ADD: since the client now calls legic prng, this is needed here too.

[proxmark3-svn] / common / lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 047c9e2893edbbdccb770f32f53a7a16965cecd5..f231cd69fd54e787506cea2cee9f4d022cf87e0a 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -148,8 +148,11 @@ 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)
 {
-       uint8_t foundCnt=0;
-       for (int idx=0; idx < *size - pLen; idx++){
+       // Sanity check.  If preamble length is bigger than bitstream length.
+       if ( *size <= pLen ) return 0;
+       
+       uint8_t foundCnt = 0;
+       for (int idx = 0; idx < *size - pLen; idx++){
                if (memcmp(BitStream+idx, preamble, pLen) == 0){
                        //first index found
                        foundCnt++;
@@ -259,13 +262,15 @@ int cleanAskRawDemod(uint8_t *BinStream, size_t *size, int clk, int invert, int
 //by marshmellow
 void askAmp(uint8_t *BitStream, size_t size)
 {
-       for(size_t i = 1; i<size; i++){
-               if (BitStream[i]-BitStream[i-1]>=30) //large jump up
-                       BitStream[i]=255;
-               else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
-                       BitStream[i]=0;
+       uint8_t last = 128;
+       for(size_t i = 1; i < size; ++i){
+               if (BitStream[i]-BitStream[i-1] >= 30) //large jump up
+                       last = 255;
+               else if(BitStream[i-1] - BitStream[i] >= 20) //large jump down
+                       last = 0;
+               
+               BitStream[i] = last;
        }
-       return;
 }
 
 //by marshmellow
@@ -721,6 +726,39 @@ int FDXBdemodBI(uint8_t *dest, size_t *size)
        return (int)startIdx;
 }
 
+// ASK/Diphase fc/64 (inverted Biphase)
+// Note: this i s not a demod, this is only a detection
+// the parameter *dest needs to be demoded before call
+int JablotronDemod(uint8_t *dest, size_t *size){
+       //make sure buffer has enough data
+       if (*size < 64) return -1;
+
+       size_t startIdx = 0;
+       // 0xFFFF preamble, 64bits
+       uint8_t preamble[] = {
+                       1,1,1,1,
+                   1,1,1,1,
+                               1,1,1,1,
+                               1,1,1,1,
+                               0
+               };
+
+       uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
+       if (errChk == 0) return -4; //preamble not found
+       if (*size != 64) return -3;
+       
+       uint8_t checkchksum = 0;
+       for (int i=16; i < 56; i += 8) {
+               checkchksum += bytebits_to_byte(dest+startIdx+i,8);
+       }
+       checkchksum ^= 0x3A;
+
+       uint8_t crc = bytebits_to_byte(dest+startIdx+56, 8);
+       
+       if ( checkchksum != crc ) return -5;    
+       return (int)startIdx;
+}
+
 // by marshmellow
 // FSK Demod then try to locate an AWID ID
 int AWIDdemodFSK(uint8_t *dest, size_t *size)
@@ -764,16 +802,16 @@ int PyramiddemodFSK(uint8_t *dest, size_t *size)
        return (int)startIdx;
 }
 
-// find presco preamble 0x10D in already demoded data
+// find nedap preamble in already demoded data
 int NedapDemod(uint8_t *dest, size_t *size) {
        //make sure buffer has data
        if (*size < 128) return -3;
 
        size_t startIdx = 0;
+       //uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0,0,0,1};
        uint8_t preamble[] = {1,1,1,1,1,1,1,1,1,0};
        uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
        if (errChk == 0) return -4; //preamble not found
-       //return start position
        return (int) startIdx;
 }