-
-int manchester_decode( int * data, const size_t len, uint8_t * dataout, size_t dataoutlen){
-
- int bitlength = 0;
- int i, clock, high, low, startindex;
- low = startindex = 0;
- high = 1;
- uint8_t * bitStream = (uint8_t* ) malloc(sizeof(uint8_t) * dataoutlen);
- memset(bitStream, 0x00, dataoutlen);
-
- /* Detect high and lows */
- for (i = 0; i < len; i++) {
- if (data[i] > high)
- high = data[i];
- else if (data[i] < low)
- low = data[i];
- }
-
- /* get clock */
- clock = GetT55x7Clock( data, len, high );
- startindex = DetectFirstTransition(data, len, high);
-
- //PrintAndLog(" Clock : %d", clock);
-
- if (high != 1)
- bitlength = ManchesterConvertFrom255(data, len, bitStream, dataoutlen, high, low, clock, startindex);
- else
- bitlength= ManchesterConvertFrom1(data, len, bitStream, dataoutlen, clock, startindex);
-
- memcpy(dataout, bitStream, bitlength);
- free(bitStream);
- return bitlength;
-}
-
- int GetT55x7Clock( const int * data, const size_t len, int peak ){
-
- int i,lastpeak,clock;
- clock = 0xFFFF;
- lastpeak = 0;
-
- /* Detect peak if we don't have one */
- if (!peak) {
- for (i = 0; i < len; ++i) {
- if (data[i] > peak) {
- peak = data[i];
- }
- }
- }
-
- for (i = 1; i < len; ++i) {
- /* if this is the beginning of a peak */
- if ( data[i-1] != data[i] && data[i] == peak) {
- /* find lowest difference between peaks */
- if (lastpeak && i - lastpeak < clock)
- clock = i - lastpeak;
- lastpeak = i;
- }
- }
-
- // When detected clock is 31 or 33 then then return
- int clockmod = clock%8;
- if ( clockmod == 0) return clock;
-
- if ( clockmod == 7 ) clock += 1;
- else if ( clockmod == 1 ) clock -= 1;
-
- return clock;
- }
-
- int DetectFirstTransition(const int * data, const size_t len, int threshold){
-
- int i =0;
- /* now look for the first threshold */
- for (; i < len; ++i) {
- if (data[i] == threshold) {
- break;
- }
- }
- return i;
- }
-
- int ManchesterConvertFrom255(const int * data, const size_t len, uint8_t * dataout, int dataoutlen, int high, int low, int clock, int startIndex){
-
- int i, j, z, hithigh, hitlow, bitIndex, startType;
- i = 0;
- bitIndex = 0;
-
- int isDamp = 0;
- int damplimit = (int)((high / 2) * 0.3);
- int dampHi = (high/2)+damplimit;
- int dampLow = (high/2)-damplimit;
- int firstST = 0;
-
- // i = clock frame of data
- for (; i < (int)(len/clock); i++)
- {
- hithigh = 0;
- hitlow = 0;
- startType = -1;
- z = startIndex + (i*clock);
- isDamp = 0;
-
- /* Find out if we hit both high and low peaks */
- for (j = 0; j < clock; j++)
- {
- if (data[z+j] == high){
- hithigh = 1;
- if ( startType == -1)
- startType = 1;
- }
-
- if (data[z+j] == low ){
- hitlow = 1;
- if ( startType == -1)
- startType = 0;
- }
-
- if (hithigh && hitlow)
- break;
- }
-
- // No high value found, are we in a dampening field?
- if ( !hithigh ) {
- //PrintAndLog(" # Entering damp test at index : %d (%d)", z+j, j);
- for (j = 0; j < clock; j++) {
- if (
- (data[z+j] <= dampHi && data[z+j] >= dampLow)
- ){
- isDamp++;
- }
- }
- }
-
- /* Manchester Switching..
