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impl trait on type alias instead of newtypes

master
Robert Jördens 2021-02-17 16:13:30 +01:00
parent b7e4f402aa
commit b69131f5f5
3 changed files with 34 additions and 32 deletions
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21
dsp/src/iir.rs
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@ -11,8 +11,7 @@ use core::f32;
/// To represent the IIR coefficients, this contains the feed-forward
/// coefficients (b0, b1, b2) followd by the negated feed-back coefficients
/// (-a1, -a2), all five normalized such that a0 = 1.
#[derive(Copy, Clone, Default, Deserialize, Serialize)]
pub struct Vec5(pub [f32; 5]);
pub type Vec5 = [f32; 5];
/// IIR configuration.
///
@ -50,7 +49,7 @@ pub struct IIR {
impl IIR {
pub const fn new(gain: f32, y_min: f32, y_max: f32) -> Self {
Self {
ba: Vec5([gain, 0., 0., 0., 0.]),
ba: [gain, 0., 0., 0., 0.],
y_offset: 0.,
y_min,
y_max,
@ -84,13 +83,13 @@ impl IIR {
}
(a1, b0, b1)
};
self.ba.0.copy_from_slice(&[b0, b1, 0., a1, 0.]);
self.ba.copy_from_slice(&[b0, b1, 0., a1, 0.]);
Ok(())
}
/// Compute the overall (DC feed-forward) gain.
pub fn get_k(&self) -> f32 {
self.ba.0[..3].iter().sum()
self.ba[..3].iter().sum()
}
/// Compute input-referred (`x`) offset from output (`y`) offset.
@ -118,21 +117,21 @@ impl IIR {
/// * `xy` - Current filter state.
/// * `x0` - New input.
pub fn update(&self, xy: &mut Vec5, x0: f32) -> f32 {
let n = self.ba.0.len();
debug_assert!(xy.0.len() == n);
let n = self.ba.len();
debug_assert!(xy.len() == n);
// `xy` contains x0 x1 y0 y1 y2
// Increment time x1 x2 y1 y2 y3
// Shift x1 x1 x2 y1 y2
// This unrolls better than xy.rotate_right(1)
xy.0.copy_within(0..n - 1, 1);
xy.copy_within(0..n - 1, 1);
// Store x0 x0 x1 x2 y1 y2
xy.0[0] = x0;
xy[0] = x0;
// Compute y0 by multiply-accumulate
let y0 = macc(self.y_offset, &xy.0, &self.ba.0);
let y0 = macc(self.y_offset, xy, &self.ba);
// Limit y0
let y0 = max(self.y_min, min(self.y_max, y0));
// Store y0 x0 x1 y0 y1 y2
xy.0[n / 2] = y0;
xy[n / 2] = y0;
y0
}
}

