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