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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>
eb191de6 12#include "lfdemod.h"
d1869c33 13#include <string.h>
6fe5c94b 14
d1869c33 15//to allow debug print calls when used not on device
6fe5c94b 16void dummy(char *fmt, ...){}
17
18#ifndef ON_DEVICE
19#include "ui.h"
709665b5 20#include "cmdparser.h"
21#include "cmddata.h"
6fe5c94b 22#define prnt PrintAndLog
23#else
709665b5 24 uint8_t g_debugMode=0;
6fe5c94b 25#define prnt dummy
26#endif
6fe5c94b 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
709665b5 69// by marshmellow
70// takes a array of binary values, start position, length of bits per parity (includes parity bit),
88e85bde 71// Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
709665b5 72size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
73{
74 uint32_t parityWd = 0;
75 size_t j = 0, bitCnt = 0;
76 for (int word = 0; word < (bLen); word+=pLen){
77 for (int bit=0; bit < pLen; bit++){
78 parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
79 BitStream[j++] = (BitStream[startIdx+word+bit]);
80 }
81 j--; // overwrite parity with next data
82 // if parity fails then return 0
88e85bde 83 switch (pType) {
84 case 3: if (BitStream[j]==1) return 0; break; //should be 0 spacer bit
85 case 2: if (BitStream[j]==0) return 0; break; //should be 1 spacer bit
86 default: //test parity
87 if (parityTest(parityWd, pLen, pType) == 0) return 0; break;
709665b5 88 }
89 bitCnt+=(pLen-1);
90 parityWd = 0;
91 }
92 // if we got here then all the parities passed
93 //return ID start index and size
94 return bitCnt;
95}
96
97// by marshmellow
98// takes a array of binary values, length of bits per parity (includes parity bit),
88e85bde 99// Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
100// Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
709665b5 101size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
102{
103 uint32_t parityWd = 0;
104 size_t j = 0, bitCnt = 0;
105 for (int word = 0; word < sourceLen; word+=pLen-1) {
106 for (int bit=0; bit < pLen-1; bit++){
107 parityWd = (parityWd << 1) | BitSource[word+bit];
108 dest[j++] = (BitSource[word+bit]);
109 }
110 // if parity fails then return 0
88e85bde 111 switch (pType) {
112 case 3: dest[j++]=0; break; // marker bit which should be a 0
113 case 2: dest[j++]=1; break; // marker bit which should be a 1
114 default:
115 dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
116 break;
709665b5 117 }
118 bitCnt += pLen;
119 parityWd = 0;
120 }
121 // if we got here then all the parities passed
122 //return ID start index and size
123 return bitCnt;
124}
125
126uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
127{
128 uint32_t num = 0;
129 for(int i = 0 ; i < numbits ; i++)
130 {
131 num = (num << 1) | (*src);
132 src++;
133 }
134 return num;
135}
136
137//least significant bit first
138uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
139{
140 uint32_t num = 0;
141 for(int i = 0 ; i < numbits ; i++)
142 {
143 num = (num << 1) | *(src + (numbits-(i+1)));
144 }
145 return num;
146}
147
a1d17964 148//by marshmellow
2147c307 149//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
a1d17964 150uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
151{
e0165dcf 152 uint8_t foundCnt=0;
153 for (int idx=0; idx < *size - pLen; idx++){
154 if (memcmp(BitStream+idx, preamble, pLen) == 0){
155 //first index found
156 foundCnt++;
157 if (foundCnt == 1){
158 *startIdx = idx;
159 }
160 if (foundCnt == 2){
161 *size = idx - *startIdx;
162 return 1;
163 }
164 }
165 }
166 return 0;
a1d17964 167}
168
2147c307 169//by marshmellow
170//takes 1s and 0s and searches for EM410x format - output EM ID
171uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
172{
e0165dcf 173 //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
174 // otherwise could be a void with no arguments
175 //set defaults
176 uint32_t i = 0;
2767fc02 177 if (BitStream[1]>1) return 0; //allow only 1s and 0s
178
e0165dcf 179 // 111111111 bit pattern represent start of frame
180 // include 0 in front to help get start pos
181 uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
182 uint32_t idx = 0;
183 uint32_t parityBits = 0;
184 uint8_t errChk = 0;
185 uint8_t FmtLen = 10;
186 *startIdx = 0;
187 errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
188 if (errChk == 0 || *size < 64) return 0;
189 if (*size > 64) FmtLen = 22;
190 *startIdx += 1; //get rid of 0 from preamble
191 idx = *startIdx + 9;
192 for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
193 parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
2eec55c8 194 //check even parity - quit if failed
195 if (parityTest(parityBits, 5, 0) == 0) return 0;
e0165dcf 196 //set uint64 with ID from BitStream
197 for (uint8_t ii=0; ii<4; ii++){
198 *hi = (*hi << 1) | (*lo >> 63);
199 *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
200 }
201 }
202 if (errChk != 0) return 1;
203 //skip last 5 bit parity test for simplicity.
204 // *size = 64 | 128;
205 return 0;
2147c307 206}
207
fef74fdc 208//by marshmellow
209//demodulates strong heavily clipped samples
23f0a7d8 210int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
211{
212 size_t bitCnt=0, smplCnt=0, errCnt=0;
213 uint8_t waveHigh = 0;
23f0a7d8 214 for (size_t i=0; i < *size; i++){
215 if (BinStream[i] >= high && waveHigh){
216 smplCnt++;
217 } else if (BinStream[i] <= low && !waveHigh){
218 smplCnt++;
219 } else { //transition
220 if ((BinStream[i] >= high && !waveHigh) || (BinStream[i] <= low && waveHigh)){
221 if (smplCnt > clk-(clk/4)-1) { //full clock
222 if (smplCnt > clk + (clk/4)+1) { //too many samples
223 errCnt++;
d1869c33 224 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
2767fc02 225 BinStream[bitCnt++]=7;
23f0a7d8 226 } else if (waveHigh) {
227 BinStream[bitCnt++] = invert;
228 BinStream[bitCnt++] = invert;
229 } else if (!waveHigh) {
230 BinStream[bitCnt++] = invert ^ 1;
231 BinStream[bitCnt++] = invert ^ 1;
232 }
233 waveHigh ^= 1;
234 smplCnt = 0;
235 } else if (smplCnt > (clk/2) - (clk/4)-1) {
236 if (waveHigh) {
237 BinStream[bitCnt++] = invert;
238 } else if (!waveHigh) {
239 BinStream[bitCnt++] = invert ^ 1;
240 }
241 waveHigh ^= 1;
242 smplCnt = 0;
243 } else if (!bitCnt) {
244 //first bit
245 waveHigh = (BinStream[i] >= high);
246 smplCnt = 1;
247 } else {
248 smplCnt++;
249 //transition bit oops
250 }
251 } else { //haven't hit new high or new low yet
252 smplCnt++;
253 }
254 }
255 }
256 *size = bitCnt;
257 return errCnt;
258}
259
eb191de6 260//by marshmellow
fef74fdc 261void askAmp(uint8_t *BitStream, size_t size)
262{
263 for(size_t i = 1; i<size; i++){
264 if (BitStream[i]-BitStream[i-1]>=30) //large jump up
cf194819 265 BitStream[i]=255;
fef74fdc 266 else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
cf194819 267 BitStream[i]=0;
fef74fdc 268 }
269 return;
270}
271
272//by marshmellow
273//attempts to demodulate ask modulations, askType == 0 for ask/raw, askType==1 for ask/manchester
274int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr, uint8_t amp, uint8_t askType)
eb191de6 275{
fef74fdc 276 if (*size==0) return -1;
6e984446 277 int start = DetectASKClock(BinStream, *size, clk, maxErr); //clock default
2eec55c8 278 if (*clk==0 || start < 0) return -3;
fef74fdc 279 if (*invert != 1) *invert = 0;
280 if (amp==1) askAmp(BinStream, *size);
d1869c33 281 if (g_debugMode==2) prnt("DEBUG ASK: clk %d, beststart %d", *clk, start);
fef74fdc 282
2eec55c8 283 uint8_t initLoopMax = 255;
284 if (initLoopMax > *size) initLoopMax = *size;
ba1a299c 285 // Detect high and lows
fef74fdc 286 //25% clip in case highs and lows aren't clipped [marshmellow]
2eec55c8 287 int high, low;
fef74fdc 288 if (getHiLo(BinStream, initLoopMax, &high, &low, 75, 75) < 1)
289 return -2; //just noise
ba1a299c 290
fef74fdc 291 size_t errCnt = 0;
23f0a7d8 292 // if clean clipped waves detected run alternate demod
293 if (DetectCleanAskWave(BinStream, *size, high, low)) {
d1869c33 294 if (g_debugMode==2) prnt("DEBUG ASK: Clean Wave Detected - using clean wave demod");
