// Copyright (c) 2021 Weird Constructor // This is a part of HexoDSP. Released under (A)GPLv3 or any later. // See README.md and COPYING for details. /// Logarithmic table size of the table in [fast_cos] / [fast_sin]. static FAST_COS_TAB_LOG2_SIZE : usize = 9; /// Table size of the table in [fast_cos] / [fast_sin]. static FAST_COS_TAB_SIZE : usize = 1 << FAST_COS_TAB_LOG2_SIZE; // =512 /// The wave table of [fast_cos] / [fast_sin]. static mut FAST_COS_TAB : [f32; 513] = [0.0; 513]; /// Initializes the cosine wave table for [fast_cos] and [fast_sin]. pub fn init_cos_tab() { for i in 0..(FAST_COS_TAB_SIZE+1) { let phase : f32 = (i as f32) * ((std::f32::consts::TAU) / (FAST_COS_TAB_SIZE as f32)); unsafe { // XXX: note: mutable statics can be mutated by multiple // threads: aliasing violations or data races // will cause undefined behavior FAST_COS_TAB[i] = phase.cos(); } } } /// Internal phase increment/scaling for [fast_cos]. const PHASE_SCALE : f32 = 1.0_f32 / (std::f32::consts::TAU); /// A faster implementation of cosine. It's not that much faster than /// Rust's built in cosine function. But YMMV. /// /// Don't forget to call [init_cos_tab] before using this! /// ///``` /// use hexodsp::dsp::helpers::*; /// init_cos_tab(); // Once on process initialization. /// /// // ... /// assert!((fast_cos(std::f32::consts::PI) - -1.0).abs() < 0.001); ///``` pub fn fast_cos(mut x: f32) -> f32 { x = x.abs(); // cosine is symmetrical around 0, let's get rid of negative values // normalize range from 0..2PI to 1..2 let phase = x * PHASE_SCALE; let index = FAST_COS_TAB_SIZE as f32 * phase; let fract = index.fract(); let index = index.floor() as usize; unsafe { // XXX: note: mutable statics can be mutated by multiple // threads: aliasing violations or data races // will cause undefined behavior let left = FAST_COS_TAB[index as usize]; let right = FAST_COS_TAB[index as usize + 1]; return left + (right - left) * fract; } } /// A faster implementation of sine. It's not that much faster than /// Rust's built in sine function. But YMMV. /// /// Don't forget to call [init_cos_tab] before using this! /// ///``` /// use hexodsp::dsp::helpers::*; /// init_cos_tab(); // Once on process initialization. /// /// // ... /// assert!((fast_sin(0.5 * std::f32::consts::PI) - 1.0).abs() < 0.001); ///``` pub fn fast_sin(x: f32) -> f32 { fast_cos(x - (std::f32::consts::PI / 2.0)) } /// A wavetable filled entirely with white noise. /// Don't forget to call [init_white_noise_tab] before using it. static mut WHITE_NOISE_TAB: [f64; 1024] = [0.0; 1024]; /// Initializes [WHITE_NOISE_TAB]. pub fn init_white_noise_tab() { let mut rng = RandGen::new(); unsafe { for i in 0..WHITE_NOISE_TAB.len() { WHITE_NOISE_TAB[i as usize] = rng.next_open01(); } } } #[derive(Debug, Copy, Clone, PartialEq)] /// Random number generator based on xoroshiro128. /// Requires two internal state variables. You may prefer [SplitMix64] or [Rng]. pub struct RandGen { r: [u64; 2], } // Taken from xoroshiro128 crate under MIT License // Implemented by Matthew Scharley (Copyright 2016) // https://github.com/mscharley/rust-xoroshiro128 /// Given the mutable `state` generates the next pseudo random number. pub fn