src/audio/SDL_audio.c
author Sam Lantinga
Fri, 17 Sep 2004 13:20:10 +0000
changeset 955 d74fbf56f2f6
parent 942 41a59de7f2ed
child 1190 173c063d4f55
permissions -rw-r--r--
Date: Fri, 25 Jun 2004 13:29:15 +0100
From: "alan buckley"
Subject: Modification for RISC OS version of SDL

Ive attached a zip file with the changes to this email, it contains the
following:

The file sdldiff.txt is the output from cvs diff u. .
The directory thread/riscos contains all the new files to support threading.

Readme.riscos is a new readme file to add.
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/*
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    SDL - Simple DirectMedia Layer
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    Copyright (C) 1997-2004 Sam Lantinga
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    This library is free software; you can redistribute it and/or
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    modify it under the terms of the GNU Library General Public
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    License as published by the Free Software Foundation; either
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    version 2 of the License, or (at your option) any later version.
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    This library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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    Library General Public License for more details.
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    You should have received a copy of the GNU Library General Public
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    License along with this library; if not, write to the Free
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    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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    Sam Lantinga
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    slouken@libsdl.org
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*/
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#ifdef SAVE_RCSID
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static char rcsid =
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 "@(#) $Id$";
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#endif
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/* Allow access to a raw mixing buffer */
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include "SDL.h"
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#include "SDL_audio.h"
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#include "SDL_timer.h"
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#include "SDL_error.h"
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#include "SDL_audio_c.h"
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#include "SDL_audiomem.h"
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#include "SDL_sysaudio.h"
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/* Available audio drivers */
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static AudioBootStrap *bootstrap[] = {
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#ifdef OPENBSD_AUDIO_SUPPORT
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	&OPENBSD_AUDIO_bootstrap,
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#endif
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#ifdef OSS_SUPPORT
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	&DSP_bootstrap,
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	&DMA_bootstrap,
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#endif
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#ifdef ALSA_SUPPORT
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	&ALSA_bootstrap,
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#endif
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#ifdef QNXNTOAUDIO_SUPPORT
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	&QNXNTOAUDIO_bootstrap,
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#endif
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#ifdef SUNAUDIO_SUPPORT
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	&SUNAUDIO_bootstrap,
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#endif
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#ifdef DMEDIA_SUPPORT
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	&DMEDIA_bootstrap,
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#endif
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#ifdef ARTSC_SUPPORT
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	&ARTSC_bootstrap,
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#endif
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#ifdef ESD_SUPPORT
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	&ESD_bootstrap,
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#endif
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#ifdef NAS_SUPPORT
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	&NAS_bootstrap,
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#endif
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#ifdef ENABLE_DIRECTX
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	&DSOUND_bootstrap,
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#endif
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#ifdef ENABLE_WINDIB
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	&WAVEOUT_bootstrap,
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#endif
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#ifdef __BEOS__
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	&BAUDIO_bootstrap,
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#endif
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#ifdef MACOSX
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	&COREAUDIO_bootstrap,
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#endif
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#if defined(macintosh) || TARGET_API_MAC_CARBON
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	&SNDMGR_bootstrap,
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#endif
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#ifdef _AIX
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	&Paud_bootstrap,
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#endif
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#ifdef ENABLE_AHI
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	&AHI_bootstrap,
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#endif
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#ifdef MMEAUDIO_SUPPORT
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	&MMEAUDIO_bootstrap,
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#endif
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#ifdef MINTAUDIO_SUPPORT
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	&MINTAUDIO_GSXB_bootstrap,
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	&MINTAUDIO_MCSN_bootstrap,
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	&MINTAUDIO_STFA_bootstrap,
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	&MINTAUDIO_XBIOS_bootstrap,
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	&MINTAUDIO_DMA8_bootstrap,
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#endif
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#ifdef DISKAUD_SUPPORT
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	&DISKAUD_bootstrap,
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#endif
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#ifdef ENABLE_DC
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	&DCAUD_bootstrap,
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#endif
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#ifdef DRENDERER_SUPPORT
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	&DRENDERER_bootstrap,
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#endif
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	NULL
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};
