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comparison Alc/alcRing.c @ 0:f9476ff7637e

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initial forking of open-al to create multiple listeners
author Robert McIntyre <rlm@mit.edu>
date Tue, 25 Oct 2011 13:02:31 -0700
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-1:000000000000 0:f9476ff7637e
1 /**
2 * OpenAL cross platform audio library
3 * Copyright (C) 1999-2007 by authors.
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library 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 GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 * Or go to http://www.gnu.org/copyleft/lgpl.html
19 */
20
21 #include "config.h"
22
23 #include <string.h>
24 #include <stdlib.h>
25
26 #include "alMain.h"
27
28
29 struct RingBuffer {
30 ALubyte *mem;
31
32 ALsizei frame_size;
33 ALsizei length;
34 ALint read_pos;
35 ALint write_pos;
36
37 CRITICAL_SECTION cs;
38 };
39
40
41 RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length)
42 {
43 RingBuffer *ring = calloc(1, sizeof(*ring) + ((length+1) * frame_size));
44 if(ring)
45 {
46 ring->mem = (ALubyte*)(ring+1);
47
48 ring->frame_size = frame_size;
49 ring->length = length+1;
50 ring->read_pos = 0;
51 ring->write_pos = 0;
52
53 InitializeCriticalSection(&ring->cs);
54 }
55 return ring;
56 }
57
58 void DestroyRingBuffer(RingBuffer *ring)
59 {
60 if(ring)
61 {
62 DeleteCriticalSection(&ring->cs);
63 free(ring);
64 }
65 }
66
67 ALsizei RingBufferSize(RingBuffer *ring)
68 {
69 ALsizei s;
70
71 EnterCriticalSection(&ring->cs);
72 s = (ring->write_pos-ring->read_pos+ring->length) % ring->length;
73 LeaveCriticalSection(&ring->cs);
74
75 return s;
76 }
77
78 void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)
79 {
80 int remain;
81
82 EnterCriticalSection(&ring->cs);
83
84 remain = (ring->read_pos-ring->write_pos-1+ring->length) % ring->length;
85 if(remain < len) len = remain;
86
87 if(len > 0)
88 {
89 remain = ring->length - ring->write_pos;
90 if(remain < len)
91 {
92 memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
93 remain*ring->frame_size);
94 memcpy(ring->mem, data+(remain*ring->frame_size),
95 (len-remain)*ring->frame_size);
96 }
97 else
98 memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
99 len*ring->frame_size);
100
101 ring->write_pos += len;
102 ring->write_pos %= ring->length;
103 }
104
105 LeaveCriticalSection(&ring->cs);
106 }
107
108 void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)
109 {
110 int remain;
111
112 EnterCriticalSection(&ring->cs);
113
114 remain = ring->length - ring->read_pos;
115 if(remain < len)
116 {
117 memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);
118 memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);
119 }
120 else
121 memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);
122
123 ring->read_pos += len;
124 ring->read_pos %= ring->length;
125
126 LeaveCriticalSection(&ring->cs);
127 }