next_xoroshiro128(state: &mut [u64; 2]) -> u64 { let s0: u64 = state[0]; let mut s1: u64 = state[1]; let result: u64 = s0.wrapping_add(s1); s1 ^= s0; state[0] = s0.rotate_left(55) ^ s1 ^ (s1 << 14); // a, b state[1] = s1.rotate_left(36); // c result } // Taken from rand::distributions // Licensed under the Apache License, Version 2.0 // Copyright 2018 Developers of the Rand project. /// Maps any `u64` to a `f64` in the open interval `[0.0, 1.0)`. pub fn u64_to_open01(u: u64) -> f64 { use core::f64::EPSILON; let float_size = std::mem::size_of::() as u32 * 8; let fraction = u >> (float_size - 52); let exponent_bits: u64 = (1023 as u64) << 52; f64::from_bits(fraction | exponent_bits) - (1.0 - EPSILON / 2.0) } impl RandGen { pub fn new() -> Self { RandGen { r: [0x193a6754a8a7d469, 0x97830e05113ba7bb], } } /// Next random unsigned 64bit integer. pub fn next(&mut self) -> u64 { next_xoroshiro128(&mut self.r) } /// Next random float between `[0.0, 1.0)`. pub fn next_open01(&mut self) -> f64 { u64_to_open01(self.next()) } } #[derive(Debug, Copy, Clone)] /// Random number generator based on [SplitMix64]. /// Requires two internal state variables. You may prefer [SplitMix64] or [Rng]. pub struct Rng { sm: SplitMix64, } impl Rng { pub fn new() -> Self { Self { sm: SplitMix64::new(0x193a67f4a8a6d769) } } pub fn seed(&mut self, seed: u64) { println!("SEED {}", seed); self.sm = SplitMix64::new(seed); } #[inline] pub fn next(&mut self) -> f32 { self.sm.next_open01() as f32 } } // Copyright 2018 Developers of the Rand project. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. //- splitmix64 (http://xoroshiro.di.unimi.it/splitmix64.c) // /// A splitmix64 random number generator. /// /// The splitmix algorithm is not suitable for cryptographic purposes, but is /// very fast and has a 64 bit state. /// /// The algorithm used here is translated from [the `splitmix64.c` /// reference source code](http://xoshiro.di.unimi.it/splitmix64.c) by /// Sebastiano Vigna. For `next_u32`, a more efficient mixing function taken /// from [`dsiutils`](http://dsiutils.di.unimi.it/) is used. #[derive(Debug, Copy, Clone)] pub struct SplitMix64(pub u64); /// Internal random constant for [SplitMix64]. const PHI: u64 = 0x9e3779b97f4a7c15; impl SplitMix64 { pub fn new(seed: u64) -> Self { Self(seed) } pub fn new_from_i64(seed: i64) -> Self { Self::new(u64::from_be_bytes(seed.to_be_bytes())) } #[inline] pub fn next_u64(&mut self) -> u64 { self.0 = self.0.wrapping_add(PHI); let mut z = self.0; z = (z ^ (z >> 30)).wrapping_mul(0xbf58476d1ce4e5b9); z = (z ^ (z >> 27)).wrapping_mul(0x94d049bb133111eb); z ^ (z >> 31) } #[inline] pub fn next_i64(&mut self) -> i64 { i64::from_be_bytes( self.next_u64().to_be_bytes()) } #[inline] pub fn next_open01(&mut self) -> f64 { u64_to_open01(self.next_u64()) } } #[inline] pub fn crossfade(v1: f32, v2: f32, mix: f32) -> f32 { v1 * (1.0 - mix) + v2 * mix } #[inline] pub fn clamp(f: f32, min: f32, max: f32) -> f32 { if f < min { min } else if f > max { max } else { f } } pub fn square_135(phase: f32) -> f32 { fast_sin(phase) + fast_sin(phase * 3.0) / 3.0 + fast_sin(phase * 5.0) / 5.0 } pub fn square_35(phase: f32) -> f32 { fast_sin(phase * 3.0) / 3.0 + fast_sin(phase * 