fef74fdc 295 errCnt = cleanAskRawDemod(BinStream, size, *clk, *invert, high, low);
296 if (askType) //askman
297 return manrawdecode(BinStream, size, 0);
298 else //askraw
299 return errCnt;
23f0a7d8 300 }
d1869c33 301 if (g_debugMode==2) prnt("DEBUG ASK: Weak Wave Detected - using weak wave demod");
23f0a7d8 302
d1869c33 303 int lastBit; //set first clock check - can go negative
fef74fdc 304 size_t i, bitnum = 0; //output counter
305 uint8_t midBit = 0;
2eec55c8 306 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
d1869c33 307 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
308 size_t MaxBits = 3072; //max bits to collect
6e984446 309 lastBit = start - *clk;
fef74fdc 310
6e984446 311 for (i = start; i < *size; ++i) {
fef74fdc 312 if (i-lastBit >= *clk-tol){
313 if (BinStream[i] >= high) {
314 BinStream[bitnum++] = *invert;
315 } else if (BinStream[i] <= low) {
316 BinStream[bitnum++] = *invert ^ 1;
317 } else if (i-lastBit >= *clk+tol) {
318 if (bitnum > 0) {
d1869c33 319 if (g_debugMode==2) prnt("DEBUG ASK: Modulation Error at: %u", i);
fef74fdc 320 BinStream[bitnum++]=7;
321 errCnt++;
322 }
323 } else { //in tolerance - looking for peak
324 continue;
325 }
326 midBit = 0;
2eec55c8 327 lastBit += *clk;
fef74fdc 328 } else if (i-lastBit >= (*clk/2-tol) && !midBit && !askType){
329 if (BinStream[i] >= high) {
330 BinStream[bitnum++] = *invert;
331 } else if (BinStream[i] <= low) {
332 BinStream[bitnum++] = *invert ^ 1;
333 } else if (i-lastBit >= *clk/2+tol) {
334 BinStream[bitnum] = BinStream[bitnum-1];
335 bitnum++;
336 } else { //in tolerance - looking for peak
337 continue;
338 }
339 midBit = 1;
2eec55c8 340 }
341 if (bitnum >= MaxBits) break;
ba1a299c 342 }
2eec55c8 343 *size = bitnum;
6e984446 344 return errCnt;
eb191de6 345}
346
347//by marshmellow
348//take 10 and 01 and manchester decode
349//run through 2 times and take least errCnt
fef74fdc 350int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert)
eb191de6 351{
13d77ef9 352 uint16_t bitnum=0, MaxBits = 512, errCnt = 0;
353 size_t i, ii;
354 uint16_t bestErr = 1000, bestRun = 0;
fef74fdc 355 if (*size < 16) return -1;
2767fc02 356 //find correct start position [alignment]
13d77ef9 357 for (ii=0;ii<2;++ii){
fef74fdc 358 for (i=ii; i<*size-3; i+=2)
2eec55c8 359 if (BitStream[i]==BitStream[i+1])
ba1a299c 360 errCnt++;
2eec55c8 361
ba1a299c 362 if (bestErr>errCnt){
363 bestErr=errCnt;
364 bestRun=ii;
365 }
366 errCnt=0;
367 }
2767fc02 368 //decode
fef74fdc 369 for (i=bestRun; i < *size-3; i+=2){
23f0a7d8 370 if(BitStream[i] == 1 && (BitStream[i+1] == 0)){
fef74fdc 371 BitStream[bitnum++]=invert;
23f0a7d8 372 } else if((BitStream[i] == 0) && BitStream[i+1] == 1){
fef74fdc 373 BitStream[bitnum++]=invert^1;
23f0a7d8 374 } else {
2767fc02 375 BitStream[bitnum++]=7;
ba1a299c 376 }
23f0a7d8 377 if(bitnum>MaxBits) break;
ba1a299c 378 }
23f0a7d8 379 *size=bitnum;
2eec55c8 380 return bestErr;
f822a063 381}
382
3606ac0a 383uint32_t manchesterEncode2Bytes(uint16_t datain) {
384 uint32_t output = 0;
385 uint8_t curBit = 0;
386 for (uint8_t i=0; i<16; i++) {
387 curBit = (datain >> (15-i) & 1);
388 output |= (1<<(((15-i)*2)+curBit));
389 }
390 return output;
391}
392
fef74fdc 393//by marshmellow
394//encode binary data into binary manchester
395int ManchesterEncode(uint8_t *BitStream, size_t size)
396{
397 size_t modIdx=20000, i=0;
398 if (size>modIdx) return -1;
399 for (size_t idx=0; idx < size; idx++){
400 BitStream[idx+modIdx++] = BitStream[idx];
401 BitStream[idx+modIdx++] = BitStream[idx]^1;
402 }
403 for (; i<(size*2); i++){
404 BitStream[i] = BitStream[i+20000];
405 }
406 return i;
407}
408
f822a063 409//by marshmellow
2147c307 410//take 01 or 10 = 1 and 11 or 00 = 0
411//check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
13d77ef9 412//decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
1e090a61 413int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert)
f822a063 414{
2eec55c8 415 uint16_t bitnum = 0;
416 uint16_t errCnt = 0;
417 size_t i = offset;
2147c307 418 uint16_t MaxBits=512;
419 //if not enough samples - error
420 if (*size < 51) return -1;
421 //check for phase change faults - skip one sample if faulty
422 uint8_t offsetA = 1, offsetB = 1;
423 for (; i<48; i+=2){
424 if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
425 if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
426 }
427 if (!offsetA && offsetB) offset++;
428 for (i=offset; i<*size-3; i+=2){
429 //check for phase error
13d77ef9 430 if (BitStream[i+1]==BitStream[i+2]) {
2767fc02 431 BitStream[bitnum++]=7;
2147c307 432 errCnt++;
433 }
ba1a299c 434 if((BitStream[i]==1 && BitStream[i+1]==0) || (BitStream[i]==0 && BitStream[i+1]==1)){
1e090a61 435 BitStream[bitnum++]=1^invert;
ba1a299c 436 } else if((BitStream[i]==0 && BitStream[i+1]==0) || (BitStream[i]==1 && BitStream[i+1]==1)){
1e090a61 437 BitStream[bitnum++]=invert;
ba1a299c 438 } else {
2767fc02 439 BitStream[bitnum++]=7;
ba1a299c 440 errCnt++;
441 }
6de43508 442 if(bitnum>MaxBits) break;
ba1a299c 443 }
444 *size=bitnum;
445 return errCnt;
eb191de6 446}
447
fef74fdc 448// by marshmellow
11081e04 449// demod gProxIIDemod
450// error returns as -x
451// success returns start position in BitStream
452// BitStream must contain previously askrawdemod and biphasedemoded data
453int gProxII_Demod(uint8_t BitStream[], size_t *size)
454{
455 size_t startIdx=0;
456 uint8_t preamble[] = {1,1,1,1,1,0};
457
458 uint8_t errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, &startIdx);
459 if (errChk == 0) return -3; //preamble not found
460 if (*size != 96) return -2; //should have found 96 bits
461 //check first 6 spacer bits to verify format
462 if (!BitStream[startIdx+5] && !BitStream[startIdx+10] && !BitStream[startIdx+15] && !BitStream[startIdx+20] && !BitStream[startIdx+25] && !BitStream[startIdx+30]){
463 //confirmed proper separator bits found
464 //return start position
465 return (int) startIdx;
466 }
cf194819 467 return -5; //spacer bits not found - not a valid gproxII
11081e04 468}
469
cf194819 470//translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
f822a063 471size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
eb191de6 472{
2eec55c8 473 size_t last_transition = 0;
474 size_t idx = 1;
ac3ba7ee 475 //uint32_t maxVal=0;
ba1a299c 476 if (fchigh==0) fchigh=10;
477 if (fclow==0) fclow=8;
84871873 478 //set the threshold close to 0 (graph) or 128 std to avoid static
479 uint8_t threshold_value = 123;
f4eadf8a 480 size_t preLastSample = 0;
481 size_t LastSample = 0;
482 size_t currSample = 0;
ba1a299c 483 // sync to first lo-hi transition, and threshold
484
485 // Need to threshold first sample
6fe5c94b 486 // skip 160 samples to allow antenna/samples to settle
487 if(dest[160] < threshold_value) dest[0] = 0;
ba1a299c 488 else dest[0] = 1;
489
490 size_t numBits = 0;
491 // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
63744b56 492 // or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
ba1a299c 493 // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
cf194819 494 // (could also be fc/5 && fc/7 for fsk1 = 4-9)
6fe5c94b 495 for(idx = 161; idx < size-20; idx++) {
ba1a299c 496 // threshold current value
497
498 if (dest[idx] < threshold_value) dest[idx] = 0;
499 else dest[idx] = 1;
500
501 // Check for 0->1 transition
cf194819 502 if (dest[idx-1] < dest[idx]) {
f4eadf8a 503 preLastSample = LastSample;
504 LastSample = currSample;
505 currSample = idx-last_transition;
cf194819 506 if (currSample < (fclow-2)) { //0-5 = garbage noise (or 0-3)
ba1a299c 507 //do nothing with extra garbage
cf194819 508 } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
509 //correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
db829602 510 if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
cf194819 511 dest[numBits-1]=1;
f4eadf8a 512 }
2eec55c8 513 dest[numBits++]=1;
f4eadf8a 514
cf194819 515 } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
13d77ef9 516 //do nothing with beginning garbage
cf194819 517 } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
