57 lines
1.3 KiB
Rust
57 lines
1.3 KiB
Rust
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// implemented from https://cytomic.com/files/dsp/SvfLinearTrapOptimised2.pdf
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// thanks, andy!
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use std::f32::consts;
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use packed_simd::f32x4;
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pub struct SVFSimper {
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pub a1: f32x4,
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pub a2: f32x4,
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pub a3: f32x4,
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pub ic1eq: f32x4,
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pub ic2eq: f32x4
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}
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impl SVFSimper {
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pub fn new(cutoff: f32, resonance: f32, sample_rate: f32) -> Self {
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let g = (consts::PI * (cutoff / sample_rate)).tan();
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let k = 2f32 - (1.9f32 * resonance.min(1f32).max(0f32));
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let a1 = 1.0 / (1.0 + (g * (g + k)));
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let a2 = g * a1;
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let a3 = g * a2;
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SVFSimper {
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a1: f32x4::splat(a1),
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a2: f32x4::splat(a2),
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a3: f32x4::splat(a3),
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ic1eq: f32x4::splat(0.0),
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ic2eq: f32x4::splat(0.0)
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}
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}
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pub fn set(&mut self, cutoff: f32, resonance: f32, sample_rate: f32) {
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let new = Self::new(cutoff, resonance, sample_rate);
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self.a1 = new.a1;
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self.a2 = new.a2;
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self.a3 = new.a3;
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}
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#[inline]
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pub fn process(&mut self, v0: f32x4) -> f32x4 {
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let v3 = v0 - self.ic2eq;
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let v1 = (self.a1 * self.ic1eq) + (self.a2 * v3);
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let v2 = self.ic2eq + (self.a2 * self.ic1eq) + (self.a3 * v3);
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self.ic1eq = (2.0 * v1) - self.ic1eq;
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self.ic2eq = (2.0 * v2) - self.ic2eq;
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v2
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}
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}
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