5.0) / 5.0 } // note: MIDI note value? pub fn note_to_freq(note: f32) -> f32 { 440.0 * (2.0_f32).powf((note - 69.0) / 12.0) } // Ported from LMMS under GPLv2 // * DspEffectLibrary.h - library with template-based inline-effects // * Copyright (c) 2006-2014 Tobias Doerffel // /// Signal distortion /// ```text /// gain: 0.1 - 5.0 default = 1.0 /// threshold: 0.0 - 100.0 default = 0.8 /// i: signal /// ``` pub fn f_distort(gain: f32, threshold: f32, i: f32) -> f32 { gain * ( i * ( i.abs() + threshold ) / ( i * i + (threshold - 1.0) * i.abs() + 1.0 )) } // Ported from LMMS under GPLv2 // * DspEffectLibrary.h - library with template-based inline-effects // * Copyright (c) 2006-2014 Tobias Doerffel // /// Foldback Signal distortion /// ```text /// gain: 0.1 - 5.0 default = 1.0 /// threshold: 0.0 - 100.0 default = 0.8 /// i: signal /// ``` pub fn f_fold_distort(gain: f32, threshold: f32, i: f32) -> f32 { if i >= threshold || i < -threshold { gain * (( ((i - threshold) % threshold * 4.0).abs() - threshold * 2.0).abs() - threshold) } else { gain * i } } pub fn lerp(x: f32, a: f32, b: f32) -> f32 { (a * (1.0 - x)) + (b * x) } pub fn lerp64(x: f64, a: f64, b: f64) -> f64 { (a * (1.0 - x)) + (b * x) } pub fn p2range(x: f32, a: f32, b: f32) -> f32 { lerp(x, a, b) } pub fn p2range_exp(x: f32, a: f32, b: f32) -> f32 { let x = x * x; (a * (1.0 - x)) + (b * x) } pub fn p2range_exp4(x: f32, a: f32, b: f32) -> f32 { let x = x * x * x * x; (a * (1.0 - x)) + (b * x) } pub fn range2p(v: f32, a: f32, b: f32) -> f32 { ((v - a) / (b - a)).abs() } pub fn range2p_exp(v: f32, a: f32, b: f32) -> f32 { (((v - a) / (b - a)).abs()).sqrt() } pub fn range2p_exp4(v: f32, a: f32, b: f32) -> f32 { (((v - a) / (b - a)).abs()).sqrt().sqrt() } /// ```text /// gain: 24.0 - -90.0 default = 0.0 /// ``` pub fn gain2coef(gain: f32) -> f32 { if gain > -90.0 { 10.0_f32.powf(gain * 0.05) } else { 0.0 } } // quickerTanh / quickerTanh64 credits to mopo synthesis library: // Under GPLv3 or any later. // Little IO // Matt Tytel pub fn quicker_tanh64(v: f64) -> f64 { let square = v * v; v / (1.0 + square / (3.0 + square / 5.0)) } pub fn quicker_tanh(v: f32) -> f32 { let square = v * v; v / (1.0 + square / (3.0 + square / 5.0)) } // quickTanh / quickTanh64 credits to mopo synthesis library: // Under GPLv3 or any later. // Little IO // Matt Tytel pub fn quick_tanh64(v: f64) -> f64 { let abs_v = v.abs(); let square = v * v; let num = v * (2.45550750702956 + 2.45550750702956 * abs_v + square * (0.893229853513558 + 0.821226666969744 * abs_v)); let den = 2.44506634652299 + (2.44506634652299 + square) * (v + 0.814642734961073 * v * abs_v).abs(); num / den } pub fn quick_tanh(v: f32) -> f32 { let abs_v = v.abs(); let square = v * v; let num = v * (2.45550750702956 + 2.45550750702956 * abs_v + square * (0.893229853513558 + 0.821226666969744 * abs_v)); let den = 2.44506634652299 + (2.44506634652299 + square) * (v + 0.814642734961073 * v * abs_v).abs(); num / den } /// A helper function for exponential envelopes. /// It's a bit faster than calling the `pow` function of Rust. /// /// * `x` the input value /// * `v' the shape value. /// Which is linear at `0.5`, the forth root of `x` at `1.0` and x to the power /// of 4 at `0.0`. You can vary `v` as you like. /// ///``` /// use hexodsp::dsp::helpers::*; /// /// assert!