diff options
Diffstat (limited to 'openpicc/application/iso14443a_miller.c')
| -rw-r--r-- | openpicc/application/iso14443a_miller.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/openpicc/application/iso14443a_miller.c b/openpicc/application/iso14443a_miller.c new file mode 100644 index 0000000..deb9a8a --- /dev/null +++ b/openpicc/application/iso14443a_miller.c @@ -0,0 +1,112 @@ +/* ISO14443A Manchester encoder for OpenPICC + * (C) 2007 by Henryk Plötz <henryk@ploetzli.ch> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ + +#include <openpicc.h> +#include <FreeRTOS.h> + +#include <string.h> + +#include "iso14443_layer3a.h" +#include "usb_print.h" +#include "cmd.h" + +#ifdef FOUR_TIMES_OVERSAMPLING +#define OVERSAMPLING_RATE 4 + +/* definitions for four-times oversampling */ +#define SEQ_X 0x4 +#define SEQ_Y 0x0 +#define SEQ_Z 0x1 +#else +#define OVERSAMPLING_RATE 2 +#define SEQ_X 0x2 +#define SEQ_Y 0x0 +#define SEQ_Z 0x1 +#endif + +enum miller_sequence { + SEQUENCE_X, + SEQUENCE_Y, + SEQUENCE_Z, +}; + +#define BIT_ENDMARKER -1 + +int iso14443a_decode_miller(iso14443_frame *frame, + const u_int8_t *sample_buf, const u_int16_t sample_buf_len) +{ + signed int i, j, bit = 0, last_bit = 0; + enum miller_sequence current_seq; + unsigned int bitpos = 0; + + memset(frame, 0, sizeof(frame)); + frame->type = TYPE_A; + frame->parameters.a.parity = GIVEN_PARITY; + + for(i=0; i<sample_buf_len && bit != BIT_ENDMARKER; i++) { + for(j=0; j<(signed)(sizeof(sample_buf[0])*8)/OVERSAMPLING_RATE && bit != BIT_ENDMARKER; j++) { + int sample = (sample_buf[i]>>(j*OVERSAMPLING_RATE)) & ~(~0 << OVERSAMPLING_RATE); + switch(sample) { + case SEQ_X: current_seq = SEQUENCE_X; break; + case SEQ_Y: current_seq = SEQUENCE_Y; break; + case SEQ_Z: current_seq = SEQUENCE_Z; break; + default: current_seq = SEQUENCE_Y; + } + + switch(current_seq) { + case SEQ_X: + DumpStringToUSB("X"); + bit = 1; break; + case SEQ_Y: /* Fall-through to SEQ_Z */ + DumpStringToUSB("Y"); + if(last_bit == 0) { + bit = BIT_ENDMARKER; + break; + } + case SEQ_Z: + DumpStringToUSB("Z"); + bit = 0; break; + } + + switch(bit) { + case BIT_ENDMARKER: + bitpos--; + break; + case 0: /* Fall-through */ + case 1: { + int bytepos = bitpos/9; + if(bitpos % 9 == 8) { /* Parity bit */ + frame->parity[ bytepos/8 ] |= (bit<<(bytepos%8)); + } else { + frame->data[ bytepos ] |= (bit<<(bitpos%9)); + } + } + } + + last_bit = bit; + bitpos++; + } + } + + frame->numbytes = bitpos/9; + frame->numbits = bitpos%9; + DumpStringToUSB("\n\r"); + + return 0; +} |