- 0: High -> Low
- 1: Low -> High
- */
- if (startType == 0)
- dataout[bitIndex++] = 1;
- else if (startType == 1)
- dataout[bitIndex++] = 0;
- else
- dataout[bitIndex++] = 2;
-
- if ( isDamp > clock/2 ) {
- firstST++;
- }
-
- if ( firstST == 4)
- break;
- if ( bitIndex >= dataoutlen-1 )
- break;
- }
- return bitIndex;
- }
-
- int ManchesterConvertFrom1(const int * data, const size_t len, uint8_t * dataout,int dataoutlen, int clock, int startIndex){
-
- PrintAndLog(" Path B");
-
- int i,j, bitindex, lc, tolerance, warnings;
- warnings = 0;
- int upperlimit = len*2/clock+8;
- i = startIndex;
- j = 0;
- tolerance = clock/4;
- uint8_t decodedArr[len];
-
- /* Detect duration between 2 successive transitions */
- for (bitindex = 1; i < len; i++) {
-
- if (data[i-1] != data[i]) {
- lc = i - startIndex;
- startIndex = i;
-
- // Error check: if bitindex becomes too large, we do not
- // have a Manchester encoded bitstream or the clock is really wrong!
- if (bitindex > upperlimit ) {
- PrintAndLog("Error: the clock you gave is probably wrong, aborting.");
- return 0;
- }
- // Then switch depending on lc length:
- // Tolerance is 1/4 of clock rate (arbitrary)
- if (abs((lc-clock)/2) < tolerance) {
- // Short pulse : either "1" or "0"
- decodedArr[bitindex++] = data[i-1];
- } else if (abs(lc-clock) < tolerance) {
- // Long pulse: either "11" or "00"
- decodedArr[bitindex++] = data[i-1];
- decodedArr[bitindex++] = data[i-1];
- } else {
- ++warnings;
- PrintAndLog("Warning: Manchester decode error for pulse width detection.");
- if (warnings > 10) {
- PrintAndLog("Error: too many detection errors, aborting.");
- return 0;
- }
- }
- }
- }
-
- /*
- * We have a decodedArr of "01" ("1") or "10" ("0")
- * parse it into final decoded dataout
- */
- for (i = 0; i < bitindex; i += 2) {
-
- if ((decodedArr[i] == 0) && (decodedArr[i+1] == 1)) {
- dataout[j++] = 1;
- } else if ((decodedArr[i] == 1) && (decodedArr[i+1] == 0)) {
- dataout[j++] = 0;
- } else {
- i++;
- warnings++;
- PrintAndLog("Unsynchronized, resync...");
- PrintAndLog("(too many of those messages mean the stream is not Manchester encoded)");
-
- if (warnings > 10) {
- PrintAndLog("Error: too many decode errors, aborting.");
- return 0;
- }
- }
- }
-
- PrintAndLog("%s", sprint_hex(dataout, j));
- return j;
- }
-
- void ManchesterDiffDecodedString(const uint8_t* bitstream, size_t len, uint8_t invert){
- /*
- * We have a bitstream of "01" ("1") or "10" ("0")
- * parse it into final decoded bitstream
- */
- int i, j, warnings;
- uint8_t decodedArr[(len/2)+1];
-
- j = warnings = 0;
-
- uint8_t lastbit = 0;
-
- for (i = 0; i < len; i += 2) {
-
- uint8_t first = bitstream[i];
- uint8_t second = bitstream[i+1];
-
- if ( first == second ) {
- ++i;
- ++warnings;
- if (warnings > 10) {
- PrintAndLog("Error: too many decode errors, aborting.");
- return;
- }
- }
- else if ( lastbit != first ) {
- decodedArr[j++] = 0 ^ invert;
- }
- else {
- decodedArr[j++] = 1 ^ invert;
- }
- lastbit = second;
- }
-
- PrintAndLog("%s", sprint_hex(decodedArr, j));
-}
projects / proxmark3-svn / blobdiff