helpers for comb and allpass, and added allpass node

src/dsp/helpers.rs

@@ -619,6 +619,73 @@ impl DelayBuffer {
     }
 }
 
+/// 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
+    }
+}
+
+
 // translated from Odin 2 Synthesizer Plugin
 // Copyright (C) 2020 TheWaveWarden
 // under GPLv3 or any later

src/dsp/mod.rs

@@ -20,6 +20,8 @@ mod node_fbwr_fbrd;
 mod node_ad;
 #[allow(non_upper_case_globals)]
 mod node_delay;
+#[allow(non_upper_case_globals)]
+mod node_allp;
 
 pub mod tracker;
 mod satom;
@@ -55,6 +57,7 @@ use node_fbwr_fbrd::FbWr;
 use node_fbwr_fbrd::FbRd;
 use node_ad::Ad;
 use node_delay::Delay;
+use node_allp::AllP;
 
 pub const MIDI_MAX_FREQ : f32 = 13289.75;
 
@@ -311,6 +314,20 @@ macro_rules! r_tms { ($x: expr, $coarse: expr) => {
     }
 } }
 
+/// The rounding function for milliseconds knobs
+macro_rules! r_fms { ($x: expr, $coarse: expr) => {
+    if $coarse {
+        if d_ftme!($x) > 1000.0 {
+            n_ftme!((d_ftme!($x) / 100.0).round() * 100.0)
+        } else if d_ftme!($x) > 100.0 {
+            n_ftme!((d_ftme!($x) / 10.0).round() * 10.0)
+        } else {
+            n_ftme!((d_ftme!($x)).round())
+        }
+    } else {
+        n_ftme!((d_ftme!($x) * 10.0).round() / 10.0)
+    }
+} }
 
 /// The default steps function:
 macro_rules! stp_d { () => { (20.0, 100.0) } }
@@ -370,7 +387,8 @@ define_exp!{n_declick d_declick 0.0, 50.0}
 
 define_exp!{n_env d_env 0.0, 1000.0}
 
-define_exp!{n_time d_time 0.5, 5000.0}
+define_exp!{n_time d_time 0.5,  5000.0}
+define_exp!{n_ftme d_ftme 0.25, 1000.0}
 
 // Special linear gain factor for the Out node, to be able
 // to reach more exact "1.0".
@@ -471,6 +489,11 @@ macro_rules! node_list {
                (4  mix   n_id      d_id  r_id   f_def stp_d  0.0, 1.0, 0.5)
                {5 0 mode setting(0) fa_delay_mode 0 1}
                [0 sig],
+            allp  => AllP UIType::Generic UICategory::Signal
+               (0  inp   n_id      d_id  r_id   f_def stp_d -1.0, 1.0, 0.0)
+               (1  time  n_ftme   d_ftme r_fms  f_ms  stp_m  0.0, 1.0, 25.0)
+               (2  g     n_id      d_id  r_id   f_def stp_d -1.0, 1.0, 0.7)
+               [0 sig],
             test => Test UIType::Generic UICategory::IOUtil
                (0 f     n_id      d_id   r_id   f_def stp_d 0.0, 1.0, 0.5)
                {1 0 p     param(0.0) fa_test_s 0  10}

src/dsp/node_allp.rs

@@ -0,0 +1,110 @@
+// 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};
+use crate::dsp::helpers::AllPass;
+
+/// A simple amplifier
+#[derive(Debug, Clone)]
+pub struct AllP {
+    allpass: Box<AllPass>,
+}
+
+impl AllP {
+    pub fn new(_nid: &NodeId) -> Self {
+        Self {
+            allpass: Box::new(AllPass::new()),
+        }
+    }
+
+    pub const inp  : &'static str =
+        "AllP inp\nThe signal input for the allpass filter.\nRange: (-1..1)";
+    pub const g : &'static str =
+        "AllP g\nThe internal factor for the allpass filter.\nRange: (-1..1)";
+    pub const time : &'static str =
+        "AllP time\nThe allpass delay time.\nRange: (0..1)";
+    pub const sig  : &'static str =
+        "AllP sig\nThe output of allpass filter.\nRange: (-1..1)";
+
+    pub const DESC : &'static str =
+r#"Simple Single Allpass Filter
+
+This is an allpass filter that can be used to build reverbs
+or anything you might find it useful for.
+"#;
+pub const HELP : &'static str =
+r#"AllP - A Simple Single Allpass Filter
+
+This is an allpass filter that can be used to build reverbs
+or anything you might find it useful for.
+
+Typical arrangements are (Schroeder Reverb):
+
+                    t=4.5ms
+                    g=0.7   -> Comb
+    AllP -> AllP -> AllP -> -> Comb
+    t=42ms  t=13.5ms        -> Comb
+    g=0.7   g=0.7           -> Comb
+
+Or:
+
+    Comb ->                 t=0.48ms
+    Comb ->                 g=0.7
+    Comb -> AllP -> AllP -> AllP
+    Comb -> t=5ms   t=1.68ms
+            g=0.7   g=0.7
+
+Typical values for the comb filters are in the range g=0.6 to 0.9
+and time in the range of 30ms to 250ms.
+
+Feel free to deviate from this and experiment around.
+
+Building your own reverbs is fun!
+
+(And don't forget that you can create feedback
+using the FbWr and FbRd nodes!)
+"#;
+}
+
+impl DspNode for AllP {
+    fn outputs() -> usize { 1 }
+
+    fn set_sample_rate(&mut self, srate: f32) {
+        self.allpass.set_sample_rate(srate);
+    }
+
+    fn reset(&mut self) {
+        self.allpass.reset();
+    }
+
+    #[inline]
+    fn process<T: NodeAudioContext>(
+        &mut self, ctx: &mut T, _ectx: &mut NodeExecContext,
+        atoms: &[SAtom], _params: &[ProcBuf], inputs: &[ProcBuf],
+        outputs: &mut [ProcBuf], ctx_vals: LedPhaseVals)
+    {
+        use crate::dsp::{at, out, inp, denorm};
+
+        let inp  = inp::AllP::inp(inputs);
+        let time = inp::AllP::time(inputs);
+        let g    = inp::AllP::g(inputs);
+        let out  = out::AllP::sig(outputs);
+
+        let ap = &mut *self.allpass;
+
+        for frame in 0..ctx.nframes() {
+            let v = inp.read(frame);
+
+            out.write(frame,
+                ap.next(
+                    denorm::AllP::time(time, frame),
+                    denorm::AllP::g(g, frame),
+                    v));
+        }
+
+        let last_frame = ctx.nframes() - 1;
+        ctx_vals[0].set(out.read(last_frame));
+    }
+}