From e88096ba259b88d0dc2edfd0e77cde5b297e1bd8 Mon Sep 17 00:00:00 2001 From: marshmellow42 Date: Thu, 23 Feb 2017 13:53:40 -0500 Subject: [PATCH] cleanup combine preamble searches (thanks @iceman1001) simplify Em410xDecode fix bug in removeParity (I made recently) move Unique TAG ID printout to avoid confusion --- client/cmddata.c | 2 +- client/cmdlfem4x.c | 8 ++--- common/lfdemod.c | 81 ++++++++++++++++++---------------------------- common/lfdemod.h | 2 +- 4 files changed, 38 insertions(+), 55 deletions(-) diff --git a/client/cmddata.c b/client/cmddata.c index 2db1f8eb..f7addc53 100644 --- a/client/cmddata.c +++ b/client/cmddata.c @@ -175,8 +175,8 @@ void printEM410x(uint32_t hi, uint64_t id) } else{ //output 40 bit em id PrintAndLog("\nEM TAG ID : %010llX", id); - PrintAndLog("Unique TAG ID : %010llX", id2lo); PrintAndLog("\nPossible de-scramble patterns"); + PrintAndLog("Unique TAG ID : %010llX", id2lo); PrintAndLog("HoneyWell IdentKey {"); PrintAndLog("DEZ 8 : %08lld",id & 0xFFFFFF); PrintAndLog("DEZ 10 : %010lld",id & 0xFFFFFFFF); diff --git a/client/cmdlfem4x.c b/client/cmdlfem4x.c index 0788b138..c26b4f39 100644 --- a/client/cmdlfem4x.c +++ b/client/cmdlfem4x.c @@ -540,7 +540,7 @@ bool EM4x05testDemodReadData(uint32_t *word, bool readCmd) { // sanity check size = (size > DemodBufferLen) ? DemodBufferLen : size; // test preamble - if ( !onePreambleSearch(DemodBuffer, preamble, sizeof(preamble), size, &startIdx) ) { + if ( !preambleSearchEx(DemodBuffer, preamble, sizeof(preamble), &size, &startIdx, true) ) { if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 preamble not found :: %d", startIdx); return false; } @@ -550,13 +550,13 @@ bool EM4x05testDemodReadData(uint32_t *word, bool readCmd) { if (g_debugMode) PrintAndLog("DEBUG: Error - End Parity check failed"); return false; } - // test for even parity bits. - if ( removeParity(DemodBuffer, startIdx + sizeof(preamble),9,0,44) == 0 ) { + // test for even parity bits and remove them. (leave out the end row of parities so 36 bits) + if ( removeParity(DemodBuffer, startIdx + sizeof(preamble),9,0,36) == 0 ) { if (g_debugMode) PrintAndLog("DEBUG: Error - Parity not detected"); return false; } - setDemodBuf(DemodBuffer, 40, 0); + setDemodBuf(DemodBuffer, 32, 0); *word = bytebits_to_byteLSBF(DemodBuffer, 32); } return true; diff --git a/common/lfdemod.c b/common/lfdemod.c index e9f19311..e1fcbf73 100644 --- a/common/lfdemod.c +++ b/common/lfdemod.c @@ -78,7 +78,7 @@ 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; + if (word+pLen > bLen) break; j--; // overwrite parity with next data // if parity fails then return 0 @@ -150,40 +150,30 @@ 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) { + return (preambleSearchEx(BitStream, preamble, pLen, size, startIdx, false)) ? 1 : 0; +} + +// search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found) and length if not fineone +// fineone does not look for a repeating preamble for em4x05/4x69 sends preamble once, so look for it once in the first pLen bits +bool preambleSearchEx(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx, bool findone) { // Sanity check. If preamble length is bigger than bitstream length. - if ( *size <= pLen ) return 0; + if ( *size <= pLen ) return false; - uint8_t foundCnt=0; - for (int idx=0; idx < *size - pLen; idx++){ - if (memcmp(BitStream+idx, preamble, pLen) == 0){ + uint8_t foundCnt = 0; + for (size_t idx = 0; idx < *size - pLen; idx++) { + if (memcmp(BitStream+idx, preamble, pLen) == 0) { //first index found foundCnt++; - if (foundCnt == 1){ + if (foundCnt == 1) { + if (g_debugMode) prnt("DEBUG: preamble found at %u", idx); *startIdx = idx; - } - if (foundCnt == 2){ + if (findone) return true; + } else if (foundCnt == 2) { *size = idx - *startIdx; - return 1; + return true; } } } - return 0; -} - -// search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found) -// does not look for a repeating preamble -// em4x05/4x69 only sends preamble once, so look for it once in the first pLen bits -// leave it generic so it could be reused later... -bool onePreambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t size, size_t *startIdx) { - // Sanity check. If preamble length is bigger than bitstream length. - if ( size <= pLen ) return false; - for (size_t idx = 0; idx < size - pLen; idx++) { - if (memcmp(BitStream+idx, preamble, pLen) == 0) { - if (g_debugMode) prnt("DEBUG: preamble found at %u", idx); - *startIdx = idx; - return true; - } - } return false; } @@ -217,39 +207,32 @@ size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_ //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) { - //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; + //sanity checks + if (*size < 64) return 0; if (BitStream[1]>1) return 0; //allow only 1s and 0s // 111111111 bit pattern represent start of frame // 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; + uint8_t FmtLen = 10; // sets of 4 bits = end data *startIdx = 0; 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> 63); - *lo = (*lo << 1) | (BitStream[(i*5)+ii+idx]); - } + if (*size == 110) FmtLen = 22; // 22 sets of 4 bits + + //skip last 4bit parity row for simplicity + *size = removeParity(BitStream, *startIdx + sizeof(preamble), 5, 0, FmtLen * 5); + if (*size == 40) { // std em410x format + *hi = 0; + *lo = ((uint64_t)(bytebits_to_byte(BitStream, 8)) << 32) | (bytebits_to_byte(BitStream + 8, 32)); + } else if (*size == 88) { // long em format + *hi = (bytebits_to_byte(BitStream, 24)); + *lo = ((uint64_t)(bytebits_to_byte(BitStream + 24, 32)) << 32) | (bytebits_to_byte(BitStream + 24 + 32, 32)); + } else { + return 0; } - if (errChk != 0) return 1; - //skip last 5 bit parity test for simplicity. - // *size = 64 | 128; - return 0; + return 1; } //by marshmellow diff --git a/common/lfdemod.h b/common/lfdemod.h index 9c5c83fb..a77eb604 100644 --- a/common/lfdemod.h +++ b/common/lfdemod.h @@ -39,7 +39,7 @@ int manrawdecode(uint8_t *BitStream, size_t *size, uint8_t invert); int nrzRawDemod(uint8_t *dest, size_t *size, int *clk, int *invert); uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType); uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx); -bool onePreambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t size, size_t *startIdx); +bool preambleSearchEx(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx, bool findone); int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert); void psk2TOpsk1(uint8_t *BitStream, size_t size); void psk1TOpsk2(uint8_t *BitStream, size_t size); -- 2.39.2