qmk_firmware/quantum/audio/audio.c

/* Copyright 2016 Jack Humbert
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <string.h>
//#include <math.h>
#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include "print.h"
#include "audio.h"
#include "keymap.h"

#include "eeconfig.h"

#define CPU_PRESCALER 8

// -----------------------------------------------------------------------------
// Timer Abstractions
// -----------------------------------------------------------------------------

// TIMSK3 - Timer/Counter #3 Interrupt Mask Register
// Turn on/off 3A interputs, stopping/enabling the ISR calls
#ifdef C6_AUDIO
    #define ENABLE_AUDIO_COUNTER_3_ISR TIMSK3 |= _BV(OCIE3A)
    #define DISABLE_AUDIO_COUNTER_3_ISR TIMSK3 &= ~_BV(OCIE3A)
#endif

#ifdef B5_AUDIO
    #define ENABLE_AUDIO_COUNTER_1_ISR TIMSK1 |= _BV(OCIE1A)
    #define DISABLE_AUDIO_COUNTER_1_ISR TIMSK1 &= ~_BV(OCIE1A)
#endif

#ifdef B6_AUDIO
    #define ENABLE_AUDIO_COUNTER_1_ISR TIMSK1 |= _BV(OCIE1B)
    #define DISABLE_AUDIO_COUNTER_1_ISR TIMSK1 &= ~_BV(OCIE1B)
#endif

#ifdef B7_AUDIO
    #define ENABLE_AUDIO_COUNTER_1_ISR TIMSK1 |= _BV(OCIE1C)
    #define DISABLE_AUDIO_COUNTER_1_ISR TIMSK1 &= ~_BV(OCIE1C)
#endif

// TCCR3A: Timer/Counter #3 Control Register
// Compare Output Mode (COM3An) = 0b00 = Normal port operation, OC3A disconnected from PC6

#ifdef C6_AUDIO
    #define ENABLE_AUDIO_COUNTER_3_OUTPUT TCCR3A |= _BV(COM3A1);
    #define DISABLE_AUDIO_COUNTER_3_OUTPUT TCCR3A &= ~(_BV(COM3A1) | _BV(COM3A0));
#endif

#ifdef B5_AUDIO
    #define ENABLE_AUDIO_COUNTER_1_OUTPUT TCCR1A |= _BV(COM1A1);
    #define DISABLE_AUDIO_COUNTER_1_OUTPUT TCCR1A &= ~(_BV(COM1A1) | _BV(COM1A0));
#endif

#ifdef B6_AUDIO
    #define ENABLE_AUDIO_COUNTER_1_OUTPUT TCCR1A |= _BV(COM1B1);
    #define DISABLE_AUDIO_COUNTER_1_OUTPUT TCCR1A &= ~(_BV(COM1B1) | _BV(COM1B0));
#endif

#ifdef B7_AUDIO
    #define ENABLE_AUDIO_COUNTER_1_OUTPUT TCCR1A |= _BV(COM1C1);
    #define DISABLE_AUDIO_COUNTER_1_OUTPUT TCCR1A &= ~(_BV(COM1C1) | _BV(COM1C0));
#endif

// Fast PWM Mode Controls

#ifdef C6_AUDIO
    #define TIMER_3_PERIOD     ICR3
    #define TIMER_3_DUTY_CYCLE OCR3A
#endif

#ifdef B5_AUDIO
    #define TIMER_1_PERIOD     ICR1
    #define TIMER_1_DUTY_CYCLE OCR1A
#endif

#ifdef B6_AUDIO
    #define TIMER_1_PERIOD     ICR1
    #define TIMER_1_DUTY_CYCLE OCR1B
#endif

#ifdef B7_AUDIO
    #define TIMER_1_PERIOD     ICR1
    #define TIMER_1_DUTY_CYCLE OCR1C
#endif


