3 * Copyright 2006 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
27 #include <gr_diff_decoder_bb.h>
28 #include <gr_io_signature.h>
30 gr_diff_decoder_bb_sptr
31 gr_make_diff_decoder_bb (unsigned int modulus)
33 return gr_diff_decoder_bb_sptr (new gr_diff_decoder_bb(modulus));
36 gr_diff_decoder_bb::gr_diff_decoder_bb (unsigned int modulus)
37 : gr_sync_block ("diff_decoder_bb",
38 gr_make_io_signature (1, 1, sizeof (unsigned char)),
39 gr_make_io_signature (1, 1, sizeof (unsigned char))),
42 set_history(2); // need to look at two inputs
46 gr_diff_decoder_bb::work (int noutput_items,
47 gr_vector_const_void_star &input_items,
48 gr_vector_void_star &output_items)
50 const unsigned char *in = (const unsigned char *) input_items[0];
51 unsigned char *out = (unsigned char *) output_items[0];
52 in += 1; // ensure that in[-1] is valid
54 unsigned modulus = d_modulus;
56 for (int i = 0; i < noutput_items; i++){
57 out[i] = (in[i] - in[i-1]) % modulus;