(((sqrt4_to_pow4(0.25, 0.0) - 0.25_f32 * 0.25 * 0.25 * 0.25) /// .abs() - 1.0) /// < 0.0001); /// /// assert!(((sqrt4_to_pow4(0.25, 1.0) - (0.25_f32).sqrt().sqrt()) /// .abs() - 1.0) /// < 0.0001); /// /// assert!(((sqrt4_to_pow4(0.25, 0.5) - 0.25_f32).abs() - 1.0) < 0.0001); ///``` #[inline] pub fn sqrt4_to_pow4(x: f32, v: f32) -> f32 { if v > 0.75 { let xsq1 = x.sqrt(); let xsq = xsq1.sqrt(); let v = (v - 0.75) * 4.0; xsq1 * (1.0 - v) + xsq * v } else if v > 0.5 { let xsq = x.sqrt(); let v = (v - 0.5) * 4.0; x * (1.0 - v) + xsq * v } else if v > 0.25 { let xx = x * x; let v = (v - 0.25) * 4.0; x * v + xx * (1.0 - v) } else { let xx = x * x; let xxxx = xx * xx; let v = v * 4.0; xx * v + xxxx * (1.0 - v) } } /// A-100 Eurorack states, that a trigger is usually 2-10 milliseconds. const TRIG_SIGNAL_LENGTH_MS : f32 = 2.0; #[derive(Debug, Clone, Copy)] pub struct TrigSignal { length: u32, scount: u32, } impl TrigSignal { pub fn new() -> Self { Self { length: ((44100.0 * TRIG_SIGNAL_LENGTH_MS) / 1000.0).ceil() as u32, scount: 0, } } pub fn reset(&mut self) { self.scount = 0; } pub fn set_sample_rate(&mut self, srate: f32) { self.length = ((srate * TRIG_SIGNAL_LENGTH_MS) / 1000.0).ceil() as u32; self.scount = 0; } #[inline] pub fn trigger(&mut self) { self.scount = self.length; } #[inline] pub fn next(&mut self) -> f32 { if self.scount > 0 { self.scount -= 1; 1.0 } else { 0.0 } } } impl Default for TrigSignal { fn default() -> Self { Self::new() } } #[derive(Debug, Clone, Copy)] pub struct Trigger { triggered: bool, } impl Trigger { pub fn new() -> Self { Self { triggered: false, } } #[inline] pub fn reset(&mut self) { self.triggered = false; } #[inline] pub fn check_trigger(&mut self, input: f32) -> bool { if self.triggered { if input <= 0.25 { self.triggered = false; } false } else if input > 0.75 { self.triggered = true; true } else { false } } } #[derive(Debug, Clone, Copy)] pub struct TriggerPhaseClock { clock_phase: f64, clock_inc: f64, prev_trigger: bool, clock_samples: u32, } impl TriggerPhaseClock { pub fn new() -> Self { Self { clock_phase: 0.0, clock_inc: 0.0, prev_trigger: true, clock_samples: 0, } } #[inline] pub fn reset(&mut self) { self.clock_samples = 0; self.clock_inc = 0.0; self.prev_trigger = true; self.clock_samples = 0; } #[inline] pub fn sync(&mut self) { self.clock_phase = 0.0; } #[inline] pub fn next_phase(&mut self, clock_limit: f64, trigger_in: f32) -> f64 { if self.prev_trigger { if trigger_in <= 0.25 { self.prev_trigger = false; } } else if trigger_in > 0.75 { self.prev_trigger = true; if self.clock_samples > 0 { self.clock_inc = 1.0 / (self.clock_samples as f64); } self.clock_samples = 0; } self.clock_samples += 1; self.clock_phase += self.clock_inc; self.clock_phase = self.clock_phase % clock_limit; self.clock_phase } } #[derive(Debug, Clone, Copy)] pub struct TriggerSampleClock { prev_trigger: bool, clock_samples: u32, counter: u32, } impl TriggerSampleClock { pub fn new() -> Self { Self { prev_trigger: true, clock_samples: 0, counter: 0, } } #[inline] pub fn reset(&mut self) { self.clock_samples = 0; self.counter = 