data psk demod minor fixes, pyramid demod add CS

also adjusted autocorrelate and added a printout for lf search u

client/cmddata.c

@@ -22,6 +22,7 @@
 #include "cmddata.h"
 #include "lfdemod.h"
 #include "usb_cmd.h"
+#include "crc.h"
 
 uint8_t DemodBuffer[MAX_DEMOD_BUF_LEN];
 uint8_t g_debugMode;
@@ -729,10 +730,52 @@ int Cmdaskrawdemod(const char *Cmd)
   return ASKrawDemod(Cmd, TRUE);
 }
 
-int CmdAutoCorr(const char *Cmd)
+int AutoCorrelate(int window, bool SaveGrph, bool verbose)
 {
   static int CorrelBuffer[MAX_GRAPH_TRACE_LEN];
+  size_t Correlation = 0;
+  int maxSum = 0;
+  int lastMax = 0;
+  if (verbose) PrintAndLog("performing %d correlations", GraphTraceLen - window);
+  for (int i = 0; i < GraphTraceLen - window; ++i) {
+    int sum = 0;
+    for (int j = 0; j < window; ++j) {
+      sum += (GraphBuffer[j]*GraphBuffer[i + j]) / 256;
+    }
+    CorrelBuffer[i] = sum;
+    if (sum >= maxSum-100 && sum <= maxSum+100){
+      //another max
+      Correlation = i-lastMax;
+      lastMax = i;
+      if (sum > maxSum) maxSum = sum;
+    } else if (sum > maxSum){
+      maxSum=sum;
+      lastMax = i;
+    }
+  }
+  if (Correlation==0){
+    //try again with wider margin
+    for (int i = 0; i < GraphTraceLen - window; i++){
+      if (CorrelBuffer[i] >= maxSum-(maxSum*0.05) && CorrelBuffer[i] <= maxSum+(maxSum*0.05)){
+        //another max
+        Correlation = i-lastMax;
+        lastMax = i;
+        //if (CorrelBuffer[i] > maxSum) maxSum = sum;
+      }
+    }
+  }
+  if (verbose && Correlation > 0) PrintAndLog("Possible Correlation: %d samples",Correlation);
 
+  if (SaveGrph){
+    GraphTraceLen = GraphTraceLen - window;
+    memcpy(GraphBuffer, CorrelBuffer, GraphTraceLen * sizeof (int));
+    RepaintGraphWindow();  
+  }
+  return Correlation;
+}
+
+int CmdAutoCorr(const char *Cmd)
+{
   int window = atoi(Cmd);
 
   if (window == 0) {
@@ -744,21 +787,7 @@ int CmdAutoCorr(const char *Cmd)
       GraphTraceLen);
     return 0;
   }
-
+  return AutoCorrelate(window, TRUE, TRUE);
-  PrintAndLog("performing %d correlations", GraphTraceLen - window);
-
-  for (int i = 0; i < GraphTraceLen - window; ++i) {
-    int sum = 0;
-    for (int j = 0; j < window; ++j) {
-      sum += (GraphBuffer[j]*GraphBuffer[i + j]) / 256;
-    }
-    CorrelBuffer[i] = sum;
-  }
-  GraphTraceLen = GraphTraceLen - window;
-  memcpy(GraphBuffer, CorrelBuffer, GraphTraceLen * sizeof (int));
-
-  RepaintGraphWindow();
-  return 0;
 }
 
 int CmdBitsamples(const char *Cmd)
@@ -1434,7 +1463,16 @@ int CmdFSKdemodPyramid(const char *Cmd)
   // w = wiegand parity, x = extra space for other formats
   // p = unknown checksum
   // (26 bit format shown)
-  
+
+  //get bytes for checksum calc
+  uint8_t checksum = bytebits_to_byte(BitStream + idx + 120, 8);
+  uint8_t csBuff[14] = {0x00};
+  for (uint8_t i = 0; i < 13; i++){
+    csBuff[i] = bytebits_to_byte(BitStream + idx + 16 + (i*8), 8);
+  }
+  //check checksum calc
+  int checkCS =  CRC8Maxim(csBuff,13);
+
   //get raw ID before removing parities
   uint32_t rawLo = bytebits_to_byte(BitStream+idx+96,32);
   uint32_t rawHi = bytebits_to_byte(BitStream+idx+64,32);
@@ -1444,7 +1482,8 @@ int CmdFSKdemodPyramid(const char *Cmd)
 
