AudioSynthWavetable.h

/* Audio Library for Teensy 3.X
 * Copyright (c) 2017, TeensyAudio PSU Team
 *
 * Development of this audio library was sponsored by PJRC.COM, LLC.
 * Please support PJRC's efforts to develop open source 
 * software by purchasing Teensy or other PJRC products.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice, development funding notice, and this permission
 * notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#pragma once

#include "Arduino.h"
#include "AudioStream.h"
#include <math.h>
#include <sample_data.h>
#include <stdint.h>

#define UNITY_GAIN INT32_MAX // Max amplitude / no attenuation
#define DEFAULT_AMPLITUDE 90
#define SAMPLES_PER_MSEC (AUDIO_SAMPLE_RATE_EXACT/1000.0)
#define TRIANGLE_INITIAL_PHASE (-0x40000000)
#define LFO_SMOOTHNESS 3
#define LFO_PERIOD (AUDIO_BLOCK_SAMPLES/(1 << (LFO_SMOOTHNESS-1)))

#define ENVELOPE_PERIOD 8

enum envelopeStateEnum { STATE_IDLE, STATE_DELAY, STATE_ATTACK, STATE_HOLD, STATE_DECAY, STATE_SUSTAIN, STATE_RELEASE };

class AudioSynthWavetable : public AudioStream
{
public:
    AudioSynthWavetable(void) : AudioStream(0, NULL) {}

    void setInstrument(const instrument_data& instrument) {
        cli();
        this->instrument = &instrument;
        current_sample = NULL;
        env_state = STATE_IDLE;
        state_change = true;
        sei();
    }

    void amplitude(float v) {
        v = (v < 0.0) ? 0.0 : (v > 1.0) ? 1.0 : v;
        tone_amp = (uint16_t)(UINT16_MAX*v);
    }

    static float midi_volume_transform(int midi_amp) {
        // scale midi_amp which is 0 t0 127 to be between
        // 0 and 1 using a logarithmic transformation
        return powf(midi_amp / 127.0, 4);
    }

    static float noteToFreq(int note) {
        float exp = note * (1.0 / 12.0) + 3.0313597;
        return powf(2.0, exp);
    }

    static int freqToNote(float freq) {
        return 12*log2f(freq) - 35.8763164;
    }

    // Defined in AudioSynthWavetable.cpp
    void stop(void);
    void playFrequency(float freq, int amp = DEFAULT_AMPLITUDE);
    void playNote(int note, int amp = DEFAULT_AMPLITUDE);
    bool isPlaying(void) { return env_state != STATE_IDLE; }
    void setFrequency(float freq);
    virtual void update(void);
    
    envelopeStateEnum getEnvState(void) { return env_state; }

private:
    void setState(int note, int amp, float freq);
    volatile bool state_change = false;

    volatile const instrument_data* instrument = NULL;
    volatile const sample_data* current_sample = NULL;

    //sample output state
    volatile uint32_t tone_phase = 0;
    volatile uint32_t tone_incr = 0;
    volatile uint16_t tone_amp = 0;

    //volume environment state
    volatile envelopeStateEnum  env_state = STATE_IDLE;
    volatile int32_t env_count = 0;
    volatile int32_t env_mult = 0;
    volatile int32_t env_incr = 0;

    //vibrato LFO state
    volatile uint32_t vib_count = 0;
    volatile uint32_t vib_phase = 0;
    volatile int32_t vib_pitch_offset_init = 0;
    volatile int32_t vib_pitch_offset_scnd = 0;

    //modulation LFO state
    volatile uint32_t mod_count = 0;
    volatile uint32_t mod_phase = TRIANGLE_INITIAL_PHASE;
    volatile int32_t mod_pitch_offset_init = 0;
    volatile int32_t mod_pitch_offset_scnd = 0;
};