slight em410xdecode adjustments

a little faster

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 2352caadbac2d7b6c048650f0237a14c50d3f489..062818ef45a62f1dfda102035b8e4fea39f9a545 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -19,21 +19,9 @@ uint64_t Em410xDecode(uint8_t *BitStream, size_t size)
        //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
-       int high=0, low=255;
        uint64_t lo=0;
-
        uint32_t i = 0;
-       uint32_t initLoopMax = 65;
-       if (initLoopMax>size) initLoopMax=size;
-
-       for (;i < initLoopMax; ++i) //65 samples should be plenty to find high and low values
-       {
-               if (BitStream[i] > high)
-                       high = BitStream[i];
-               else if (BitStream[i] < low)
-                       low = BitStream[i];
-       }
-       if (((high !=1)||(low !=0))){  //allow only 1s and 0s
+       if (BitStream[10]>1){  //allow only 1s and 0s
                // PrintAndLog("no data found");
                return 0;
        }
@@ -51,9 +39,9 @@ uint64_t Em410xDecode(uint8_t *BitStream, size_t size)
                        idx+=9;
                        for (i=0; i<10;i++){
                                for(ii=0; ii<5; ++ii){
-                                       parityTest += BitStream[(i*5)+ii+idx];
+                                       parityTest ^= BitStream[(i*5)+ii+idx];
                                }
-                               if (parityTest== ((parityTest>>1)<<1)){
+                               if (!parityTest){
                                        parityTest=0;
                                        for (ii=0; ii<4;++ii){
                                                lo=(lo<<1LL)|(BitStream[(i*5)+ii+idx]);
@@ -63,7 +51,7 @@ uint64_t Em410xDecode(uint8_t *BitStream, size_t size)
                                        //PrintAndLog("DEBUG: EM parity failed parity val: %d, i:%d, ii:%d,idx:%d, Buffer: %d%d%d%d%d",parityTest,i,ii,idx,BitStream[idx+ii+(i*5)-5],BitStream[idx+ii+(i*5)-4],BitStream[idx+ii+(i*5)-3],BitStream[idx+ii+(i*5)-2],BitStream[idx+ii+(i*5)-1]);
                                        parityTest=0;
                                        idx-=8;
-                                       if (resetCnt>5)return 0;
+                                       if (resetCnt>5)return 0; //try 5 times
                                        resetCnt++;
                                        goto restart;//continue;
                                }