github/RRG-Proxmark3
1
0
Fork 0
mirror of https://github.com/RfidResearchGroup/proxmark3.git synced 2025-08-14 18:48:13 -07:00
Code Issues Projects Releases Packages Wiki Activity Actions

CHG: lf em - added @marshmellow42 's changes

Browse source
This commit is contained in:
iceman1001 2017-02-19 00:12:35 +01:00
commit 4ac9f07840
3 changed files with 308 additions and 112 deletions
Download patch file Download diff file Expand all files Collapse all files

114
common/lfdemod.c
View file

@ -58,7 +58,7 @@ uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
for (uint8_t i = 0; i < bitLen; i++){
ans ^= ((bits >> i) & 1);
}
//prnt("DEBUG: ans: %d, ptype: %d",ans,pType);
if (g_debugMode) prnt("DEBUG: ans: %d, ptype: %d, bits: %08X",ans,pType,bits);
return (ans == pType);
}
@ -74,6 +74,8 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
BitStream[j++] = (BitStream[startIdx+word+bit]);
}
if (word+pLen >= bLen) break;
j--; // overwrite parity with next data
// if parity fails then return 0
switch (pType) {
@ -480,19 +482,42 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
size_t preLastSample = 0;
size_t LastSample = 0;
size_t currSample = 0;
// sync to first lo-hi transition, and threshold
if ( size < 1024 ) return 0; // not enough samples
// jump to modulating data by finding the first 4 threshold crossings (or first 2 waves)
// in case you have junk or noise at the beginning of the trace...
uint8_t thresholdCnt = 0;
size_t waveSizeCnt = 0;
bool isAboveThreshold = dest[idx++] >= threshold_value;
for (; idx < size-20; idx++ ) {
if(dest[idx] < threshold_value && isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < fchigh+1) break;
isAboveThreshold = false;
waveSizeCnt = 0;
} else if (dest[idx] >= threshold_value && !isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < fchigh+1) break;
isAboveThreshold = true;
waveSizeCnt = 0;
} else {
waveSizeCnt++;
}
if (thresholdCnt > 10) break;
}
if (g_debugMode == 2) prnt("threshold Count reached at %u",idx);
// Need to threshold first sample
// skip 160 samples to allow antenna/samples to settle
if(dest[160] < threshold_value) dest[0] = 0;
if(dest[idx] < threshold_value) dest[0] = 0;
else dest[0] = 1;
idx++;
size_t numBits = 0;
// count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
// or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
// (could also be fc/5 && fc/7 for fsk1 = 4-9)
for(idx = 161; idx < size-20; idx++) {
for(; idx < size-20; idx++) {
// threshold current value
if (dest[idx] < threshold_value) dest[idx] = 0;
@ -507,13 +532,14 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
//do nothing with extra garbage
} else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves (or 3-6 = 5)
//correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample == 0 )){
if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1))){
dest[numBits-1]=1;
}
dest[numBits++]=1;
} else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
//do nothing with beginning garbage
} else if (currSample > (fchigh+1) && numBits < 3) { //12 + and first two bit = unusable garbage
//do nothing with beginning garbage and reset.. should be rare..
numBits = 0;
} 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)
dest[numBits++]=1;
} else { //9+ = 10 sample waves (or 6+ = 7)
@ -1248,36 +1274,32 @@ int DetectNRZClock(uint8_t dest[], size_t size, int clock)
// by marshmellow
// convert psk1 demod to psk2 demod
// only transition waves are 1s
void psk1TOpsk2(uint8_t *BitStream, size_t size)
{
size_t i=1;
uint8_t lastBit=BitStream[0];
for (; i<size; i++){
if (BitStream[i]==7){
//ignore errors
} else if (lastBit!=BitStream[i]){
lastBit=BitStream[i];
BitStream[i]=1;
void psk1TOpsk2(uint8_t *bits, size_t size) {
uint8_t lastBit = bits[0];
for (size_t i = 1; i < size; i++){
//ignore errors
if (bits[i] == 7) continue;
if (lastBit != bits[i]){
lastBit = bits[i];
bits[i] = 1;
} else {
BitStream[i]=0;
bits[i] = 0;
}
}
return;
}
// by marshmellow
// convert psk2 demod to psk1 demod
// from only transition waves are 1s to phase shifts change bit
void psk2TOpsk1(uint8_t *BitStream, size_t size)
{
uint8_t phase=0;
for (size_t i=0; i<size; i++){
if (BitStream[i]==1){
phase ^=1;
void psk2TOpsk1(uint8_t *bits, size_t size) {
uint8_t phase = 0;
for (size_t i = 0; i < size; i++){
if (bits[i] == 1){
phase ^= 1;
}
BitStream[i]=phase;
bits[i] = phase;
}
return;
}
// redesigned by marshmellow adjusted from existing decode functions
@ -1538,7 +1560,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
size_t numBits=0;
uint8_t curPhase = *invert;
size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
size_t i=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
uint8_t fc=0, fullWaveLen=0, tol=1;
uint16_t errCnt=0, waveLenCnt=0;
fc = countFC(dest, *size, 0);
@ -1546,19 +1568,45 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
//prnt("DEBUG: FC: %d",fc);
*clock = DetectPSKClock(dest, *size, *clock);
if (*clock == 0) return -1;
// jump to modulating data by finding the first 2 threshold crossings (or first 1 waves)
// in case you have junk or noise at the beginning of the trace...
uint8_t thresholdCnt = 0;
size_t waveSizeCnt = 0;
uint8_t threshold_value = 123; //-5
bool isAboveThreshold = dest[i++] >= threshold_value;
for (; i < *size-20; i++ ) {
if(dest[i] < threshold_value && isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < fc+1) break;
isAboveThreshold = false;
waveSizeCnt = 0;
} else if (dest[i] >= threshold_value && !isAboveThreshold) {
thresholdCnt++;
if (thresholdCnt > 2 && waveSizeCnt < fc+1) break;
isAboveThreshold = true;
waveSizeCnt = 0;
} else {
waveSizeCnt++;
}
if (thresholdCnt > 10) break;
}
if (g_debugMode == 2) prnt("DEBUG PSK: threshold Count reached at %u, count: %u",i, thresholdCnt);
int avgWaveVal=0, lastAvgWaveVal=0;
waveStart = i+1;
//find first phase shift
for (i=0; i<loopCnt; i++){
for (; i<loopCnt; i++){
if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
waveEnd = i+1;
//prnt("DEBUG: waveEnd: %d",waveEnd);
if (g_debugMode == 2) prnt("DEBUG PSK: waveEnd: %u, waveStart: %u",waveEnd, waveStart);
waveLenCnt = waveEnd-waveStart;
if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+2)){ //not first peak and is a large wave but not out of whack
if (waveLenCnt > fc && waveStart > fc && !(waveLenCnt > fc+3)){ //not first peak and is a large wave but not out of whack
lastAvgWaveVal = avgWaveVal/(waveLenCnt);
firstFullWave = waveStart;
fullWaveLen=waveLenCnt;
//if average wave value is > graph 0 then it is an up wave or a 1
if (lastAvgWaveVal > 123) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
if (lastAvgWaveVal > threshold_value) curPhase ^= 1; //fudge graph 0 a little 123 vs 128
break;
}
waveStart = i+1;