f4eadf8a 518 dest[numBits++]=1;
cf194819 519 } else { //9+ = 10 sample waves (or 6+ = 7)
2eec55c8 520 dest[numBits++]=0;
ba1a299c 521 }
522 last_transition = idx;
ba1a299c 523 }
524 }
525 return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
eb191de6 526}
527
ba1a299c 528//translate 11111100000 to 10
cf194819 529//rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
2eec55c8 530size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
e0165dcf 531 uint8_t invert, uint8_t fchigh, uint8_t fclow)
eb191de6 532{
ba1a299c 533 uint8_t lastval=dest[0];
2eec55c8 534 size_t idx=0;
ba1a299c 535 size_t numBits=0;
536 uint32_t n=1;
ba1a299c 537 for( idx=1; idx < size; idx++) {
13d77ef9 538 n++;
cf194819 539 if (dest[idx]==lastval) continue; //skip until we hit a transition
2eec55c8 540
cf194819 541 //find out how many bits (n) we collected
ba1a299c 542 //if lastval was 1, we have a 1->0 crossing
13d77ef9 543 if (dest[idx-1]==1) {
6fe5c94b 544 n = (n * fclow + rfLen/2) / rfLen;
13d77ef9 545 } else {// 0->1 crossing
75cbbe9a 546 n = (n * fchigh + rfLen/2) / rfLen;
ba1a299c 547 }
548 if (n == 0) n = 1;
549
cf194819 550 //add to our destination the bits we collected
2eec55c8 551 memset(dest+numBits, dest[idx-1]^invert , n);
552 numBits += n;
ba1a299c 553 n=0;
554 lastval=dest[idx];
555 }//end for
13d77ef9 556 // if valid extra bits at the end were all the same frequency - add them in
75cbbe9a 557 if (n > rfLen/fchigh) {
13d77ef9 558 if (dest[idx-2]==1) {
75cbbe9a 559 n = (n * fclow + rfLen/2) / rfLen;
13d77ef9 560 } else {
75cbbe9a 561 n = (n * fchigh + rfLen/2) / rfLen;
13d77ef9 562 }
2eec55c8 563 memset(dest+numBits, dest[idx-1]^invert , n);
13d77ef9 564 numBits += n;
565 }
ba1a299c 566 return numBits;
eb191de6 567}
6fe5c94b 568
eb191de6 569//by marshmellow (from holiman's base)
570// full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod)
f822a063 571int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow)
eb191de6 572{
ba1a299c 573 // FSK demodulator
574 size = fsk_wave_demod(dest, size, fchigh, fclow);
2eec55c8 575 size = aggregate_bits(dest, size, rfLen, invert, fchigh, fclow);
ba1a299c 576 return size;
eb191de6 577}
a1d17964 578
eb191de6 579// loop to get raw HID waveform then FSK demodulate the TAG ID from it
ec75f5c1 580int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
eb191de6 581{
e0165dcf 582 if (justNoise(dest, *size)) return -1;
583
584 size_t numStart=0, size2=*size, startIdx=0;
585 // FSK demodulator
586 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
2eec55c8 587 if (*size < 96*2) return -2;
e0165dcf 588 // 00011101 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
589 uint8_t preamble[] = {0,0,0,1,1,1,0,1};
590 // find bitstring in array
591 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
592 if (errChk == 0) return -3; //preamble not found
593
594 numStart = startIdx + sizeof(preamble);
595 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
596 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
597 if (dest[idx] == dest[idx+1]){
598 return -4; //not manchester data
599 }
600 *hi2 = (*hi2<<1)|(*hi>>31);
601 *hi = (*hi<<1)|(*lo>>31);
602 //Then, shift in a 0 or one into low
603 if (dest[idx] && !dest[idx+1]) // 1 0
604 *lo=(*lo<<1)|1;
605 else // 0 1
606 *lo=(*lo<<1)|0;
607 }
608 return (int)startIdx;
eb191de6 609}
610
ec75f5c1 611// loop to get raw paradox waveform then FSK demodulate the TAG ID from it
a1d17964 612int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32_t *lo)
ec75f5c1 613{
a1d17964 614 if (justNoise(dest, *size)) return -1;
615
616 size_t numStart=0, size2=*size, startIdx=0;
ec75f5c1 617 // FSK demodulator
a1d17964 618 *size = fskdemod(dest, size2,50,1,10,8); //fsk2a
619 if (*size < 96) return -2;
ec75f5c1 620
a1d17964 621 // 00001111 bit pattern represent start of frame, 01 pattern represents a 0 and 10 represents a 1
622 uint8_t preamble[] = {0,0,0,0,1,1,1,1};
623
624 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
625 if (errChk == 0) return -3; //preamble not found
626
627 numStart = startIdx + sizeof(preamble);
628 // final loop, go over previously decoded FSK data and manchester decode into usable tag ID
629 for (size_t idx = numStart; (idx-numStart) < *size - sizeof(preamble); idx+=2){
630 if (dest[idx] == dest[idx+1])
631 return -4; //not manchester data
632 *hi2 = (*hi2<<1)|(*hi>>31);
633 *hi = (*hi<<1)|(*lo>>31);
634 //Then, shift in a 0 or one into low
635 if (dest[idx] && !dest[idx+1]) // 1 0
636 *lo=(*lo<<1)|1;
637 else // 0 1
638 *lo=(*lo<<1)|0;
ec75f5c1 639 }
a1d17964 640 return (int)startIdx;
ec75f5c1 641}
642
eb191de6 643int IOdemodFSK(uint8_t *dest, size_t size)
644{
a1d17964 645 if (justNoise(dest, size)) return -1;
ba1a299c 646 //make sure buffer has data
a1d17964 647 if (size < 66*64) return -2;
ba1a299c 648 // FSK demodulator
a1d17964 649 size = fskdemod(dest, size, 64, 1, 10, 8); // FSK2a RF/64
650 if (size < 65) return -3; //did we get a good demod?
ba1a299c 651 //Index map
652 //0 10 20 30 40 50 60
653 //| | | | | | |
654 //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
655 //-----------------------------------------------------------------------------
656 //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11
657 //
658 //XSF(version)facility:codeone+codetwo
659 //Handle the data
a1d17964 660 size_t startIdx = 0;
661 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,1};
662 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), &size, &startIdx);
663 if (errChk == 0) return -4; //preamble not found
eb191de6 664
a1d17964 665 if (!dest[startIdx+8] && dest[startIdx+17]==1 && dest[startIdx+26]==1 && dest[startIdx+35]==1 && dest[startIdx+44]==1 && dest[startIdx+53]==1){
666 //confirmed proper separator bits found
667 //return start position
668 return (int) startIdx;
1e090a61 669 }
a1d17964 670 return -5;
415274a7 671}
672
673// by marshmellow
674// find viking preamble 0xF200 in already demoded data
675int VikingDemod_AM(uint8_t *dest, size_t *size) {
415274a7 676 //make sure buffer has data
677 if (*size < 64*2) return -2;
678
679 size_t startIdx = 0;
680 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};
681 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
682 if (errChk == 0) return -4; //preamble not found
3ea7254a 683 uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
684 ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
685 ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
686 if ( checkCalc != 0xA8 ) return -5;
14331320 687 if (*size != 64) return -6;
415274a7 688 //return start position
689 return (int) startIdx;
1e090a61 690}
691
6923d3f1 692// find presco preamble 0x10D in already demoded data
693int PrescoDemod(uint8_t *dest, size_t *size) {
694 //make sure buffer has data
695 if (*size < 64*2) return -2;
696
697 size_t startIdx = 0;
698 uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
699 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
700 if (errChk == 0) return -4; //preamble not found
701 //return start position
702 return (int) startIdx;
703}
704
04bb0567 705// Ask/Biphase Demod then try to locate an ISO 11784/85 ID
706// BitStream must contain previously askrawdemod and biphasedemoded data
b2c330b3 707int FDXBdemodBI(uint8_t *dest, size_t *size)
04bb0567 708{
709 //make sure buffer has enough data
710 if (*size < 128) return -1;
711
712 size_t startIdx = 0;
713 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,1};
714
715 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
716 if (errChk == 0) return -2; //preamble not found
717 return (int)startIdx;
718}
719
1e090a61 720// by marshmellow
721// FSK Demod then try to locate an AWID ID
a1d17964 722int AWIDdemodFSK(uint8_t *dest, size_t *size)
1e090a61 723{
a1d17964 724 //make sure buffer has enough data
725 if (*size < 96*50) return -1;
726
727 if (justNoise(dest, *size)) return -2;
1e090a61 728
729 // FSK demodulator
a1d17964 730 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
731 if (*size < 96) return -3; //did we get a good demod?