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SDL_AudioDevice *current_audio = NULL;
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/* Various local functions */
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int SDL_AudioInit(const char *driver_name);
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void SDL_AudioQuit(void);
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#ifdef ENABLE_AHI
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static int audio_configured = 0;
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#endif
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/* The general mixing thread function */
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int SDL_RunAudio(void *audiop)
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{
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	SDL_AudioDevice *audio = (SDL_AudioDevice *)audiop;
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	Uint8 *stream;
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	int    stream_len;
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	void  *udata;
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	void (*fill)(void *userdata,Uint8 *stream, int len);
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	int    silence;
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#ifdef ENABLE_AHI
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	int started = 0;
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/* AmigaOS NEEDS that the audio driver is opened in the thread that uses it! */
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	D(bug("Task audio started audio struct:<%lx>...\n",audiop));
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	D(bug("Before Openaudio..."));
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	if(audio->OpenAudio(audio, &audio->spec)==-1)
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	{
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		D(bug("Open audio failed...\n"));
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		return(-1);
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	}
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	D(bug("OpenAudio...OK\n"));
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#endif
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	/* Perform any thread setup */
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	if ( audio->ThreadInit ) {
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		audio->ThreadInit(audio);
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	}
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	audio->threadid = SDL_ThreadID();
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	/* Set up the mixing function */
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	fill  = audio->spec.callback;
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	udata = audio->spec.userdata;
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#ifdef ENABLE_AHI
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	audio_configured = 1;
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	D(bug("Audio configured... Checking for conversion\n"));
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	SDL_mutexP(audio->mixer_lock);
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	D(bug("Semaphore obtained...\n"));
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#endif
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	if ( audio->convert.needed ) {
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		if ( audio->convert.src_format == AUDIO_U8 ) {
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			silence = 0x80;
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		} else {
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			silence = 0;
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		}
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		stream_len = audio->convert.len;
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	} else {
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		silence = audio->spec.silence;
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		stream_len = audio->spec.size;
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	}
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	stream = audio->fake_stream;
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#ifdef ENABLE_AHI
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	SDL_mutexV(audio->mixer_lock);
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	D(bug("Entering audio loop...\n"));
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#endif
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	/* Loop, filling the audio buffers */
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	while ( audio->enabled ) {
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		/* Wait for new current buffer to finish playing */
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		if ( stream == audio->fake_stream ) {
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			SDL_Delay((audio->spec.samples*1000)/audio->spec.freq);
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		} else {
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#ifdef ENABLE_AHI
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			if ( started > 1 )
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#endif
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			audio->WaitAudio(audio);
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		}
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		/* Fill the current buffer with sound */
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		if ( audio->convert.needed ) {
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			if ( audio->convert.buf ) {
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				stream = audio->convert.buf;
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			} else {
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				continue;
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			}
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		} else {
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			stream = audio->GetAudioBuf(audio);
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			if ( stream == NULL ) {
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				stream = audio->fake_stream;
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			}
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		}
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		memset(stream, silence, stream_len);
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		if ( ! audio->paused ) {
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			SDL_mutexP(audio->mixer_lock);
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			(*fill)(udata, stream, stream_len);
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			SDL_mutexV(audio->mixer_lock);
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		}
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		/* Convert the audio if necessary */
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		if ( audio->convert.needed ) {
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			SDL_ConvertAudio(&audio->convert);
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			stream = audio->GetAudioBuf(audio);
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			if ( stream == NULL ) {
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				stream = audio->fake_stream;
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			}
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			memcpy(stream, audio->convert.buf,
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			               audio->convert.len_cvt);
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		}
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		/* Ready current buffer for play and change current buffer */
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		if ( stream != audio->fake_stream ) {