27
dsp/src/iir_int.rs
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@ -4,10 +4,9 @@ use serde::{Deserialize, Serialize};
/// Generic vector for integer IIR filter.
/// This struct is used to hold the x/y input/output data vector or the b/a coefficient
/// vector.
#[derive(Copy, Clone, Default, Deserialize, Serialize)]
pub struct Vec5(pub [i32; 5]);
pub type Vec5 = [i32; 5];
impl Vec5 {
trait Coeff {
/// Lowpass biquad filter using cutoff and sampling frequencies. Taken from:
/// https://webaudio.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html
///
@ -19,7 +18,11 @@ impl Vec5 {
///
/// # Returns
/// 2nd-order IIR filter coefficients in the form [b0,b1,b2,a1,a2]. a0 is set to -1.
pub fn lowpass(f: f64, q: f64, k: f64) -> Self {
fn lowpass(f: f64, q: f64, k: f64) -> Self;
}
impl Coeff for Vec5 {
fn lowpass(f: f64, q: f64, k: f64) -> Self {
// 3rd order Taylor approximation of sin and cos.
let f = f * 2. * PI;
let f2 = f * f * 0.5;
@ -32,7 +35,7 @@ impl Vec5 {
let a1 = (2. * fcos / a0 + 0.5) as _;
let a2 = ((alpha - 1.) / a0 + 0.5) as _;
Self([b0, 2 * b0, b0, a1, a2])
[b0, 2 * b0, b0, a1, a2]
}
}
@ -72,21 +75,21 @@ impl IIR {
/// * `xy` - Current filter state.
/// * `x0` - New input.
pub fn update(&self, xy: &mut Vec5, x0: i32) -> i32 {
let n = self.ba.0.len();
debug_assert!(xy.0.len() == n);
let n = self.ba.len();
debug_assert!(xy.len() == n);
// `xy` contains x0 x1 y0 y1 y2
// Increment time x1 x2 y1 y2 y3
// Shift x1 x1 x2 y1 y2
// This unrolls better than xy.rotate_right(1)
xy.0.copy_within(0..n - 1, 1);
xy.copy_within(0..n - 1, 1);
// Store x0 x0 x1 x2 y1 y2
xy.0[0] = x0;
xy[0] = x0;
// Compute y0 by multiply-accumulate
let y0 = macc(0, &xy.0, &self.ba.0, IIR::SHIFT);
let y0 = macc(0, xy, &self.ba, IIR::SHIFT);
// Limit y0
// let y0 = y0.max(self.y_min).min(self.y_max);
// Store y0 x0 x1 y0 y1 y2
xy.0[n / 2] = y0;
xy[n / 2] = y0;
y0
}
}
@ -98,6 +101,6 @@ mod test {
#[test]
fn lowpass_gen() {
let ba = Vec5::lowpass(1e-5, 1. / 2f64.sqrt(), 2.);
println!("{:?}", ba.0);
println!("{:?}", ba);
}
}

18
src/bin/dual-iir.rs
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@ -33,7 +33,7 @@ const APP: () = {
net_interface: hardware::Ethernet,
// Format: iir_state[ch][cascade-no][coeff]
#[init([[iir::Vec5([0.; 5]); IIR_CASCADE_LENGTH]; 2])]
#[init([[[0.; 5]; IIR_CASCADE_LENGTH]; 2])]
iir_state: [[iir::Vec5; IIR_CASCADE_LENGTH]; 2],
#[init([[iir::IIR::new(1., -SCALE, SCALE); IIR_CASCADE_LENGTH]; 2])]
iir_ch: [[iir::IIR; IIR_CASCADE_LENGTH]; 2],
@ -158,10 +158,10 @@ const APP: () = {
let state = c.resources.iir_state.lock(|iir_state|
server::Status {
t: time,
x0: iir_state[0][0].0[0],
y0: iir_state[0][0].0[2],
x1: iir_state[1][0].0[0],
y1: iir_state[1][0].0[2],
x0: iir_state[0][0][0],
y0: iir_state[0][0][2],
x1: iir_state[1][0][0],
y1: iir_state[1][0][2],
});
Ok::<server::Status, ()>(state)
@ -170,10 +170,10 @@ const APP: () = {
"stabilizer/iir_b/state": (|| { let state = c.resources.iir_state.lock(|iir_state|
server::Status {
t: time,
x0: iir_state[0][IIR_CASCADE_LENGTH-1].0[0],
y0: iir_state[0][IIR_CASCADE_LENGTH-1].0[2],
x1: iir_state[1][IIR_CASCADE_LENGTH-1].0[0],
y1: iir_state[1][IIR_CASCADE_LENGTH-1].0[2],
x0: iir_state[0][IIR_CASCADE_LENGTH-1][0],
y0: iir_state[0][IIR_CASCADE_LENGTH-1][2],
x1: iir_state[1][IIR_CASCADE_LENGTH-1][0],
y1: iir_state[1][IIR_CASCADE_LENGTH-1][2],
});
Ok::<server::Status, ()>(state)