+//by marshmellow
+//attempt to detect the field clock and bit clock for FSK
+uint8_t GetFskClock(const char str[], bool printAns, bool verbose)
+{
+ int clock;
+ sscanf(str, "%i", &clock);
+ if (!strcmp(str, ""))
+ clock = 0;
+ if (clock != 0) return (uint8_t)clock;
+
+
+ uint8_t fc1=0, fc2=0, rf1=0;
+ int firstClockEdge = 0;
+ uint8_t ans = fskClocks(&fc1, &fc2, &rf1, verbose, &firstClockEdge);
+ if (ans == 0) return 0;
+ if ((fc1==10 && fc2==8) || (fc1==8 && fc2==5)){
+ if (printAns) PrintAndLog("Detected Field Clocks: FC/%d, FC/%d - Bit Clock: RF/%d", fc1, fc2, rf1);
+ setClockGrid(rf1, firstClockEdge);
+ return rf1;
+ }
+ if (verbose){
+ PrintAndLog("DEBUG: unknown fsk field clock detected");
+ PrintAndLog("Detected Field Clocks: FC/%d, FC/%d - Bit Clock: RF/%d", fc1, fc2, rf1);
+ }
+ return 0;
+}
+uint8_t fskClocks(uint8_t *fc1, uint8_t *fc2, uint8_t *rf1, bool verbose, int *firstClockEdge)
+{
+ uint8_t BitStream[MAX_GRAPH_TRACE_LEN]={0};
+ size_t size = getFromGraphBuf(BitStream);
+ if (size==0) return 0;
+ uint16_t ans = countFC(BitStream, size, 1);
+ if (ans==0) {
+ if (verbose || g_debugMode) PrintAndLog("DEBUG: No data found");
+ return 0;
+ }
+ *fc1 = (ans >> 8) & 0xFF;
+ *fc2 = ans & 0xFF;
+ //int firstClockEdge = 0;
+ *rf1 = detectFSKClk(BitStream, size, *fc1, *fc2, firstClockEdge);
+ if (*rf1==0) {
+ if (verbose || g_debugMode) PrintAndLog("DEBUG: Clock detect error");
+ return 0;
+ }
+ return 1;
+}
+bool graphJustNoise(int *BitStream, int size)
+{
+ static const uint8_t THRESHOLD = 15; //might not be high enough for noisy environments
+ //test samples are not just noise
+ bool justNoise1 = 1;
+ for(int idx=0; idx < size && justNoise1 ;idx++){
+ justNoise1 = BitStream[idx] < THRESHOLD;
+ }
+ return justNoise1;
+}
+int autoCorr(const int* in, int *out, size_t len, int window)
+{
+ static int CorrelBuffer[MAX_GRAPH_TRACE_LEN];
+
+ if (window == 0) {
+ PrintAndLog("needs a window");
+ return 0;
+ }
+ if (window >= len) {
+ PrintAndLog("window must be smaller than trace (%d samples)",
+ len);
+ return 0;
+ }
+
+ PrintAndLog("performing %d correlations", len - window);
+
+ for (int i = 0; i < len - window; ++i) {
+ int sum = 0;
+ for (int j = 0; j < window; ++j) {
+ sum += (in[j]*in[i + j]) / 256;
+ }
+ CorrelBuffer[i] = sum;
+ }
+ //GraphTraceLen = GraphTraceLen - window;
+ memcpy(out, CorrelBuffer, len * sizeof (int));
+ return 0;
+}
+int directionalThreshold(const int* in, int *out, size_t len, int8_t up, int8_t down)
+{
+ int lastValue = in[0];
+ out[0] = 0; // Will be changed at the end, but init 0 as we adjust to last samples value if no threshold kicks in.
+
+ for (int i = 1; i < len; ++i) {
+ // Apply first threshold to samples heading up
+ if (in[i] >= up && in[i] > lastValue)
+ {
+ lastValue = out[i]; // Buffer last value as we overwrite it.
+ out[i] = 1;
+ }
+ // Apply second threshold to samples heading down
+ else if (in[i] <= down && in[i] < lastValue)
+ {
+ lastValue = out[i]; // Buffer last value as we overwrite it.
+ out[i] = -1;
+ }
+ else
+ {
+ lastValue = out[i]; // Buffer last value as we overwrite it.
+ out[i] = out[i-1];
+ }
+ }
+ out[0] = out[1]; // Align with first edited sample.
+ return 0;
+}