732
733 uint8_t preamble[] = {0,0,0,0,0,0,0,1};
734 size_t startIdx = 0;
735 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
736 if (errChk == 0) return -4; //preamble not found
737 if (*size != 96) return -5;
738 return (int)startIdx;
1e090a61 739}
740
741// by marshmellow
6fe5c94b 742// FSK Demod then try to locate a Farpointe Data (pyramid) ID
a1d17964 743int PyramiddemodFSK(uint8_t *dest, size_t *size)
1e090a61 744{
f3bf15e4 745 //make sure buffer has data
746 if (*size < 128*50) return -5;
a1d17964 747
f3bf15e4 748 //test samples are not just noise
749 if (justNoise(dest, *size)) return -1;
1e090a61 750
f3bf15e4 751 // FSK demodulator
752 *size = fskdemod(dest, *size, 50, 1, 10, 8); // fsk2a RF/50
753 if (*size < 128) return -2; //did we get a good demod?
a1d17964 754
f3bf15e4 755 uint8_t preamble[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
a1d17964 756 size_t startIdx = 0;
757 uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
758 if (errChk == 0) return -4; //preamble not found
759 if (*size != 128) return -3;
760 return (int)startIdx;
1e090a61 761}
762
fef74fdc 763// by marshmellow
764// to detect a wave that has heavily clipped (clean) samples
cc15a118 765uint8_t DetectCleanAskWave(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
6de43508 766{
6fe5c94b 767 bool allArePeaks = true;
6de43508 768 uint16_t cntPeaks=0;
db829602 769 size_t loopEnd = 512+160;
1fbf8956 770 if (loopEnd > size) loopEnd = size;
db829602 771 for (size_t i=160; i<loopEnd; i++){
6de43508 772 if (dest[i]>low && dest[i]<high)
6fe5c94b 773 allArePeaks = false;
6de43508 774 else
775 cntPeaks++;
776 }
6fe5c94b 777 if (!allArePeaks){
778 if (cntPeaks > 300) return true;
6de43508 779 }
6fe5c94b 780 return allArePeaks;
6de43508 781}
2eec55c8 782// by marshmellow
783// to help detect clocks on heavily clipped samples
cc15a118 784// based on count of low to low
785int DetectStrongAskClock(uint8_t dest[], size_t size, uint8_t high, uint8_t low)
13d77ef9 786{
cc15a118 787 uint8_t fndClk[] = {8,16,32,40,50,64,128};
788 size_t startwave;
db829602 789 size_t i = 100;
cc15a118 790 size_t minClk = 255;
791 // get to first full low to prime loop and skip incomplete first pulse
792 while ((dest[i] < high) && (i < size))
793 ++i;
794 while ((dest[i] > low) && (i < size))
795 ++i;
796
797 // loop through all samples
798 while (i < size) {
799 // measure from low to low
800 while ((dest[i] > low) && (i < size))
801 ++i;
802 startwave= i;
803 while ((dest[i] < high) && (i < size))
804 ++i;
805 while ((dest[i] > low) && (i < size))
806 ++i;
807 //get minimum measured distance
808 if (i-startwave < minClk && i < size)
809 minClk = i - startwave;
13d77ef9 810 }
cc15a118 811 // set clock
709665b5 812 if (g_debugMode==2) prnt("DEBUG ASK: detectstrongASKclk smallest wave: %d",minClk);
cc15a118 813 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
814 if (minClk >= fndClk[clkCnt]-(fndClk[clkCnt]/8) && minClk <= fndClk[clkCnt]+1)
815 return fndClk[clkCnt];
13d77ef9 816 }
cc15a118 817 return 0;
13d77ef9 818}
819
eb191de6 820// by marshmellow
821// not perfect especially with lower clocks or VERY good antennas (heavy wave clipping)
822// maybe somehow adjust peak trimming value based on samples to fix?
6de43508 823// return start index of best starting position for that clock and return clock (by reference)
824int DetectASKClock(uint8_t dest[], size_t size, int *clock, int maxErr)
eb191de6 825{
6e984446 826 size_t i=1;
cc15a118 827 uint8_t clk[] = {255,8,16,32,40,50,64,100,128,255};
828 uint8_t clkEnd = 9;
2eec55c8 829 uint8_t loopCnt = 255; //don't need to loop through entire array...
db829602 830 if (size <= loopCnt+60) return -1; //not enough samples
831 size -= 60; //sometimes there is a strange end wave - filter out this....
6e984446 832 //if we already have a valid clock
833 uint8_t clockFnd=0;
cc15a118 834 for (;i<clkEnd;++i)
835 if (clk[i] == *clock) clockFnd = i;
6e984446 836 //clock found but continue to find best startpos
e0165dcf 837
838 //get high and low peak
839 int peak, low;
2eec55c8 840 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return -1;
e0165dcf 841
842 //test for large clean peaks
cc15a118 843 if (!clockFnd){
844 if (DetectCleanAskWave(dest, size, peak, low)==1){
845 int ans = DetectStrongAskClock(dest, size, peak, low);
709665b5 846 if (g_debugMode==2) prnt("DEBUG ASK: detectaskclk Clean Ask Wave Detected: clk %d",ans);
cc15a118 847 for (i=clkEnd-1; i>0; i--){
848 if (clk[i] == ans) {
849 *clock = ans;
850 //clockFnd = i;
851 return 0; // for strong waves i don't use the 'best start position' yet...
852 //break; //clock found but continue to find best startpos [not yet]
853 }
e0165dcf 854 }
855 }
856 }
2eec55c8 857 uint8_t ii;
858 uint8_t clkCnt, tol = 0;
859 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
860 uint8_t bestStart[]={0,0,0,0,0,0,0,0,0};
861 size_t errCnt = 0;
862 size_t arrLoc, loopEnd;
6e984446 863
cc15a118 864 if (clockFnd>0) {
865 clkCnt = clockFnd;
866 clkEnd = clockFnd+1;
867 }
868 else clkCnt=1;
869
870 //test each valid clock from smallest to greatest to see which lines up
871 for(; clkCnt < clkEnd; clkCnt++){
fef74fdc 872 if (clk[clkCnt] <= 32){
e0165dcf 873 tol=1;
874 }else{
875 tol=0;
876 }
2767fc02 877 //if no errors allowed - keep start within the first clock
cc15a118 878 if (!maxErr && size > clk[clkCnt]*2 + tol && clk[clkCnt]<128) loopCnt=clk[clkCnt]*2;
e0165dcf 879 bestErr[clkCnt]=1000;
6e984446 880 //try lining up the peaks by moving starting point (try first few clocks)
cc15a118 881 for (ii=0; ii < loopCnt; ii++){
2eec55c8 882 if (dest[ii] < peak && dest[ii] > low) continue;
883
884 errCnt=0;
885 // now that we have the first one lined up test rest of wave array
886 loopEnd = ((size-ii-tol) / clk[clkCnt]) - 1;
887 for (i=0; i < loopEnd; ++i){
888 arrLoc = ii + (i * clk[clkCnt]);
889 if (dest[arrLoc] >= peak || dest[arrLoc] <= low){
890 }else if (dest[arrLoc-tol] >= peak || dest[arrLoc-tol] <= low){
891 }else if (dest[arrLoc+tol] >= peak || dest[arrLoc+tol] <= low){
892 }else{ //error no peak detected
893 errCnt++;
e0165dcf 894 }
895 }
cc15a118 896 //if we found no errors then we can stop here and a low clock (common clocks)
2eec55c8 897 // this is correct one - return this clock
709665b5 898 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, err %d, startpos %d, endpos %d",clk[clkCnt],errCnt,ii,i);
cc15a118 899 if(errCnt==0 && clkCnt<7) {
900 if (!clockFnd) *clock = clk[clkCnt];
2eec55c8 901 return ii;
902 }
903 //if we found errors see if it is lowest so far and save it as best run
904 if(errCnt<bestErr[clkCnt]){
905 bestErr[clkCnt]=errCnt;
906 bestStart[clkCnt]=ii;
907 }
e0165dcf 908 }
909 }
cc15a118 910 uint8_t iii;
e0165dcf 911 uint8_t best=0;
cc15a118 912 for (iii=1; iii<clkEnd; ++iii){
2eec55c8 913 if (bestErr[iii] < bestErr[best]){
914 if (bestErr[iii] == 0) bestErr[iii]=1;
e0165dcf 915 // current best bit to error ratio vs new bit to error ratio
2eec55c8 916 if ( (size/clk[best])/bestErr[best] < (size/clk[iii])/bestErr[iii] ){
e0165dcf 917 best = iii;
918 }
919 }
709665b5 920 if (g_debugMode == 2) prnt("DEBUG ASK: clk %d, # Errors %d, Current Best Clk %d, bestStart %d",clk[iii],bestErr[iii],clk[best],bestStart[best]);
e0165dcf 921 }
cc15a118 922 if (!clockFnd) *clock = clk[best];
e0165dcf 923 return bestStart[best];
eb191de6 924}
ba1a299c 925
926//by marshmellow
6de43508 927//detect psk clock by reading each phase shift
928// a phase shift is determined by measuring the sample length of each wave
929int DetectPSKClock(uint8_t dest[], size_t size, int clock)
ba1a299c 930{
e0165dcf 931 uint8_t clk[]={255,16,32,40,50,64,100,128,255}; //255 is not a valid clock
932 uint16_t loopCnt = 4096; //don't need to loop through entire array...
