//----------------------------------------------------------------------------- // Copyright (C) 2014 // // This code is licensed to you under the terms of the GNU GPL, version 2 or, // at your option, any later version. See the LICENSE.txt file for the text of // the license. //----------------------------------------------------------------------------- // Low frequency commands //----------------------------------------------------------------------------- #include #include #include #include "lfdemod.h" //by marshmellow //takes 1s and 0s and searches for EM410x format - output EM ID uint64_t Em410xDecode(uint8_t *BitStream, uint32_t BitLen) { //no arguments needed - built this way in case we want this to be a direct call from "data " cmds in the future // otherwise could be a void with no arguments //set defaults int high = 0, low = 128; uint64_t lo = 0; uint32_t i = 0; uint32_t initLoopMax = 65; if (initLoopMax > BitLen) initLoopMax = BitLen; for (; i < initLoopMax; ++i) //65 samples should be plenty to find high and low values { if (BitStream[i] > high) high = BitStream[i]; else if (BitStream[i] < low) low = BitStream[i]; } if (((high !=1)||(low !=0))){ //allow only 1s and 0s return 0; } uint8_t parityTest = 0; // 111111111 bit pattern represent start of frame uint8_t frame_marker_mask[] = {1,1,1,1,1,1,1,1,1}; uint32_t idx = 0; uint32_t j = 0; uint8_t resetCnt = 0; while( (idx + 64) < BitLen) { restart: // search for a start of frame marker if ( memcmp(BitStream+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0) { // frame marker found idx += 9;//sizeof(frame_marker_mask); for ( i = 0; i < 10; ++i){ for( j = 0; j < 5; ++j){ parityTest += BitStream[(i*5) + j + idx]; } if (parityTest == ( (parityTest >> 1) << 1)){ parityTest = 0; for (j = 0; j < 4; ++j){ lo = ( lo << 1LL)|( BitStream[( i * 5 ) + j + idx]); } } else { //parity failed parityTest = 0; idx -= 8; if (resetCnt > 5) return 0; resetCnt++; goto restart;//continue; } } //skip last 5 bit parity test for simplicity. return lo; } else { idx++; } } return 0; } //by marshmellow //takes 2 arguments - clock and invert both as integers //attempts to demodulate ask while decoding manchester //prints binary found and saves in graphbuffer for further commands int askmandemod(uint8_t *BinStream, uint32_t *BitLen, int *clk, int *invert) { int i; int high = 0, low = 128; *clk = DetectASKClock(BinStream, (size_t)*BitLen, *clk); //clock default if (*clk < 8 ) *clk = 64; if (*clk < 32 ) *clk = 32; if (*invert != 1) *invert = 0; uint32_t initLoopMax = 200; if (initLoopMax > *BitLen) initLoopMax = *BitLen; // Detect high and lows // 200 samples should be enough to find high and low values for (i = 0; i < initLoopMax; ++i) { if (BinStream[i] > high) high = BinStream[i]; else if (BinStream[i] < low) low = BinStream[i]; } //throw away static if ((high < 158) ) return -2; //25% fuzz in case highs and lows aren't clipped [marshmellow] high = (int)(high * .75); low = (int)(low+128 * .25); int lastBit = 0; // set first clock check uint32_t bitnum = 0; // output counter // clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave //clock tolerance may not be needed anymore currently set to + or - 1 but could be increased for poor waves or removed entirely int tol = ( *clk == 32 ) ? 