1 /* libSoX ADPCM codecs: IMA, OKI, CL.   (c) 2007-8 robs@users.sourceforge.net
2  *
3  * This library is free software; you can redistribute it and/or modify it
4  * under the terms of the GNU Lesser General Public License as published by
5  * the Free Software Foundation; either version 2.1 of the License, or (at
6  * your option) any later version.
7  *
8  * This library is distributed in the hope that it will be useful, but
9  * WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU Lesser General Public License
14  * along with this library; if not, write to the Free Software Foundation,
15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
16  */
17 
18 typedef struct {
19   int max_step_index;
20   int sign;
21   int shift;
22   int const * steps;
23   int const * changes;
24   int mask;
25 } adpcm_setup_t;
26 
27 typedef struct {
28   adpcm_setup_t setup;
29   int last_output;
30   int step_index;
31   int errors;
32 } adpcm_t;
33 
34 void lsx_adpcm_init(adpcm_t * p, int type, int first_sample);
35 int lsx_adpcm_decode(int code, adpcm_t * p);
36 int lsx_adpcm_encode(int sample, adpcm_t * p);
37 
38 typedef struct {
39   adpcm_t encoder;
40   struct {
41     uint8_t byte;               /* write store */
42     uint8_t flag;
43   } store;
44   sox_fileinfo_t file;
45 } adpcm_io_t;
46 
47 /* Format methods */
48 void lsx_adpcm_reset(adpcm_io_t * state, sox_encoding_t type);
49 int lsx_adpcm_oki_start(sox_format_t * ft, adpcm_io_t * state);
50 int lsx_adpcm_ima_start(sox_format_t * ft, adpcm_io_t * state);
51 size_t lsx_adpcm_read(sox_format_t * ft, adpcm_io_t * state, sox_sample_t *buffer, size_t len);
52 int lsx_adpcm_stopread(sox_format_t * ft, adpcm_io_t * state);
53 size_t lsx_adpcm_write(sox_format_t * ft, adpcm_io_t * state, const sox_sample_t *buffer, size_t length);
54 void lsx_adpcm_flush(sox_format_t * ft, adpcm_io_t * state);
55 int lsx_adpcm_stopwrite(sox_format_t * ft, adpcm_io_t * state);
56