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			audio->PlayAudio(audio);
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#ifdef ENABLE_AHI
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/* AmigaOS don't have to wait the first time audio is played! */
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			started++;
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#endif
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		}
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	}
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	/* Wait for the audio to drain.. */
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	if ( audio->WaitDone ) {
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		audio->WaitDone(audio);
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	}
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#ifdef ENABLE_AHI
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	D(bug("WaitAudio...Done\n"));
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	audio->CloseAudio(audio);
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	D(bug("CloseAudio..Done, subtask exiting...\n"));
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	audio_configured = 0;
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#endif
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	return(0);
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}
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static void SDL_LockAudio_Default(SDL_AudioDevice *audio)
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{
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	if ( audio->thread && (SDL_ThreadID() == audio->threadid) ) {
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		return;
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	}
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	SDL_mutexP(audio->mixer_lock);
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}
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static void SDL_UnlockAudio_Default(SDL_AudioDevice *audio)
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{
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	if ( audio->thread && (SDL_ThreadID() == audio->threadid) ) {
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		return;
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	}
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	SDL_mutexV(audio->mixer_lock);
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}
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int SDL_AudioInit(const char *driver_name)
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{
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	SDL_AudioDevice *audio;
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	int i = 0, idx;
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	/* Check to make sure we don't overwrite 'current_audio' */
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	if ( current_audio != NULL ) {
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		SDL_AudioQuit();
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	}
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	/* Select the proper audio driver */
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	audio = NULL;
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	idx = 0;
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#ifdef unix
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	if ( (driver_name == NULL) && (getenv("ESPEAKER") != NULL) ) {
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		/* Ahem, we know that if ESPEAKER is set, user probably wants
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		   to use ESD, but don't start it if it's not already running.
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		   This probably isn't the place to do this, but... Shh! :)
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		 */
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		for ( i=0; bootstrap[i]; ++i ) {
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			if ( strcmp(bootstrap[i]->name, "esd") == 0 ) {
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				const char *esd_no_spawn;
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				/* Don't start ESD if it's not running */
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				esd_no_spawn = getenv("ESD_NO_SPAWN");
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				if ( esd_no_spawn == NULL ) {
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					putenv("ESD_NO_SPAWN=1");
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				}
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				if ( bootstrap[i]->available() ) {
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					audio = bootstrap[i]->create(0);
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					break;
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				}
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#ifdef linux	/* No unsetenv() on most platforms */
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				if ( esd_no_spawn == NULL ) {
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					unsetenv("ESD_NO_SPAWN");
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				}
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#endif
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			}
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   309
		}
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   310
	}
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#endif /* unix */
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	if ( audio == NULL ) {
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		if ( driver_name != NULL ) {
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#if 0	/* This will be replaced with a better driver selection API */
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			if ( strrchr(driver_name, ':') != NULL ) {
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				idx = atoi(strrchr(driver_name, ':')+1);
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			}
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#endif
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			for ( i=0; bootstrap[i]; ++i ) {
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				if (strncmp(bootstrap[i]->name, driver_name,
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				            strlen(bootstrap[i]->name)) == 0) {
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   322
					if ( bootstrap[i]->available() ) {
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						audio=bootstrap[i]->create(idx);
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   324
						break;
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   325
					}
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   326
				}
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   327
			}
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   328
		} else {
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   329
			for ( i=0; bootstrap[i]; ++i ) {
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   330
				if ( bootstrap[i]->available() ) {
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   331
					audio = bootstrap[i]->create(idx);
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   332
					if ( audio != NULL ) {
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   333
						break;
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   334
					}
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   335
				}
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   336
			}
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   337
		}
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   338
		if ( audio == NULL ) {
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   339
			SDL_SetError("No available audio device");
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   340
#if 0 /* Don't fail SDL_Init() if audio isn't available.
