SDL_artsaudio.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2006 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 Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 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,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Sam Lantinga
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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/* Allow access to a raw mixing buffer */
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#include "SDL_timer.h"
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#include "SDL_audio.h"
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#include "../SDL_audiomem.h"
#include "../SDL_audio_c.h"
#include "../SDL_audiodev_c.h"
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#include "SDL_artsaudio.h"
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#ifdef SDL_AUDIO_DRIVER_ARTS_DYNAMIC
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#include "SDL_name.h"
#include "SDL_loadso.h"
#else
#define SDL_NAME(X) X
#endif
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/* The tag name used by artsc audio */
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#define ARTS_DRIVER_NAME "arts"
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/* Audio driver functions */
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static int ARTS_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void ARTS_WaitAudio(_THIS);
static void ARTS_PlayAudio(_THIS);
static Uint8 *ARTS_GetAudioBuf(_THIS);
static void ARTS_CloseAudio(_THIS);
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#ifdef SDL_AUDIO_DRIVER_ARTS_DYNAMIC
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static const char *arts_library = SDL_AUDIO_DRIVER_ARTS_DYNAMIC;
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static void *arts_handle = NULL;
static int arts_loaded = 0;
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static int (*SDL_NAME(arts_init))(void);
static void (*SDL_NAME(arts_free))(void);
static arts_stream_t (*SDL_NAME(arts_play_stream))(int rate, int bits, int channels, const char *name);
static int (*SDL_NAME(arts_stream_set))(arts_stream_t s, arts_parameter_t param, int value);
static int (*SDL_NAME(arts_stream_get))(arts_stream_t s, arts_parameter_t param);
static int (*SDL_NAME(arts_write))(arts_stream_t s, const void *buffer, int count);
static void (*SDL_NAME(arts_close_stream))(arts_stream_t s);
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static int (*SDL_NAME(arts_suspended))(void);
static const char *(*SDL_NAME(arts_error_text))(int errorcode);
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static struct {
const char *name;
void **func;
} arts_functions[] = {
{ "arts_init", (void **)&SDL_NAME(arts_init) },
{ "arts_free", (void **)&SDL_NAME(arts_free) },
{ "arts_play_stream", (void **)&SDL_NAME(arts_play_stream) },
{ "arts_stream_set", (void **)&SDL_NAME(arts_stream_set) },
{ "arts_stream_get", (void **)&SDL_NAME(arts_stream_get) },
{ "arts_write", (void **)&SDL_NAME(arts_write) },
{ "arts_close_stream", (void **)&SDL_NAME(arts_close_stream) },
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{ "arts_suspended", (void **)&SDL_NAME(arts_suspended) },
{ "arts_error_text", (void **)&SDL_NAME(arts_error_text) },
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};
static void UnloadARTSLibrary()
{
if ( arts_loaded ) {
SDL_UnloadObject(arts_handle);
arts_handle = NULL;
arts_loaded = 0;
}
}
static int LoadARTSLibrary(void)
{
int i, retval = -1;
arts_handle = SDL_LoadObject(arts_library);
if ( arts_handle ) {
arts_loaded = 1;
retval = 0;
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for ( i=0; i<SDL_arraysize(arts_functions); ++i ) {
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*arts_functions[i].func = SDL_LoadFunction(arts_handle, arts_functions[i].name);
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if ( !*arts_functions[i].func ) {
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retval = -1;
UnloadARTSLibrary();
break;
}
}
}
return retval;
}
#else
static void UnloadARTSLibrary()
{
return;
}
static int LoadARTSLibrary(void)
{
return 0;
}
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#endif /* SDL_AUDIO_DRIVER_ARTS_DYNAMIC */
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/* Audio driver bootstrap functions */
static int Audio_Available(void)
{
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int available = 0;
if ( LoadARTSLibrary() < 0 ) {
return available;
}
if ( SDL_NAME(arts_init)() == 0 ) {
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if ( SDL_NAME(arts_suspended)() ) {
/* Play a stream so aRts doesn't crash */
arts_stream_t stream2;
stream2=SDL_NAME(arts_play_stream)(44100, 16, 2, "SDL");
SDL_NAME(arts_write)(stream2, "", 0);
SDL_NAME(arts_close_stream)(stream2);
available = 1;
}
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SDL_NAME(arts_free)();
}
UnloadARTSLibrary();
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return available;
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}
static void Audio_DeleteDevice(SDL_AudioDevice *device)
{
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SDL_free(device->hidden);
SDL_free(device);
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UnloadARTSLibrary();
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}
static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
SDL_AudioDevice *this;
/* Initialize all variables that we clean on shutdown */
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LoadARTSLibrary();
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this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));
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if ( this ) {
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SDL_memset(this, 0, (sizeof *this));
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this->hidden = (struct SDL_PrivateAudioData *)
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SDL_malloc((sizeof *this->hidden));
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}
if ( (this == NULL) || (this->hidden == NULL) ) {
SDL_OutOfMemory();
if ( this ) {
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SDL_free(this);
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}
return(0);
}
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SDL_memset(this->hidden, 0, (sizeof *this->hidden));
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stream = 0;
/* Set the function pointers */
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this->OpenAudio = ARTS_OpenAudio;
this->WaitAudio = ARTS_WaitAudio;
this->PlayAudio = ARTS_PlayAudio;
this->GetAudioBuf = ARTS_GetAudioBuf;
this->CloseAudio = ARTS_CloseAudio;
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this->free = Audio_DeleteDevice;
return this;
}
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AudioBootStrap ARTS_bootstrap = {
ARTS_DRIVER_NAME, "Analog Realtime Synthesizer",
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Audio_Available, Audio_CreateDevice
};
/* This function waits until it is possible to write a full sound buffer */
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static void ARTS_WaitAudio(_THIS)
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{
Sint32 ticks;
/* Check to see if the thread-parent process is still alive */
{ static int cnt = 0;
/* Note that this only works with thread implementations
that use a different process id for each thread.
