beeper/src/beep/osc.rs

use std::sync::Arc;
use std::time::Duration;

use parking_lot::RwLock;

use crate::beep::tween::{Tween, GainScale};
use crate::beep::sample::StereoSample;

#[derive(Clone,Debug)]
pub struct HarmonicOscillator {
    /// Amplitude fader 0..1
    pub(crate) gain: Tween,
    /// Frequency fader 1..22050
    freq: Tween,
    /// Sample rate (Hz)
    sample_rate: f32,
    /// Phase increment per sample
    phase_step: f32,
    /// Phase 0-TAU
    phase: f32,
    /// Harmonic multiple
    pub harmonic: f32,
}

impl HarmonicOscillator {
    /// New oscillator with a frequency and amplitude
    pub fn new(amp: f32, n: f32) -> Self {
        let mut o = Self {
            gain: Tween {
                actual: amp,
                target: amp,
                min: 0.0,
                max: 1.0,
                step: None,
                sample_rate: 0.0,
            },
            freq: Tween {
                actual: 440.0,
                target: 440.0,
                min: 1.0,
                max: 20000.0,
                step: None,
                sample_rate: 0.0,
            },
            phase_step: 0.0,
            sample_rate: 0.0,
            phase: 0.0,
            harmonic: n,
        };
        o.update_step();
        o
    }

    pub(crate) fn set_sample_rate(&mut self, sample_rate : f32) {
        self.sample_rate = sample_rate;
        self.gain.sample_rate = sample_rate;
        self.freq.sample_rate = sample_rate;
        self.freq.max = sample_rate / 2.0;
        self.update_step();
    }

    /// Update the step variable
    fn update_step(&mut self) {
        self.phase_step = (self.freq.actual / self.sample_rate) * std::f32::consts::TAU;
    }

    /// Get actual amplitude (0..1)
    pub fn get_amp(&self) -> f32 {
        self.gain.actual
    }

    /// Set amplitude (0..1), change at the end of the current waveform to reduce popping
    pub fn set_amp(&mut self, amp : f32) {
        self.gain.set_at_crossover(amp);
    }

    /// Set amplitude (0..1) immediate
    pub fn set_amp_imm(&mut self, amp : f32) {
        self.gain.set_immediate(amp);
    }


    /// Fade to amplitude (0..1) over a given time
    pub fn fade_amp(&mut self, amp : f32, time: Duration) {
        self.gain.fade(amp, time);
    }

    /// Get frequency value (1..22050)
    pub fn get_freq(&self) -> f32 {
        self.freq.actual
    }

    /// Set frequency (1..22050), change at the end of the current waveform to reduce popping
    pub fn set_freq(&mut self, freq : f32) {
        self.freq.set_at_crossover(freq * self.harmonic);
        self.update_step();
    }

    /// Set frequency (1..22050) immediate
    pub fn set_freq_imm(&mut self, freq : f32) {
        self.freq.set_immediate(freq * self.harmonic);
        self.update_step();
    }

    /// Fade to frequency (1..22050) over a given time
    pub fn fade_freq(&mut self, freq : f32, time: Duration) {
        self.freq.fade(freq * self.harmonic, time);
        self.update_step();
    }

    /// Take a sample. Mutable to update faders.
    pub fn sample(&mut self) -> f32 {
        if self.freq.is_fading() {
            self.freq.tick();
            self.update_step();
        }

        let ph0 = self.phase;
        self.phase = (self.phase + self.phase_step) % std::f32::consts::TAU;

        // "zero crossing detection"
        if self.phase < ph0 {
            if self.gain.is_change_scheduled_at_crossover() {
                self.gain.actual = self.gain.target;
            }

            if self.freq.is_change_scheduled_at_crossover() {
                self.freq.actual = self.freq.target;
            }
        }

        self.phase.sin() * self.gain.actual
    }
}