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         SDL_OpenAudio() will handle it at that point.  *sigh*
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   342
       */
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   343
			return(-1);
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   344
#endif
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   345
		}
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   346
	}
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   347
	current_audio = audio;
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   348
	if ( current_audio ) {
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   349
		current_audio->name = bootstrap[i]->name;
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   350
		if ( !current_audio->LockAudio && !current_audio->UnlockAudio ) {
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   351
			current_audio->LockAudio = SDL_LockAudio_Default;
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   352
			current_audio->UnlockAudio = SDL_UnlockAudio_Default;
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   353
		}
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   354
	}
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   355
	return(0);
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   356
}
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   357
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   358
char *SDL_AudioDriverName(char *namebuf, int maxlen)
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   359
{
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   360
	if ( current_audio != NULL ) {
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   361
		strncpy(namebuf, current_audio->name, maxlen-1);
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   362
		namebuf[maxlen-1] = '\0';
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   363
		return(namebuf);
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   364
	}
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   365
	return(NULL);
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   366
}
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   367
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   368
int SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained)
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   369
{
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   370
	SDL_AudioDevice *audio;
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   371
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   372
	/* Start up the audio driver, if necessary */
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   373
	if ( ! current_audio ) {
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   374
		if ( (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) ||
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   375
		     (current_audio == NULL) ) {
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   376
			return(-1);
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   377
		}
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   378
	}
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   379
	audio = current_audio;
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   380
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   381
	if (audio->opened) {
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   382
		SDL_SetError("Audio device is already opened");
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   383
		return(-1);
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   384
	}
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   385
