linux_audio.h (4297B)
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#ifndef _LINUX_AUDIO_H_
#define _LINUX_AUDIO_H_
#include <stdio.h>
#include <stdarg.h>
#include <dlfcn.h>
#include <alsa/asoundlib.h>
#include "intrinsics.h"
#include "log.h"
struct AudioOutputDevice {
snd_pcm_t * pcm;
};
void audio_output_open( AudioOutputDevice * device );
void audio_output_close( AudioOutputDevice * device );
void audio_output_write( AudioOutputDevice * device, s16 * samples, size_t num_samples );
#endif // _LINUX_AUDIO_H_
#ifdef PLATFORM_AUDIO_IMPLEMENTATION
// copied from alsa headers
static int ( *_snd_lib_error_set_handler )( snd_lib_error_handler_t handler ) = NULL;
static const char * ( *_snd_strerror )( int errnum ) = NULL;
static int ( *_snd_pcm_open )( snd_pcm_t ** pcm, const char * name, snd_pcm_stream_t stream, int mode ) = NULL;
static int ( *_snd_pcm_set_params )( snd_pcm_t * pcm, snd_pcm_format_t format, snd_pcm_access_t access, unsigned int channels, unsigned int rate, int soft_resample, unsigned int latency ) = NULL;
static snd_pcm_sframes_t ( *_snd_pcm_writen )( snd_pcm_t * pcm, void ** bufs, snd_pcm_uframes_t size ) = NULL;
static int ( *_snd_pcm_recover )( snd_pcm_t * pcm, int err, int silent ) = NULL;
static int ( *_snd_pcm_close )( snd_pcm_t * pcm ) = NULL;
static void audio_error_handler( const char * file, int line, const char * function, int err, const char * fmt, ... ) {
printf( "error in %s at %s:%d\n", file, function, line );
va_list args;
va_start( args, fmt );
vprintf( fmt, args );
va_end( args );
printf( "\n" );
}
void audio_output_open( AudioOutputDevice * device ) {
// TODO: make an audio_output_init_lib function to do this + dlload
static bool audio_inited = false;
if( !audio_inited ) {
void * alsa_lib = dlopen( "libasound.so", RTLD_NOW );
if( alsa_lib == NULL ) {
FATAL( "Couldn't open libasound.so: %s", dlerror() );
}
_snd_lib_error_set_handler = ( int ( * )( snd_lib_error_handler_t ) ) dlsym( alsa_lib, "snd_lib_error_set_handler" );
_snd_strerror = ( const char * ( * )( int ) ) dlsym( alsa_lib, "snd_strerror" );
_snd_pcm_open = ( int ( * ) ( snd_pcm_t **, const char *, snd_pcm_stream_t, int ) ) dlsym( alsa_lib, "snd_pcm_open" );
_snd_pcm_set_params = ( int ( * ) ( snd_pcm_t *, snd_pcm_format_t, snd_pcm_access_t, unsigned int, unsigned int, int, unsigned int ) ) dlsym( alsa_lib, "snd_pcm_set_params" );
_snd_pcm_writen = ( snd_pcm_sframes_t ( * ) ( snd_pcm_t *, void **, snd_pcm_uframes_t ) ) dlsym( alsa_lib, "snd_pcm_writen" );
_snd_pcm_recover = ( int ( * )( snd_pcm_t *, int, int ) ) dlsym( alsa_lib, "snd_pcm_recover" );
_snd_pcm_close = ( int ( * ) ( snd_pcm_t * ) ) dlsym( alsa_lib, "snd_pcm_close" );
if(
_snd_lib_error_set_handler == NULL
|| _snd_strerror == NULL
|| _snd_pcm_open == NULL
|| _snd_pcm_set_params == NULL
|| _snd_pcm_writen == NULL
|| _snd_pcm_recover == NULL
|| _snd_pcm_close == NULL
) {
FATAL( "Couldn't load ALSA functions" );
}
_snd_lib_error_set_handler( audio_error_handler );
audio_inited = true;
}
const int channels = 2;
const int sample_rate = 44100;
const int ms = 1000;
const int latency = 10 * ms;
int err_open = _snd_pcm_open( &device->pcm, "default", SND_PCM_STREAM_PLAYBACK, 0 );
if( err_open != 0 ) {
// TODO: maybe don't kill the program
FATAL( "Couldn't open sound output: %s", _snd_strerror( err_open ) );
}
int err_params = _snd_pcm_set_params( device->pcm,
SND_PCM_FORMAT_S16_LE, SND_PCM_ACCESS_RW_NONINTERLEAVED,
channels, sample_rate, 1, latency );
if( err_params != 0 ) {
// TODO: maybe don't kill the program
FATAL( "Couldn't configure sound output: %s", _snd_strerror( err_params ) );
}
}
void audio_output_close( AudioOutputDevice * device ) {
int err = _snd_pcm_close( device->pcm );
if( err != 0 ) {
// TODO: maybe don't kill the program
FATAL( "Couldn't close sound output: %s", _snd_strerror( err ) );
}
}
void audio_output_write( AudioOutputDevice * device, s16 * samples, size_t num_samples ) {
for( u32 i = 0; i < num_samples; ) {
s16 * channels[ 2 ] = { samples + i, samples + i };
snd_pcm_sframes_t written = _snd_pcm_writen( device->pcm, ( void ** ) channels, num_samples - i );
if( written <= 0 ) {
_snd_pcm_recover( device->pcm, written, 1 );
}
else {
i += written;
}
}
}
#endif
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