// -----------------------------------------------------------------------------


int voices = 0;
int voice_place = 0;
float frequency = 0;
float frequency_alt = 0;
int volume = 0;
long position = 0;

float frequencies[8] = {0, 0, 0, 0, 0, 0, 0, 0};
int volumes[8] = {0, 0, 0, 0, 0, 0, 0, 0};
bool sliding = false;

float place = 0;

uint8_t * sample;
uint16_t sample_length = 0;

bool     playing_notes = false;
bool     playing_note = false;
float    note_frequency = 0;
float    note_length = 0;
uint8_t  note_tempo = TEMPO_DEFAULT;
float    note_timbre = TIMBRE_DEFAULT;
uint16_t note_position = 0;
float (* notes_pointer)[][2];
uint16_t notes_count;
bool     notes_repeat;
bool     note_resting = false;

uint8_t current_note = 0;
uint8_t rest_counter = 0;

#ifdef VIBRATO_ENABLE
float vibrato_counter = 0;
float vibrato_strength = .5;
float vibrato_rate = 0.125;
#endif

float polyphony_rate = 0;

static bool audio_initialized = false;

audio_config_t audio_config;

uint16_t envelope_index = 0;
bool glissando = true;

#ifndef STARTUP_SONG
    #define STARTUP_SONG SONG(STARTUP_SOUND)
#endif
float startup_song[][2] = STARTUP_SONG;

void audio_init()
{

    if (audio_initialized)
        return;

    // Check EEPROM
    if (!eeconfig_is_enabled())
    {
        eeconfig_init();
    }
    audio_config.raw = eeconfig_read_audio();

    // Set port PC6 (OC3A and /OC4A) as output

    #ifdef C6_AUDIO
        DDRC |= _BV(PORTC6);
    #else
        DDRC |= _BV(PORTC6);
        PORTC &= ~_BV(PORTC6);
    #endif

    #ifdef B5_AUDIO
        DDRB |= _BV(PORTB5);
    #else
        DDRB |= _BV(PORTB5);
        PORTB &= ~_BV(PORTB5);
    #endif

    #ifdef B6_AUDIO
        DDRB |= _BV(PORTB6);
    #else
        DDRB |= _BV(PORTB6);
        PORTB &= ~_BV(PORTB6);
    #endif

    #ifdef B7_AUDIO
        DDRB |= _BV(PORTB7);
    #else
        DDRB |= _BV(PORTB7);
        PORTB &= ~_BV(PORTB7);
    #endif

    #ifdef C6_AUDIO
        DISABLE_AUDIO_COUNTER_3_ISR;
    #endif
    
    #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
        DISABLE_AUDIO_COUNTER_1_ISR;
    #endif

    // TCCR3A / TCCR3B: Timer/Counter #3 Control Registers
    // Compare Output Mode (COM3An) = 0b00 = Normal port operation, OC3A disconnected from PC6
    // Waveform Generation Mode (WGM3n) = 0b1110 = Fast PWM Mode 14 (Period = ICR3, Duty Cycle = OCR3A)
    // Clock Select (CS3n) = 0b010 = Clock / 8

    #ifdef C6_AUDIO
        TCCR3A = (0 << COM3A1) | (0 << COM3A0) | (1 << WGM31) | (0 << WGM30);
        TCCR3B = (1 << WGM33)  | (1 << WGM32)  | (0 << CS32)  | (1 << CS31) | (0 << CS30);
    #endif

    #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
        TCCR1A = (0 << COM1A1) | (0 << COM1A0) | (1 << WGM11) | (0 << WGM10);
        TCCR1B = (1 << WGM13)  | (1 << WGM12)  | (0 << CS12)  | (1 << CS11) | (0 << CS10);
    #endif

    audio_initialized = true;

    if (audio_config.enable) {
        PLAY_SONG(startup_song);
    }

}

void stop_all_notes()
{
    dprintf("audio stop all notes");

    if (!audio_initialized) {
        audio_init();
    }
    voices = 0;


    #ifdef C6_AUDIO
        DISABLE_AUDIO_COUNTER_3_ISR;
        DISABLE_AUDIO_COUNTER_3_OUTPUT;
    #endif

    #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
        DISABLE_AUDIO_COUNTER_1_ISR;
        DISABLE_AUDIO_COUNTER_1_OUTPUT;
    #endif

    playing_notes = false;
    playing_note = false;
    frequency = 0;
    frequency_alt = 0;
    volume = 0;

    for (uint8_t i = 0; i < 8; i++)
    {
        frequencies[i] = 0;
        volumes[i] = 0;
    }
}

void stop_note(float freq)
{
    dprintf("audio stop note freq=%d", (int)freq);