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   386
	/* Verify some parameters */
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   387
	if ( desired->callback == NULL ) {
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   388
		SDL_SetError("SDL_OpenAudio() passed a NULL callback");
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   389
		return(-1);
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   390
	}
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   391
	switch ( desired->channels ) {
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   392
	    case 1:	/* Mono */
slouken@0
   393
	    case 2:	/* Stereo */
slouken@942
   394
	    case 4:	/* surround */
slouken@942
   395
	    case 6:	/* surround with center and lfe */
slouken@0
   396
		break;
slouken@0
   397
	    default:
slouken@0
   398
		SDL_SetError("1 (mono) and 2 (stereo) channels supported");
slouken@0
   399
		return(-1);
slouken@0
   400
	}
slouken@0
   401
slouken@955
   402
#if defined(macintosh) || (defined(__riscos__) && !defined(DISABLE_THREADS))
slouken@0
   403
	/* FIXME: Need to implement PPC interrupt asm for SDL_LockAudio() */
slouken@0
   404
#else
slouken@398
   405
#if defined(__MINT__) && !defined(ENABLE_THREADS)
slouken@398
   406
	/* Uses interrupt driven audio, without thread */
slouken@398
   407
#else
slouken@0
   408
	/* Create a semaphore for locking the sound buffers */
slouken@0
   409
	audio->mixer_lock = SDL_CreateMutex();
slouken@0
   410
	if ( audio->mixer_lock == NULL ) {
slouken@0
   411
		SDL_SetError("Couldn't create mixer lock");
slouken@0
   412
		SDL_CloseAudio();
slouken@0
   413
		return(-1);
slouken@0
   414
	}
slouken@398
   415
#endif /* __MINT__ */
slouken@398
   416
#endif /* macintosh */
slouken@0
   417
slouken@0
   418
	/* Calculate the silence and size of the audio specification */
slouken@0
   419
	SDL_CalculateAudioSpec(desired);
slouken@0
   420
slouken@0
   421
	/* Open the audio subsystem */
slouken@0
   422
	memcpy(&audio->spec, desired, sizeof(audio->spec));
slouken@0
   423
	audio->convert.needed = 0;
slouken@0
   424
	audio->enabled = 1;
slouken@0
   425
	audio->paused  = 1;
slouken@21
   426
slouken@21
   427
#ifndef ENABLE_AHI
slouken@21
   428
slouken@21
   429
/* AmigaOS opens audio inside the main loop */
slouken@0
   430
	audio->opened = audio->OpenAudio(audio, &audio->spec)+1;
slouken@21
   431
slouken@0
   432
	if ( ! audio->opened ) {
slouken@0
   433
		SDL_CloseAudio();
slouken@0
   434
		return(-1);
slouken@0
   435
	}
slouken@21
   436
#else
slouken@21
   437
	D(bug("Locking semaphore..."));
slouken@21
   438
	SDL_mutexP(audio->mixer_lock);
slouken@21
   439
slouken@21
   440
	audio->thread = SDL_CreateThread(SDL_RunAudio, audio);
slouken@21
   441
	D(bug("Created thread...\n"));
slouken@21
   442
slouken@21
   443
	if ( audio->thread == NULL ) {
slouken@21
   444
		SDL_mutexV(audio->mixer_lock);
slouken@21
   445
		SDL_CloseAudio();
slouken@21
   446
		SDL_SetError("Couldn't create audio thread");
slouken@21
   447
		return(-1);
slouken@21
   448
	}
slouken@21
   449
slouken@21
   450
	while(!audio_configured)
slouken@21
   451
		SDL_Delay(100);
slouken@21
   452
#endif
slouken@0
   453
slouken@0
   454
	/* If the audio driver changes the buffer size, accept it */
slouken@0
   455
	if ( audio->spec.samples != desired->samples ) {
slouken@0
   456
		desired->samples = audio->spec.samples;
slouken@0
   457
		SDL_CalculateAudioSpec(desired);
slouken@0
   458
	}
slouken@0
   459
slouken@0
   460
	/* Allocate a fake audio memory buffer */
slouken@0
   461
	audio->fake_stream = SDL_AllocAudioMem(audio->spec.size);
slouken@0
   462
	if ( audio->fake_stream == NULL ) {