933 if (size == 0) return 0;
db829602 934 if (size<loopCnt) loopCnt = size-20;
e0165dcf 935
936 //if we already have a valid clock quit
937 size_t i=1;
938 for (; i < 8; ++i)
939 if (clk[i] == clock) return clock;
940
941 size_t waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
942 uint8_t clkCnt, fc=0, fullWaveLen=0, tol=1;
943 uint16_t peakcnt=0, errCnt=0, waveLenCnt=0;
944 uint16_t bestErr[]={1000,1000,1000,1000,1000,1000,1000,1000,1000};
945 uint16_t peaksdet[]={0,0,0,0,0,0,0,0,0};
2eec55c8 946 fc = countFC(dest, size, 0);
947 if (fc!=2 && fc!=4 && fc!=8) return -1;
709665b5 948 if (g_debugMode==2) prnt("DEBUG PSK: FC: %d",fc);
e0165dcf 949
950 //find first full wave
db829602 951 for (i=160; i<loopCnt; i++){
e0165dcf 952 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
953 if (waveStart == 0) {
954 waveStart = i+1;
db829602 955 //prnt("DEBUG: waveStart: %d",waveStart);
e0165dcf 956 } else {
957 waveEnd = i+1;
db829602 958 //prnt("DEBUG: waveEnd: %d",waveEnd);
e0165dcf 959 waveLenCnt = waveEnd-waveStart;
960 if (waveLenCnt > fc){
961 firstFullWave = waveStart;
962 fullWaveLen=waveLenCnt;
963 break;
964 }
965 waveStart=0;
966 }
967 }
968 }
709665b5 969 if (g_debugMode ==2) prnt("DEBUG PSK: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
e0165dcf 970
971 //test each valid clock from greatest to smallest to see which lines up
972 for(clkCnt=7; clkCnt >= 1 ; clkCnt--){
973 lastClkBit = firstFullWave; //set end of wave as clock align
974 waveStart = 0;
975 errCnt=0;
976 peakcnt=0;
709665b5 977 if (g_debugMode == 2) prnt("DEBUG PSK: clk: %d, lastClkBit: %d",clk[clkCnt],lastClkBit);
e0165dcf 978
979 for (i = firstFullWave+fullWaveLen-1; i < loopCnt-2; i++){
980 //top edge of wave = start of new wave
981 if (dest[i] < dest[i+1] && dest[i+1] >= dest[i+2]){
982 if (waveStart == 0) {
983 waveStart = i+1;
984 waveLenCnt=0;
985 } else { //waveEnd
986 waveEnd = i+1;
987 waveLenCnt = waveEnd-waveStart;
988 if (waveLenCnt > fc){
989 //if this wave is a phase shift
709665b5 990 if (g_debugMode == 2) prnt("DEBUG PSK: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+clk[clkCnt]-tol,i+1,fc);
e0165dcf 991 if (i+1 >= lastClkBit + clk[clkCnt] - tol){ //should be a clock bit
992 peakcnt++;
993 lastClkBit+=clk[clkCnt];
994 } else if (i<lastClkBit+8){
995 //noise after a phase shift - ignore
996 } else { //phase shift before supposed to based on clock
997 errCnt++;
998 }
999 } else if (i+1 > lastClkBit + clk[clkCnt] + tol + fc){
1000 lastClkBit+=clk[clkCnt]; //no phase shift but clock bit
1001 }
1002 waveStart=i+1;
1003 }
1004 }
1005 }
1006 if (errCnt == 0){
1007 return clk[clkCnt];
1008 }
1009 if (errCnt <= bestErr[clkCnt]) bestErr[clkCnt]=errCnt;
1010 if (peakcnt > peaksdet[clkCnt]) peaksdet[clkCnt]=peakcnt;
1011 }
1012 //all tested with errors
1013 //return the highest clk with the most peaks found
1014 uint8_t best=7;
1015 for (i=7; i>=1; i--){
1016 if (peaksdet[i] > peaksdet[best]) {
1017 best = i;
1018 }
709665b5 1019 if (g_debugMode == 2) prnt("DEBUG PSK: Clk: %d, peaks: %d, errs: %d, bestClk: %d",clk[i],peaksdet[i],bestErr[i],clk[best]);
e0165dcf 1020 }
1021 return clk[best];
ba1a299c 1022}
1023
db829602 1024int DetectStrongNRZClk(uint8_t *dest, size_t size, int peak, int low){
1025 //find shortest transition from high to low
1026 size_t i = 0;
1027 size_t transition1 = 0;
1028 int lowestTransition = 255;
6fe5c94b 1029 bool lastWasHigh = false;
1030
1031 //find first valid beginning of a high or low wave
1032 while ((dest[i] >= peak || dest[i] <= low) && (i < size))
1033 ++i;
1034 while ((dest[i] < peak && dest[i] > low) && (i < size))
1035 ++i;
1036 lastWasHigh = (dest[i] >= peak);
1037
db829602 1038 if (i==size) return 0;
1039 transition1 = i;
1040
1041 for (;i < size; i++) {
1042 if ((dest[i] >= peak && !lastWasHigh) || (dest[i] <= low && lastWasHigh)) {
1043 lastWasHigh = (dest[i] >= peak);
1044 if (i-transition1 < lowestTransition) lowestTransition = i-transition1;
1045 transition1 = i;
1046 }
1047 }
1048 if (lowestTransition == 255) lowestTransition = 0;
709665b5 1049 if (g_debugMode==2) prnt("DEBUG NRZ: detectstrongNRZclk smallest wave: %d",lowestTransition);
db829602 1050 return lowestTransition;
1051}
1052
6de43508 1053//by marshmellow
1054//detect nrz clock by reading #peaks vs no peaks(or errors)
1055int DetectNRZClock(uint8_t dest[], size_t size, int clock)
ba1a299c 1056{
2eec55c8 1057 size_t i=0;
1058 uint8_t clk[]={8,16,32,40,50,64,100,128,255};
1059 size_t loopCnt = 4096; //don't need to loop through entire array...
e0165dcf 1060 if (size == 0) return 0;
db829602 1061 if (size<loopCnt) loopCnt = size-20;
e0165dcf 1062 //if we already have a valid clock quit
1063 for (; i < 8; ++i)
1064 if (clk[i] == clock) return clock;
1065
1066 //get high and low peak
1067 int peak, low;
2eec55c8 1068 if (getHiLo(dest, loopCnt, &peak, &low, 75, 75) < 1) return 0;
e0165dcf 1069
db829602 1070 int lowestTransition = DetectStrongNRZClk(dest, size-20, peak, low);
2eec55c8 1071 size_t ii;
e0165dcf 1072 uint8_t clkCnt;
1073 uint8_t tol = 0;
db829602 1074 uint16_t smplCnt = 0;
1075 int16_t peakcnt = 0;
1076 int16_t peaksdet[] = {0,0,0,0,0,0,0,0};
1077 uint16_t maxPeak = 255;
6fe5c94b 1078 bool firstpeak = false;
e0165dcf 1079 //test for large clipped waves
1080 for (i=0; i<loopCnt; i++){
1081 if (dest[i] >= peak || dest[i] <= low){
db829602 1082 if (!firstpeak) continue;
1083 smplCnt++;
e0165dcf 1084 } else {
6fe5c94b 1085 firstpeak=true;
db829602 1086 if (smplCnt > 6 ){
1087 if (maxPeak > smplCnt){
1088 maxPeak = smplCnt;
1089 //prnt("maxPk: %d",maxPeak);
1090 }
1091 peakcnt++;
1092 //prnt("maxPk: %d, smplCnt: %d, peakcnt: %d",maxPeak,smplCnt,peakcnt);
1093 smplCnt=0;
e0165dcf 1094 }
e0165dcf 1095 }
1096 }
6fe5c94b 1097 bool errBitHigh = 0;
1098 bool bitHigh = 0;
1099 uint8_t ignoreCnt = 0;
1100 uint8_t ignoreWindow = 4;
1101 bool lastPeakHigh = 0;
1102 int lastBit = 0;
e0165dcf 1103 peakcnt=0;
1104 //test each valid clock from smallest to greatest to see which lines up
1105 for(clkCnt=0; clkCnt < 8; ++clkCnt){
db829602 1106 //ignore clocks smaller than smallest peak
1107 if (clk[clkCnt] < maxPeak - (clk[clkCnt]/4)) continue;
e0165dcf 1108 //try lining up the peaks by moving starting point (try first 256)
db829602 1109 for (ii=20; ii < loopCnt; ++ii){
e0165dcf 1110 if ((dest[ii] >= peak) || (dest[ii] <= low)){
6fe5c94b 1111 peakcnt = 0;
1112 bitHigh = false;
1113 ignoreCnt = 0;
1114 lastBit = ii-clk[clkCnt];
db829602 1115 //loop through to see if this start location works
1116 for (i = ii; i < size-20; ++i) {
6fe5c94b 1117 //if we are at a clock bit
db829602 1118 if ((i >= lastBit + clk[clkCnt] - tol) && (i <= lastBit + clk[clkCnt] + tol)) {
1119 //test high/low
1120 if (dest[i] >= peak || dest[i] <= low) {
6fe5c94b 1121 //if same peak don't count it
1122 if ((dest[i] >= peak && !lastPeakHigh) || (dest[i] <= low && lastPeakHigh)) {
1123 peakcnt++;
1124 }
1125 lastPeakHigh = (dest[i] >= peak);
1126 bitHigh = true;
1127 errBitHigh = false;
db829602 1128 ignoreCnt = ignoreWindow;
1129 lastBit += clk[clkCnt];
db829602 1130 } else if (i == lastBit + clk[clkCnt] + tol) {
1131 lastBit += clk[clkCnt];
db829602 1132 }
1133 //else if not a clock bit and no peaks
1134 } else if (dest[i] < peak && dest[i] > low){
db829602 1135 if (ignoreCnt==0){
6fe5c94b 1136 bitHigh=false;
1137 if (errBitHigh==true) peakcnt--;
1138 errBitHigh=false;
db829602 1139 } else {
1140 ignoreCnt--;
1141 }
1142 // else if not a clock bit but we have a peak
6fe5c94b 1143 } else if ((dest[i]>=peak || dest[i]<=low) && (!bitHigh)) {
db829602 1144 //error bar found no clock...
