CHG: `lf em` - @marshmellow42 's latest changes

diff --git a/client/cmdlfem4x.c b/client/cmdlfem4x.c
index 636d2596b29609b740ae1a1b0cbefdabb4ed1e90..2cc034300c020c8bbdc81ecf39acf767550e2f43 100644 (file)
--- a/client/cmdlfem4x.c
+++ b/client/cmdlfem4x.c
@@ -500,7 +500,7 @@ int CmdEM4x50Read(const char *Cmd) {
 }
 
 int usage_lf_em_read(void) {
-       PrintAndLog("Read EM4x50.  Tag must be on antenna. ");
+       PrintAndLog("Read EM4x05/EM4x69.  Tag must be on antenna. ");
        PrintAndLog("");
        PrintAndLog("Usage:  lf em readword [h] <address> <pwd>");
        PrintAndLog("Options:");
@@ -512,6 +512,125 @@ int usage_lf_em_read(void) {
        PrintAndLog("      lf em readword 1 11223344");
        return 0;
 }
+
+//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex
+uint8_t EMpreambleSearch(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 0;
+       // em only sends preamble once, so look for it once in the first x bits
+       uint8_t foundCnt = 0;
+       for (int idx = 0; idx < size - pLen; idx++){
+               if (memcmp(BitStream+idx, preamble, pLen) == 0){
+                       //first index found
+                       foundCnt++;
+                       if (foundCnt == 1) {
+                               *startIdx = idx;
+                               return 1;
+                       }
+               }
+       }
+       return 0;
+}
+
+int demodEM4x05resp(uint8_t bitsNeeded) {
+       int ans = 0;
+       bool demodFound = false;
+       DemodBufferLen = 0x00;
+       // skip first two 0 bits as they might have been missed in the demod 
+       uint8_t preamble[6] = {0,0,1,0,1,0};
+
+       // test for FSK wave (easiest to 99% ID)
+       if (GetFskClock("", FALSE, FALSE)) {
+               //valid fsk clocks found
+               ans = FSKrawDemod("0 0", false);
+               if (!ans) {
+                       if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305: FSK Demod failed");
+                       //return -1;
+               } else {
+                       // set size to 10 to only test first 4 positions for the preamble
+                       size_t size = (10 > DemodBufferLen) ? DemodBufferLen : 10;
+                       size_t startIdx = 0; 
+
+                       if (g_debugMode) PrintAndLog("ANS: %d | %u | %u", ans, startIdx, size);
+
+                       uint8_t errChk = !EMpreambleSearch(DemodBuffer, preamble, sizeof(preamble), size, &startIdx);
+                       if ( errChk == 0) {
+                               if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 preamble not found :: %d", startIdx);
+                               //return -1;
+                       } else {
+                               //can't test size because the preamble doesn't repeat :(
+                               //meaning chances of false positives are high.
+                               demodFound = true;
+                       }
+               }
+       }
+
+       ans = GetPskClock("", FALSE, FALSE);
+       if (ans>0) {
+               PrintAndLog("PSK response possibly found, run `data rawd p1` to attempt to demod");
+       }
+
+       if (!demodFound) {
+               DemodBufferLen = 0x00;
+               //try biphase
+               ans = ASKbiphaseDemod("0 0 1", FALSE);
+               if (!ans) { 
+                       if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305: ASK/biphase Demod failed");
+                       //return -1;
+               } else {
+                       // set size to 10 to only test first 4 positions for the preamble
+                       size_t size = (10 > DemodBufferLen) ? DemodBufferLen : 10;
+                       size_t startIdx = 0; 
+
+                       if (g_debugMode) PrintAndLog("ANS: %d | %u | %u", ans, startIdx, size);
+
+                       uint8_t errChk = !EMpreambleSearch(DemodBuffer, preamble, sizeof(preamble), size, &startIdx);
+                       if ( errChk == 0) {
+                               if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 preamble not found :: %d", startIdx);
+                               //return -1;