slouken@0
   463
		SDL_CloseAudio();
slouken@0
   464
		SDL_OutOfMemory();
slouken@0
   465
		return(-1);
slouken@0
   466
	}
slouken@0
   467
slouken@0
   468
	/* See if we need to do any conversion */
slouken@808
   469
	if ( obtained != NULL ) {
slouken@808
   470
		memcpy(obtained, &audio->spec, sizeof(audio->spec));
slouken@808
   471
	} else if ( desired->freq != audio->spec.freq ||
slouken@808
   472
                    desired->format != audio->spec.format ||
slouken@808
   473
	            desired->channels != audio->spec.channels ) {
slouken@808
   474
		/* Build an audio conversion block */
slouken@808
   475
		if ( SDL_BuildAudioCVT(&audio->convert,
slouken@808
   476
			desired->format, desired->channels,
slouken@808
   477
					desired->freq,
slouken@808
   478
			audio->spec.format, audio->spec.channels,
slouken@808
   479
					audio->spec.freq) < 0 ) {
slouken@808
   480
			SDL_CloseAudio();
slouken@808
   481
			return(-1);
slouken@0
   482
		}
slouken@808
   483
		if ( audio->convert.needed ) {
slouken@808
   484
			audio->convert.len = desired->size;
slouken@808
   485
			audio->convert.buf =(Uint8 *)SDL_AllocAudioMem(
slouken@808
   486
			   audio->convert.len*audio->convert.len_mult);
slouken@808
   487
			if ( audio->convert.buf == NULL ) {
slouken@0
   488
				SDL_CloseAudio();
slouken@808
   489
				SDL_OutOfMemory();
slouken@0
   490
				return(-1);
slouken@0
   491
			}
slouken@0
   492
		}
slouken@0
   493
	}
slouken@0
   494
slouken@21
   495
#ifndef ENABLE_AHI
slouken@0
   496
	/* Start the audio thread if necessary */
slouken@0
   497
	switch (audio->opened) {
slouken@0
   498
		case  1:
slouken@0
   499
			/* Start the audio thread */
slouken@0
   500
			audio->thread = SDL_CreateThread(SDL_RunAudio, audio);
slouken@0
   501
			if ( audio->thread == NULL ) {
slouken@0
   502
				SDL_CloseAudio();
slouken@0
   503
				SDL_SetError("Couldn't create audio thread");
slouken@0
   504
				return(-1);
slouken@0
   505
			}
slouken@0
   506
			break;
slouken@0
   507
slouken@0
   508
		default:
slouken@0
   509
			/* The audio is now playing */
slouken@0
   510
			break;
slouken@0
   511
	}
slouken@21
   512
#else
slouken@21
   513
	SDL_mutexV(audio->mixer_lock);
slouken@21
   514
	D(bug("SDL_OpenAudio USCITA...\n"));
slouken@21
   515
slouken@21
   516
#endif
slouken@21
   517
slouken@0
   518
	return(0);
slouken@0
   519
}
slouken@0
   520
slouken@0
   521
SDL_audiostatus SDL_GetAudioStatus(void)
slouken@0
   522
{
slouken@0
   523
	SDL_AudioDevice *audio = current_audio;
slouken@0
   524
	SDL_audiostatus status;
slouken@0
   525
slouken@0
   526
	status = SDL_AUDIO_STOPPED;
slouken@0
   527
	if ( audio && audio->enabled ) {
slouken@0
   528
		if ( audio->paused ) {
slouken@0
   529
			status = SDL_AUDIO_PAUSED;
slouken@0
   530
		} else {
slouken@0
   531
			status = SDL_AUDIO_PLAYING;
slouken@0
   532
		}
slouken@0
   533
	}
slouken@0
   534
	return(status);
slouken@0
   535
}
slouken@0
   536
slouken@0
   537
void SDL_PauseAudio (int pause_on)
slouken@0
   538
{
slouken@0
   539
	SDL_AudioDevice *audio = current_audio;
slouken@0
   540
slouken@0
   541
	if ( audio ) {
slouken@0
   542
		audio->paused = pause_on;
slouken@0
   543
	}
slouken@0
   544
}
slouken@0
   545
slouken@0
   546
void SDL_LockAudio (void)
slouken@0
   547
{
slouken@0
   548
	SDL_AudioDevice *audio = current_audio;
slouken@0
   549
slouken@0
   550
	/* Obtain a lock on the mixing buffers */
slouken@322
   551
	if ( audio && audio->LockAudio ) {
slouken@322
   552
		audio->LockAudio(audio);
slouken@0
   553
	}
slouken@0
   554
}
slouken@0
   555
slouken@0
   556
void SDL_UnlockAudio (void)
slouken@0
   557
{
slouken@0
   558
