FIX: @marshmellow42 's ST detection fix.

[proxmark3-svn] / common / lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index ca126df32c696f7be98961c642dd0159397e07b7..c177468f0c312b7e59ed4d4ca05b5fca75a9ad5e 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -203,10 +203,10 @@ size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_
 //by marshmellow
 //takes 1s and 0s and searches for EM410x format - output EM ID
 // actually, no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future
-uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
+int Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
 {
        // sanity check
-       if (BitStream[1] > 1) return 0; 
+       if (BitStream[1] > 1) return -1; 
        
        uint8_t fmtlen;
        *startIdx = 0;
@@ -215,8 +215,8 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
        // include 0 in front to help get start pos
        uint8_t preamble[] = {0,1,1,1,1,1,1,1,1,1};
        if (!preambleSearch(BitStream, preamble, sizeof(preamble), size, startIdx)) 
-               return 0;
-       if (*size < 64) return 0;
+               return -2;
+       if (*size < 64) return -3;
        
        fmtlen = (*size == 110) ? 22 : 10;
 
@@ -236,14 +236,14 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
                *lo = ((uint64_t)(bytebits_to_byte(BitStream + 24, 32)) << 32) | (bytebits_to_byte(BitStream + 24 + 32, 32));
                break;
            } 
-           default: return 0;
-       
+           default: return -4; 
        }
        return 1;
 }
 
 //by marshmellow
 //demodulates strong heavily clipped samples
+//RETURN: num of errors.  if 0, is ok.
 int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int high, int low)
 {
        size_t bitCnt=0, smplCnt=0, errCnt=0;
@@ -387,25 +387,30 @@ int askdemod(uint8_t *BinStream, size_t *size, int *clk, int *invert, int maxErr
 //by marshmellow
 //take 10 and 01 and manchester decode
 //run through 2 times and take least errCnt
-int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert){
+int manrawdecode(uint8_t *BitStream, size_t *size, uint8_t invert){
+
+       // sanity check
+       if (*size < 16) return -1;
+       
        int errCnt = 0, bestErr = 1000;
        uint16_t bitnum = 0, MaxBits = 512, bestRun = 0;
        size_t i, k;
-       if (*size < 16) return -1;
+
        //find correct start position [alignment]
-       for (k=0; k < 2; ++k){
-               for (i=k; i<*size-3; i += 2)
+       for (k = 0; k < 2; ++k){
+               for (i = k; i < *size-3; i += 2) {
                        if (BitStream[i] == BitStream[i+1])
                                errCnt++;
-
+               }
                if (bestErr > errCnt){
                        bestErr = errCnt;
                        bestRun = k;
                }
-               errCnt=0;
+               errCnt = 0;
        }
+       
        //decode
-       for (i=bestRun; i < *size-3; i += 2){
+       for (i = bestRun; i < *size-3; i += 2){
                if (BitStream[i] == 1 && (BitStream[i+1] == 0)){
                        BitStream[bitnum++] = invert;
                } else if ((BitStream[i] == 0) && BitStream[i+1] == 1){
@@ -413,9 +418,9 @@ int manrawdecode(uint8_t * BitStream, size_t *size, uint8_t invert){
                } else {
                        BitStream[bitnum++] = 7;
                }
-               if (bitnum>MaxBits) break;
+               if (bitnum > MaxBits) break;
        }
-       *size=bitnum;
+       *size = bitnum;
        return bestErr;
 }
 
@@ -1840,6 +1845,10 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
                        for(i=0; i < clk/2-tol; ++i) {
                                buffer[dataloc+i] = high+5;
                        }
+               } //test for single sample outlier (high between two lows) in the case of very strong waves
+               if (buffer[dataloc] >= high && buffer[dataloc+2] <= low) {
+                       buffer[dataloc] = buffer[dataloc+2];
+                       buffer[dataloc+1] = buffer[dataloc+2];
                }
                for (i=0; i<datalen; ++i) {
                        if (i+newloc < bufsize) {