6fe5c94b 1145 errBitHigh=true;
e0165dcf 1146 }
1147 }
1148 if(peakcnt>peaksdet[clkCnt]) {
1149 peaksdet[clkCnt]=peakcnt;
1150 }
1151 }
1152 }
1153 }
1154 int iii=7;
2eec55c8 1155 uint8_t best=0;
e0165dcf 1156 for (iii=7; iii > 0; iii--){
6fe5c94b 1157 if ((peaksdet[iii] >= (peaksdet[best]-1)) && (peaksdet[iii] <= peaksdet[best]+1) && lowestTransition) {
1158 if (clk[iii] > (lowestTransition - (clk[iii]/8)) && clk[iii] < (lowestTransition + (clk[iii]/8))) {
db829602 1159 best = iii;
1160 }
6fe5c94b 1161 } else if (peaksdet[iii] > peaksdet[best]){
1162 best = iii;
e0165dcf 1163 }
709665b5 1164 if (g_debugMode==2) prnt("DEBUG NRZ: Clk: %d, peaks: %d, maxPeak: %d, bestClk: %d, lowestTrs: %d",clk[iii],peaksdet[iii],maxPeak, clk[best], lowestTransition);
e0165dcf 1165 }
db829602 1166
e0165dcf 1167 return clk[best];
ba1a299c 1168}
1169
04d2721b 1170// by marshmellow
1171// convert psk1 demod to psk2 demod
1172// only transition waves are 1s
1173void psk1TOpsk2(uint8_t *BitStream, size_t size)
1174{
1175 size_t i=1;
1176 uint8_t lastBit=BitStream[0];
1177 for (; i<size; i++){
2767fc02 1178 if (BitStream[i]==7){
7a8a982b 1179 //ignore errors
1180 } else if (lastBit!=BitStream[i]){
04d2721b 1181 lastBit=BitStream[i];
1182 BitStream[i]=1;
1183 } else {
1184 BitStream[i]=0;
1185 }
1186 }
1187 return;
1188}
ba1a299c 1189
3bc66a96 1190// by marshmellow
1191// convert psk2 demod to psk1 demod
1192// from only transition waves are 1s to phase shifts change bit
1193void psk2TOpsk1(uint8_t *BitStream, size_t size)
1194{
712ebfa6 1195 uint8_t phase=0;
1196 for (size_t i=0; i<size; i++){
1197 if (BitStream[i]==1){
3bc66a96 1198 phase ^=1;
1199 }
1200 BitStream[i]=phase;
1201 }
1202 return;
1203}
1204
04d2721b 1205// redesigned by marshmellow adjusted from existing decode functions
1206// indala id decoding - only tested on 26 bit tags, but attempted to make it work for more
ba1a299c 1207int indala26decode(uint8_t *bitStream, size_t *size, uint8_t *invert)
1208{
1209 //26 bit 40134 format (don't know other formats)
14331320 1210 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};
1211 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};
1212 size_t startidx = 0;
1213 if (!preambleSearch(bitStream, preamble, sizeof(preamble), size, &startidx)){
1214 // if didn't find preamble try again inverting
1215 if (!preambleSearch(bitStream, preamble_i, sizeof(preamble_i), size, &startidx)) return -1;
1216 *invert ^= 1;
1217 }
1218 if (*size != 64 && *size != 224) return -2;
1219 if (*invert==1)
1220 for (size_t i = startidx; i < *size; i++)
1221 bitStream[i] ^= 1;
ba1a299c 1222
14331320 1223 return (int) startidx;
ba1a299c 1224}
1225
d1869c33 1226// by marshmellow - demodulate NRZ wave - requires a read with strong signal
04d2721b 1227// peaks invert bit (high=1 low=0) each clock cycle = 1 bit determined by last peak
db829602 1228int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert){
e0165dcf 1229 if (justNoise(dest, *size)) return -1;
1230 *clk = DetectNRZClock(dest, *size, *clk);
1231 if (*clk==0) return -2;
2eec55c8 1232 size_t i, gLen = 4096;
db829602 1233 if (gLen>*size) gLen = *size-20;
e0165dcf 1234 int high, low;
1235 if (getHiLo(dest, gLen, &high, &low, 75, 75) < 1) return -3; //25% fuzz on high 25% fuzz on low
db829602 1236
1237 uint8_t bit=0;
1238 //convert wave samples to 1's and 0's
1239 for(i=20; i < *size-20; i++){
1240 if (dest[i] >= high) bit = 1;
1241 if (dest[i] <= low) bit = 0;
1242 dest[i] = bit;
e0165dcf 1243 }
db829602 1244 //now demod based on clock (rf/32 = 32 1's for one 1 bit, 32 0's for one 0 bit)
1245 size_t lastBit = 0;
1246 size_t numBits = 0;
1247 for(i=21; i < *size-20; i++) {
1248 //if transition detected or large number of same bits - store the passed bits
1249 if (dest[i] != dest[i-1] || (i-lastBit) == (10 * *clk)) {
1250 memset(dest+numBits, dest[i-1] ^ *invert, (i - lastBit + (*clk/4)) / *clk);
1251 numBits += (i - lastBit + (*clk/4)) / *clk;
1252 lastBit = i-1;
e0165dcf 1253 }
e0165dcf 1254 }
db829602 1255 *size = numBits;
1256 return 0;
ba1a299c 1257}
1258
1e090a61 1259//by marshmellow
03e6bb4a 1260//detects the bit clock for FSK given the high and low Field Clocks
1261uint8_t detectFSKClk(uint8_t *BitStream, size_t size, uint8_t fcHigh, uint8_t fcLow)
1e090a61 1262{
e0165dcf 1263 uint8_t clk[] = {8,16,32,40,50,64,100,128,0};
1264 uint16_t rfLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1265 uint8_t rfCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1266 uint8_t rfLensFnd = 0;
2eec55c8 1267 uint8_t lastFCcnt = 0;
1268 uint16_t fcCounter = 0;
e0165dcf 1269 uint16_t rfCounter = 0;
1270 uint8_t firstBitFnd = 0;
1271 size_t i;
1272 if (size == 0) return 0;
1273
6fe5c94b 1274 uint8_t fcTol = ((fcHigh*100 - fcLow*100)/2 + 50)/100; //(uint8_t)(0.5+(float)(fcHigh-fcLow)/2);
e0165dcf 1275 rfLensFnd=0;
1276 fcCounter=0;
1277 rfCounter=0;
1278 firstBitFnd=0;
1279 //PrintAndLog("DEBUG: fcTol: %d",fcTol);
6fe5c94b 1280 // prime i to first peak / up transition
1281 for (i = 160; i < size-20; i++)
e0165dcf 1282 if (BitStream[i] > BitStream[i-1] && BitStream[i]>=BitStream[i+1])
1283 break;
1284
6fe5c94b 1285 for (; i < size-20; i++){
2eec55c8 1286 fcCounter++;
1287 rfCounter++;
1288
1289 if (BitStream[i] <= BitStream[i-1] || BitStream[i] < BitStream[i+1])
1290 continue;
1291 // else new peak
1292 // if we got less than the small fc + tolerance then set it to the small fc
1293 if (fcCounter < fcLow+fcTol)
1294 fcCounter = fcLow;
1295 else //set it to the large fc
1296 fcCounter = fcHigh;
1297
1298 //look for bit clock (rf/xx)
1299 if ((fcCounter < lastFCcnt || fcCounter > lastFCcnt)){
1300 //not the same size as the last wave - start of new bit sequence
1301 if (firstBitFnd > 1){ //skip first wave change - probably not a complete bit
1302 for (int ii=0; ii<15; ii++){
6fe5c94b 1303 if (rfLens[ii] >= (rfCounter-4) && rfLens[ii] <= (rfCounter+4)){
2eec55c8 1304 rfCnts[ii]++;
1305 rfCounter = 0;
1306 break;
e0165dcf 1307 }
e0165dcf 1308 }
2eec55c8 1309 if (rfCounter > 0 && rfLensFnd < 15){
1310 //PrintAndLog("DEBUG: rfCntr %d, fcCntr %d",rfCounter,fcCounter);
1311 rfCnts[rfLensFnd]++;
1312 rfLens[rfLensFnd++] = rfCounter;
1313 }
1314 } else {
1315 firstBitFnd++;
e0165dcf 1316 }
2eec55c8 1317 rfCounter=0;
1318 lastFCcnt=fcCounter;
e0165dcf 1319 }
2eec55c8 1320 fcCounter=0;
e0165dcf 1321 }
1322 uint8_t rfHighest=15, rfHighest2=15, rfHighest3=15;
1323
1324 for (i=0; i<15; i++){
e0165dcf 1325 //get highest 2 RF values (might need to get more values to compare or compare all?)