    if (playing_note) {
        if (!audio_initialized) {
            audio_init();
        }
        for (int i = 7; i >= 0; i--) {
            if (frequencies[i] == freq) {
                frequencies[i] = 0;
                volumes[i] = 0;
                for (int j = i; (j < 7); j++) {
                    frequencies[j] = frequencies[j+1];
                    frequencies[j+1] = 0;
                    volumes[j] = volumes[j+1];
                    volumes[j+1] = 0;
                }
                break;
            }
        }
        voices--;
        if (voices < 0)
            voices = 0;
        if (voice_place >= voices) {
            voice_place = 0;
        }
        if (voices == 0) {
            #ifdef C6_AUDIO
                DISABLE_AUDIO_COUNTER_3_ISR;
                DISABLE_AUDIO_COUNTER_3_OUTPUT;
            #endif
            #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
                DISABLE_AUDIO_COUNTER_1_ISR;
                DISABLE_AUDIO_COUNTER_1_OUTPUT;
            #endif
            frequency = 0;
            frequency_alt = 0;
            volume = 0;
            playing_note = false;
        }
    }
}

#ifdef VIBRATO_ENABLE

float mod(float a, int b)
{
    float r = fmod(a, b);
    return r < 0 ? r + b : r;
}

float vibrato(float average_freq) {
    #ifdef VIBRATO_STRENGTH_ENABLE
        float vibrated_freq = average_freq * pow(vibrato_lut[(int)vibrato_counter], vibrato_strength);
    #else
        float vibrated_freq = average_freq * vibrato_lut[(int)vibrato_counter];
    #endif
    vibrato_counter = mod((vibrato_counter + vibrato_rate * (1.0 + 440.0/average_freq)), VIBRATO_LUT_LENGTH);
    return vibrated_freq;
}

#endif

#ifdef C6_AUDIO
ISR(TIMER3_COMPA_vect)
{
    float freq;

    if (playing_note) {
        if (voices > 0) {

            #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
            float freq_alt = 0;
                if (voices > 1) {
                    if (polyphony_rate == 0) {
                        if (glissando) {
                            if (frequency_alt != 0 && frequency_alt < frequencies[voices - 2] && frequency_alt < frequencies[voices - 2] * pow(2, -440/frequencies[voices - 2]/12/2)) {
                                frequency_alt = frequency_alt * pow(2, 440/frequency_alt/12/2);
                            } else if (frequency_alt != 0 && frequency_alt > frequencies[voices - 2] && frequency_alt > frequencies[voices - 2] * pow(2, 440/frequencies[voices - 2]/12/2)) {
                                frequency_alt = frequency_alt * pow(2, -440/frequency_alt/12/2);
                            } else {
                                frequency_alt = frequencies[voices - 2];
                            }
                        } else {
                            frequency_alt = frequencies[voices - 2];
                        }

                        #ifdef VIBRATO_ENABLE
                            if (vibrato_strength > 0) {
                                freq_alt = vibrato(frequency_alt);
                            } else {
                                freq_alt = frequency_alt;
                            }
                        #else
                            freq_alt = frequency_alt;
                        #endif
                    }

                    if (envelope_index < 65535) {
                        envelope_index++;
                    }

                    freq_alt = voice_envelope(freq_alt);

                    if (freq_alt < 30.517578125) {
                        freq_alt = 30.52;
                    }

                    TIMER_1_PERIOD = (uint16_t)(((float)F_CPU) / (freq_alt * CPU_PRESCALER));
                    TIMER_1_DUTY_CYCLE = (uint16_t)((((float)F_CPU) / (freq_alt * CPU_PRESCALER)) * note_timbre);
                }
            #endif

            if (polyphony_rate > 0) {
                if (voices > 1) {
                    voice_place %= voices;
                    if (place++ > (frequencies[voice_place] / polyphony_rate / CPU_PRESCALER)) {
                        voice_place = (voice_place + 1) % voices;
                        place = 0.0;
                    }
                }