*/
if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
if ( kill(parent, 0) < 0 ) {
this->enabled = 0;
}
}
}
/* Use timer for general audio synchronization */
ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
if ( ticks > 0 ) {
SDL_Delay(ticks);
}
}
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static void ARTS_PlayAudio(_THIS)
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{
int written;
/* Write the audio data */
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written = SDL_NAME(arts_write)(stream, mixbuf, mixlen);
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/* If timer synchronization is enabled, set the next write frame */
if ( frame_ticks ) {
next_frame += frame_ticks;
}
/* If we couldn't write, assume fatal error for now */
if ( written < 0 ) {
this->enabled = 0;
}
#ifdef DEBUG_AUDIO
fprintf(stderr, "Wrote %d bytes of audio data\n", written);
#endif
}
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static Uint8 *ARTS_GetAudioBuf(_THIS)
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{
return(mixbuf);
}
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static void ARTS_CloseAudio(_THIS)
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{
if ( mixbuf != NULL ) {
SDL_FreeAudioMem(mixbuf);
mixbuf = NULL;
}
if ( stream ) {
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SDL_NAME(arts_close_stream)(stream);
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stream = 0;
}
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SDL_NAME(arts_free)();
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}
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static int ARTS_OpenAudio(_THIS, SDL_AudioSpec *spec)
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{
int bits, frag_spec;
Uint16 test_format, format;
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int error_code;
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/* Reset the timer synchronization flag */
frame_ticks = 0.0;
mixbuf = NULL;
/* Try for a closest match on audio format */
format = 0;
bits = 0;
for ( test_format = SDL_FirstAudioFormat(spec->format);
! format && test_format; ) {
#ifdef DEBUG_AUDIO
fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
#endif
switch ( test_format ) {
case AUDIO_U8:
bits = 8;
format = 1;
break;
case AUDIO_S16LSB:
bits = 16;
format = 1;
break;
default:
format = 0;
break;
}
if ( ! format ) {
test_format = SDL_NextAudioFormat();
}
}
if ( format == 0 ) {
SDL_SetError("Couldn't find any hardware audio formats");
return(-1);
}
spec->format = test_format;
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error_code = SDL_NAME(arts_init)();
if ( error_code != 0 ) {
SDL_SetError("Unable to initialize ARTS: %s", SDL_NAME(arts_error_text)(error_code));
return(-1);
}
if ( ! SDL_NAME(arts_suspended)() ) {
SDL_SetError("ARTS can not open audio device");
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return(-1);
}
stream = SDL_NAME(arts_play_stream)(spec->freq, bits, spec->channels, "SDL");
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/* Calculate the final parameters for this audio specification */
SDL_CalculateAudioSpec(spec);
/* Determine the power of two of the fragment size */
for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
if ( (0x01<<frag_spec) != spec->size ) {
SDL_SetError("Fragment size must be a power of two");
return(-1);
}
frag_spec |= 0x00020000; /* two fragments, for low latency */
#ifdef ARTS_P_PACKET_SETTINGS
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SDL_NAME(arts_stream_set)(stream, ARTS_P_PACKET_SETTINGS, frag_spec);
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#else
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SDL_NAME(arts_stream_set)(stream, ARTS_P_PACKET_SIZE, frag_spec&0xffff);
SDL_NAME(arts_stream_set)(stream, ARTS_P_PACKET_COUNT, frag_spec>>16);
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#endif
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spec->size = SDL_NAME(arts_stream_get)(stream, ARTS_P_PACKET_SIZE);
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/* Allocate mixing buffer */
mixlen = spec->size;
mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
if ( mixbuf == NULL ) {
return(-1);
}
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SDL_memset(mixbuf, spec->silence, spec->size);
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/* Get the parent process id (we're the parent of the audio thread) */
parent = getpid();
/* We're ready to rock and roll. :-) */
return(0);
}