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