   size = removeParity(BitStream, idx+8, 8, 1, 120);
   if (size != 105){
-    if (g_debugMode==1) PrintAndLog("DEBUG: Error at parity check-tag size does not match Pyramid format, SIZE: %d, IDX: %d, hi3: %x",size, idx, rawHi3);
+    if (g_debugMode==1) 
+      PrintAndLog("DEBUG: Error at parity check - tag size does not match Pyramid format, SIZE: %d, IDX: %d, hi3: %x",size, idx, rawHi3);
     return 0;
   }
 
@@ -1502,6 +1541,11 @@ int CmdFSKdemodPyramid(const char *Cmd)
       PrintAndLog("Pyramid ID Found - BitLength: %d -unknown BitLength- (%d), Raw: %08x%08x%08x%08x", fmtLen, cardnum, rawHi3, rawHi2, rawHi, rawLo);
     }
   }
+  if (checksum == checkCS)
+    PrintAndLog("Checksum %02x passed", checksum);
+  else
+    PrintAndLog("Checksum %02x failed - should have been %02x", checksum, checkCS);
+
   if (g_debugMode){
     PrintAndLog("DEBUG: idx: %d, Len: %d, Printing Demod Buffer:", idx, 128);
     printDemodBuff();

client/cmddata.h

@@ -23,6 +23,7 @@ int CmdAskEM410xDemod(const char *Cmd);
 int CmdG_Prox_II_Demod(const char *Cmd);
 int Cmdaskrawdemod(const char *Cmd);
 int Cmdaskmandemod(const char *Cmd);
+int AutoCorrelate(int window, bool SaveGrph, bool verbose);
 int CmdAutoCorr(const char *Cmd);
 int CmdBiphaseDecodeRaw(const char *Cmd);
 int CmdBitsamples(const char *Cmd);

client/cmdlf.c

@@ -1080,7 +1080,9 @@ int CmdLFfind(const char *Cmd)
   if (testRaw=='u' || testRaw=='U'){
     //test unknown tag formats (raw mode)
     PrintAndLog("\nChecking for Unknown tags:\n");
-    ans=CmdDetectClockRate("f");
+    ans=AutoCorrelate(4000, FALSE, FALSE);
+    if (ans > 0) PrintAndLog("Possible Auto Correlation of %d repeating samples",ans);
+    ans=CmdDetectClockRate("F"); //GetFSKClock("",TRUE,FALSE);
     if (ans != 0){ //fsk
       ans=CmdFSKrawdemod("");
       if (ans>0) {

common/crc.c

@@ -5,8 +5,9 @@
 //-----------------------------------------------------------------------------
 // Generic CRC calculation code.
 //-----------------------------------------------------------------------------
-
 #include "crc.h"
+#include <stdint.h>
+#include <stddef.h>
 
 void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor)
 {
@@ -40,3 +41,15 @@ uint32_t crc_finish(crc_t *crc)
 {
 	return ( crc->state ^ crc->final_xor ) & crc->mask;
 }
+
+uint32_t CRC8Maxim(uint8_t *buff, size_t size  ) 
+{
+	crc_t crc;
+	crc_init(&crc, 9, 0x8c, 0x00, 0x00);
+	crc_clear(&crc);
+
+	for (size_t i=0; i < size; ++i){
+		crc_update(&crc, buff[i], 8);
+	}
+	return crc_finish(&crc);
+}

common/crc.h

@@ -10,6 +10,7 @@
 #define __CRC_H
 
 #include <stdint.h>
+#include <stddef.h>
 
 typedef struct crc {
 	uint32_t state;
@@ -36,6 +37,8 @@ extern void crc_clear(crc_t *crc);
 /* Get the result of the crc calculation */
 extern uint32_t crc_finish(crc_t *crc);
 
