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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
parent 9680b11d9e
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");
return 0;
}
uint32_t hi;
uint64_t lo;
uint32_t hi = 0;
uint64_t lo = 0;
if (AskEm410xDemod(Cmd, &hi, &lo)) {
PrintAndLog("EM410x pattern found: ");
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;
}
// 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 parityBits = 0;
uint8_t errChk = 0;
uint8_t FmtLen = 10;
*startIdx = 0;
for (uint8_t extraBitChk=0; extraBitChk<5; extraBitChk++){
errChk = preambleSearch(BitStream+extraBitChk+*startIdx, preamble, sizeof(preamble), size, startIdx);
if (errChk == 0) return 0;
if (*size>64) FmtLen = 22;
if (*size<64) return 0;
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
if (parityTest(parityBits, 5, 0) == 0){
//parity failed try next bit (in the case of 1111111111) but last 9 = preamble
startIdx++;
errChk = 0;
break;
}
//set uint64 with ID from BitStream
for (uint8_t ii=0; ii<4; ii++){
*hi = (*hi << 1) | (*lo >> 63);
*lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]);
}
errChk = preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx);
if (errChk == 0 || *size < 64) return 0;
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
if (parityTest(parityBits, 5, 0) == 0){
//parity failed quit
return 0;
}
//set uint64 with ID from BitStream
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;
}