MPD
pcm_volume.h
Go to the documentation of this file.
1 /*
2  * Copyright (C) 2003-2010 The Music Player Daemon Project
3  * http://www.musicpd.org
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License along
16  * with this program; if not, write to the Free Software Foundation, Inc.,
17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18  */
19 
20 #ifndef PCM_VOLUME_H
21 #define PCM_VOLUME_H
22 
23 #include "pcm_prng.h"
24 
25 #include <stdint.h>
26 #include <stdbool.h>
27 
28 enum {
30  PCM_VOLUME_1 = 1024,
31 };
32 
33 struct audio_format;
34 
39 static inline int
40 pcm_float_to_volume(float volume)
41 {
42  return volume * PCM_VOLUME_1 + 0.5;
43 }
44 
49 static inline int
51 {
52  static unsigned long state;
53  uint32_t r;
54 
55  r = state = pcm_prng(state);
56 
57  return (r & 511) - ((r >> 9) & 511);
58 }
59 
69 bool
70 pcm_volume(void *buffer, int length,
71  const struct audio_format *format,
72  int volume);
73 
74 #endif