1326 if (rfCnts[i]>rfCnts[rfHighest]){
1327 rfHighest3=rfHighest2;
1328 rfHighest2=rfHighest;
1329 rfHighest=i;
1330 } else if(rfCnts[i]>rfCnts[rfHighest2]){
1331 rfHighest3=rfHighest2;
1332 rfHighest2=i;
1333 } else if(rfCnts[i]>rfCnts[rfHighest3]){
1334 rfHighest3=i;
1335 }
709665b5 1336 if (g_debugMode==2) prnt("DEBUG FSK: RF %d, cnts %d",rfLens[i], rfCnts[i]);
e0165dcf 1337 }
1338 // set allowed clock remainder tolerance to be 1 large field clock length+1
1339 // we could have mistakenly made a 9 a 10 instead of an 8 or visa versa so rfLens could be 1 FC off
1340 uint8_t tol1 = fcHigh+1;
1341
709665b5 1342 if (g_debugMode==2) prnt("DEBUG FSK: most counted rf values: 1 %d, 2 %d, 3 %d",rfLens[rfHighest],rfLens[rfHighest2],rfLens[rfHighest3]);
e0165dcf 1343
1344 // loop to find the highest clock that has a remainder less than the tolerance
1345 // compare samples counted divided by
6fe5c94b 1346 // test 128 down to 32 (shouldn't be possible to have fc/10 & fc/8 and rf/16 or less)
e0165dcf 1347 int ii=7;
6fe5c94b 1348 for (; ii>=2; ii--){
e0165dcf 1349 if (rfLens[rfHighest] % clk[ii] < tol1 || rfLens[rfHighest] % clk[ii] > clk[ii]-tol1){
1350 if (rfLens[rfHighest2] % clk[ii] < tol1 || rfLens[rfHighest2] % clk[ii] > clk[ii]-tol1){
1351 if (rfLens[rfHighest3] % clk[ii] < tol1 || rfLens[rfHighest3] % clk[ii] > clk[ii]-tol1){
709665b5 1352 if (g_debugMode==2) prnt("DEBUG FSK: clk %d divides into the 3 most rf values within tolerance",clk[ii]);
e0165dcf 1353 break;
1354 }
1355 }
1356 }
1357 }
1358
1359 if (ii<0) return 0; // oops we went too far
1360
1361 return clk[ii];
03e6bb4a 1362}
1e090a61 1363
03e6bb4a 1364//by marshmellow
1365//countFC is to detect the field clock lengths.
1366//counts and returns the 2 most common wave lengths
6de43508 1367//mainly used for FSK field clock detection
2eec55c8 1368uint16_t countFC(uint8_t *BitStream, size_t size, uint8_t fskAdj)
03e6bb4a 1369{
6fe5c94b 1370 uint8_t fcLens[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1371 uint16_t fcCnts[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
e0165dcf 1372 uint8_t fcLensFnd = 0;
1373 uint8_t lastFCcnt=0;
2eec55c8 1374 uint8_t fcCounter = 0;
e0165dcf 1375 size_t i;
1376 if (size == 0) return 0;
1377
1378 // prime i to first up transition
6fe5c94b 1379 for (i = 160; i < size-20; i++)
e0165dcf 1380 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1])
1381 break;
1382
6fe5c94b 1383 for (; i < size-20; i++){
e0165dcf 1384 if (BitStream[i] > BitStream[i-1] && BitStream[i] >= BitStream[i+1]){
1385 // new up transition
1386 fcCounter++;
2eec55c8 1387 if (fskAdj){
1388 //if we had 5 and now have 9 then go back to 8 (for when we get a fc 9 instead of an 8)
1389 if (lastFCcnt==5 && fcCounter==9) fcCounter--;
1390 //if fc=9 or 4 add one (for when we get a fc 9 instead of 10 or a 4 instead of a 5)
1391 if ((fcCounter==9) || fcCounter==4) fcCounter++;
e0165dcf 1392 // save last field clock count (fc/xx)
2eec55c8 1393 lastFCcnt = fcCounter;
1394 }
e0165dcf 1395 // find which fcLens to save it to:
6fe5c94b 1396 for (int ii=0; ii<15; ii++){
e0165dcf 1397 if (fcLens[ii]==fcCounter){
1398 fcCnts[ii]++;
1399 fcCounter=0;
1400 break;
1401 }
1402 }
6fe5c94b 1403 if (fcCounter>0 && fcLensFnd<15){
e0165dcf 1404 //add new fc length
1405 fcCnts[fcLensFnd]++;
1406 fcLens[fcLensFnd++]=fcCounter;
1407 }
1408 fcCounter=0;
1409 } else {
1410 // count sample
1411 fcCounter++;
1412 }
1413 }
1414
6fe5c94b 1415 uint8_t best1=14, best2=14, best3=14;
e0165dcf 1416 uint16_t maxCnt1=0;
1417 // go through fclens and find which ones are bigest 2
6fe5c94b 1418 for (i=0; i<15; i++){
e0165dcf 1419 // get the 3 best FC values
1420 if (fcCnts[i]>maxCnt1) {
1421 best3=best2;
1422 best2=best1;
1423 maxCnt1=fcCnts[i];
1424 best1=i;
1425 } else if(fcCnts[i]>fcCnts[best2]){
1426 best3=best2;
1427 best2=i;
1428 } else if(fcCnts[i]>fcCnts[best3]){
1429 best3=i;
1430 }
709665b5 1431 if (g_debugMode==2) prnt("DEBUG countfc: FC %u, Cnt %u, best fc: %u, best2 fc: %u",fcLens[i],fcCnts[i],fcLens[best1],fcLens[best2]);
e0165dcf 1432 }
6fe5c94b 1433 if (fcLens[best1]==0) return 0;
e0165dcf 1434 uint8_t fcH=0, fcL=0;
1435 if (fcLens[best1]>fcLens[best2]){
1436 fcH=fcLens[best1];
1437 fcL=fcLens[best2];
1438 } else{
1439 fcH=fcLens[best2];
1440 fcL=fcLens[best1];
1441 }
709665b5 1442 if ((size-180)/fcH/3 > fcCnts[best1]+fcCnts[best2]) {
1443 if (g_debugMode==2) prnt("DEBUG countfc: fc is too large: %u > %u. Not psk or fsk",(size-180)/fcH/3,fcCnts[best1]+fcCnts[best2]);
1444 return 0; //lots of waves not psk or fsk
1445 }
e0165dcf 1446 // TODO: take top 3 answers and compare to known Field clocks to get top 2
1447
1448 uint16_t fcs = (((uint16_t)fcH)<<8) | fcL;
2eec55c8 1449 if (fskAdj) return fcs;
1450 return fcLens[best1];
6de43508 1451}
1452
1453//by marshmellow - demodulate PSK1 wave
1454//uses wave lengths (# Samples)
1455int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
1456{
e0165dcf 1457 if (size == 0) return -1;
2eec55c8 1458 uint16_t loopCnt = 4096; //don't need to loop through entire array...