                #ifdef VIBRATO_ENABLE
                    if (vibrato_strength > 0) {
                        freq = vibrato(frequencies[voice_place]);
                    } else {
                        freq = frequencies[voice_place];
                    }
                #else
                    freq = frequencies[voice_place];
                #endif
            } else {
                if (glissando) {
                    if (frequency != 0 && frequency < frequencies[voices - 1] && frequency < frequencies[voices - 1] * pow(2, -440/frequencies[voices - 1]/12/2)) {
                        frequency = frequency * pow(2, 440/frequency/12/2);
                    } else if (frequency != 0 && frequency > frequencies[voices - 1] && frequency > frequencies[voices - 1] * pow(2, 440/frequencies[voices - 1]/12/2)) {
                        frequency = frequency * pow(2, -440/frequency/12/2);
                    } else {
                        frequency = frequencies[voices - 1];
                    }
                } else {
                    frequency = frequencies[voices - 1];
                }

                #ifdef VIBRATO_ENABLE
                    if (vibrato_strength > 0) {
                        freq = vibrato(frequency);
                    } else {
                        freq = frequency;
                    }
                #else
                    freq = frequency;
                #endif
            }

            if (envelope_index < 65535) {
                envelope_index++;
            }

            freq = voice_envelope(freq);

            if (freq < 30.517578125) {
                freq = 30.52;
            }

            TIMER_3_PERIOD = (uint16_t)(((float)F_CPU) / (freq * CPU_PRESCALER));
            TIMER_3_DUTY_CYCLE = (uint16_t)((((float)F_CPU) / (freq * CPU_PRESCALER)) * note_timbre);
        }
    }

    if (playing_notes) {
        if (note_frequency > 0) {
            #ifdef VIBRATO_ENABLE
                if (vibrato_strength > 0) {
                    freq = vibrato(note_frequency);
                } else {
                    freq = note_frequency;
                }
            #else
                    freq = note_frequency;
            #endif

            if (envelope_index < 65535) {
                envelope_index++;
            }
            freq = voice_envelope(freq);

            TIMER_3_PERIOD = (uint16_t)(((float)F_CPU) / (freq * CPU_PRESCALER));
            TIMER_3_DUTY_CYCLE = (uint16_t)((((float)F_CPU) / (freq * CPU_PRESCALER)) * note_timbre);
        } else {
            TIMER_3_PERIOD = 0;
            TIMER_3_DUTY_CYCLE = 0;
        }

        note_position++;
        bool end_of_note = false;
        if (TIMER_3_PERIOD > 0) {
            if (!note_resting) 
                end_of_note = (note_position >= (note_length / TIMER_3_PERIOD * 0xFFFF - 1));
            else
                end_of_note = (note_position >= (note_length));
        } else {
            end_of_note = (note_position >= (note_length));
        }

        if (end_of_note) {
            current_note++;
            if (current_note >= notes_count) {
                if (notes_repeat) {
                    current_note = 0;
                } else {
                    DISABLE_AUDIO_COUNTER_3_ISR;
                    DISABLE_AUDIO_COUNTER_3_OUTPUT;
                    playing_notes = false;
                    return;
                }
            }
            if (!note_resting) {
                note_resting = true;
                current_note--;
                if ((*notes_pointer)[current_note][0] == (*notes_pointer)[current_note + 1][0]) {
                    note_frequency = 0;
                    note_length = 1;
                } else {
                    note_frequency = (*notes_pointer)[current_note][0];
                    note_length = 1;
                }
            } else {
                note_resting = false;
                envelope_index = 0;
                note_frequency = (*notes_pointer)[current_note][0];
                note_length = ((*notes_pointer)[current_note][1] / 4) * (((float)note_tempo) / 100);
            }

            note_position = 0;
        }
    }

    if (!audio_config.enable) {
        playing_notes = false;
        playing_note = false;
    }
}
#endif

#if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
ISR(TIMER1_COMPA_vect)
{
    #if (defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)) && !defined(C6_AUDIO)
    float freq = 0;

    if (playing_note) {
        if (voices > 0) {
            if (polyphony_rate > 0) {
                if (voices > 1) {
                    voice_place %= voices;
                    if (place++ > (frequencies[voice_place] / polyphony_rate / CPU_PRESCALER)) {
                        voice_place = (voice_place + 1) % voices;
                        place = 0.0;
                    }
                }

