+//attempt to identify a Sequence Terminator in ASK modulated raw wave
+bool DetectST_ext(uint8_t buffer[], size_t *size, int *foundclock, size_t *ststart, size_t *stend) {
+ size_t bufsize = *size;
+ //need to loop through all samples and identify our clock, look for the ST pattern
+ int clk = 0;
+ int tol = 0;
+ int j, high, low, skip, start, end, minClk=255;
+ size_t i = 0;
+ //probably should malloc... || test if memory is available ... handle device side? memory danger!!! [marshmellow]
+ int tmpbuff[bufsize / LOWEST_DEFAULT_CLOCK]; // low to low wave count //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
+ int waveLen[bufsize / LOWEST_DEFAULT_CLOCK]; // high to low wave count //if clock is larger then we waste memory in array size that is not needed...
+ //size_t testsize = (bufsize < 512) ? bufsize : 512;
+ int phaseoff = 0;
+ high = low = 128;
+ memset(tmpbuff, 0, sizeof(tmpbuff));
+ memset(waveLen, 0, sizeof(waveLen));
+
+ if (!loadWaveCounters(buffer, bufsize, tmpbuff, waveLen, &j, &skip, &minClk, &high, &low)) return false;
+ // set clock - might be able to get this externally and remove this work...
+ clk = getClosestClock(minClk);
+ // clock not found - ERROR
+ if (clk == 0) {
+ if (g_debugMode==2) prnt("DEBUG STT: clock not found - quitting");
+ return false;
+ }
+ *foundclock = clk;
+
+ tol = clk/8;
+ if (!findST(&start, &skip, tmpbuff, waveLen, clk, tol, j, &i)) {
+ // first ST not found - ERROR
+ if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
+ return false;
+ } else {
+ if (g_debugMode==2) prnt("DEBUG STT: first STT found at wave: %i, skip: %i, j=%i", start, skip, j);
+ }
+ if (waveLen[i+2] > clk*1+tol)
+ phaseoff = 0;
+ else
+ phaseoff = clk/2;
+
+ // skip over the remainder of ST
+ skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
+
+ // now do it again to find the end
+ int dummy1 = 0;
+ end = skip;
+ i+=3;
+ if (!findST(&dummy1, &end, tmpbuff, waveLen, clk, tol, j, &i)) {
+ //didn't find second ST - ERROR
+ if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
+ return false;
+ }
+ end -= phaseoff;
+ if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d, phaseoff: %d", skip, end, end-skip, clk, (end-skip)/clk, phaseoff);
+ //now begin to trim out ST so we can use normal demod cmds
+ start = skip;
+ size_t datalen = end - start;
+ // check validity of datalen (should be even clock increments) - use a tolerance of up to 1/8th a clock
+ if ( clk - (datalen % clk) <= clk/8) {
+ // padd the amount off - could be problematic... but shouldn't happen often
+ datalen += clk - (datalen % clk);
+ } else if ( (datalen % clk) <= clk/8 ) {
+ // padd the amount off - could be problematic... but shouldn't happen often
+ datalen -= datalen % clk;
+ } else {
+ if (g_debugMode==2) prnt("DEBUG STT: datalen not divisible by clk: %u %% %d = %d - quitting", datalen, clk, datalen % clk);
+ return false;
+ }
+ // if datalen is less than one t55xx block - ERROR
+ if (datalen/clk < 8*4) {
+ if (g_debugMode==2) prnt("DEBUG STT: datalen is less than 1 full t55xx block - quitting");
+ return false;
+ }
+ size_t dataloc = start;
+ if (buffer[dataloc-(clk*4)-(clk/8)] <= low && buffer[dataloc] <= low && buffer[dataloc-(clk*4)] >= high) {
+ //we have low drift (and a low just before the ST and a low just after the ST) - compensate by backing up the start
+ for ( i=0; i <= (clk/8); ++i ) {
+ if ( buffer[dataloc - (clk*4) - i] <= low ) {
+ dataloc -= i;
+ break;
+ }
+ }
+ }
+
+ size_t newloc = 0;
+ i=0;
+ if (g_debugMode==2) prnt("DEBUG STT: Starting STT trim - start: %d, datalen: %d ",dataloc, datalen);
+ bool firstrun = true;
+ // warning - overwriting buffer given with raw wave data with ST removed...
