Waveform function generator. More...

#include <stdlib.h>
#include <avr/pgmspace.h>
#include "background_tasks.h"
#include "leds.h"
#include "lookup_tables.h"
#include "midi.h"
#include "program.h"
#include "wave.h"

Include dependency graph for wave.c:

Functions
static void	advance_step_counter (struct wave *wave)
	Increments or decrements the step counter depending on its the current direction. More...

static midi_value_t	compute_ramp (struct wave *wave)
	Derives a rising ramp from the step counter. More...

static midi_value_t	compute_random_wave (struct wave *wave)
	Computes a random wave. More...

static midi_value_t	compute_saw_down_wave (struct wave *wave)
	Computes a saw down wave. More...

static midi_value_t	compute_saw_up_wave (struct wave *wave)
	Computes a saw up wave. More...

static midi_value_t	compute_sine_wave (struct wave *wave)
	Computes a sine wave through a lookup table. More...

static midi_value_t	compute_square_wave (struct wave *wave)
	Computes a square wave. More...

static midi_value_t	compute_stairs_wave (struct wave *wave)
	Computes a stairs wave. More...

static midi_value_t	compute_triangle_wave (struct wave *wave)
	Computes a triangle wave. More...

void	configure_tap_tempo_wave (struct wave *const wave)
	Configures a wave for tap tempo functionality. More...

void	init_wave (struct wave *const wave, enum waveform waveform, midi_value_t speed, midi_value_t amplitude, midi_value_t offset)
	Initializes a wave. More...

void	register_tap (void)
	Registers a tempo tap event. More...

void	reset_wave (struct wave *const wave)
	Resets a wave. More...

void	set_frequency (struct wave *const wave, fixed_t frequency)
	Updates the frequency of a wave. More...

void	set_speed (struct wave *const wave, midi_value_t speed)
	Updates the speed of a wave. More...

void	set_waveform (struct wave *const wave, enum waveform waveform)
	Updates the waveform of a wave. More...

void	tap_tempo_task (void)
	Background task for the tap tempo function. More...

midi_value_t	update_wave (struct wave *const wave)
	Computes the current wave output value. More...

Variables
static bool	tap_arrived = false
	This flag indicates if a tempo tap occurred. More...

static struct wave *	tap_tempo_wave = NULL
	Points to the waveform whose speed can be tapped in. More...

Detailed Description

Waveform function generator.

Function Documentation

◆ advance_step_counter()

static void advance_step_counter ( struct wave * wave )

static

Increments or decrements the step counter depending on its the current direction.

When the top or bottom value is reached, the direction is switched automatically. The step counter consequently follows a triangle wave.

Parameters

wave the wave

◆ compute_ramp()

static midi_value_t compute_ramp ( struct wave * wave )

static

Derives a rising ramp from the step counter.

Parameters

wave the wave

Returns: the wave output

◆ compute_random_wave()

static midi_value_t compute_random_wave ( struct wave * wave )

static

Computes a random wave.

Note that this uses static variables, so only one random wave can be computed!

Parameters

wave the wave

Returns: the wave output

◆ compute_saw_down_wave()

static midi_value_t compute_saw_down_wave ( struct wave * wave )

static

Computes a saw down wave.

Parameters

wave the wave

Returns: the wave output

◆ compute_saw_up_wave()

static midi_value_t compute_saw_up_wave ( struct wave * wave )

static

Computes a saw up wave.

Parameters

wave the wave

Returns: the wave output

◆ compute_sine_wave()

static midi_value_t compute_sine_wave ( struct wave * wave )

static

Computes a sine wave through a lookup table.

Parameters

wave the wave

Returns: the wave output

◆ compute_square_wave()

static midi_value_t compute_square_wave ( struct wave * wave )

static

Computes a square wave.

Parameters

wave the wave

Returns: the wave output

◆ compute_stairs_wave()

static midi_value_t compute_stairs_wave ( struct wave * wave )

static

Computes a stairs wave.

Parameters

wave the wave

Returns: the wave output

◆ compute_triangle_wave()

static midi_value_t compute_triangle_wave ( struct wave * wave )

static

Computes a triangle wave.

Parameters

wave the wave

Returns: the wave output

◆ configure_tap_tempo_wave()

void configure_tap_tempo_wave ( struct wave *const wave )

Configures a wave for tap tempo functionality.

Parameters

wave	the wave to configure

See also: tap_tempo_task

◆ init_wave()

void init_wave	(	struct wave *	wave,
		enum waveform	waveform,
		midi_value_t	speed,
		midi_value_t	amplitude,
		midi_value_t	offset
	)

Initializes a wave.

Parameters

wave	the wave to initialize
waveform	the initial waveform
speed	the initial speed
amplitude	the amplitude
offset	the static offset

See also: wave; waveform

◆ register_tap()

void register_tap ( void )

Registers a tempo tap event.

This function must be called whenever a tempo tap event occurrs. It sets an internal flag to inform the background task about the event.

See also: tap_tempo_task

◆ reset_wave()

void reset_wave ( struct wave *const wave )

Resets a wave.

Re-initializes all internal counters and states of the supplied wave

Parameters

wave	the wave to reset

◆ set_frequency()

void set_frequency	(	struct wave *	wave,
		fixed_t	frequency
	)

Updates the frequency of a wave.

Parameters

wave	the wave to update
frequency	the new frequency

See also: wave

◆ set_speed()

void set_speed	(	struct wave *	wave,
		midi_value_t	speed
	)

Updates the speed of a wave.

Sets the wave frequency to the given speed in [BPM], adding an offset of 15 BPM.

Parameters

wave	the wave to update
speed	the new speed in [BPM]

See also: wave

◆ set_waveform()

void set_waveform	(	struct wave *	wave,
		enum waveform	waveform
	)

Updates the waveform of a wave.

Parameters

wave	the wave to update
waveform	the new waveform

◆ tap_tempo_task()

void tap_tempo_task ( void )

Background task for the tap tempo function.

This function must be registered as a slow background task. It computes a frequency from an incrementing internal counter and the task frequency and updates the speed of the wave configured for tap tempo operation.

See also: configure_tap_tempo_wave; register_tap

◆ update_wave()

midi_value_t update_wave ( struct wave * wave )

Computes the current wave output value.

This function must be called in a fast background task. Over time the output value follows the configured waveform.

Parameters

wave	the wave whose output should be computed

Returns: the current output value

Variable Documentation

◆ tap_arrived

bool tap_arrived = false

static

This flag indicates if a tempo tap occurred.

◆ tap_tempo_wave

struct wave* tap_tempo_wave = NULL

static

Points to the waveform whose speed can be tapped in.

Functions

Variables

Detailed Description

Function Documentation

◆ advance_step_counter()

◆ compute_ramp()

◆ compute_random_wave()

◆ compute_saw_down_wave()

◆ compute_saw_up_wave()

◆ compute_sine_wave()

◆ compute_square_wave()

◆ compute_stairs_wave()

◆ compute_triangle_wave()

◆ configure_tap_tempo_wave()

◆ init_wave()

◆ register_tap()

◆ reset_wave()

◆ set_frequency()

◆ set_speed()

◆ set_waveform()

◆ tap_tempo_task()

◆ update_wave()

Variable Documentation

◆ tap_arrived

◆ tap_tempo_wave