                #ifdef VIBRATO_ENABLE
                    if (vibrato_strength > 0) {
                        freq = vibrato(frequencies[voice_place]);
                    } else {
                        freq = frequencies[voice_place];
                    }
                #else
                    freq = frequencies[voice_place];
                #endif
            } else {
                if (glissando) {
                    if (frequency != 0 && frequency < frequencies[voices - 1] && frequency < frequencies[voices - 1] * pow(2, -440/frequencies[voices - 1]/12/2)) {
                        frequency = frequency * pow(2, 440/frequency/12/2);
                    } else if (frequency != 0 && frequency > frequencies[voices - 1] && frequency > frequencies[voices - 1] * pow(2, 440/frequencies[voices - 1]/12/2)) {
                        frequency = frequency * pow(2, -440/frequency/12/2);
                    } else {
                        frequency = frequencies[voices - 1];
                    }
                } else {
                    frequency = frequencies[voices - 1];
                }

                #ifdef VIBRATO_ENABLE
                    if (vibrato_strength > 0) {
                        freq = vibrato(frequency);
                    } else {
                        freq = frequency;
                    }
                #else
                    freq = frequency;
                #endif
            }

            if (envelope_index < 65535) {
                envelope_index++;
            }

            freq = voice_envelope(freq);

            if (freq < 30.517578125) {
                freq = 30.52;
            }

            TIMER_1_PERIOD = (uint16_t)(((float)F_CPU) / (freq * CPU_PRESCALER));
            TIMER_1_DUTY_CYCLE = (uint16_t)((((float)F_CPU) / (freq * CPU_PRESCALER)) * note_timbre);
        }
    }

    if (playing_notes) {
        if (note_frequency > 0) {
            #ifdef VIBRATO_ENABLE
                if (vibrato_strength > 0) {
                    freq = vibrato(note_frequency);
                } else {
                    freq = note_frequency;
                }
            #else
                    freq = note_frequency;
            #endif

            if (envelope_index < 65535) {
                envelope_index++;
            }
            freq = voice_envelope(freq);

            TIMER_1_PERIOD = (uint16_t)(((float)F_CPU) / (freq * CPU_PRESCALER));
            TIMER_1_DUTY_CYCLE = (uint16_t)((((float)F_CPU) / (freq * CPU_PRESCALER)) * note_timbre);
        } else {
            TIMER_1_PERIOD = 0;
            TIMER_1_DUTY_CYCLE = 0;
        }

        note_position++;
        bool end_of_note = false;
        if (TIMER_1_PERIOD > 0) {
            if (!note_resting) 
                end_of_note = (note_position >= (note_length / TIMER_1_PERIOD * 0xFFFF - 1));
            else
                end_of_note = (note_position >= (note_length));
        } else {
            end_of_note = (note_position >= (note_length));
        }

        if (end_of_note) {
            current_note++;
            if (current_note >= notes_count) {
                if (notes_repeat) {
                    current_note = 0;
                } else {
                    DISABLE_AUDIO_COUNTER_1_ISR;
                    DISABLE_AUDIO_COUNTER_1_OUTPUT;
                    playing_notes = false;
                    return;
                }
            }
            if (!note_resting) {
                note_resting = true;
                current_note--;
                if ((*notes_pointer)[current_note][0] == (*notes_pointer)[current_note + 1][0]) {
                    note_frequency = 0;
                    note_length = 1;
                } else {
                    note_frequency = (*notes_pointer)[current_note][0];
                    note_length = 1;
                }
            } else {
                note_resting = false;
                envelope_index = 0;
                note_frequency = (*notes_pointer)[current_note][0];
                note_length = ((*notes_pointer)[current_note][1] / 4) * (((float)note_tempo) / 100);
            }

            note_position = 0;
        }
    }

    if (!audio_config.enable) {
        playing_notes = false;
        playing_note = false;
    }
#endif
}
#endif

void play_note(float freq, int vol) {

    dprintf("audio play note freq=%d vol=%d", (int)freq, vol);

    if (!audio_initialized) {
        audio_init();
    }

    if (audio_config.enable && voices < 8) {
        #ifdef C6_AUDIO
            DISABLE_AUDIO_COUNTER_3_ISR;
        #endif
        #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
            DISABLE_AUDIO_COUNTER_1_ISR;
        #endif