+// Calculate CRC-8/Maxim checksum
+uint32_t CRC8Maxim(uint8_t *buff, size_t size  );
 /* Static initialization of a crc structure */
 #define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
 	.state = ((_initial_value) & ((1L<<(_order))-1)), \

common/lfdemod.c

@@ -1589,7 +1589,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
   if (*size<loopCnt) loopCnt = *size;
 
   uint8_t curPhase = *invert;
-  size_t i, waveStart=0, waveEnd=0, firstFullWave=0, lastClkBit=0;
+  size_t i, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
   uint8_t fc=0, fullWaveLen=0, tol=1;
   uint16_t errCnt=0, waveLenCnt=0;
   fc = countPSK_FC(dest, *size);
@@ -1601,27 +1601,21 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
   //find first phase shift
   for (i=0; i<loopCnt; i++){
     if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
-      if (waveStart == 0) {
+      waveEnd = i+1;
-        waveStart = i+1;
+      //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
-        avgWaveVal=dest[i+1];
+      waveLenCnt = waveEnd-waveStart;
-        //PrintAndLog("DEBUG: waveStart: %d",waveStart);
+      if (waveLenCnt > fc && waveStart > fc){ //not first peak and is a large wave 
-      } else {
+        lastAvgWaveVal = avgWaveVal/(waveLenCnt);
-        waveEnd = i+1;
+        firstFullWave = waveStart;
-        //PrintAndLog("DEBUG: waveEnd: %d",waveEnd);
+        fullWaveLen=waveLenCnt;
-        waveLenCnt = waveEnd-waveStart;
+        //if average wave value is > graph 0 then it is an up wave or a 1
-        lastAvgWaveVal = avgWaveVal/waveLenCnt;
+        if (lastAvgWaveVal > 123) curPhase^=1;  //fudge graph 0 a little 123 vs 128
-        if (waveLenCnt > fc){
+        break;
-          firstFullWave = waveStart;
+      } 
-          fullWaveLen=waveLenCnt;
+      waveStart = i+1;
-          //if average wave value is > graph 0 then it is an up wave or a 1
+      avgWaveVal = 0;
-          if (lastAvgWaveVal > 128) curPhase^=1;
-          break;
-        } 
-        waveStart=0;
-        avgWaveVal=0;
-      }
     }
-    avgWaveVal+=dest[i+1];
+    avgWaveVal+=dest[i+2];
   }
   //PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);  
   lastClkBit = firstFullWave; //set start of wave as clock align
@@ -1629,7 +1623,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
   errCnt=0;
   size_t numBits=0;
   //PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
-
+  dest[numBits++] = curPhase; //set first read bit
   for (i = firstFullWave+fullWaveLen-1; i < *size-3; i++){
     //top edge of wave = start of new wave 
     if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
@@ -1641,26 +1635,23 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
         waveEnd = i+1;
         waveLenCnt = waveEnd-waveStart;
         lastAvgWaveVal = avgWaveVal/waveLenCnt;
-        if (waveLenCnt > fc){ 
+        if (waveLenCnt > fc){  
           //PrintAndLog("DEBUG: avgWaveVal: %d, waveSum: %d",lastAvgWaveVal,avgWaveVal);
           //if this wave is a phase shift
           //PrintAndLog("DEBUG: phase shift at: %d, len: %d, nextClk: %d, i: %d, fc: %d",waveStart,waveLenCnt,lastClkBit+*clock-tol,i+1,fc);
           if (i+1 >= lastClkBit + *clock - tol){ //should be a clock bit
             curPhase^=1;
-            dest[numBits] = curPhase;
+            dest[numBits++] = curPhase;
-            numBits++;
             lastClkBit += *clock;
-          } else if (i<lastClkBit+10){
+          } else if (i<lastClkBit+10+fc){
             //noise after a phase shift - ignore
           } else { //phase shift before supposed to based on clock
             errCnt++;
-            dest[numBits] = 77;
+            dest[numBits++] = 77;
-            numBits++;
           }
         } else if (i+1 > lastClkBit + *clock + tol + fc){
           lastClkBit += *clock; //no phase shift but clock bit
-          dest[numBits] = curPhase;
+          dest[numBits++] = curPhase;
-          numBits++;
         }
         avgWaveVal=0;
         waveStart=i+1;