Audio::PCSpeaker Class Reference

Inheritance diagram for Audio::PCSpeaker:

Classes
struct	Command

Public Types
enum	WaveForm {   kWaveFormSquare = 0, kWaveFormSine, kWaveFormSaw, kWaveFormTriangle,   kWaveFormSilence }

Public Member Functions
	PCSpeaker (int rate=44100)
void	play (WaveForm wave, int freq, int32 length)
void	playQueue (WaveForm wave, float freq, uint32 lengthus)
void	stop (int32 delay=0)
void	setVolume (byte volume)
bool	isPlaying () const
int	readBuffer (int16 *buffer, const int numSamples)
bool	isStereo () const
bool	endOfData () const
bool	endOfStream () const
int	getRate () const

Protected Types
typedef int8(*	generatorFunc) (uint32, uint32)

Static Protected Member Functions
static int8	generateSquare (uint32 x, uint32 oscLength)
static int8	generateSine (uint32 x, uint32 oscLength)
static int8	generateSaw (uint32 x, uint32 oscLength)
static int8	generateTriangle (uint32 x, uint32 oscLength)
static int8	generateSilence (uint32 x, uint32 oscLength)

Protected Attributes
Common::Mutex	_mutex
int	_rate
WaveForm	_wave
bool	_playForever
uint32	_oscLength
uint32	_oscSamples
uint32	_remainingSamples
uint32	_mixedSamples
byte	_volume
Common::Queue< Command > *	_commandQueue
bool	_commandActive

Static Protected Attributes
static const generatorFunc	generateWave []

Member Function Documentation

play()

void Audio::PCSpeaker::play	(	WaveForm	wave,
		int	freq,
		int32	length
	)

Play a note for length ms.

If length is negative, play until told to stop.

playQueue()

void Audio::PCSpeaker::playQueue	(	WaveForm	wave,
		float	freq,
		uint32	lengthus
	)

Queue the specified playback instruction. It will be executed when all previously queued instructions have finished. Use this method for playback of effects which require timing precision of less than a millisecond.

Calling this method will terminate any waveform started with the play method. Calling the play method will terminate the active queued instruction and clear the instruction queue.

Use isPlaying to check if all queued instructions have finished playing. This will return true even if the current instruction is "playing" silence.

Parameters

wave	The waveform to use. For PC speaker, use square wave or silence.
freq	The frequency (in Hertz) to play.
lengthus	The length in microseconds for which to play the waveform.

stop()

void Audio::PCSpeaker::stop

(

int32

delay = 0

)

Stop the currently playing note after delay ms.

setVolume()

void Audio::PCSpeaker::setVolume

(

byte

volume

)

Adjust the volume.

readBuffer()

int Audio::PCSpeaker::readBuffer ( int16 *  buffer, const int  numSamples  )

virtual

Fill the given buffer with up to numSamples samples.

Data must be in native endianness, 16 bits per sample, signed. For stereo stream, the buffer will be filled with interleaved left and right channel samples, starting with the left sample. Furthermore, the samples in the left and right are summed up. So if you request 4 samples from a stereo stream, you will get a total of two left channel and two right channel samples.

Returns

The actual number of samples read, or -1 if a critical error occurred.

Note

You must check whether the returned value is less than what you requested. This indicates that the stream is fully used up.

Implements Audio::AudioStream.

isStereo()

bool Audio::PCSpeaker::isStereo ( ) const

inlinevirtual

Check whether this is a stereo stream.

Implements Audio::AudioStream.

endOfData()

bool Audio::PCSpeaker::endOfData ( ) const

inlinevirtual

Check whether end of data has been reached.

If this returns true, it indicates that at this time there is no data available in the stream. However, there might be more data in the future.

This is used by e.g. a rate converter to decide whether to keep on converting data or to stop.

Implements Audio::AudioStream.

endOfStream()

bool Audio::PCSpeaker::endOfStream ( ) const

inlinevirtual

Check whether end of stream has been reached.

If this returns true, it indicates that all data in this stream is used up and no additional data will appear in it in the future.

This is used by the mixer to decide whether a given stream shall be removed from the list of active streams (and thus be destroyed). By default, this maps to endOfData().

Reimplemented from Audio::AudioStream.

Reimplemented in Freescape::SizedPCSpeaker.

getRate()

int Audio::PCSpeaker::getRate ( ) const

inlinevirtual

Sample rate of the stream.

Implements Audio::AudioStream.

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The documentation for this class was generated from the following file:

• audio/softsynth/pcspk.h