Alc/alcRing.c

   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));
  44     if(ring)
  45     {
  46         ring->frame_size = frame_size;
  47         ring->length = length+1;
  48         ring->write_pos = 1;
  49         ring->mem = malloc(ring->length * ring->frame_size);
  50         if(!ring->mem)
  51         {
  52             free(ring);
  53             ring = NULL;
  54         }
  55
  56         InitializeCriticalSection(&ring->cs);
  57     }
  58     return ring;
  59 }
  60
  61 void DestroyRingBuffer(RingBuffer *ring)
  62 {
  63     if(ring)
  64     {
  65         DeleteCriticalSection(&ring->cs);
  66         free(ring->mem);
  67         free(ring);
  68     }
  69 }
  70
  71 ALsizei RingBufferSize(RingBuffer *ring)
  72 {
  73     ALsizei s;
  74
  75     EnterCriticalSection(&ring->cs);
  76     s = (ring->write_pos-ring->read_pos-1+ring->length) % ring->length;
  77     LeaveCriticalSection(&ring->cs);
  78
  79     return s;
  80 }
  81
  82 void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)
  83 {
  84     int remain;
  85
  86     EnterCriticalSection(&ring->cs);
  87
  88     remain = (ring->read_pos-ring->write_pos+ring->length) % ring->length;
  89     if(remain < len) len = remain;
  90
  91     if(len > 0)
  92     {
  93         remain = ring->length - ring->write_pos;
  94         if(remain < len)
  95         {
  96             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
  97                    remain*ring->frame_size);
  98             memcpy(ring->mem, data+(remain*ring->frame_size),
  99                    (len-remain)*ring->frame_size);
 100         }
 101         else
 102             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
 103                    len*ring->frame_size);
 104
 105         ring->write_pos += len;
 106         ring->write_pos %= ring->length;
 107     }
 108
 109     LeaveCriticalSection(&ring->cs);
 110 }
 111
 112 void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)
 113 {
 114     int remain;
 115
 116     EnterCriticalSection(&ring->cs);
 117
 118     remain = ring->length - ring->read_pos;
 119     if(remain < len)
 120     {
 121         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);
 122         memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);
 123     }
 124     else
 125         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);
 126
 127     ring->read_pos += len;
 128     ring->read_pos %= ring->length;
 129
 130     LeaveCriticalSection(&ring->cs);
 131 }