0; } #[inline] pub fn next(&mut self, trigger_in: f32) -> u32 { if self.prev_trigger { if trigger_in <= 0.25 { self.prev_trigger = false; } } else if trigger_in > 0.75 { self.prev_trigger = true; self.clock_samples = self.counter; self.counter = 0; } self.counter += 1; self.clock_samples } } /// Default size of the delay buffer: 5 seconds at 8 times 48kHz const DEFAULT_DELAY_BUFFER_SAMPLES : usize = 8 * 48000 * 5; #[derive(Debug, Clone)] pub struct DelayBuffer { data: Vec, wr: usize, srate: f32, } impl DelayBuffer { pub fn new() -> Self { Self { data: vec![0.0; DEFAULT_DELAY_BUFFER_SAMPLES], wr: 0, srate: 44100.0, } } pub fn new_with_size(size: usize) -> Self { Self { data: vec![0.0; size], wr: 0, srate: 44100.0, } } pub fn set_sample_rate(&mut self, srate: f32) { self.srate = srate; } pub fn reset(&mut self) { self.data.fill(0.0); self.wr = 0; } /// Feed one sample into the delay line and increment the write pointer. /// Please note: For sample accurate feedback you need to retrieve the /// output of the delay line before feeding in a new signal. #[inline] pub fn feed(&mut self, input: f32) { self.data[self.wr] = input; self.wr = (self.wr + 1) % self.data.len(); } #[inline] pub fn cubic_interpolate_at(&self, delay_time: f32) -> f32 { let data = &self.data[..]; let len = data.len(); let s_offs = (delay_time * self.srate) / 1000.0; let offs = s_offs.floor() as usize % len; let fract = s_offs.fract(); let i = (self.wr + len) - offs; // Hermite interpolation, take from // https://github.com/eric-wood/delay/blob/main/src/delay.rs#L52 // // Thanks go to Eric Wood! // // For the interpolation code: // MIT License, Copyright (c) 2021 Eric Wood let xm1 = data[(i - 1) % len]; let x0 = data[i % len]; let x1 = data[(i + 1) % len]; let x2 = data[(i + 2) % len]; let c = (x1 - xm1) * 0.5; let v = x0 - x1; let w = c + v; let a = w + v + (x2 - x0) * 0.5; let b_neg = w + a; let fract = fract as f32; (((a * fract) - b_neg) * fract + c) * fract + x0 } #[inline] pub fn nearest_at(&self, delay_time: f32) -> f32 { let len = self.data.len(); let offs = (delay_time * self.srate).floor() as usize % len; let idx = ((self.wr + len) - offs) % len; self.data[idx] } #[inline] pub fn at(&self, delay_sample_count: usize) -> f32 { let len = self.data.len(); let idx = ((self.wr + len) - delay_sample_count) % len; self.data[idx] } } /// Default size of the delay buffer: 1 seconds at 8 times 48kHz const DEFAULT_ALLPASS_COMB_SAMPLES : usize = 8 * 48000; #[derive(Debug, Clone)] pub struct AllPass { delay: DelayBuffer, } impl AllPass { pub fn new() -> Self { Self { delay: DelayBuffer::new_with_size(DEFAULT_ALLPASS_COMB_SAMPLES), } } pub fn set_sample_rate(&mut self, srate: f32) { self.delay.set_sample_rate(srate); } pub fn reset(&mut self) { self.delay.reset(); } #[inline] pub fn next(&mut self, time: f32, g: f32, v: f32) -> f32 { let s = self.delay.cubic_interpolate_at(time); self.delay.feed(v + s * g); s + -1.0 * g * v } } #[derive(Debug, Clone)] pub struct Comb { delay: DelayBuffer, } impl Comb { pub fn new() -> Self { Self { delay: DelayBuffer::new_with_size(DEFAULT_ALLPASS_COMB_SAMPLES), } } pub fn set_sample_rate(&mut self, srate: f32) { self.delay.set_sample_rate(srate); } pub fn