core/dsp: document module

[nihav.git] / nihav-core / src / dsp / window.rs

diff --git a/nihav-core/src/dsp/window.rs b/nihav-core/src/dsp/window.rs
index 42b6b6d1d556f4918006b15ac51428fd26c2a102..eb350e3ecbd319208e8b9312a90cecaad6f31358 100644 (file)
--- a/nihav-core/src/dsp/window.rs
+++ b/nihav-core/src/dsp/window.rs
@@ -1,31 +1,38 @@
+//! Window generating functions.
 use std::f32::consts;
 
+/// Known window types.
 #[derive(Debug,Clone,Copy,PartialEq)]
 pub enum WindowType {
+    /// Simple square window.
     Square,
+    /// Simple sine window.
     Sine,
+    /// Kaiser-Bessel derived window.
     KaiserBessel(f32),
 }
 
+/// Calculates window coefficients for the requested window type and size.
+///
+/// Set `half` flag to calculate only the first half of the window.
 pub fn generate_window(mode: WindowType, scale: f32, size: usize, half: bool, dst: &mut [f32]) {
     match mode {
         WindowType::Square => {
                 for n in 0..size { dst[n] = scale; }
             },
         WindowType::Sine => {
-                let param;
-                if half {
-                    param = consts::PI / ((2 * size) as f32);
-                } else {
-                    param = consts::PI / (size as f32);
-                }
+                let param = if half {
+                        consts::PI / ((2 * size) as f32)
+                    } else {
+                        consts::PI / (size as f32)
+                    };
                 for n in 0..size {
                     dst[n] = (((n as f32) + 0.5) * param).sin() * scale;
                 }
             },
         WindowType::KaiserBessel(alpha) => {
                 let dlen = if half { size as f32 } else { (size as f32) * 0.5 };
-                let alpha2 = ((alpha * consts::PI / dlen) * (alpha * consts::PI / dlen)) as f64;
+                let alpha2 = f64::from((alpha * consts::PI / dlen) * (alpha * consts::PI / dlen));
 
                 let mut kb: Vec<f64> = Vec::with_capacity(size);
                 let mut sum = 0.0;
@@ -45,7 +52,7 @@ pub fn generate_window(mode: WindowType, scale: f32, size: usize, half: bool, ds
 fn bessel_i0(inval: f64) -> f64 {
     let mut val: f64 = 1.0;
     for n in (1..64).rev() {
-        val *= inval / ((n * n) as f64);
+        val *= inval / f64::from(n * n);
         val += 1.0;
     }
     val