Audio Subsystem. More...

Macros
#define	NUM_BUFFERS 4
	Number of buffers the audio subsytem allocates and manages.

#define	BUFFERS_PER_SECOND 25
	How many different audio buffers we want to schedule in one second.

#define	CALC_BUFFER(x) ( ( ( ( x ) / BUFFERS_PER_SECOND ) >> 3 ) << 3 )
	Macro that calculates the size of a buffer based on frequency.

DAC rates for different regions
#define	AI_NTSC_DACRATE 48681818
	NTSC DAC rate.

#define	AI_PAL_DACRATE 49656530
	PAL DAC rate.

#define	AI_MPAL_DACRATE 48628322
	MPAL DAC rate.

AI Status Register Values
#define	AI_STATUS_BUSY ( 1 << 30 )
	Bit representing that the AI is busy.

#define	AI_STATUS_FULL ( 1 << 31 )
	Bit representing that the AI is full.

Functions
void	audio_init (const int frequency, int numbuffers)
	Initialize the audio subsystem.

void	audio_set_buffer_callback (audio_fill_buffer_callback fill_buffer_callback)
	Install a audio callback to fill the audio buffer when required.

void	audio_close ()
	Close the audio subsystem.

void	audio_pause (bool pause)
	Pause or resume audio playback.

void	audio_write (const short *const buffer)
	Write a chunk of audio data.

short *	audio_write_begin (void)
	Start writing to the first free internal buffer.

void	audio_write_end (void)
	Complete writing to an internal buffer.

void	audio_write_silence ()
	Write a chunk of silence.

volatile int	audio_can_write ()
	Return whether there is an empty buffer to write to.

int	audio_push (const short *buffer, int nsamples, bool blocking)
	Push a chunk of audio data (high-level function)

int	audio_get_frequency ()
	Return actual frequency of audio playback.

int	audio_get_buffer_length ()
	Get the number of stereo samples that fit into an allocated buffer.

Detailed Description

Audio Subsystem.

Macro Definition Documentation

#define CALC_BUFFER ( x ) ( ( ( ( x ) / BUFFERS_PER_SECOND ) >> 3 ) << 3 )

Macro that calculates the size of a buffer based on frequency.

Parameters

[in] x Frequency the AI is running at