1 : 0; int j = 0; uint32_t gLen = *BitLen; if (gLen > 3000) gLen = 3000; uint8_t errCnt = 0; uint32_t bestStart = *BitLen; uint32_t bestErrCnt = (*BitLen/1000); uint32_t maxErr = bestErrCnt; //loop to find first wave that works for (j=0; j < gLen; ++j){ if ((BinStream[j] >= high)||(BinStream[j] <= low)){ lastBit = j - *clk; errCnt = 0; //loop through to see if this start location works for (i = j; i < *BitLen; ++i) { if ((BinStream[i] >= high) && ((i-lastBit)>(*clk-tol))){ lastBit += *clk; } else if ((BinStream[i] <= low) && ((i-lastBit)>(*clk-tol))){ //low found and we are expecting a bar lastBit += *clk; } else { //mid value found or no bar supposed to be here if ((i-lastBit) > (*clk + tol)){ //should have hit a high or low based on clock!! errCnt++; lastBit += *clk;//skip over until hit too many errors if (errCnt > maxErr) break; //allow 1 error for every 1000 samples else start over } } if ((i-j) >(400 * *clk)) break; //got plenty of bits } //we got more than 64 good bits and not all errors if ((((i-j)/ *clk) > (64 + errCnt)) && (errCnt < maxErr)) { //possible good read if (errCnt == 0){ bestStart = j; bestErrCnt = errCnt; break; //great read - finish } if (errCnt < bestErrCnt){ //set this as new best run bestErrCnt = errCnt; bestStart = j; } } } } if (bestErrCnt < maxErr){ //best run is good enough set to best run and set overwrite BinStream j = bestStart; lastBit = bestStart - *clk; bitnum = 0; for (i = j; i < *BitLen; ++i) { if ((BinStream[i] >= high) && ((i-lastBit)>(*clk-tol))){ lastBit += *clk; BinStream[bitnum] = *invert; bitnum++; } else if ((BinStream[i] <= low) && ((i-lastBit)>(*clk-tol))){ //low found and we are expecting a bar lastBit += *clk; BinStream[bitnum] = 1 - *invert; bitnum++; } else { //mid value found or no bar supposed to be here if ((i-lastBit) > (*clk+tol)){ //should have hit a high or low based on clock!! if (bitnum > 0){ BinStream[bitnum] = 77; bitnum++; } lastBit += *clk;//skip over error } } if (bitnum >= 400) break; } *BitLen = bitnum; } else { *invert = bestStart; *clk = j; return -1; } return bestErrCnt; } //by marshmellow //take 10 and 01 and manchester decode //run through 2 times and take least errCnt int manrawdecode(uint8_t * bits, int *bitlen) { int bitnum = 0; int errCnt = 0; int bestErr = 1000; int bestRun = 0; int i = 1; int j = 1; for (; j < 3; ++j){ i = 1; for ( i = i + j; i < *bitlen-2; i += 2){ if ( bits[i]==1 && (bits[i+1]==0)){ } else if ((bits[i]==0)&& bits[i+1]==1){ } else { errCnt++; } if(bitnum > 300) break; } if (bestErr > errCnt){ bestErr = errCnt; bestRun = j; } errCnt = 0; } errCnt = bestErr; if (errCnt < 20){ j = bestRun; i = 1; for ( i = i+j; i < *bitlen-2; i += 2){ if ( bits[i] == 1 && bits[i + 1] == 0 ){ bits[bitnum++] = 0; } else if ( bits[i] == 0 && bits[i + 1] == 1 ){ bits[bitnum++] = 1; } else { bits[bitnum++] = 77; } if ( bitnum > 300 ) break; } *bitlen = bitnum; } return errCnt; } //by marshmellow //take 01 or 10 = 0 and 11 or 00 = 1 int BiphaseRawDecode(uint8_t * bits, int *bitlen, int offset) { uint8_t bitnum = 0; uint32_t errCnt = 0; uint32_t i = offset; for (; i < *bitlen-2; i += 2 ){ if ( (bits[i]==1 && bits[i+1]==0)|| (bits[i]==0 && bits[i+1]==1)){ bits[bitnum++] = 1; } else if ( (bits[i]==0 && bits[i+1]==0)|| (bits[i]==1 && bits[i+1]==1)){ bits[bitnum++] = 0; } else { bits[bitnum++] = 77; errCnt++; } if ( bitnum > 250) break; } *bitlen = bitnum; return errCnt; } //by marshmellow //takes 2 arguments - clock and invert both as integers //attempts to demodulate ask only //prints binary found and saves in graphbuffer for further commands int askrawdemod(uint8_t *BinStream, int *bitLen, int *clk, int *invert) { uint32_t i; uint32_t initLoopMax = 200; int high = 0, low = 128; uint8_t BitStream[502] = {0x00}; *clk = DetectASKClock(BinStream, *bitLen, *clk); //clock default if (*clk < 8) *clk = 64; if (*clk < 32) *clk = 32; if (*invert != 1) *invert = 0; if (initLoopMax > *bitLen) initLoopMax = *bitLen; // Detect high