X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/cd0bed3c98514fcc53c65bd40fef78709378783c..06eb3b1a8cbbab569b330a45a5e29dce9de273cd:/common/lfdemod.c
diff --git a/common/lfdemod.c b/common/lfdemod.c
index 1c05920d..cb3e9f0b 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -68,7 +68,7 @@ uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
//by marshmellow
// takes a array of binary values, start position, length of bits per parity (includes parity bit),
-// Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
+// Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
{
uint32_t parityWd = 0;
@@ -80,10 +80,11 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
}
j--; // overwrite parity with next data
// if parity fails then return 0
- if (pType == 2) { // then marker bit which should be a 1
- if (!BitStream[j]) return 0;
- } else {
- if (parityTest(parityWd, pLen, pType) == 0) return 0;
+ switch (pType) {
+ case 3: if (BitStream[j]==1) return 0; break; //should be 0 spacer bit
+ case 2: if (BitStream[j]==0) return 0; break; //should be 1 spacer bit
+ default: //test parity
+ if (parityTest(parityWd, pLen, pType) == 0) return 0; break;
}
bitCnt+=(pLen-1);
parityWd = 0;
@@ -95,7 +96,8 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
// by marshmellow
// takes a array of binary values, length of bits per parity (includes parity bit),
-// Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run)
+// Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
+// Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
{
uint32_t parityWd = 0;
@@ -105,11 +107,14 @@ size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t p
parityWd = (parityWd << 1) | BitSource[word+bit];
dest[j++] = (BitSource[word+bit]);
}
+
// if parity fails then return 0
- if (pType == 2) { // then marker bit which should be a 1
- dest[j++]=1;
- } else {
- dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
+ switch (pType) {
+ case 3: dest[j++]=0; break; // marker bit which should be a 0
+ case 2: dest[j++]=1; break; // marker bit which should be a 1
+ default:
+ dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
+ break;
}
bitCnt += pLen;
parityWd = 0;
@@ -122,8 +127,7 @@ size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t p
uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
{
uint32_t num = 0;
- for(int i = 0 ; i < numbits ; i++)
- {
+ for(int i = 0 ; i < numbits ; i++) {
num = (num << 1) | (*src);
src++;
}
@@ -257,9 +261,9 @@ void askAmp(uint8_t *BitStream, size_t size)
{
for(size_t i = 1; i<size; i++){
if (BitStream[i]-BitStream[i-1]>=30) //large jump up
- BitStream[i]=127;
+ BitStream[i]=255;
else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
- BitStream[i]=-127;
+ BitStream[i]=0;
}
return;
}
@@ -459,10 +463,10 @@ int gProxII_Demod(uint8_t BitStream[], size_t *size)
//return start position
return (int) startIdx;
}
- return -5;
+ return -5; //spacer bits not found - not a valid gproxII
}
-//translate wave to 11111100000 (1 for each short wave 0 for each long wave)
+//translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
{
size_t last_transition = 0;
@@ -486,6 +490,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
// 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++) {
// threshold current value
@@ -493,23 +498,24 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
else dest[idx] = 1;
// Check for 0->1 transition
- if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
+ if (dest[idx-1] < dest[idx]) {
preLastSample = LastSample;
LastSample = currSample;
currSample = idx-last_transition;
if (currSample < (fclow-2)){ //0-5 = garbage noise (or 0-3)
//do nothing with extra garbage
- } else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves or 3-6 = 5
+ } 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 )){
- dest[numBits-1]=1; //correct previous 9 wave surrounded by 8 waves
+ dest[numBits-1]=1;
}
dest[numBits++]=1;
- } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage
+ } else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage
//do nothing with beginning garbage
- } else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
+ } 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
+ } else { //9+ = 10 sample waves (or 6+ = 7)
dest[numBits++]=0;
}
last_transition = idx;
@@ -519,6 +525,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
}
//translate 11111100000 to 10
+//rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
uint8_t invert, uint8_t fchigh, uint8_t fclow)
{
@@ -530,6 +537,7 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
n++;
if (dest[idx]==lastval) continue;
+ //find out how many bits (n) we collected
//if lastval was 1, we have a 1->0 crossing
if (dest[idx-1]==1) {
n = (n * fclow + rfLen/2) / rfLen;
@@ -538,6 +546,7 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
}
if (n == 0) n = 1;
+ //add to our destination the bits we collected
memset(dest+numBits, dest[idx-1]^invert , n);
numBits += n;
n=0;
@@ -692,7 +701,6 @@ int PrescoDemod(uint8_t *dest, size_t *size) {
return (int) startIdx;
}
-
// Ask/Biphase Demod then try to locate an ISO 11784/85 ID
// BitStream must contain previously askrawdemod and biphasedemoded data
int FDXBdemodBI(uint8_t *dest, size_t *size)
@@ -1491,8 +1499,8 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
numBits += (firstFullWave / *clock);
//set start of wave as clock align
lastClkBit = firstFullWave;
- //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);
- //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
+ if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);
+ if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
waveStart = 0;
dest[numBits++] = curPhase; //set first read bit
for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
@@ -1675,7 +1683,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
i=0;
// warning - overwriting buffer given with raw wave data with ST removed...
while ( dataloc < bufsize-(clk/2) ) {
- //compensate for long high at end of ST not being high... (we cut out the high part)
+ //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)
if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
for(i=0; i < clk/2-tol; ++i) {
buffer[dataloc+i] = high+5;
@@ -1690,7 +1698,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
}
}
newloc += i;
- //skip next ST
+ //skip next ST - we just assume it will be there from now on...
dataloc += clk*4;
}
*size = newloc;