	SDL_AudioDevice *audio = current_audio;
slouken@0
   559
slouken@0
   560
	/* Release lock on the mixing buffers */
slouken@322
   561
	if ( audio && audio->UnlockAudio ) {
slouken@322
   562
		audio->UnlockAudio(audio);
slouken@0
   563
	}
slouken@0
   564
}
slouken@0
   565
slouken@0
   566
void SDL_CloseAudio (void)
slouken@0
   567
{
slouken@0
   568
	SDL_QuitSubSystem(SDL_INIT_AUDIO);
slouken@0
   569
}
slouken@0
   570
slouken@0
   571
void SDL_AudioQuit(void)
slouken@0
   572
{
slouken@0
   573
	SDL_AudioDevice *audio = current_audio;
slouken@0
   574
slouken@0
   575
	if ( audio ) {
slouken@0
   576
		audio->enabled = 0;
slouken@0
   577
		if ( audio->thread != NULL ) {
slouken@0
   578
			SDL_WaitThread(audio->thread, NULL);
slouken@0
   579
		}
slouken@0
   580
		if ( audio->mixer_lock != NULL ) {
slouken@0
   581
			SDL_DestroyMutex(audio->mixer_lock);
slouken@0
   582
		}
slouken@0
   583
		if ( audio->fake_stream != NULL ) {
slouken@0
   584
			SDL_FreeAudioMem(audio->fake_stream);
slouken@0
   585
		}
slouken@0
   586
		if ( audio->convert.needed ) {
slouken@0
   587
			SDL_FreeAudioMem(audio->convert.buf);
slouken@21
   588
slouken@0
   589
		}
slouken@21
   590
#ifndef ENABLE_AHI
slouken@0
   591
		if ( audio->opened ) {
slouken@0
   592
			audio->CloseAudio(audio);
slouken@0
   593
			audio->opened = 0;
slouken@0
   594
		}
slouken@21
   595
#endif
slouken@0
   596
		/* Free the driver data */
slouken@0
   597
		audio->free(audio);
slouken@0
   598
		current_audio = NULL;
slouken@0
   599
	}
slouken@0
   600
}
slouken@0
   601
slouken@0
   602
#define NUM_FORMATS	6
slouken@0
   603
static int format_idx;
slouken@0
   604
static int format_idx_sub;
slouken@0
   605
static Uint16 format_list[NUM_FORMATS][NUM_FORMATS] = {
slouken@0
   606
 { AUDIO_U8, AUDIO_S8, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U16LSB, AUDIO_U16MSB },
slouken@0
   607
 { AUDIO_S8, AUDIO_U8, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U16LSB, AUDIO_U16MSB },
slouken@0
   608
 { AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U16LSB, AUDIO_U16MSB, AUDIO_U8, AUDIO_S8 },
slouken@0
   609
 { AUDIO_S16MSB, AUDIO_S16LSB, AUDIO_U16MSB, AUDIO_U16LSB, AUDIO_U8, AUDIO_S8 },
slouken@0
   610
 { AUDIO_U16LSB, AUDIO_U16MSB, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U8, AUDIO_S8 },
slouken@0
   611
 { AUDIO_U16MSB, AUDIO_U16LSB, AUDIO_S16MSB, AUDIO_S16LSB, AUDIO_U8, AUDIO_S8 },
slouken@0
   612
};
slouken@0
   613
slouken@0
   614
Uint16 SDL_FirstAudioFormat(Uint16 format)
slouken@0
   615
{
slouken@0
   616
	for ( format_idx=0; format_idx < NUM_FORMATS; ++format_idx ) {
slouken@0
   617
		if ( format_list[format_idx][0] == format ) {
slouken@0
   618
			break;
slouken@0
   619
		}
slouken@0
   620
	}
slouken@0
   621
	format_idx_sub = 0;
slouken@0
   622
	return(SDL_NextAudioFormat());
slouken@0
   623
}
slouken@0
   624
slouken@0
   625
Uint16 SDL_NextAudioFormat(void)
slouken@0
   626
{
slouken@0
   627
	if ( (format_idx == NUM_FORMATS) || (format_idx_sub == NUM_FORMATS) ) {
slouken@0
   628
		return(0);
slouken@0
   629
	}
slouken@0
   630
	return(format_list[format_idx][format_idx_sub++]);
slouken@0
   631
}
slouken@0
   632
slouken@0
   633
void SDL_CalculateAudioSpec(SDL_AudioSpec *spec)
slouken@0
   634
{
slouken@0
   635
	switch (spec->format) {
slouken@0
   636
		case AUDIO_U8:
slouken@0
   637
			spec->silence = 0x80;
slouken@0
   638
			break;
slouken@0
   639
		default:
slouken@0
   640
			spec->silence = 0x00;
slouken@0
   641
			break;
slouken@0
   642
	}
slouken@0
   643
	spec->size = (spec->format&0xFF)/8;
slouken@0
   644
	spec->size *= spec->channels;
slouken@0
   645
	spec->size *= spec->samples;
slouken@0
   646
}