X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/6c283951062aaad9d0d1ba8670b02895047be438..87a513aa1d0f6eccd85b46d06cd13499d048f8c9:/common/lfdemod.c
diff --git a/common/lfdemod.c b/common/lfdemod.c
index 2f376e5f..5fec933f 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -25,15 +25,13 @@ void dummy(char *fmt, ...){}
#define prnt dummy
#endif
-uint8_t justNoise(uint8_t *BitStream, size_t size)
-{
- static const uint8_t THRESHOLD = 123;
- //test samples are not just noise
- uint8_t justNoise1 = 1;
- for(size_t idx=0; idx < size && justNoise1 ;idx++){
- justNoise1 = BitStream[idx] < THRESHOLD;
- }
- return justNoise1;
+//test samples are not just noise
+uint8_t justNoise(uint8_t *bits, size_t size) {
+ #define THRESHOLD 123
+ uint8_t val = 1;
+ for(size_t idx=0; idx < size && val ;idx++)
+ val = bits[idx] < THRESHOLD;
+ return val;
}
//by marshmellow
@@ -81,10 +79,9 @@ 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
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;
+ 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: if (parityTest(parityWd, pLen, pType) == 0) { return 0; } break; //test parity
}
bitCnt+=(pLen-1);
parityWd = 0;
@@ -148,8 +145,11 @@ uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
{
- uint8_t foundCnt=0;
- for (int idx=0; idx < *size - pLen; idx++){
+ // Sanity check. If preamble length is bigger than bitstream length.
+ if ( *size <= pLen ) return 0;
+
+ uint8_t foundCnt = 0;
+ for (int idx = 0; idx < *size - pLen; idx++){
if (memcmp(BitStream+idx, preamble, pLen) == 0){
//first index found
foundCnt++;
@@ -167,13 +167,13 @@ uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_
//by marshmellow
//takes 1s and 0s and searches for EM410x format - output EM ID
-uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
+int Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
{
//no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
// otherwise could be a void with no arguments
//set defaults
uint32_t i = 0;
- if (BitStream[1]>1) return 0; //allow only 1s and 0s
+ if (BitStream[1]>1) return -1; //allow only 1s and 0s
// 111111111 bit pattern represent start of frame
// include 0 in front to help get start pos
@@ -184,14 +184,15 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
uint8_t FmtLen = 10;
*startIdx = 0;
errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
- if (errChk == 0 || *size < 64) return 0;
+ if (errChk == 0 ) return -4;
+ if (*size < 64) return -3;
if (*size > 64) FmtLen = 22;
*startIdx += 1; //get rid of 0 from preamble
idx = *startIdx + 9;
for (i=0; i<FmtLen; i++){ //loop through 10 or 22 sets of 5 bits (50-10p = 40 bits or 88 bits)
parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5);
//check even parity - quit if failed
- if (parityTest(parityBits, 5, 0) == 0) return 0;
+ if (parityTest(parityBits, 5, 0) == 0) return -5;
//set uint64 with ID from BitStream
for (uint8_t ii=0; ii<4; ii++){
*hi = (*hi << 1) | (*lo >> 63);
@@ -582,7 +583,7 @@ int HIDdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, uint32
{
if (justNoise(dest, *size)) return -1;
- size_t numStart=0, size2=*size, startIdx=0;
+ size_t numStart=0, size2 = *size, startIdx=0;
// FSK demodulator
*size = fskdemod(dest, size2,50,1,10,8); //fsk2a
if (*size < 96*2) return -2;
@@ -614,7 +615,7 @@ int ParadoxdemodFSK(uint8_t *dest, size_t *size, uint32_t *hi2, uint32_t *hi, ui
{
if (justNoise(dest, *size)) return -1;
- size_t numStart=0, size2=*size, startIdx=0;
+ size_t numStart=0, size2 = *size, startIdx=0;
// FSK demodulator
*size = fskdemod(dest, size2,50,1,10,8); //fsk2a
if (*size < 96) return -2;
@@ -732,21 +733,27 @@ int JablotronDemod(uint8_t *dest, size_t *size){
size_t startIdx = 0;
// 0xFFFF preamble, 64bits
- uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};
+ uint8_t preamble[] = {
+ 1,1,1,1,
+ 1,1,1,1,
+ 1,1,1,1,
+ 1,1,1,1,
+ 0
+ };
uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
if (errChk == 0) return -4; //preamble not found
+ if (*size != 64) return -3;
- uint8_t checkCalc = 0;
+ uint8_t checkchksum = 0;
for (int i=16; i < 56; i += 8) {
- checkCalc += bytebits_to_byte(dest+startIdx+i,8);
+ checkchksum += bytebits_to_byte(dest+startIdx+i,8);
}
- checkCalc ^= 0x3A;
+ checkchksum ^= 0x3A;
- uint8_t crc = bytebits_to_byte(dest+startIdx+56,8);
+ uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
- if ( checkCalc != crc ) return -5;
- if (*size != 64) return -6;
+ if ( checkchksum != crc ) return -5;
return (int)startIdx;
}