From 7574c5c7acaebe120de3efbaba56b8e9f474d330 Mon Sep 17 00:00:00 2001
From: Grant Shangreaux <grant@unabridgedsoftware.com>
Date: Thu, 2 Dec 2021 21:45:12 -0600
Subject: Clean: factor out a utils module and fix some tests

---
 klangfarbrs/src/lib.rs    |  2 ++
 klangfarbrs/src/line.rs   | 49 ++++++++++++++++++++++-------------------------
 klangfarbrs/src/phasor.rs |  7 +++----
 klangfarbrs/src/utils.rs  | 10 ++++++++++
 4 files changed, 38 insertions(+), 30 deletions(-)
 create mode 100644 klangfarbrs/src/utils.rs

(limited to 'klangfarbrs/src')

diff --git a/klangfarbrs/src/lib.rs b/klangfarbrs/src/lib.rs
index e64246c..0d78e01 100644
--- a/klangfarbrs/src/lib.rs
+++ b/klangfarbrs/src/lib.rs
@@ -22,6 +22,8 @@ use osc::{Osc, Waveform};
 pub mod envelope;
 use envelope::Envelope;
 
+mod utils;
+
 /// Aliasing some types to distinguish various audio properties.
 type Sample = f32;
 type SamplesPerSecond = f32;
diff --git a/klangfarbrs/src/line.rs b/klangfarbrs/src/line.rs
index f57b103..5f862a8 100644
--- a/klangfarbrs/src/line.rs
+++ b/klangfarbrs/src/line.rs
@@ -1,19 +1,25 @@
 use super::{Millisecond, Amplitude, SamplesPerSecond};
+use super::utils::*;
 
 pub struct Line {
-    pub start: Amplitude,
-    pub end: Amplitude,
-    pub duration: Millisecond,
-    pub index: u32,
+    index: u32,
+    samples: u32,
     slope: f32,
-    samples: u32
+    y_intercept: f32,
 }
 
 impl Line {
     pub fn new(
         start: Amplitude, end: Amplitude, duration: Millisecond, sample_rate: SamplesPerSecond
     ) -> Self {
-        Self { start, end, duration, index: 0, slope: slope(start, end, ms_to_samples(duration, sample_rate)), samples: ms_to_samples(duration, sample_rate) }
+        let number_of_samples = ms_to_samples(duration, sample_rate);
+
+        Self {
+            index: 0,
+            slope: slope(start, end, number_of_samples),
+            samples: number_of_samples,
+            y_intercept: start,
+        }
     }
 }
 
@@ -22,25 +28,16 @@ impl Iterator for Line {
 
     fn next(&mut self) -> Option<Self::Item> {
         let idx = self.index;
-        let val = self.slope * idx as f32 + self.start;
+        let val = self.slope * idx as f32 + self.y_intercept;
         self.index += 1;
- 
+
         if idx <= self.samples {
             Some(val)
         } else {
             None
         }
-          
-    }
-}
-
-fn slope(start: Amplitude, end: Amplitude, duration: Millisecond) -> f32 {
-  return (end - start) / duration as f32 ;
-}
 
-fn ms_to_samples(ms: Millisecond, sample_rate: SamplesPerSecond) -> u32 {
-    let multiplier = sample_rate as u32 / 1000;
-    multiplier * ms
+    }
 }
 
 #[cfg(test)]
@@ -51,18 +48,18 @@ mod tests {
     fn it_calculates_a_slope() {
       let expected = 0.5;
       let slope = slope(0.0, 0.5, 1);
-      assert_eq! (expected, slope)
+      assert_eq! (slope, expected)
     }
 
     #[test]
     fn it_calculates_the_next_values() {
       let mut line = Line::new(0.0, 0.5, 1, 5000.0);
-      assert_eq!(0.0, line.next().unwrap());
-      assert_eq!(0.1, line.next().unwrap());
-      assert_eq!(0.2, line.next().unwrap());
-      assert_eq!(0.3, line.next().unwrap());
-      assert_eq!(0.4, line.next().unwrap());
-      assert_eq!(0.5, line.next().unwrap());
-      assert_eq!(None, line.next());
+      assert_eq!(line.next(), Some(0.0));
+      assert_eq!(line.next(), Some(0.1));
+      assert_eq!(line.next(), Some(0.2));
+      assert_eq!(line.next(), Some(0.3));
+      assert_eq!(line.next(), Some(0.4));
+      assert_eq!(line.next(), Some(0.5));
+      assert_eq!(line.next(), None);
     }
 }
diff --git a/klangfarbrs/src/phasor.rs b/klangfarbrs/src/phasor.rs
index 5bfc79e..4d6a714 100644
--- a/klangfarbrs/src/phasor.rs
+++ b/klangfarbrs/src/phasor.rs
@@ -39,11 +39,10 @@ mod tests {
     }
 
     #[test]
-    fn it_produces_expected_next_values() {
+    fn it_wraps_around_as_expected() {
         let phasor = Phasor::new(10.0, 100.0);
-        let taken_iterator  = phasor.take(11);
-        assert_eq!(taken_iterator.last(), Some(0.1))
-        // assert_eq!([0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 0.1], next)
+        let last_val = phasor.take(11).last().unwrap();
+        assert_eq!(last_val.floor(), 0.0)
     }
 }
 
diff --git a/klangfarbrs/src/utils.rs b/klangfarbrs/src/utils.rs
new file mode 100644
index 0000000..9f99e23
--- /dev/null
+++ b/klangfarbrs/src/utils.rs
@@ -0,0 +1,10 @@
+use super::{ Amplitude, Millisecond, SamplesPerSecond };
+
+pub fn slope(start: Amplitude, end: Amplitude, duration: Millisecond) -> f32 {
+    return (end - start) / duration as f32 ;
+}
+
+pub fn ms_to_samples(ms: Millisecond, sample_rate: SamplesPerSecond) -> u32 {
+    let multiplier = sample_rate as u32 / 1000;
+    multiplier * ms
+}
-- 
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