and lows for (i = 0; i < initLoopMax; ++i) //200 samples should be plenty to find high and low values { if (BinStream[i] > high) high = BinStream[i]; else if (BinStream[i] < low) low = BinStream[i]; } //throw away static if ((high < 158)){ return -2; } //25% fuzz in case highs and lows aren't clipped [marshmellow] high = (int)(high * .75); low = (int)(low+128 * .25); int lastBit = 0; //set first clock check uint32_t bitnum = 0; //output counter uint8_t tol = 0; //clock tolerance adjust - waves will be accepted as within the clock if they fall + or - this value + clock from last valid wave if (*clk==32) tol = 1; //clock tolerance may not be needed anymore currently set to + or - 1 but could be increased for poor waves or removed entirely uint32_t gLen = *bitLen; if (gLen > 500) gLen = 500; uint32_t j = 0; uint8_t errCnt = 0; uint32_t bestStart = *bitLen; uint32_t bestErrCnt = (*bitLen / 1000); uint32_t errCntLimit = bestErrCnt; uint8_t midBit = 0; //loop to find first wave that works for (j = 0; j < gLen; ++j){ if ((BinStream[j] >= high)||(BinStream[j] <= low)){ lastBit = j - *clk; //loop through to see if this start location works for (i = j; i < *bitLen; ++i) { if ((BinStream[i] >= high) && ((i-lastBit)>(*clk-tol))){ lastBit += *clk; BitStream[bitnum] = *invert; bitnum++; midBit = 0; } else if ((BinStream[i] <= low) && ((i-lastBit)>(*clk-tol))){ //low found and we are expecting a bar lastBit += *clk; BitStream[bitnum] = 1-*invert; bitnum++; midBit=0; } else if ((BinStream[i]<=low) && (midBit==0) && ((i-lastBit)>((*clk/2)-tol))){ //mid bar? midBit = 1; BitStream[bitnum] = 1 - *invert; bitnum++; } else if ((BinStream[i]>=high)&&(midBit==0) && ((i-lastBit)>((*clk/2)-tol))){ //mid bar? midBit = 1; BitStream[bitnum] = *invert; bitnum++; } else if ((i-lastBit)>((*clk/2)+tol)&&(midBit==0)){ //no mid bar found midBit = 1; BitStream[bitnum] = BitStream[bitnum-1]; bitnum++; } else { //mid value found or no bar supposed to be here if (( i - lastBit) > ( *clk + tol)){ //should have hit a high or low based on clock!! if (bitnum > 0){ BitStream[bitnum] = 77; bitnum++; } errCnt++; lastBit += *clk;//skip over until hit too many errors if (errCnt > errCntLimit){ //allow 1 error for every 1000 samples else start over errCnt = 0; bitnum = 0;//start over break; } } } if (bitnum > 500) break; } //we got more than 64 good bits and not all errors //possible good read if ((bitnum > (64 + errCnt)) && (errCnt < errCntLimit)) { //great read - finish if (errCnt == 0) break; //if current run == bestErrCnt run (after exhausted testing) then finish if (bestStart == j) break; //set this as new best run if (errCnt < bestErrCnt){ bestErrCnt = errCnt; bestStart = j; } } } if (j >= gLen){ //exhausted test //if there was a ok test go back to that one and re-run the best run (then dump after that run) if (bestErrCnt < errCntLimit) j = bestStart; } } if (bitnum > 16){ for (i = 0; i < bitnum; ++i){ BinStream[i] = BitStream[i]; } *bitLen = bitnum; } else { return -1; } return errCnt; } //translate wave to 11111100000 (1 for each short wave 0 for each long wave) size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow) { uint32_t last_transition = 0; uint32_t idx = 1; uint32_t maxVal = 0; if (fchigh == 0) fchigh = 10; if (fclow == 0) fclow = 8; // we do care about the actual theshold value as sometimes near the center of the // wave we may get static that changes direction of wave for one value // if our value is too low it might affect the read. and if our tag or // antenna is weak a setting too high might not see anything. [marshmellow] if ( size < 100) return 0; // Find high from first 100 samples for ( idx = 1; idx < 100; idx++ ){ if ( maxVal < dest[idx]) maxVal = dest[idx]; } // set close to the top of the wave threshold with 25% margin for error // less likely to get a false transition up there. // (but have to be careful not to go too high and miss some short waves) uint8_t threshold_value = (uint8_t)(maxVal * .75); // sync to first lo-hi transition, and threshold // Need to threshold first sample dest[0] = (dest[0] < threshold_value) ? 