1396 return fcLens[best1];
6de43508 1397}
1398
1399//by marshmellow - demodulate PSK1 wave
1400//uses wave lengths (# Samples)
1401int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1402{
e0165dcf 1403 if (size == 0) return -1;
2eec55c8 1404 uint16_t loopCnt = 4096; //don't need to loop through entire array...
e0165dcf 1405 if (*size<loopCnt) loopCnt = *size;
1406
6426f6ba 1407 size_t numBits=0;
e0165dcf 1408 uint8_t curPhase = *invert;
1409 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1410 uint8_t fc=0, fullWaveLen=0, tol=1;
1411 uint16_t errCnt=0, waveLenCnt=0;
2eec55c8 1412 fc = countFC(dest, *size, 0);
e0165dcf 1413 if (fc!=2 && fc!=4 && fc!=8) return -1;
1414 //PrintAndLog("DEBUG: FC: %d",fc);
1415 *clock = DetectPSKClock(dest, *size, *clock);
2eec55c8 1416 if (*clock == 0) return -1;
e0165dcf 1417 int avgWaveVal=0, lastAvgWaveVal=0;
1418 //find first phase shift
1419 for (i=0; i<loopCnt; i++){
1420 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1421 waveEnd = i+1;
1422 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1423 waveLenCnt = waveEnd-waveStart;
6426f6ba 1424 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
e0165dcf 1425 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1426 firstFullWave = waveStart;
1427 fullWaveLen=waveLenCnt;
1428 //if average wave value is > graph 0 then it is an up wave or a 1
2eec55c8 1429 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
e0165dcf 1430 break;
1431 }
1432 waveStart = i+1;
1433 avgWaveVal = 0;
1434 }
2eec55c8 1435 avgWaveVal += dest[i+2];
e0165dcf 1436 }
6426f6ba 1437 if (firstFullWave == 0) {
1438 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1439 // so skip a little to ensure we are past any Start Signal
1440 firstFullWave = 160;
1441 memset(dest, curPhase, firstFullWave / *clock);
1442 } else {
1443 memset(dest, curPhase^1, firstFullWave / *clock);
1444 }
1445 //advance bits
1446 numBits += (firstFullWave / *clock);
1447 //set start of wave as clock align
1448 lastClkBit = firstFullWave;
e0165dcf 1449 //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
e0165dcf 1450 //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
1451 waveStart = 0;
e0165dcf 1452 dest[numBits++] = curPhase; //set first read bit
2eec55c8 1453 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
e0165dcf 1454 //top edge of wave = start of new wave
1455 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1456 if (waveStart == 0) {
1457 waveStart = i+1;
2eec55c8 1458 waveLenCnt = 0;
e0165dcf 1459 avgWaveVal = dest[i+1];
1460 } else { //waveEnd
1461 waveEnd = i+1;
1462 waveLenCnt = waveEnd-waveStart;
1463 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1464 if (waveLenCnt > fc){
1465 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
2eec55c8 1466 //this wave is a phase shift
e0165dcf 1467 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1468 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
2eec55c8 1469 curPhase ^= 1;
e0165dcf 1470 dest[numBits++] = curPhase;
1471 lastClkBit += *clock;
2eec55c8 1472 } else if (i < lastClkBit+10+fc){
e0165dcf 1473 //noise after a phase shift - ignore
1474 } else { //phase shift before supposed to based on clock
1475 errCnt++;
2767fc02 1476 dest[numBits++] = 7;
e0165dcf 1477 }
1478 } else if (i+1 > lastClkBit + *clock + tol + fc){
1479 lastClkBit += *clock; //no phase shift but clock bit
1480 dest[numBits++] = curPhase;
1481 }
2eec55c8 1482 avgWaveVal = 0;
1483 waveStart = i+1;
e0165dcf 1484 }
1485 }
2eec55c8 1486 avgWaveVal += dest[i+1];
e0165dcf 1487 }
1488 *size = numBits;
1489 return errCnt;
6de43508 1490}
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