From cbc69f3ca3bbba442550506d7a871eff65823ad0 Mon Sep 17 00:00:00 2001
From: Weird Constructor <weirdconstructor@gmail.com>
Date: Sat, 19 Jun 2021 12:17:22 +0200
Subject: [PATCH] implemented untested DSP part of Delay

---
 src/dsp/helpers.rs    |  7 ++++--
 src/dsp/mod.rs        |  3 ++-
 src/dsp/node_delay.rs | 54 ++++++++++++++++++++++++++++++++-----------
 3 files changed, 47 insertions(+), 17 deletions(-)

diff --git a/src/dsp/helpers.rs b/src/dsp/helpers.rs
index 067e9ed..a8e1837 100644
--- a/src/dsp/helpers.rs
+++ b/src/dsp/helpers.rs
@@ -160,10 +160,12 @@ impl SplitMix64 {
     }
 }
 
-pub fn mix(v1: f32, v2: f32, mix: f32) -> f32 {
+#[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 }
@@ -482,7 +484,8 @@ impl TriggerClock {
 /// Default size of the delay buffer: 5 seconds at 8 times 48kHz
 const DEFAULT_DELAY_BUFFER_SAMPLES : usize = 8 * 48000 * 5;
 
-struct DelayBuffer {
+#[derive(Debug, Clone)]
+pub struct DelayBuffer {
     data:   Vec<f32>,
     wr:     usize,
     srate:  f32,
diff --git a/src/dsp/mod.rs b/src/dsp/mod.rs
index 087ee30..12e11ac 100644
--- a/src/dsp/mod.rs
+++ b/src/dsp/mod.rs
@@ -363,10 +363,11 @@ 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 0.0, 5000.0}
+
 // Special linear gain factor for the Out node, to be able
 // to reach more exact "1.0".
 define_lin!{n_ogin d_ogin 0.0, 2.0}
-define_lin!{n_time d_time 0.0, 5000.0}
 
 // A note about the input-indicies:
 //
diff --git a/src/dsp/node_delay.rs b/src/dsp/node_delay.rs
index f34c4fd..02e7a09 100644
--- a/src/dsp/node_delay.rs
+++ b/src/dsp/node_delay.rs
@@ -3,7 +3,8 @@
 // See README.md and COPYING for details.
 
 use crate::nodes::{NodeAudioContext, NodeExecContext};
-use crate::dsp::{NodeId, SAtom, ProcBuf, GraphFun, GraphAtomData, DspNode, LedPhaseVals};
+use crate::dsp::{NodeId, SAtom, ProcBuf, DspNode, LedPhaseVals};
+use crate::dsp::helpers::{DelayBuffer, crossfade};
 
 #[macro_export]
 macro_rules! fa_dly_s { ($formatter: expr, $v: expr, $denorm_v: expr) => { {
@@ -28,11 +29,15 @@ macro_rules! fa_dly_s { ($formatter: expr, $v: expr, $denorm_v: expr) => { {
 /// A simple amplifier
 #[derive(Debug, Clone)]
 pub struct Delay {
+    buffer:    Box<DelayBuffer>,
+    fb_sample: f32,
 }
 
 impl Delay {
     pub fn new(_nid: &NodeId) -> Self {
         Self {
+            buffer:     Box::new(DelayBuffer::new()),
+            fb_sample:  0.0,
         }
     }
 
@@ -75,27 +80,48 @@ For other kinds of delay/feedback please see also the 'FbWr'/'FbRd' nodes.
 impl DspNode for Delay {
     fn outputs() -> usize { 1 }
 
-    fn set_sample_rate(&mut self, _srate: f32) { }
-    fn reset(&mut self) { }
+    fn set_sample_rate(&mut self, srate: f32) {
+        self.buffer.set_sample_rate(srate);
+    }
+
+    fn reset(&mut self) {
+        self.buffer.reset();
+    }
 
     #[inline]
     fn process<T: NodeAudioContext>(
         &mut self, ctx: &mut T, _ectx: &mut NodeExecContext,
-        atoms: &[SAtom], _params: &[ProcBuf], _inputs: &[ProcBuf],
+        _atoms: &[SAtom], _params: &[ProcBuf], inputs: &[ProcBuf],
         outputs: &mut [ProcBuf], _led: LedPhaseVals)
     {
-        use crate::dsp::{out, at};
+        use crate::dsp::{out, inp, denorm};
 
-//        let p    = at::Delay::p(atoms);
+        let buffer = &mut *self.buffer;
+
+        let inp  = inp::Delay::inp(inputs);
+        let time = inp::Delay::time(inputs);
+        let fb   = inp::Delay::fb(inputs);
+        let mix  = inp::Delay::mix(inputs);
         let out  = out::Delay::sig(outputs);
-        for frame in 0..ctx.nframes() {
-            out.write(frame, 0.0);
-        }
-    }
 
-    fn graph_fun() -> Option<GraphFun> {
-        Some(Box::new(|_gd: &dyn GraphAtomData, _init: bool, x: f32| -> f32 {
-            x
-        }))
+        let mut fb_s = self.fb_sample;
+
+        for frame in 0..ctx.nframes() {
+            let dry = inp.read(frame);
+            buffer.feed(
+                dry + fb_s * denorm::Delay::fb(fb, frame));
+
+            let out_sample =
+                buffer.cubic_interpolate_at(
+                    denorm::Delay::time(time, frame));
+
+            out.write(frame,
+                crossfade(dry, out_sample,
+                    denorm::Delay::mix(mix, frame).clamp(0.0, 1.0)));
+
+            fb_s = out_sample;
+        }
+
+        self.fb_sample = fb_s;
     }
 }