+                       } else {
+                               //can't test size because the preamble doesn't repeat :(
+                               //meaning chances of false positives are high.
+                               demodFound = true;
+                       }
+               }
+       }
+
+       if (!demodFound) {
+               DemodBufferLen = 0x00;
+               // try manchester - NOTE: ST only applies to T55x7 tags.
+               ans = ASKDemod_ext("0,0,1", false, false, 1, false);
+               if (!ans) {
+                       if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305: ASK/Manchester Demod failed");
+                       //return -1;
+               } else {
+                       // set size to 10 to only test first 4 positions for the preamble
+                       size_t size = (10 > DemodBufferLen) ? DemodBufferLen : 10;
+                       size_t startIdx = 0; 
+
+                       if (g_debugMode) PrintAndLog("ANS: %d | %u | %u", ans, startIdx, size);
+
+                       uint8_t errChk = !EMpreambleSearch(DemodBuffer, preamble, sizeof(preamble), size, &startIdx);
+                       if ( errChk == 0) {
+                               if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 preamble not found :: %d", startIdx);
+                               //return -1;
+                       } else {
+                               //can't test size because the preamble doesn't repeat :(
+                               //meaning chances of false positives are high.
+                               demodFound = true;
+                       }
+               }
+       }
+
+       if (demodFound && bitsNeeded < DemodBufferLen) {
+               setDemodBuf(DemodBuffer + ans + sizeof(preamble), bitsNeeded, 0);
+               CmdPrintDemodBuff("x");
+               return 1;
+       }
+       return -1;
+}
+
 int CmdReadWord(const char *Cmd) {
        int addr, pwd;
        bool usePwd = false;
@@ -548,44 +667,20 @@ int CmdReadWord(const char *Cmd) {
                return -1;
        }
        setGraphBuf(got, sizeof(got));
-       
-       
-       int ans = 0;
-       //bool ST = true;
-       DemodBufferLen = 0x00;  
-
-       //ans = ASKDemod_ext("0 0 1", FALSE, FALSE, 1, &ST);
-       ans = ASKbiphaseDemod("0 0 1", FALSE);
-       if (!ans) { 
-               if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305: ASK/Manchester Demod failed");
-               return -1;
-       }
-
-       size_t startIdx = 0, size = DemodBufferLen; 
-
-       PrintAndLog("ANS: %d | %u | %u", ans, startIdx, size);
-
-       
-       uint8_t preamble[8] = {0,0,0,0,1,0,1,0};        
-       uint8_t errChk = !preambleSearch(DemodBuffer, preamble, sizeof(preamble), &size, &startIdx);
-       if ( errChk == 0) {
-               if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 preamble not found :: %d", startIdx);
-               return -1;
-       }
-
-       // sanity check. 
-       if (size != 32) {
-               if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 incorrect data length found,  %u", size );
+       int testLen = (GraphTraceLen < 1000) ? GraphTraceLen : 1000;
+       if (graphJustNoise(GraphBuffer, testLen)) {
+               PrintAndLog("no tag not found");
                return -1;
        }
 
-       //setDemodBuf(BitStream, 32, preambleIndex);
+       //need 32 bits for read word
+       demodEM4x05resp(32);
        
        return 1;
 }
 
 int usage_lf_em_write(void) {
-       PrintAndLog("Write EM4x50.  Tag must be on antenna. ");
+       PrintAndLog("Write EM4x05/EM4x69.  Tag must be on antenna. ");
        PrintAndLog("");
        PrintAndLog("Usage:  lf em writeword [h] <address> <data> <pwd>");
        PrintAndLog("Options:");
@@ -654,7 +749,6 @@ int CmdWriteWord(const char *Cmd) {
                if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305: ASK/Manchester Demod failed");
                return -3;
        }
-       PrintAndLog("ANS: %d", ans);
        
        //todo: check response for 00001010 then write data for write confirmation!     
        size_t startIdx = 0, size = DemodBufferLen;