Sine wave generator that does not use any floating point operations in the readSample() hot path: it advances a 32 bit phase accumulator with an integer increment and looks up the result in a Q15 fixed point table. All floating point math (converting frequency/sample_rate into the phase increment) is done once in setFrequency()/setAudioInfo(), never per sample. This makes it a good fit for MCUs without a hardware FPU - e.g. the RP2040 - where sinf() is comparatively expensive. More...

#include <SoundGenerator.h>

Inheritance diagram for FastIntSineGenerator< T >:

Public Member Functions
	FastIntSineGenerator (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 ()
	Ends the processing.

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 or sin() calls!

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.

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.

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

uint8_t	downPercent = 40

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

uint32_t	rampDownSamples = 0

float	rampUpInc = 0.0

RingBuffer< uint8_t >	ring_buffer {0}

uint8_t	upPercent = 5

uint32_t	upSamples = 0

Static Protected Attributes
static const int	kIndexShift = 32 - kTableBits

static const int	kTableBits = 8

static const int	kTableSize = 1 << kTableBits

static constexpr int16_t	sine_table [kTableSize]

Detailed Description

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

Sine wave generator that does not use any floating point operations in the readSample() hot path: it advances a 32 bit phase accumulator with an integer increment and looks up the result in a Q15 fixed point table. All floating point math (converting frequency/sample_rate into the phase increment) is done once in setFrequency()/setAudioInfo(), never per sample. This makes it a good fit for MCUs without a hardware FPU - e.g. the RP2040 - where sinf() is comparatively expensive.

Author: Phil Schatzmann

Copyright: GPLv3

Template Parameters

T

Constructor & Destructor Documentation

◆ FastIntSineGenerator()

template<class T = int16_t>

FastIntSineGenerator	(	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 >, SineGenerator< T >, and SineGenerator< int16_t >.

◆ end()

template<class T = int16_t>

virtual void end ( )

inlinevirtualinherited

Ends the processing.

Reimplemented in GeneratorFromArray< T >.

◆ 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.

◆ 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 or sin() calls!

Implements SoundGenerator< T >.

◆ recalculatePlayTime()

template<class T = int16_t>

void recalculatePlayTime ( )

inlineprotectedinherited

◆ 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>

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

inlineinherited

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

◆ 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

◆ downPercent

template<class T = int16_t>

uint8_t downPercent = 40

protectedinherited

◆ factor

template<class T = int16_t>

float factor = 1.0f

protectedinherited

◆ info

template<class T = int16_t>

AudioInfo info

protectedinherited

◆ kIndexShift

template<class T = int16_t>

const int kIndexShift = 32 - kTableBits

staticprotected

◆ kTableBits

template<class T = int16_t>

const int kTableBits = 8

staticprotected

◆ kTableSize

template<class T = int16_t>

const int kTableSize = 1 << kTableBits

staticprotected

◆ 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

◆ rampDownSamples

template<class T = int16_t>

uint32_t rampDownSamples = 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

◆ sine_table

template<class T = int16_t>

constexpr int16_t sine_table[kTableSize]

staticconstexprprotected

Initial value:

= {
      0,     804,   1608,  2410,  3212,  4011,  4808,  5602,  6393,  7179,
      7962,  8739,  9512,  10278, 11039, 11793, 12539, 13279, 14010, 14732,
      15446, 16151, 16846, 17530, 18204, 18868, 19519, 20159, 20787, 21403,
      22005, 22594, 23170, 23731, 24279, 24811, 25329, 25832, 26319, 26790,
      27245, 27683, 28105, 28510, 28898, 29268, 29621, 29956, 30273, 30571,
      30852, 31113, 31356, 31580, 31785, 31971, 32137, 32285, 32412, 32521,
      32609, 32678, 32728, 32757, 32767, 32757, 32728, 32678, 32609, 32521,
      32412, 32285, 32137, 31971, 31785, 31580, 31356, 31113, 30852, 30571,
      30273, 29956, 29621, 29268, 28898, 28510, 28105, 27683, 27245, 26790,
      26319, 25832, 25329, 24811, 24279, 23731, 23170, 22594, 22005, 21403,
      20787, 20159, 19519, 18868, 18204, 17530, 16846, 16151, 15446, 14732,
      14010, 13279, 12539, 11793, 11039, 10278, 9512,  8739,  7962,  7179,
      6393,  5602,  4808,  4011,  3212,  2410,  1608,  804,   0,     -804,
      -1608, -2410, -3212, -4011, -4808, -5602, -6393, -7179, -7962, -8739,
      -9512, -10278,-11039,-11793,-12539,-13279,-14010,-14732,-15446,-16151,
      -16846,-17530,-18204,-18868,-19519,-20159,-20787,-21403,-22005,-22594,
      -23170,-23731,-24279,-24811,-25329,-25832,-26319,-26790,-27245,-27683,
      -28105,-28510,-28898,-29268,-29621,-29956,-30273,-30571,-30852,-31113,
      -31356,-31580,-31785,-31971,-32137,-32285,-32412,-32521,-32609,-32678,
      -32728,-32757,-32767,-32757,-32728,-32678,-32609,-32521,-32412,-32285,
      -32137,-31971,-31785,-31580,-31356,-31113,-30852,-30571,-30273,-29956,
      -29621,-29268,-28898,-28510,-28105,-27683,-27245,-26790,-26319,-25832,
      -25329,-24811,-24279,-23731,-23170,-22594,-22005,-21403,-20787,-20159,
      -19519,-18868,-18204,-17530,-16846,-16151,-15446,-14732,-14010,-13279,
      -12539,-11793,-11039,-10278,-9512, -8739, -7962, -7179, -6393, -5602,
      -4808, -4011, -3212, -2410, -1608, -804}

◆ 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

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ FastIntSineGenerator()

Member Function Documentation

◆ applyRamp()

◆ audioInfo()

◆ begin() [1/4]

◆ begin() [2/4]

◆ begin() [3/4]

◆ begin() [4/4]

◆ defaultConfig()

◆ end()

◆ isActive()

◆ readBytes()

◆ readBytesFrames()

◆ readBytesFromBuffer()

◆ readSample()

◆ recalculatePlayTime()

◆ setAmplitude()

◆ setAudioInfo()

◆ setFrequency()

◆ setPhase()

◆ setPlayTime()

◆ updatePhaseIncrement()

Member Data Documentation

◆ active

◆ activeWarningIssued

◆ currentSample

◆ downPercent

◆ factor

◆ info

◆ kIndexShift

◆ kTableBits

◆ kTableSize

◆ m_amplitude

◆ m_amplitude_i

◆ m_frequency

◆ m_phase_acc

◆ m_phase_increment

◆ m_phase_offset

◆ playMs

◆ playSamples

◆ rampDownDec

◆ rampDownSamples

◆ rampUpInc

◆ ring_buffer

◆ sine_table

◆ upPercent

◆ upSamples