Generates a square wave sound. Uses the same 32 bit phase accumulator as SawToothGenerator/FastIntSineGenerator: no floating point operations or sin() calls in the readSample() hot path. A square wave needs neither a sine approximation nor a lookup table - just the sign bit of the ramp - so readSample() is a single comparison, making this a good fit for MCUs without a hardware FPU (e.g. RP2040), where the previous FastSineGenerator based implementation still did a float polynomial evaluation per sample just to keep its sign. More...

#include <SoundGenerator.h>

Inheritance diagram for SquareWaveGenerator< T >:

Public Member Functions
	SquareWaveGenerator (float amplitude=NumberConverter::maxValueT< T >(), float phase=0.0f)

virtual AudioInfo	audioInfo ()
	Provides the AudioInfo.

bool	begin () override
	Starts the processing.

bool	begin (AudioInfo info) override
	Starts the processing with the provided AudioInfo.

bool	begin (AudioInfo info, float frequency)

bool	begin (int channels, int sample_rate, float frequency)

virtual AudioInfo	defaultConfig ()
	Provides the default configuration.

virtual void	end ()

virtual void	end (bool allow_rampdown)

virtual bool	isActive ()
	Checks if the begin method has been called - after end() isActive is false.

virtual size_t	readBytes (uint8_t *data, size_t len)
	Provides the data as byte array with the requested number of channels.

virtual T	readSample () override
	Provides a single sample - integer only, no float ops!

virtual size_t	readSamples (T *data, size_t len)

virtual void	restart ()
	Restarts the generator, e.g. after a play time has been defined and reached.

void	setAmplitude (float amp)

virtual void	setAudioInfo (AudioInfo info) override
	Defines/updates the AudioInfo.

void	setFrequency (float frequency) override
	Defines the frequency - the only place where float math is used.

void	setPhase (float phase)
	Defines the starting phase in radians.

virtual void	setPlayTime (uint32_t playMs, uint8_t upPercent=20, uint8_t downPercent=30)
	Defines the play time in ms and the ramp up and ramp down time in percent.

virtual void	setRampTimes (uint32_t playMs, uint32_t upMs=5, uint32_t downMs=5)

Protected Member Functions
T	applyRamp (T sample)

size_t	readBytesFrames (uint8_t *buffer, size_t lengthBytes, int frames, int channels)

size_t	readBytesFromBuffer (uint8_t *buffer, size_t lengthBytes, int frame_size, int channels)

void	recalculatePlayTime ()

void	updatePhaseIncrement ()

Protected Attributes
bool	active = false

bool	activeWarningIssued = false

uint32_t	currentSample = 0

uint32_t	downMs = 0

uint8_t	downPercent = 40

uint32_t	downSamples = 0

float	factor = 1.0f

AudioInfo	info

float	m_amplitude = 1.0f

int32_t	m_amplitude_i = 32767

volatile float	m_frequency = 0.0f

uint32_t	m_phase_acc = 0

uint32_t	m_phase_increment = 0

uint32_t	m_phase_offset = 0

uint32_t	playMs = 0

uint32_t	playSamples = 0

float	rampDownDec = 0.0

float	rampUpInc = 0.0

RingBuffer< uint8_t >	ring_buffer {0}

uint32_t	upMs = 0

uint8_t	upPercent = 5

uint32_t	upSamples = 0

Detailed Description

template<class T = int16_t>
class audio_tools::SquareWaveGenerator< T >

Generates a square wave sound. Uses the same 32 bit phase accumulator as SawToothGenerator/FastIntSineGenerator: no floating point operations or sin() calls in the readSample() hot path. A square wave needs neither a sine approximation nor a lookup table - just the sign bit of the ramp - so readSample() is a single comparison, making this a good fit for MCUs without a hardware FPU (e.g. RP2040), where the previous FastSineGenerator based implementation still did a float polynomial evaluation per sample just to keep its sign.

Author: Phil Schatzmann

Copyright: GPLv3

Constructor & Destructor Documentation

◆ SquareWaveGenerator()

template<class T = int16_t>

SquareWaveGenerator	(	float	amplitude = `NumberConverter::maxValueT<T>()`,
		float	phase = `0.0f`
	)

inline

Member Function Documentation

◆ applyRamp()

template<class T = int16_t>

T applyRamp ( T sample )

inlineprotectedinherited

◆ audioInfo()

template<class T = int16_t>

virtual AudioInfo audioInfo ( )

inlinevirtualinherited

Provides the AudioInfo.