reset(&mut self) { self.delay.reset(); } #[inline] pub fn next_feedback(&mut self, time: f32, g: f32, v: f32) -> f32 { let s = self.delay.cubic_interpolate_at(time); self.delay.feed(v + s * g); v } #[inline] pub fn next_feedforward(&mut self, time: f32, g: f32, v: f32) -> f32 { let s = self.delay.cubic_interpolate_at(time); self.delay.feed(v); v + s * g } } // one pole lp from valley rack free: // https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Common/DSP/OnePoleFilters.cpp #[inline] /// Process a very simple one pole 6dB low pass filter. /// Useful in various applications, from usage in a synthesizer to /// damping stuff in a reverb/delay. /// /// * `input` - Input sample /// * `freq` - Frequency between 1.0 and 22000.0Hz /// * `israte` - 1.0 / samplerate /// * `z` - The internal one sample buffer of the filter. /// ///``` /// use hexodsp::dsp::helpers::*; /// /// let samples = vec![0.0; 44100]; /// let mut z = 0.0; /// let mut freq = 1000.0; /// /// for s in samples.iter() { /// let s_out = /// process_1pole_lowpass(*s, freq, 1.0 / 44100.0, &mut z); /// // ... do something with the result here. /// } ///``` pub fn process_1pole_lowpass(input: f32, freq: f32, israte: f32, z: &mut f32) -> f32 { let b = (-std::f32::consts::TAU * freq * israte).exp(); let a = 1.0 - b; *z = a * input + *z * b; *z } // one pole hp from valley rack free: // https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Common/DSP/OnePoleFilters.cpp #[inline] /// Process a very simple one pole 6dB high pass filter. /// Useful in various applications. /// /// * `input` - Input sample /// * `freq` - Frequency between 1.0 and 22000.0Hz /// * `israte` - 1.0 / samplerate /// * `z` - The first internal buffer of the filter. /// * `y` - The second internal buffer of the filter. /// ///``` /// use hexodsp::dsp::helpers::*; /// /// let samples = vec![0.0; 44100]; /// let mut z = 0.0; /// let mut y = 0.0; /// let mut freq = 1000.0; /// /// for s in samples.iter() { /// let s_out = /// process_1pole_highpass(*s, freq, 1.0 / 44100.0, &mut z, &mut y); /// // ... do something with the result here. /// } ///``` pub fn process_1pole_highpass(input: f32, freq: f32, israte: f32, z: &mut f32, y: &mut f32) -> f32 { let b = (-std::f32::consts::TAU * freq * israte).exp(); let a = (1.0 + b) / 2.0; let v = a * input - a * *z + b * *y; *y = v; *z = input; v } // one pole from: // http://www.willpirkle.com/Downloads/AN-4VirtualAnalogFilters.pdf // (page 5) #[inline] /// Process a very simple one pole 6dB low pass filter in TPT form. /// Useful in various applications, from usage in a synthesizer to /// damping stuff in a reverb/delay. /// /// * `input` - Input sample /// * `freq` - Frequency between 1.0 and 22000.0Hz /// * `israte` - 1.0 / samplerate /// * `z` - The internal one sample buffer of the filter. /// ///``` /// use hexodsp::dsp::helpers::*; /// /// let samples = vec![0.0; 44100]; /// let mut z = 0.0; /// let mut freq = 1000.0; /// /// for s in samples.iter() { /// let s_out = /// process_1pole_tpt_highpass(*s, freq, 1.0 / 44100.0, &mut z); /// // ... do something with the result here. /// } ///``` pub fn process_1pole_tpt_lowpass(input: f32, freq: f32, israte: f32, z: &mut f32) -> f32 { let g = (std::f32::consts::PI * freq * israte).tan(); let a = g / (1.0 + g); let v1 = a * (input - *z); let v2 = v1 + *z; *z = v2 + v1; // let (m0, m1) = (0.0, 1.0); // (m0 * input + m1 * v2) as f32); v2 } // one pole from: // http://www.willpirkle.com/Downloads/AN-4VirtualAnalogFilters.pdf // (page 5) #[inline] /// Process a very simple one pole 6dB high pass filter in TPT form. /// Useful in various applications. /// /// * `input` - Input sample /// * `freq` - Frequency between 1.0 and 22000.0Hz /// * `israte` - 1.0 / samplerate /// * `z` - The internal one sample buffer of the filter. /// ///``` /// use hexodsp::dsp::helpers::*; /// /// let samples = vec![0.0; 44100]; /// let mut z = 0.0; /// let mut freq = 1000.0; /// /// for s in samples.iter() { /// let s_out = /// process_1pole_tpt_lowpass(*s, freq, 1.0 / 44100.0, &mut z); /// // ... do something with the result here. /// } ///``` pub fn process_1pole_tpt_highpass(input: f32, freq: f32, israte: f32, z: &mut f32) -> f32 { let g = (std::f32::consts::PI * freq * israte).tan(); let a1 = g / (1.0 + g); let v1 = a1 * (input - *z); let v2 = v1 + *z; *z = v2 + v1; input - v2 } /// The internal oversampling factor of [process_hal_chamberlin_svf]. const FILTER_OVERSAMPLE_HAL_CHAMBERLIN : usize = 2; // Hal Chamberlin's State Variable (12dB/oct) filter // https://www.earlevel.com/main/2003/03/02/the-digital-state-variable-filter/ // Inspired by SynthV1 by Rui Nuno Capela, under the terms of // GPLv2 or any later: /// Process a HAL Chamberlin filter with two delays/state variables. /// The filter does internal oversampling with very simple decimation to /// rise the stability for cutoff frequency up to 16kHz. /// /// * `input` - Input sample. /// * `freq` - Frequency in Hz. Please keep it inside 0.0 to 16000.0 Hz! /// otherwise the filter becomes unstable. /// * `res` - Resonance from 0.0 to 0.99. Resonance of 1.0 is not recommended, /// as the filter will then oscillate itself out of control. /// * `israte` - 1.0 divided by the sampling rate (eg. 1.0 / 44100.0). /// * `band` - First state variable, containing the band pass result /// after processing. /// * `low` - Second state variable, containing the low pass result /// after processing. /// /// Returned are the results of the high and notch filter. /// ///``` /// use hexodsp::dsp::helpers::*; /// /// let samples = vec![0.0; 44100]; /// let mut band = 0.0; /// let mut low = 0.0; /// let mut freq = 1000.0; /// /// for s in samples.iter() { /// let (high, notch) = /// process_hal_chamberlin_svf( /// *s, freq, 0.5, 1.0 / 44100.0, &mut band, &mut low); /// // ... do something with the result here. /// } ///``` #[inline] pub fn process_hal_chamberlin_svf( input: f32, freq: f32, res: f32, israte: f32, band: &mut f32, low: &mut f32) -> (f32, f32) { let q = 1.0 - res; let cutoff = 2.0 * (std::f32::consts::PI * freq * 0.5 * israte).sin(); let mut high = 0.0; let mut notch = 0.0; for _ in 0..FILTER_OVERSAMPLE_HAL_CHAMBERLIN { *low += cutoff * *band; high = input - *low - q * *band; *band += cutoff * high; notch = high + *low; } //d// println!