0 : 1; size_t numBits = 0; // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8) // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10 for(idx = 1; idx < size; idx++) { // threshold current value dest[idx] = (dest[idx] < threshold_value) ? 0 : 1; // Check for 0->1 transition if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition if ( ( idx - last_transition ) <( fclow - 2 ) ) { //0-5 = garbage noise //do nothing with extra garbage } else if ((idx - last_transition) < ( fchigh - 1 )) { //6-8 = 8 waves dest[numBits]=1; } else { //9+ = 10 waves dest[numBits]=0; } last_transition = idx; numBits++; } } //it returns the number of bytes, but each byte represents a bit: 1 or 0 return numBits; } uint32_t myround2(float f) { if (f >= 2000) return 2000;//something bad happened return (uint32_t) (f + (float)0.5); } //translate 11111100000 to 10 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t maxConsequtiveBits, uint8_t invert, uint8_t fchigh, uint8_t fclow ) { uint8_t lastval = dest[0]; uint32_t idx = 0; uint32_t n = 1; size_t numBits = 0; for( idx = 1; idx < size; idx++) { if (dest[idx] == lastval) { n++; continue; } //if lastval was 1, we have a 1->0 crossing if ( dest[idx-1] == 1 ) { n = myround2( (float)( n + 1 ) / ((float)(rfLen)/(float)fclow)); } else { // 0->1 crossing n = myround2( (float)( n + 1 ) / ((float)(rfLen-2)/(float)fchigh)); //-2 for fudge factor } if (n == 0) n = 1; if(n < maxConsequtiveBits) //Consecutive { if(invert == 0){ //invert bits memset(dest+numBits, dest[idx-1] , n); }else{ memset(dest+numBits, dest[idx-1]^1 , n); } numBits += n; } n = 0; lastval = dest[idx]; }//end for return numBits; } //by marshmellow (from holiman's base) // full fsk demod from GraphBuffer wave to decoded 1s and 0s (no mandemod) int fskdemod(uint8_t *dest, size_t size, uint8_t rfLen, uint8_t invert, uint8_t fchigh, uint8_t fclow) { // FSK demodulator size = fsk_wave_demod(dest, size, fchigh, fclow); if ( size > 0 ) size = aggregate_bits(dest, size, rfLen, 192, invert, fchigh, fclow); return size; } // loop to get raw HID waveform then FSK demodulate the TAG ID from it int HIDdemodFSK(uint8_t *dest, size_t size, uint32_t *hi2, uint32_t *hi, uint32_t *lo) { size_t idx = 0; int numshifts = 0; // FSK demodulator size = fskdemod(dest, size, 50, 0, 10, 8); // final loop, go over previously decoded manchester data and decode into usable tag ID // 111000 bit pattern represent start of frame, 01 pattern represents a 1 and 10 represents a 0 uint8_t frame_marker_mask[] = {1,1,1,0,0,0}; uint8_t mask_len = sizeof frame_marker_mask / sizeof frame_marker_mask[0]; //one scan while( idx + mask_len < size) { // search for a start of frame marker if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0) { // frame marker found idx += mask_len; while(dest[idx] != dest[idx+1] && idx < size-2) { // Keep going until next frame marker (or error) // Shift in a bit. Start by shifting high registers *hi2 = ( *hi2 << 1 ) | ( *hi >> 31 ); *hi = ( *hi << 1 ) | ( *lo >> 31 ); //Then, shift in a 0 or one into low if (dest[idx] && !dest[idx+1]) // 1 0 *lo = ( *lo << 1 ) | 0; else // 0 1 *lo = ( *lo << 1 ) | 1; numshifts++; idx += 2; } // Hopefully, we read a tag and hit upon the next frame marker if(idx + mask_len < size) { if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0) { //good return return idx; } } // reset *hi2 = *hi = *lo = 0; numshifts = 0; }else { idx++; } } return -1; } uint32_t bytebits_to_byte(uint8_t *src, int numbits) { //HACK: potential overflow in numbits is larger then uint32 bits. uint32_t num = 0; for(int i = 0 ; i < numbits ; ++i) { num = (num << 1) | (*src); src++; } return num; } int IOdemodFSK(uint8_t *dest, size_t size) { //make sure buffer has data if (size < 100) return -1; uint32_t idx = 0; uint8_t testMax = 0; //test samples are not just noise for (; idx < 65; ++idx ){ if (testMax < dest[idx]) testMax = dest[idx]; } //if not just noise if (testMax < 170) return -2; // FSK demodulator size = fskdemod(dest, size, 64, 1, 10, 8); // RF/64 and invert //did we get a good demod? if (size < 65) return -3; //Index map //0 10 20 30 40 50 60 //| | | | | | | //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23 //----------------------------------------------------------------------------- //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 ???????? 11 // //XSF(version)facility:codeone+codetwo //Handle the data uint8_t mask[] = {0,0,0,0,0,0,0,0,0,1}; for( idx = 0; idx < (size - 65); ++idx) { if ( memcmp(dest + idx, mask, sizeof(mask))==0) { //frame marker found if (!dest[idx+8] && dest[idx+17] == 1 && dest[idx+26] == 1 && dest[idx+35] == 1 && dest[idx+44] == 1 && dest[idx+53] == 1){ //confirmed proper separator bits found //return start position return (int) idx; } } } return 0; } // by marshmellow // not perfect especially with lower clocks or VERY good antennas (heavy wave clipping) // maybe somehow adjust peak trimming value based on samples to fix? int DetectASKClock(uint8_t dest[], size_t size, int clock) { int i = 0; int clk[] = {16,32,40,50,64,100,128,256}; uint8_t clkLen = sizeof clk / sizeof clk[0]; //if we already have a valid clock quit for (; i < clkLen; ++i) if (clk[i] == clock) return clock; int peak = 0; int low = 128; int loopCnt = 256; if (size < loopCnt) loopCnt = size; //get high and low peak for ( i = 0; i < loopCnt; ++i ){ if(dest[i] > peak) peak = dest[i]; if(dest[i] < low) low = dest[i]; } peak = (int)(peak * .75); low = (int)(low+128 * .25); int ii, cnt, bestErr, tol = 0; int errCnt[clkLen]; memset(errCnt, 0x00, clkLen); int tmpIndex, tmphigh, tmplow; //test each valid clock from smallest to greatest to see which lines up for( cnt = 0; cnt < clkLen; ++cnt ){ tol = (clk[cnt] == 32) ? 1 : 0; bestErr = 1000; tmpIndex = tmphigh = tmplow = 0; //try lining up the peaks by moving starting point (try first 256) for (ii=0; ii < loopCnt; ++ii){ // not a peak? continue if ( (dest[ii] < peak) && (dest[ii] > low)) continue; errCnt[cnt] = 0; // now that we have the first one lined up test rest of wave array for ( i = 0; i < ((int)(size / clk[cnt]) - 1); ++i){ tmpIndex = ii + (i * clk[cnt] ); tmplow = dest[ tmpIndex - tol]; tmphigh = dest[ tmpIndex + tol]; if ( dest[tmpIndex] >= peak || dest[tmpIndex] <= low ) { } else if ( tmplow >= peak || tmplow <= low){ } else if ( tmphigh >= peak || tmphigh <= low){ } else errCnt[cnt]++; //error no peak detected } //if we found no errors this is correct one - return this clock if ( errCnt[cnt] == 0 ) return clk[cnt]; if ( errCnt[cnt] < bestErr) bestErr = errCnt[cnt]; } // save the least error. errCnt[cnt] = bestErr; } // find best clock which has lowest number of errors int j = 0, bestIndex = 0; for (; j < clkLen; ++j){ if ( errCnt[j] < errCnt[bestIndex] ) bestIndex = j; } return clk[bestIndex]; }