        // Cancel notes if notes are playing
        if (playing_notes)
            stop_all_notes();

        playing_note = true;

        envelope_index = 0;

        if (freq > 0) {
            frequencies[voices] = freq;
            volumes[voices] = vol;
            voices++;
        }

        #ifdef C6_AUDIO
            ENABLE_AUDIO_COUNTER_3_ISR;
            ENABLE_AUDIO_COUNTER_3_OUTPUT;
        #endif
        #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
            #ifdef C6_AUDIO
            if (voices > 1) {
                ENABLE_AUDIO_COUNTER_1_ISR;
                ENABLE_AUDIO_COUNTER_1_OUTPUT;
            }
            #else
            ENABLE_AUDIO_COUNTER_1_ISR;
            ENABLE_AUDIO_COUNTER_1_OUTPUT;
            #endif
        #endif
    }

}

void play_notes(float (*np)[][2], uint16_t n_count, bool n_repeat)
{

    if (!audio_initialized) {
        audio_init();
    }

    if (audio_config.enable) {

        #ifdef C6_AUDIO
            DISABLE_AUDIO_COUNTER_3_ISR;
        #endif
        #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
            DISABLE_AUDIO_COUNTER_1_ISR;
        #endif

        // Cancel note if a note is playing
        if (playing_note)
            stop_all_notes();

        playing_notes = true;

        notes_pointer = np;
        notes_count = n_count;
        notes_repeat = n_repeat;

        place = 0;
        current_note = 0;

        note_frequency = (*notes_pointer)[current_note][0];
        note_length = ((*notes_pointer)[current_note][1] / 4) * (((float)note_tempo) / 100);
        note_position = 0;


        #ifdef C6_AUDIO
            ENABLE_AUDIO_COUNTER_3_ISR;
            ENABLE_AUDIO_COUNTER_3_OUTPUT;
        #endif
        #if defined(B5_AUDIO) || defined(B6_AUDIO) || defined(B7_AUDIO)
            #ifndef C6_AUDIO
            ENABLE_AUDIO_COUNTER_1_ISR;
            ENABLE_AUDIO_COUNTER_1_OUTPUT;
            #endif
        #endif
    }

}

bool is_playing_notes(void) {
    return playing_notes;
}

bool is_audio_on(void) {
    return (audio_config.enable != 0);
}

void audio_toggle(void) {
    audio_config.enable ^= 1;
    eeconfig_update_audio(audio_config.raw);
    if (audio_config.enable)
        audio_on_user();
}

void audio_on(void) {
    audio_config.enable = 1;
    eeconfig_update_audio(audio_config.raw);
    audio_on_user();
}

void audio_off(void) {
    audio_config.enable = 0;
    eeconfig_update_audio(audio_config.raw);
}

#ifdef VIBRATO_ENABLE

// Vibrato rate functions

void set_vibrato_rate(float rate) {
    vibrato_rate = rate;
}

void increase_vibrato_rate(float change) {
    vibrato_rate *= change;
}

void decrease_vibrato_rate(float change) {
    vibrato_rate /= change;
}

#ifdef VIBRATO_STRENGTH_ENABLE

void set_vibrato_strength(float strength) {
    vibrato_strength = strength;
}

void increase_vibrato_strength(float change) {
    vibrato_strength *= change;
}

void decrease_vibrato_strength(float change) {
    vibrato_strength /= change;
}

#endif  /* VIBRATO_STRENGTH_ENABLE */

#endif /* VIBRATO_ENABLE */

// Polyphony functions

void set_polyphony_rate(float rate) {
    polyphony_rate = rate;
}

void enable_polyphony() {
    polyphony_rate = 5;
}

void disable_polyphony() {
    polyphony_rate = 0;
}

void increase_polyphony_rate(float change) {
    polyphony_rate *= change;
}

void decrease_polyphony_rate(float change) {
    polyphony_rate /= change;
}

// Timbre function

void set_timbre(float timbre) {
    note_timbre = timbre;
}

// Tempo functions

void set_tempo(uint8_t tempo) {
    note_tempo = tempo;
}

void decrease_tempo(uint8_t tempo_change) {
    note_tempo += tempo_change;
}

void increase_tempo(uint8_t tempo_change) {
    if (note_tempo - tempo_change < 10) {
        note_tempo = 10;
    } else {
        note_tempo -= tempo_change;
    }
}