◆ begin() [1/4]

template<class T = int16_t>

bool begin ( )

inlineoverridevirtual

Starts the processing.

Reimplemented from SoundGenerator< T >.

◆ begin() [2/4]

template<class T = int16_t>

bool begin ( AudioInfo info )

inlineoverridevirtual

Starts the processing with the provided AudioInfo.

Reimplemented from SoundGenerator< T >.

◆ begin() [3/4]

template<class T = int16_t>

bool begin	(	AudioInfo	info,
		float	frequency
	)

inline

◆ begin() [4/4]

template<class T = int16_t>

bool begin	(	int	channels,
		int	sample_rate,
		float	frequency
	)

inline

◆ defaultConfig()

template<class T = int16_t>

virtual AudioInfo defaultConfig ( )

inlinevirtualinherited

Provides the default configuration.

Reimplemented in STKGenerator< StkCls, T >, STKGenerator< stk::Instrmnt, int16_t >, STKGenerator< StkCls, int16_t >, FloatSineGenerator< T >, and FloatSineGenerator< int16_t >.

◆ end() [1/2]

template<class T = int16_t>

virtual void end ( )

inlinevirtualinherited

Reimplemented in GeneratorFromArray< T >, and GeneratorQueue< T >.

◆ end() [2/2]

template<class T = int16_t>

virtual void end ( bool allow_rampdown )

inlinevirtualinherited

Ends the processing. If either setPlayTime() or setRampTimes() have been set, then allow_rampdown=true will start a ramp-down instead of stopping immediately.

◆ isActive()

template<class T = int16_t>

virtual bool isActive ( )

inlinevirtualinherited

Checks if the begin method has been called - after end() isActive is false.

◆ readBytes()

template<class T = int16_t>

virtual size_t readBytes	(	uint8_t *	data,
		size_t	len
	)

inlinevirtualinherited

Provides the data as byte array with the requested number of channels.

Reimplemented in GeneratorQueue< T >.

◆ readBytesFrames()

template<class T = int16_t>

size_t readBytesFrames	(	uint8_t *	buffer,
		size_t	lengthBytes,
		int	frames,
		int	channels
	)

inlineprotectedinherited

◆ readBytesFromBuffer()

template<class T = int16_t>

size_t readBytesFromBuffer	(	uint8_t *	buffer,
		size_t	lengthBytes,
		int	frame_size,
		int	channels
	)

inlineprotectedinherited

◆ readSample()

template<class T = int16_t>

virtual T readSample ( )

inlineoverridevirtual

Provides a single sample - integer only, no float ops!

Implements SoundGenerator< T >.

◆ readSamples()

template<class T = int16_t>

virtual size_t readSamples	(	T *	data,
		size_t	len
	)

inlinevirtualinherited

Provides the data as T array (interleaved by channel) with the requested number of samples (values, not frames)

Reimplemented in GeneratorQueue< T >.

◆ recalculatePlayTime()

template<class T = int16_t>

void recalculatePlayTime ( )

inlineprotectedinherited

◆ restart()

template<class T = int16_t>

virtual void restart ( )

inlinevirtualinherited

Restarts the generator, e.g. after a play time has been defined and reached.

◆ setAmplitude()

template<class T = int16_t>

void setAmplitude ( float amp )

inline

◆ setAudioInfo()

template<class T = int16_t>

virtual void setAudioInfo ( AudioInfo info )

inlineoverridevirtual

Defines/updates the AudioInfo.

Reimplemented from SoundGenerator< T >.

◆ setFrequency()

template<class T = int16_t>

void setFrequency ( float frequency )

inlineoverridevirtual

Defines the frequency - the only place where float math is used.

Reimplemented from SoundGenerator< T >.

◆ setPhase()

template<class T = int16_t>

void setPhase ( float phase )

inline

Defines the starting phase in radians.

◆ setPlayTime()

template<class T = int16_t>

virtual void setPlayTime	(	uint32_t	playMs,
		uint8_t	upPercent = `20`,
		uint8_t	downPercent = `30`
	)

inlinevirtualinherited

Defines the play time in ms and the ramp up and ramp down time in percent.

