cleanup

[proxmark3-svn] / common / lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index e9f19311c8b6c248d0ffcdabd1b4e1bc3c04f1c9..e1fcbf736ed4ffd5d6ed73e916d04271eba06415 100644 (file)
--- 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<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;
-               //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 (*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