("q={:4.2} cut={:8.3} freq={:8.1} LP={:8.3} HP={:8.3} BP={:8.3} N={:8.3}", //d// q, cutoff, freq, *low, high, *band, notch); (high, notch) } /// This function processes a Simper SVF. It's a much newer algorithm /// for filtering and provides easy to calculate multiple outputs. /// /// * `input` - Input sample. /// * `freq` - Frequency in Hz. /// otherwise the filter becomes unstable. /// * `res` - Resonance from 0.0 to 0.99. Resonance of 1.0 is not recommended, /// as the filter will then oscillate itself out of control. /// * `israte` - 1.0 divided by the sampling rate (eg. 1.0 / 44100.0). /// * `band` - First state variable, containing the band pass result /// after processing. /// * `low` - Second state variable, containing the low pass result /// after processing. /// /// This function returns the low pass, band pass and high pass signal. /// For a notch or peak filter signal, please consult the following example: /// ///``` /// use hexodsp::dsp::helpers::*; /// /// let samples = vec![0.0; 44100]; /// let mut ic1eq = 0.0; /// let mut ic2eq = 0.0; /// let mut freq = 1000.0; /// /// for s in samples.iter() { /// let (low, band, high) = /// process_simper_svf( /// *s, freq, 0.5, 1.0 / 44100.0, &mut ic1eq, &mut ic2eq); /// /// // You can easily calculate the notch and peak results too: /// let notch = low + high; /// let peak = low - high; /// // ... do something with the result here. /// } ///``` // Simper SVF taken from baseplug (Rust crate) example svf_simper.rs: // implemented from https://cytomic.com/files/dsp/SvfLinearTrapOptimised2.pdf // thanks, andy! #[inline] pub fn process_simper_svf( input: f32, freq: f32, res: f32, israte: f32, ic1eq: &mut f32, ic2eq: &mut f32 ) -> (f32, f32, f32) { let g = (std::f32::consts::PI * freq * israte).tan(); // XXX: the 1.989 were tuned by hand, so the resonance is more audible. let k = 2f32 - (1.989f32 * res); let a1 = 1.0 / (1.0 + (g * (g + k))); let a2 = g * a1; let a3 = g * a2; let v3 = input - *ic2eq; let v1 = (a1 * *ic1eq) + (a2 * v3); let v2 = *ic2eq + (a2 * *ic1eq) + (a3 * v3); *ic1eq = (2.0 * v1) - *ic1eq; *ic2eq = (2.0 * v2) - *ic2eq; // low = v2 // band = v1 // high = input - k * v1 - v2 // notch = low + high = input - k * v1 // peak = low - high = 2 * v2 - input + k * v1 // all = low + high - k * band = input - 2 * k * v1 (v2, v1, input - k * v1 - v2) } // translated from Odin 2 Synthesizer Plugin // Copyright (C) 2020 TheWaveWarden // under GPLv3 or any later #[derive(Debug, Clone)] pub struct DCBlockFilter { xm1: f64, ym1: f64, r: f64, } impl DCBlockFilter { pub fn new() -> Self { Self { xm1: 0.0, ym1: 0.0, r: 0.995, } } pub fn reset(&mut self) { self.xm1 = 0.0; self.ym1 = 0.0; } pub fn set_sample_rate(&mut self, srate: f32) { self.r = 0.995; if srate > 90000.0 { self.r = 0.9965; } else if srate > 120000.0 { self.r = 0.997; } } pub fn next(&mut self, input: f32) -> f32 { let y = input as f64 - self.xm1 + self.r * self.ym1; self.xm1 = input as f64; self.ym1 = y; y as f32 } } #[cfg(test)] mod tests { use super::*; #[test] fn check_range2p_exp() { let a = p2range_exp(0.5, 1.0, 100.0); let x = range2p_exp(a, 1.0, 100.0); assert!((x - 0.5).abs() < std::f32::EPSILON); } #[test] fn check_range2p() { let a = p2range(0.5, 1.0, 100.0); let x = range2p(a, 1.0, 100.0); assert!((x - 0.5).abs() < std::f32::EPSILON); } }