From 3d2c4c0c749fd322eeb57db602a1a3786039f2f9 Mon Sep 17 00:00:00 2001
From: Weird Constructor <weirdconstructor@gmail.com>
Date: Fri, 6 Aug 2021 06:05:13 +0200
Subject: [PATCH] Started implementing the Dattorro plate reverb

---
 src/dsp/dattorro.rs |  27 +++++++++++
 src/dsp/helpers.rs  | 112 ++++++++++++++++++++++++++++++++++++++++++++
 src/dsp/mod.rs      |   1 +
 3 files changed, 140 insertions(+)

diff --git a/src/dsp/dattorro.rs b/src/dsp/dattorro.rs
index 7f6d9a7..b03027b 100644
--- a/src/dsp/dattorro.rs
+++ b/src/dsp/dattorro.rs
@@ -9,4 +9,31 @@
 // ValleyRackFree Copyright (C) 2020, Valley Audio Soft, Dale Johnson
 // Adapted under the GPL-3.0-or-later License.
 
+use crate::dsp::helpers::{
+    AllPass,
+    TriSawLFO,
+    OnePoleLPF,
+    OnePoleHPF,
+    DelayBuffer,
+    DCBlockFilter
+};
 
+pub struct DattorroReverb {
+    inp_dc_block:   [DCBlockFilter; 2],
+    out_dc_block:   [DCBlockFilter; 2],
+
+    lfos: [TriSawLFO; 4],
+
+    input_hpf: OnePoleHPF,
+    input_lpf: OnePoleLPF,
+
+    pre_delay:  DelayBuffer,
+    input_apfs: [AllPass; 4],
+
+    apf1:   [AllPass; 2],
+    hpf:    [OnePoleHPF; 2],
+    lpf:    [OnePoleLPF; 2],
+    apf2:   [AllPass; 2],
+    delay1: [DelayBuffer; 2],
+    delay2: [DelayBuffer; 2],
+}
diff --git a/src/dsp/helpers.rs b/src/dsp/helpers.rs
index e2d9456..55e1293 100644
--- a/src/dsp/helpers.rs
+++ b/src/dsp/helpers.rs
@@ -844,6 +844,56 @@ pub fn process_1pole_lowpass(input: f32, freq: f32, israte: f32, z: &mut f32) ->
     *z
 }
 
+#[derive(Debug, Clone, Copy, Default)]
+pub struct OnePoleLPF {
+    israte:     f32,
+    a:          f32,
+    b:          f32,
+    freq:       f32,
+    z:          f32,
+}
+
+impl OnePoleLPF {
+    pub fn new() -> Self {
+        Self {
+            israte: 1.0 / 44100.0,
+            a:      0.0,
+            b:      0.0,
+            freq:   1000.0,
+            z:      0.0,
+        }
+    }
+
+    pub fn reset(&mut self) {
+        self.z = 0.0;
+    }
+
+    #[inline]
+    fn recalc(&mut self) {
+        self.b = (-std::f32::consts::TAU * self.freq * self.israte).exp();
+        self.a = 1.0 - self.b;
+    }
+
+    pub fn set_sample_rate(&mut self, srate: f32) {
+        self.israte = 1.0 / srate;
+        self.recalc();
+    }
+
+    #[inline]
+    pub fn set_freq(&mut self, freq: f32) {
+        if freq != self.freq {
+            self.freq = freq;
+            self.recalc();
+        }
+    }
+
+    #[inline]
+    pub fn process(&mut self, input: f32) -> f32 {
+        self.z = self.a * input + self.z * self.b;
+        self.z
+    }
+}
+
 // one pole hp from valley rack free:
 // https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Common/DSP/OnePoleFilters.cpp
 #[inline]
@@ -883,6 +933,68 @@ pub fn process_1pole_highpass(input: f32, freq: f32, israte: f32, z: &mut f32, y
     v
 }
 
+#[derive(Debug, Clone, Copy, Default)]
+pub struct OnePoleHPF {
+    israte:     f32,
+    a:          f32,
+    b:          f32,
+    freq:       f32,
+    z:          f32,
+    y:          f32,
+}
+
+impl OnePoleHPF {
+    pub fn new() -> Self {
+        Self {
+            israte: 1.0 / 44100.0,
+            a:      0.0,
+            b:      0.0,
+            freq:   1000.0,
+            z:      0.0,
+            y:      0.0,
+        }
+    }
+
+    pub fn reset(&mut self) {
+        self.z = 0.0;
+        self.y = 0.0;
+    }
+
+    #[inline]
+    fn recalc(&mut self) {
+        self.b = (-std::f32::consts::TAU * self.freq * self.israte).exp();
+        self.a = (1.0 + self.b) / 2.0;
+    }
+
+
+    pub fn set_sample_rate(&mut self, srate: f32) {
+        self.israte = 1.0 / srate;
+        self.recalc();
+    }
+
+    #[inline]
+    pub fn set_freq(&mut self, freq: f32) {
+        if freq != self.freq {
+            self.freq = freq;
+            self.recalc();
+        }
+    }
+
+    #[inline]
+    pub fn process(&mut self, input: f32) -> f32 {
+        let v =
+              self.a * input
+            - self.a * self.z
+            + self.b * self.y;
+
+        self.y = v;
+        self.z = input;
+
+        v
+    }
+}
+
+
 // one pole from:
 // http://www.willpirkle.com/Downloads/AN-4VirtualAnalogFilters.pdf
 // (page 5)
diff --git a/src/dsp/mod.rs b/src/dsp/mod.rs
index 6d7ecb6..ac25490 100644
--- a/src/dsp/mod.rs
+++ b/src/dsp/mod.rs
@@ -45,6 +45,7 @@ mod node_tslfo;
 
 pub mod biquad;
 pub mod tracker;
+pub mod dattorro;
 mod satom;
 pub mod helpers;