firmware/src/picc/decoder.c

   1 /* Decoder Core for OpenPICC
   2  * (C) 2006 by Harald Welte <hwelte@hmw-consulting.de>
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License, or
   7  *  (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, write to the Free Software
  16  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  *
  18  */
  19
  20 #include <errno.h>
  21 #include <sys/types.h>
  22 #include <picc/decoder.h>
  23
  24 #include <os/dbgu.h>
  25
  26 static struct decoder_algo *decoder_algo[DECODER_NUM_ALGOS];
  27
  28 static int get_next_data(struct decoder_state *st, u_int8_t *data)
  29 {
  30         u_int8_t parity_sample;
  31         u_int32_t bytesample;
  32
  33         bytesample = st->algo->get_next_bytesample(st, &parity_sample);
  34
  35         return st->algo->decode_sample(bytesample, data);
  36 }
  37
  38 /* iterate over sample buffer (size N bytes) and decode data */
  39 int decoder_decode(u_int8_t algo, const char *sample_buf,
  40                    int sample_buf_size, char *data_buf)
  41 {
  42         int i, ret;
  43         struct decoder_state st;
  44
  45         if (algo >= DECODER_NUM_ALGOS)
  46                 return -EINVAL;
  47
  48         st.buf = sample_buf;
  49         st.buf32 = (u_int32_t *) st.buf;
  50         st.bit_ofs = 0;
  51         st.algo = decoder_algo[algo];
  52
  53         for (i = 0; i < (sample_buf_size*8)/st.algo->bits_per_sampled_char;
  54              i++) {
  55                 ret = get_next_data(&st, &data_buf[i]);
  56                 if (ret < 0) {
  57                         DEBUGPCR("decoder error %d at data byte %u",
  58                                  ret, i);
  59                         return ret;
  60                 }
  61         }
  62
  63         return i+1;
  64 }
  65
  66 int decoder_register(int algnum, struct decoder_algo *algo)
  67 {
  68         if (algnum >= DECODER_NUM_ALGOS)
  69                 return -EINVAL;
  70
  71         decoder_algo[algnum] = algo;
  72
  73         return 0;
  74 }
  75
  76 void decoder_init(void)
  77 {
  78         decoder_register(DECODER_MILLER, &miller_decoder);
  79         decoder_register(DECODER_NRZL, &nrzl_decoder);
  80 }