HexoDSP/src/dsp/node_noise.rs

// Copyright (c) 2021 Weird Constructor <weirdconstructor@gmail.com>
// This is a part of HexoDSP. Released under (A)GPLv3 or any later.
// See README.md and COPYING for details.

use crate::nodes::{NodeAudioContext, NodeExecContext};
use crate::dsp::{NodeId, SAtom, ProcBuf, DspNode, LedPhaseVals, NodeContext};
use crate::dsp::helpers::Rng;

#[macro_export]
macro_rules! fa_noise_mode { ($formatter: expr, $v: expr, $denorm_v: expr) => { {
        let s =
            match ($v.round() as usize) {
                0  => "Bipolar",
                1  => "Unipolar",
                _  => "?",
            };
        write!($formatter, "{}", s)
} } }

/// A simple amplifier
#[derive(Debug, Clone)]
pub struct Noise {
    seed:   u64,
    rng:    Rng,
}

impl Noise {
    pub fn new(nid: &NodeId) -> Self {
        let mut rng = Rng::new();
        rng.seed(
            (0x193a67f4a8a6d769_u64).wrapping_add(
                0x131415 * (nid.instance() as u64 + 1)));

        Self {
            seed: nid.instance() as u64,
            rng,
        }
    }

    pub const atv  : &'static str =
        "Noise atv\n.Attenuverter input, to attenuate or inverter \
        the noise.\nRange: (-1..1)";
    pub const offs : &'static str =
        "Noise offs\n.Offset input, that is added to the output \
        signal after attenuvertig it.\nRange: (-1..1)";
    pub const mode : &'static str =
        "Noise mode\nYou can switch between 'Bipolar' noise, which \
         uses the full range from -1 to 1, or 'Unipolar' noise that \
         only uses the range from 0 to 1.";
    pub const sig  : &'static str =
        "Noise sig\nThe noise output.\nRange: (-1..1)";

    pub const DESC : &'static str =
r#"A Simple Noise Oscillator

This is a very simple noise oscillator, which can be used for any kind of audio rate noise.
And as a source for sample & hold like nodes to generate low frequency modulation.
"#;
pub const HELP : &'static str =
r#"Noise - A Simple Noise Oscillator

This is a very simple noise oscillator, which can be used for
any kind of audio rate noise. And as a source for sample & hold
like nodes to generate low frequency modulation.

The 'atv' attenuverter and 'offs' parameters control the value range
of the noise, and the 'mode' allows to switch the oscillator between
unipolar and bipolar output.
"#;
}

impl DspNode for Noise {
    fn outputs() -> usize { 1 }

    fn set_sample_rate(&mut self, _srate: f32) {
    }

    fn reset(&mut self) {
        self.rng.seed(
            (0x193a67f4a8a6d769_u64).wrapping_add(
                0x131415 * (self.seed + 1)));
    }

    #[inline]
    fn process<T: NodeAudioContext>(
        &mut self, ctx: &mut T, _ectx: &mut NodeExecContext,
        _nctx: &NodeContext,
        atoms: &[SAtom], inputs: &[ProcBuf],
        outputs: &mut [ProcBuf], ctx_vals: LedPhaseVals)
    {
        use crate::dsp::{at, out, inp, denorm};

        let mode = at::Noise::mode(atoms);
        let atv  = inp::Noise::atv(inputs);
        let offs = inp::Noise::offs(inputs);
        let out  = out::Noise::sig(outputs);

        let rng = &mut self.rng;

        if mode.i() == 0 {
            for frame in 0..ctx.nframes() {
                let s = (rng.next() * 2.0) - 1.0;
                let s = s
                    * denorm::Noise::atv(atv, frame)
                    + denorm::Noise::offs(offs, frame);
                out.write(frame, s);
            }

        } else {
            for frame in 0..ctx.nframes() {
                let s = rng.next()
                    * denorm::Noise::atv(atv, frame)
                    + denorm::Noise::offs(offs, frame);
                out.write(frame, s);
            }
        }

        let last_frame = ctx.nframes() - 1;
        ctx_vals[0].set(out.read(last_frame));
    }
}