add first attempt at lf miller decoding

[proxmark3-svn] / common / lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 750dbf1b43a17bd1d2c011abde63f752748fff0e..fb10f6864d81b813bef66cd79b61e9d5d9ac7ac2 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -1074,17 +1074,18 @@ bool DetectST(uint8_t   buffer[], size_t *size, int *foundclock) {
 }
 
 //by marshmellow
-//take 11 10 01 11 00 and make 01100 ... miller decoding
+//take 11 10 01 11 00 and make 01100 ... miller decoding 
 //check for phase errors - should never have half a 1 or 0 by itself and should never exceed 1111 or 0000 in a row
 //decodes miller encoded binary
 //NOTE  askrawdemod will NOT demod miller encoded ask unless the clock is manually set to 1/2 what it is detected as!
-/*int millerRawDecode(uint8_t *BitStream, size_t *size, int invert) {
+int millerRawDecode(uint8_t *BitStream, size_t *size, int invert) {
        if (*size < 16) return -1;
-       uint16_t MaxBits = 512, errCnt = 0, bestErr = 1000, bestRun = 0;
-       size_t i, ii, bitCnt=0;
-       uint8_t alignCnt = 0, curBit = BitStream[0];
+       uint16_t MaxBits = 512, errCnt = 0;
+       size_t i, bitCnt=0;
+       uint8_t alignCnt = 0, curBit = BitStream[0], alignedIdx = 0;
+       uint8_t halfClkErr = 0;
        //find alignment, needs 4 1s or 0s to properly align
-       for (i=1; i < *size; i++) {
+       for (i=1; i < *size-1; i++) {
                alignCnt = (BitStream[i] == curBit) ? alignCnt+1 : 0;
                curBit = BitStream[i];
                if (alignCnt == 4) break;
@@ -1094,8 +1095,21 @@ bool DetectST(uint8_t    buffer[], size_t *size, int *foundclock) {
                if (g_debugMode) prnt("ERROR MillerDecode: alignment not found so either your bitstream is not miller or your data does not have a 101 in it");
                return -1;
        }
+       alignedIdx = (i-1) % 2;
+       for (i=alignedIdx; i < *size-3; i+=2) {
+               halfClkErr = (uint8_t)((halfClkErr << 1 | BitStream[i]) & 0xFF);
+               if ( (halfClkErr & 0x7) == 5 || (halfClkErr & 0x7) == 2 || (i > 2 && (halfClkErr & 0x7) == 0) || (halfClkErr & 0x1F) == 0x1F) {
+                       errCnt++;
+                       BitStream[bitCnt++] = 7;
+                       continue;
+               }
+               BitStream[bitCnt++] = BitStream[i] ^ BitStream[i+1] ^ invert;
 
-}*/
+               if (bitCnt > MaxBits) break;
+       }
+       *size = bitCnt;
+       return errCnt;
+}
 
 //by marshmellow
 //take 01 or 10 = 1 and 11 or 00 = 0
@@ -1876,7 +1890,6 @@ int VikingDemod_AM(uint8_t *dest, size_t *size) {
        return (int) startIdx;
 }
 
-
 // by iceman
 // find Visa2000 preamble in already demoded data
 int Visa2kDemod_AM(uint8_t *dest, size_t *size) {