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/**
* OpenAL cross platform audio library
* Copyright (C) 1999-2007 by authors.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include <string.h>
#include <stdlib.h>
#include "alMain.h"
struct RingBuffer {
ALubyte *mem;
ALsizei frame_size;
ALsizei length;
ALint read_pos;
ALint write_pos;
CRITICAL_SECTION cs;
};
RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length)
{
RingBuffer *ring = calloc(1, sizeof(*ring) + ((length+1) * frame_size));
if(ring)
{
ring->mem = (ALubyte*)(ring+1);
ring->frame_size = frame_size;
ring->length = length+1;
ring->read_pos = 0;
ring->write_pos = 0;
InitializeCriticalSection(&ring->cs);
}
return ring;
}
void DestroyRingBuffer(RingBuffer *ring)
{
if(ring)
{
DeleteCriticalSection(&ring->cs);
free(ring);
}
}
ALsizei RingBufferSize(RingBuffer *ring)
{
ALsizei s;
EnterCriticalSection(&ring->cs);
s = (ring->write_pos-ring->read_pos+ring->length) % ring->length;
LeaveCriticalSection(&ring->cs);
return s;
}
void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)
{
int remain;
EnterCriticalSection(&ring->cs);
remain = (ring->read_pos-ring->write_pos-1+ring->length) % ring->length;
if(remain < len) len = remain;
if(len > 0)
{
remain = ring->length - ring->write_pos;
if(remain < len)
{
memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
remain*ring->frame_size);
memcpy(ring->mem, data+(remain*ring->frame_size),
(len-remain)*ring->frame_size);
}
else
memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,
len*ring->frame_size);
ring->write_pos += len;
ring->write_pos %= ring->length;
}
LeaveCriticalSection(&ring->cs);
}
void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)
{
int remain;
EnterCriticalSection(&ring->cs);
remain = ring->length - ring->read_pos;
if(remain < len)
{
memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);
memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);
}
else
memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);
ring->read_pos += len;
ring->read_pos %= ring->length;
LeaveCriticalSection(&ring->cs);
}