More synth work, but think I'm going to startover

src/source/mod.rs

@@ -30,7 +30,7 @@ pub use self::skippable::Skippable;
 pub use self::spatial::Spatial;
 pub use self::speed::Speed;
 pub use self::stoppable::Stoppable;
-pub use self::synth_waveforms::SynthWaveform;
+pub use self::synth_waveforms::{BufferedSynthWaveform, SynthWaveformFunction};
 pub use self::take::TakeDuration;
 pub use self::uniform::UniformSourceIterator;
 pub use self::zero::Zero;

src/source/synth_waveforms.rs

@@ -4,6 +4,16 @@ use std::time::Duration;
 use super::SeekError;
 use crate::{buffer::SamplesBuffer, source::Repeat, Source};
 
+
+/// Express a frequency as a rational number.
+///     .0 Cycles per time quanta
+///     .1 Time quanta per second
+///
+/// Examples:
+///     1000,1      1000 Hz
+///     12345,100   123.45 Hz
+pub struct RationalFrequency(u32, u32);
+
 /// Syntheizer waveform functions. All of the synth waveforms are in the
 /// codomain [-1.0, 1.0].
 #[derive(Clone, Debug)]
@@ -15,60 +25,67 @@ pub enum SynthWaveformFunction {
 }
 
 impl SynthWaveformFunction {
-    /// Create a `SamplesBuffer` containing one period of `self` with the given
-    /// sample rate and frequency.
-    pub fn create_buffer(&self, sample_rate: u32, frequency: u32) -> SamplesBuffer<f32> {
-        let p: usize = (sample_rate / frequency) as usize;
-        let mut samples_vec = vec![0.0f32; p];
+    /// Create a single sample for the given waveform
+    #[inline]
+    pub fn render(&self, sample: u32, period: u32) -> f32 {
+        let i_div_p: f32 = sample as f32 / period as f32;
             
-        fn _pwm_impl(duty: f32, t: f32) -> f32 {
-            if t < duty.abs() {
-                1f32
-            } else {
-                -1f32
-            }
-        }
-
-        for i in 0..p {
-            let i_div_p: f32 = i as f32 / p as f32;
-            samples_vec[i] = match self {
+        match self {
             Self::Sine => (TAU * i_div_p).sin(),
-                Self::Triangle => 4.0f32 * (i_div_p - (i_div_p + 0.5f32).floor()).abs() - 1f32,
+            Self::Triangle => 04.0f32 * (i_div_p - (i_div_p + 0.5f32).floor()).abs() - 1f32,
             Self::Square => {
                     if i_div_p < 0.5f32 {
                         1.0f32
                     } else {
                         -1.0f32
                     }
-                }
+                },
             Self::Sawtooth => 2.0f32 * (i_div_p - (i_div_p + 0.5f32).floor()),
         }
     }
 
-        SamplesBuffer::new(1, sample_rate, samples_vec)
+    /// Create a `SamplesBuffer` containing one period of `self` with the given
+    /// sample rate and frequency.
+    pub fn create_buffer(
+        &self,
+        sample_rate: cpal::SampleRate,
+        frequency: u32,
+    ) -> SamplesBuffer<f32> {
+        let period: usize = (sample_rate.0 / frequency) as usize;
+        let mut samples_vec = vec![0.0f32; period];
+
+        for i in 0..period {
+            samples_vec[i] = self.render(i as u32, period as u32);
+        }
+
+        SamplesBuffer::new(1, sample_rate.0, samples_vec)
     }
 }
 
 /// An infinite source that produces one of a selection of synthesizer
 /// waveforms from a buffered source.
 #[derive(Clone)]
-pub struct SynthWaveform {
+pub struct BufferedSynthWaveform {
     input: Repeat<SamplesBuffer<f32>>,
 }
 
-impl SynthWaveform {
+impl BufferedSynthWaveform {
     /// Create a new `SynthWaveform` object that generates an endless waveform
     /// `f`.
     #[inline]
-    pub fn new(sample_rate: u32, frequency: u32, f: SynthWaveformFunction) -> SynthWaveform {
+    pub fn new(
+        sample_rate: cpal::SampleRate,
+        frequency: u32,
+        f: SynthWaveformFunction,
+    ) -> BufferedSynthWaveform {
         let buffer = f.create_buffer(sample_rate, frequency);
-        SynthWaveform {
+        BufferedSynthWaveform {
             input: buffer.repeat_infinite(),
         }
     }
 }
 
-impl Iterator for SynthWaveform {
+impl Iterator for BufferedSynthWaveform {
     type Item = f32;
 
     #[inline]
@@ -77,7 +94,7 @@ impl Iterator for SynthWaveform {
     }
 }
 
-impl Source for SynthWaveform {
+impl Source for BufferedSynthWaveform {
     #[inline]
     fn current_frame_len(&self) -> Option<usize> {
         self.input.current_frame_len()
@@ -110,7 +127,8 @@ mod tests {
 
     #[test]
     fn square() {
-        let mut wf = SynthWaveform::new(1000, 250, SynthWaveformFunction::Square);
+        let mut wf =
+            BufferedSynthWaveform::new(cpal::SampleRate(1000), 250, SynthWaveformFunction::Square);
         assert_eq!(wf.next(), Some(1.0f32));
         assert_eq!(wf.next(), Some(1.0f32));
         assert_eq!(wf.next(), Some(-1.0f32));
@@ -123,7 +141,11 @@ mod tests {
 
     #[test]
     fn triangle() {
-        let mut wf = SynthWaveform::new(8000, 1000, SynthWaveformFunction::Triangle);
+        let mut wf = BufferedSynthWaveform::new(
+            cpal::SampleRate(8000),
+            1000,
+            SynthWaveformFunction::Triangle,
+        );
         assert_eq!(wf.next(), Some(-1.0f32));
         assert_eq!(wf.next(), Some(-0.5f32));
         assert_eq!(wf.next(), Some(0.0f32));
@@ -144,7 +166,8 @@ mod tests {
 
     #[test]
     fn saw() {
-        let mut wf = SynthWaveform::new(200, 50, SynthWaveformFunction::Sawtooth);
+        let mut wf =
+            BufferedSynthWaveform::new(cpal::SampleRate(200), 50, SynthWaveformFunction::Sawtooth);
         assert_eq!(wf.next(), Some(0.0f32));
         assert_eq!(wf.next(), Some(0.5f32));
         assert_eq!(wf.next(), Some(-1.0f32));