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EM410x bug fix

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This commit is contained in:
marshmellow42 2015-03-24 20:26:14 -04:00
commit 90677ad99b
2 changed files with 23 additions and 26 deletions
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4
client/cmddata.c
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@ -400,8 +400,8 @@ int CmdAskEM410xDemod(const char *Cmd)
PrintAndLog(" : data askem410xdemod 64 1 0 = demod an EM410x Tag ID from GraphBuffer using a clock of RF/64 and inverting data and allowing 0 demod errors"); PrintAndLog(" : data askem410xdemod 64 1 0 = demod an EM410x Tag ID from GraphBuffer using a clock of RF/64 and inverting data and allowing 0 demod errors");
return 0; return 0;
} }
uint32_t hi; uint32_t hi = 0;
uint64_t lo; uint64_t lo = 0;
if (AskEm410xDemod(Cmd, &hi, &lo)) { if (AskEm410xDemod(Cmd, &hi, &lo)) {
PrintAndLog("EM410x pattern found: "); PrintAndLog("EM410x pattern found: ");
printEM410x(hi, lo); printEM410x(hi, lo);

45
common/lfdemod.c
View file

@ -88,37 +88,34 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
return 0; return 0;
} }
// 111111111 bit pattern represent start of frame // 111111111 bit pattern represent start of frame
uint8_t preamble[] = {1,1,1,1,1,1,1,1,1}; // include 0 in front to help get start pos
uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
uint32_t idx = 0; uint32_t idx = 0;
uint32_t parityBits = 0; uint32_t parityBits = 0;
uint8_t errChk = 0; uint8_t errChk = 0;
uint8_t FmtLen = 10; uint8_t FmtLen = 10;
*startIdx = 0; *startIdx = 0;
for (uint8_t extraBitChk=0; extraBitChk<5; extraBitChk++){ errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
errChk = preambleSearch(BitStream+extraBitChk+*startIdx, preamble, sizeof(preamble), size, startIdx); if (errChk == 0 || *size < 64) return 0;
if (errChk == 0) return 0; if (*size > 64) FmtLen = 22;
if (*size>64) FmtLen = 22; *startIdx += 1; //get rid of 0 from preamble
if (*size<64) return 0; idx = *startIdx + 9;
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)
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);
parityBits = bytebits_to_byte(BitStream+(i*5)+idx,5); //check even parity
//check even parity if (parityTest(parityBits, 5, 0) == 0){
if (parityTest(parityBits, 5, 0) == 0){ //parity failed quit
//parity failed try next bit (in the case of 1111111111) but last 9 = preamble return 0;
startIdx++; }
errChk = 0; //set uint64 with ID from BitStream
break; for (uint8_t ii=0; ii<4; ii++){
} *hi = (*hi << 1) | (*lo >> 63);
//set uint64 with ID from BitStream *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
for (uint8_t ii=0; ii<4; ii++){
*hi = (*hi << 1) | (*lo >> 63);
*lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
}
} }
if (errChk != 0) return 1;
//skip last 5 bit parity test for simplicity.
// *size = 64 | 128;
} }
if (errChk != 0) return 1;
//skip last 5 bit parity test for simplicity.
// *size = 64 | 128;
return 0; return 0;
} }