+ while ( dataloc < bufsize-(clk/2) ) {
+ //compensate for long high at end of ST not being high due to signal loss... (and we cut out the start of wave high part)
+ if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
+ for(i=0; i < clk/2-tol; ++i) {
+ buffer[dataloc+i] = high+5;
+ }
+ } //test for single sample outlier (high between two lows) in the case of very strong waves
+ if (buffer[dataloc] >= high && buffer[dataloc+2] <= low) {
+ buffer[dataloc] = buffer[dataloc+2];
+ buffer[dataloc+1] = buffer[dataloc+2];
+ }
+ if (firstrun) {
+ *stend = dataloc;
+ *ststart = dataloc-(clk*4);
+ firstrun=false;
+ }
+ for (i=0; i<datalen; ++i) {
+ if (i+newloc < bufsize) {
+ if (i+newloc < dataloc)
+ buffer[i+newloc] = buffer[dataloc];
+
+ dataloc++;
+ }
+ }
+ newloc += i;
+ //skip next ST - we just assume it will be there from now on...
+ if (g_debugMode==2) prnt("DEBUG STT: skipping STT at %d to %d", dataloc, dataloc+(clk*4));
+ dataloc += clk*4;
+ }
+ *size = newloc;
+ return true;
+}
+bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
+ size_t ststart = 0, stend = 0;
+ return DetectST_ext(buffer, size, foundclock, &ststart, &stend);
+}
+
+//by marshmellow
+//take 11 10 01 11 00 and make 01100 ... miller decoding
+//check for phase errors - should never have half a 1 or 0 by itself and should never exceed 1111 or 0000 in a row
+//decodes miller encoded binary
+//NOTE askrawdemod will NOT demod miller encoded ask unless the clock is manually set to 1/2 what it is detected as!
+int millerRawDecode(uint8_t *BitStream, size_t *size, int invert) {
+ if (*size < 16) return -1;
+ uint16_t MaxBits = 512, errCnt = 0;
+ size_t i, bitCnt=0;
+ uint8_t alignCnt = 0, curBit = BitStream[0], alignedIdx = 0;
+ uint8_t halfClkErr = 0;
+ //find alignment, needs 4 1s or 0s to properly align
+ for (i=1; i < *size-1; i++) {
+ alignCnt = (BitStream[i] == curBit) ? alignCnt+1 : 0;
+ curBit = BitStream[i];
+ if (alignCnt == 4) break;
+ }
+ // for now error if alignment not found. later add option to run it with multiple offsets...
+ if (alignCnt != 4) {
+ if (g_debugMode) prnt("ERROR MillerDecode: alignment not found so either your bitstream is not miller or your data does not have a 101 in it");
+ return -1;
+ }
+ alignedIdx = (i-1) % 2;
+ for (i=alignedIdx; i < *size-3; i+=2) {
+ halfClkErr = (uint8_t)((halfClkErr << 1 | BitStream[i]) & 0xFF);
+ if ( (halfClkErr & 0x7) == 5 || (halfClkErr & 0x7) == 2 || (i > 2 && (halfClkErr & 0x7) == 0) || (halfClkErr & 0x1F) == 0x1F) {
+ errCnt++;
+ BitStream[bitCnt++] = 7;
+ continue;
+ }
+ BitStream[bitCnt++] = BitStream[i] ^ BitStream[i+1] ^ invert;
+
+ if (bitCnt > MaxBits) break;
+ }
+ *size = bitCnt;
+ return errCnt;
+}
+
+//by marshmellow
+//take 01 or 10 = 1 and 11 or 00 = 0
+//check for phase errors - should never have 111 or 000 should be 01001011 or 10110100 for 1010
+//decodes biphase or if inverted it is AKA conditional dephase encoding AKA differential manchester encoding
+int BiphaseRawDecode(uint8_t *BitStream, size_t *size, int offset, int invert) {
+ uint16_t bitnum = 0;
+ uint16_t errCnt = 0;
+ size_t i = offset;
+ uint16_t MaxBits=512;
+ //if not enough samples - error
+ if (*size < 51) return -1;
+ //check for phase change faults - skip one sample if faulty
+ uint8_t offsetA = 1, offsetB = 1;
+ for (; i<48; i+=2){
+ if (BitStream[i+1]==BitStream[i+2]) offsetA=0;
+ if (BitStream[i+2]==BitStream[i+3]) offsetB=0;
+ }
+ if (!offsetA && offsetB) offset++;
+ for (i=offset; i<*size-3; i+=2){
+ //check for phase error
+ if (BitStream[i+1]==BitStream[i+2]) {
+ BitStream[bitnum++]=7;
+ errCnt++;
+ }
projects / proxmark3-svn / blobdiff