e0165dcf 1459 if (*size<loopCnt) loopCnt = *size;
1460
db829602 1461 size_t numBits=0;
e0165dcf 1462 uint8_t curPhase = *invert;
1463 size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
1464 uint8_t fc=0, fullWaveLen=0, tol=1;
1465 uint16_t errCnt=0, waveLenCnt=0;
2eec55c8 1466 fc = countFC(dest, *size, 0);
e0165dcf 1467 if (fc!=2 && fc!=4 && fc!=8) return -1;
1468 //PrintAndLog("DEBUG: FC: %d",fc);
1469 *clock = DetectPSKClock(dest, *size, *clock);
2eec55c8 1470 if (*clock == 0) return -1;
e0165dcf 1471 int avgWaveVal=0, lastAvgWaveVal=0;
1472 //find first phase shift
1473 for (i=0; i<loopCnt; i++){
1474 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1475 waveEnd = i+1;
1476 //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
1477 waveLenCnt = waveEnd-waveStart;
db829602 1478 if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
e0165dcf 1479 lastAvgWaveVal = avgWaveVal/(waveLenCnt);
1480 firstFullWave = waveStart;
1481 fullWaveLen=waveLenCnt;
1482 //if average wave value is > graph 0 then it is an up wave or a 1
2eec55c8 1483 if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
e0165dcf 1484 break;
1485 }
1486 waveStart = i+1;
1487 avgWaveVal = 0;
1488 }
2eec55c8 1489 avgWaveVal += dest[i+2];
e0165dcf 1490 }
db829602 1491 if (firstFullWave == 0) {
1492 // no phase shift detected - could be all 1's or 0's - doesn't matter where we start
1493 // so skip a little to ensure we are past any Start Signal
1494 firstFullWave = 160;
1495 memset(dest, curPhase, firstFullWave / *clock);
1496 } else {
1497 memset(dest, curPhase^1, firstFullWave / *clock);
1498 }
1499 //advance bits
1500 numBits += (firstFullWave / *clock);
1501 //set start of wave as clock align
1502 lastClkBit = firstFullWave;
cf194819 1503 if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
1504 if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
e0165dcf 1505 waveStart = 0;
e0165dcf 1506 dest[numBits++] = curPhase; //set first read bit
2eec55c8 1507 for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
e0165dcf 1508 //top edge of wave = start of new wave
1509 if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
1510 if (waveStart == 0) {
1511 waveStart = i+1;
2eec55c8 1512 waveLenCnt = 0;
e0165dcf 1513 avgWaveVal = dest[i+1];
1514 } else { //waveEnd
1515 waveEnd = i+1;
1516 waveLenCnt = waveEnd-waveStart;
1517 lastAvgWaveVal = avgWaveVal/waveLenCnt;
1518 if (waveLenCnt > fc){
1519 //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
2eec55c8 1520 //this wave is a phase shift
e0165dcf 1521 //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
1522 if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
2eec55c8 1523 curPhase ^= 1;
e0165dcf 1524 dest[numBits++] = curPhase;
1525 lastClkBit += *clock;
2eec55c8 1526 } else if (i < lastClkBit+10+fc){
e0165dcf 1527 //noise after a phase shift - ignore
1528 } else { //phase shift before supposed to based on clock
1529 errCnt++;
2767fc02 1530 dest[numBits++] = 7;
e0165dcf 1531 }
1532 } else if (i+1 > lastClkBit + *clock + tol + fc){
1533 lastClkBit += *clock; //no phase shift but clock bit
1534 dest[numBits++] = curPhase;
1535 }
2eec55c8 1536 avgWaveVal = 0;
1537 waveStart = i+1;
e0165dcf 1538 }
1539 }
2eec55c8 1540 avgWaveVal += dest[i+1];
e0165dcf 1541 }
1542 *size = numBits;
1543 return errCnt;
6de43508 1544}
d1869c33 1545
1546//by marshmellow
1547//attempt to identify a Sequence Terminator in ASK modulated raw wave
1548bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
1549 size_t bufsize = *size;
1550 //need to loop through all samples and identify our clock, look for the ST pattern
1551 uint8_t fndClk[] = {8,16,32,40,50,64,128};
1552 int clk = 0;
1553 int tol = 0;
b96bcc79 1554 int i, j, skip, start, end, low, high, minClk, waveStart;
d1869c33 1555 bool complete = false;
1556 int tmpbuff[bufsize / 64];
b96bcc79 1557 int waveLen[bufsize / 64];
d1869c33 1558 size_t testsize = (bufsize < 512) ? bufsize : 512;
b96bcc79 1559 int phaseoff = 0;
d1869c33 1560 high = low = 128;
1561 memset(tmpbuff, 0, sizeof(tmpbuff));
1562
1563 if ( getHiLo(buffer, testsize, &high, &low, 80, 80) == -1 ) {
1564 if (g_debugMode==2) prnt("DEBUG STT: just noise detected - quitting");
1565 return false; //just noise
1566 }
d1869c33 1567 i = 0;
1568 j = 0;
1569 minClk = 255;
1570 // get to first full low to prime loop and skip incomplete first pulse
1571 while ((buffer[i] < high) && (i < bufsize))
1572 ++i;
1573 while ((buffer[i] > low) && (i < bufsize))
1574 ++i;
1575 skip = i;
1576
1577 // populate tmpbuff buffer with pulse lengths
1578 while (i < bufsize) {
1579 // measure from low to low
1580 while ((buffer[i] > low) && (i < bufsize))
1581 ++i;
1582 start= i;
1583 while ((buffer[i] < high) && (i < bufsize))
1584 ++i;
b96bcc79 1585 //first high point for this wave
1586 waveStart = i;
d1869c33 1587 while ((buffer[i] > low) && (i < bufsize))
1588 ++i;
1589 if (j >= (bufsize/64)) {
1590 break;
1591 }
b96bcc79 1592 waveLen[j] = i - waveStart; //first high to first low
d1869c33 1593 tmpbuff[j++] = i - start;
1594 if (i-start < minClk && i < bufsize) {
1595 minClk = i - start;
1596 }
1597 }
1598 // set clock - might be able to get this externally and remove this work...
1599 if (!clk) {
1600 for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
1601 tol = fndClk[clkCnt]/8;
1602 if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
1603 clk=fndClk[clkCnt];
1604 break;
1605 }
1606 }
1607 // clock not found - ERROR
1608 if (!clk) {
1609 if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
1610 return false;
1611 }
1612 } else tol = clk/8;
1613
1614 *foundclock = clk;
1615
1616 // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
1617 start = -1;
1618 for (i = 0; i < j - 4; ++i) {
1619 skip += tmpbuff[i];
b96bcc79 1620 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
1621 if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
1622 if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
1623 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
d1869c33 1624 start = i + 3;
1625 break;
1626 }
1627 }
1628 }
1629 }
1630 }
1631 // first ST not found - ERROR
1632 if (start < 0) {
1633 if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
1634 return false;
1635 }
b96bcc79 1636 if (waveLen[i+2] > clk*1+tol)
1637 phaseoff = 0;
1638 else
1639 phaseoff = clk/2;
1640
d1869c33 1641 // skip over the remainder of ST
1642 skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
1643
1644 // now do it again to find the end
1645 end = skip;
1646 for (i += 3; i < j - 4; ++i) {
1647 end += tmpbuff[i];
1648 if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol) { //1 to 2 clocks depending on 2 bits prior
b96bcc79 1649 if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
1650 if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
1651 if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
d1869c33 1652 complete = true;
1653 break;
1654 }
1655 }
1656 }
1657 }
1658 }
b96bcc79 1659 end -= phaseoff;
d1869c33 1660 //didn't find second ST - ERROR
1661 if (!complete) {
1662 if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
1663 return false;
1664 }
b96bcc79 1665 if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d, phaseoff: %d", skip, end, end-skip, clk, (end-skip)/clk, phaseoff);
d1869c33 1666 //now begin to trim out ST so we can use normal demod cmds
1667 start = skip;
1668 size_t datalen = end - start;
1669 // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
1670 if (datalen % clk > clk/8) {
1671 if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
1672 return false;
1673 } else {
1674 // padd the amount off - could be problematic... but shouldn't happen often
1675 datalen += datalen % clk;
1676 }
1677 // if datalen is less than one t55xx block - ERROR
1678 if (datalen/clk < 8*4) {
1679 if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
1680 return false;
1681 }
1682 size_t dataloc = start;
1683 size_t newloc = 0;
1684 i=0;
1685 // warning - overwriting buffer given with raw wave data with ST removed...
1686 while ( dataloc < bufsize-(clk/2) ) {
cf194819 1687 //compensate for long high at end of ST not being high due to signal loss... (and we cut out the start of wave high part)
d1869c33 1688 if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
1689 for(i=0; i < clk/2-tol; ++i) {
1690 buffer[dataloc+i] = high+5;
1691 }
1692 }
1693 for (i=0; i<datalen; ++i) {
1694 if (i+newloc < bufsize) {
1695 if (i+newloc < dataloc)
1696 buffer[i+newloc] = buffer[dataloc];
1697
1698 dataloc++;
1699 }
1700 }
1701 newloc += i;
cf194819 1702 //skip next ST - we just assume it will be there from now on...
d1869c33 1703 dataloc += clk*4;
1704 }
1705 *size = newloc;
1706 return true;
1707}
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