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 "threads.h"
  28 #include "compat.h"
  29
  30
  31 struct RingBuffer {
  32     ALubyte *mem;
  33
  34     ALsizei frame_size;
  35     ALsizei length;
  36     ALint read_pos;
  37     ALint write_pos;
  38
  39     almtx_t mtx;
  40 };
  41
  42
  43 RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length)
  44 {
  45     RingBuffer *ring = calloc(1, sizeof(*ring) + ((length+1) * frame_size));
  46     if(ring)
  47     {
  48         ring->mem = (ALubyte*)(ring+1);
  49
  50         ring->frame_size = frame_size;
  51         ring->length = length+1;
  52         ring->read_pos = 0;
  53         ring->write_pos = 0;
  54
  55         almtx_init(&ring->mtx, almtx_plain);
  56     }
  57     return ring;
  58 }
  59
  60 void DestroyRingBuffer(RingBuffer *ring)
  61 {
  62     if(ring)
  63     {
  64         almtx_destroy(&ring->mtx);
  65         free(ring);
  66     }
  67 }
  68
  69 ALsizei RingBufferSize(RingBuffer *ring)
  70 {
  71     ALsizei s;
  72
  73     almtx_lock(&ring->mtx);
  74     s = (ring->write_pos-ring->read_pos+ring->length) % ring->length;
  75     almtx_unlock(&ring->mtx);
  76
  77     return s;
  78 }
  79
  80 void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)
  81 {
  82     int remain;
  83
  84     almtx_lock(&ring->mtx);
  85
  86     remain = (ring->read_pos-ring->write_pos-1+ring->length) % ring->length;
  87     if(remain < len) len = remain;
  88
  89     if(len > 0)
  90     {
  91         remain = ring->length - ring->write_pos;
  92         if(remain < len)
  93         {
  94             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
  95                    remain*ring->frame_size);
  96             memcpy(ring->mem, data+(remain*ring->frame_size),
  97                    (len-remain)*ring->frame_size);
  98         }
  99         else
 100             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
 101                    len*ring->frame_size);
 102
 103         ring->write_pos += len;
 104         ring->write_pos %= ring->length;
 105     }
 106
 107     almtx_unlock(&ring->mtx);
 108 }
 109
 110 void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)
 111 {
 112     int remain;
 113
 114     almtx_lock(&ring->mtx);
 115
 116     remain = ring->length - ring->read_pos;
 117     if(remain < len)
 118     {
 119         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);
 120         memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);
 121     }
 122     else
 123         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);
 124
 125     ring->read_pos += len;
 126     ring->read_pos %= ring->length;
 127
 128     almtx_unlock(&ring->mtx);
 129 }