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 #include "compat.h"
  28
  29
  30 struct RingBuffer {
  31     ALubyte *mem;
  32
  33     ALsizei frame_size;
  34     ALsizei length;
  35     ALint read_pos;
  36     ALint write_pos;
  37
  38     CRITICAL_SECTION cs;
  39 };
  40
  41
  42 RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length)
  43 {
  44     RingBuffer *ring = calloc(1, sizeof(*ring) + ((length+1) * frame_size));
  45     if(ring)
  46     {
  47         ring->mem = (ALubyte*)(ring+1);
  48
  49         ring->frame_size = frame_size;
  50         ring->length = length+1;
  51         ring->read_pos = 0;
  52         ring->write_pos = 0;
  53
  54         InitializeCriticalSection(&ring->cs);
  55     }
  56     return ring;
  57 }
  58
  59 void DestroyRingBuffer(RingBuffer *ring)
  60 {
  61     if(ring)
  62     {
  63         DeleteCriticalSection(&ring->cs);
  64         free(ring);
  65     }
  66 }
  67
  68 ALsizei RingBufferSize(RingBuffer *ring)
  69 {
  70     ALsizei s;
  71
  72     EnterCriticalSection(&ring->cs);
  73     s = (ring->write_pos-ring->read_pos+ring->length) % ring->length;
  74     LeaveCriticalSection(&ring->cs);
  75
  76     return s;
  77 }
  78
  79 void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)
  80 {
  81     int remain;
  82
  83     EnterCriticalSection(&ring->cs);
  84
  85     remain = (ring->read_pos-ring->write_pos-1+ring->length) % ring->length;
  86     if(remain < len) len = remain;
  87
  88     if(len > 0)
  89     {
  90         remain = ring->length - ring->write_pos;
  91         if(remain < len)
  92         {
  93             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
  94                    remain*ring->frame_size);
  95             memcpy(ring->mem, data+(remain*ring->frame_size),
  96                    (len-remain)*ring->frame_size);
  97         }
  98         else
  99             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
 100                    len*ring->frame_size);
 101
 102         ring->write_pos += len;
 103         ring->write_pos %= ring->length;
 104     }
 105
 106     LeaveCriticalSection(&ring->cs);
 107 }
 108
 109 void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)
 110 {
 111     int remain;
 112
 113     EnterCriticalSection(&ring->cs);
 114
 115     remain = ring->length - ring->read_pos;
 116     if(remain < len)
 117     {
 118         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);
 119         memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);
 120     }
 121     else
 122         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);
 123
 124     ring->read_pos += len;
 125     ring->read_pos %= ring->length;
 126
 127     LeaveCriticalSection(&ring->cs);
 128 }