Reimplemented in GeneratorQueue< T >.

◆ setRampTimes()

template<class T = int16_t>

virtual void setRampTimes	(	uint32_t	playMs,
		uint32_t	upMs = `5`,
		uint32_t	downMs = `5`
	)

inlinevirtualinherited

Alternative to setPlayTime. It sets ramp-up and ramp-down times in ms instead of percentages. If playMs == 0, it will play indefinitely. restart();begin(); starts the ramp-up and sustain as normal, but it will sustain forever. end(true) triggers a ramp-down then inactive.

◆ updatePhaseIncrement()

template<class T = int16_t>

void updatePhaseIncrement ( )

inlineprotected

Member Data Documentation

◆ active

template<class T = int16_t>

bool active = false

protectedinherited

◆ activeWarningIssued

template<class T = int16_t>

bool activeWarningIssued = false

protectedinherited

◆ currentSample

template<class T = int16_t>

uint32_t currentSample = 0

protectedinherited

◆ downMs

template<class T = int16_t>

uint32_t downMs = 0

protectedinherited

◆ downPercent

template<class T = int16_t>

uint8_t downPercent = 40

protectedinherited

◆ downSamples

template<class T = int16_t>

uint32_t downSamples = 0

protectedinherited

◆ factor

template<class T = int16_t>

float factor = 1.0f

protectedinherited

◆ info

template<class T = int16_t>

AudioInfo info

protectedinherited

◆ m_amplitude

template<class T = int16_t>

float m_amplitude = 1.0f

protected

◆ m_amplitude_i

template<class T = int16_t>

int32_t m_amplitude_i = 32767

protected

◆ m_frequency

template<class T = int16_t>

volatile float m_frequency = 0.0f

protected

◆ m_phase_acc

template<class T = int16_t>

uint32_t m_phase_acc = 0

protected

◆ m_phase_increment

template<class T = int16_t>

uint32_t m_phase_increment = 0

protected

◆ m_phase_offset

template<class T = int16_t>

uint32_t m_phase_offset = 0

protected

◆ playMs

template<class T = int16_t>

uint32_t playMs = 0

protectedinherited

◆ playSamples

template<class T = int16_t>

uint32_t playSamples = 0

protectedinherited

◆ rampDownDec

template<class T = int16_t>

float rampDownDec = 0.0

protectedinherited

◆ rampUpInc

template<class T = int16_t>

float rampUpInc = 0.0

protectedinherited

◆ ring_buffer

template<class T = int16_t>

RingBuffer<uint8_t> ring_buffer {0}

protectedinherited

◆ upMs

template<class T = int16_t>

uint32_t upMs = 0

protectedinherited

◆ upPercent

template<class T = int16_t>

uint8_t upPercent = 5

protectedinherited

◆ upSamples

template<class T = int16_t>

uint32_t upSamples = 0

protectedinherited

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

src/AudioTools/CoreAudio/AudioEffects/SoundGenerator.h

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ SquareWaveGenerator()

Member Function Documentation

◆ applyRamp()

◆ audioInfo()

◆ begin() [1/4]

◆ begin() [2/4]

◆ begin() [3/4]

◆ begin() [4/4]

◆ defaultConfig()

◆ end() [1/2]

◆ end() [2/2]

◆ isActive()

◆ readBytes()

◆ readBytesFrames()

◆ readBytesFromBuffer()

◆ readSample()

◆ readSamples()

◆ recalculatePlayTime()

◆ restart()

◆ setAmplitude()

◆ setAudioInfo()

◆ setFrequency()

◆ setPhase()

◆ setPlayTime()

◆ setRampTimes()

◆ updatePhaseIncrement()

Member Data Documentation

◆ active

◆ activeWarningIssued

◆ currentSample

◆ downMs

◆ downPercent

◆ downSamples

◆ factor

◆ info

◆ m_amplitude

◆ m_amplitude_i

◆ m_frequency

◆ m_phase_acc

◆ m_phase_increment

◆ m_phase_offset

◆ playMs

◆ playSamples

◆ rampDownDec

◆ rampUpInc

◆ ring_buffer

◆ upMs

◆ upPercent

◆ upSamples