From 7333743d879acc6306e9407b9bf45c7f469bb16f Mon Sep 17 00:00:00 2001
From: LongHairedHacker <sebastian@sebastians-site.de>
Date: Tue, 17 Mar 2020 22:41:25 +0100
Subject: [PATCH] Made fir filter generic

---
 src/firfilter.rs | 56 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/src/firfilter.rs b/src/firfilter.rs
index 39baae9..90b45fd 100644
--- a/src/firfilter.rs
+++ b/src/firfilter.rs
@@ -1,18 +1,25 @@
-pub struct FIRFilter<'a> {
-    coeffs: &'a [f32],
-    state: Vec<f32>,
+use num::traits::Num;
+use std::iter::FromIterator;
+
+pub struct FIRFilter<'a, NumType>
+where
+    NumType: Num + Copy {
+    coeffs: &'a [NumType],
+    state: Vec<NumType>,
     pos: usize,
-    iterator: Box<dyn Iterator<Item = f32> + 'a>,
+    iterator: Box<dyn Iterator<Item = NumType> + 'a>,
 }
 
-impl<'a> FIRFilter<'a> {
-    pub fn from<I>(iterator: I, coeffs: &'a [f32]) -> FIRFilter<'a>
+impl<'a, NumType> FIRFilter<'a, NumType>
+where
+    NumType: Num + Copy {
+    pub fn from<I>(iterator: I, coeffs: &'a [NumType]) -> FIRFilter<'a, NumType>
     where
-        I: Iterator<Item = f32> + 'a,
+        I: Iterator<Item = NumType> + 'a,
     {
         let mut state = Vec::new();
         for _ in 0..coeffs.len() {
-            state.push(0.0);
+            state.push(NumType::zero());
         }
 
         FIRFilter {
@@ -24,10 +31,12 @@ impl<'a> FIRFilter<'a> {
     }
 }
 
-impl<'a> Iterator for FIRFilter<'a> {
-    type Item = f32;
+impl<'a, NumType> Iterator for FIRFilter<'a, NumType>
+    where
+        NumType: Num + Copy {
+    type Item = NumType;
 
-    fn next(&mut self) -> Option<Self::Item> {
+    fn next(&mut self) -> Option<NumType> {
         let cur = match self.iterator.next() {
             Some(x) => x,
             None => return None,
@@ -36,12 +45,33 @@ impl<'a> Iterator for FIRFilter<'a> {
         self.pos = (self.pos + 1) % self.coeffs.len();
         self.state[self.pos] = cur;
 
-        let mut result = 0.0;
+        let mut result = NumType::zero();
         for i in 0..self.coeffs.len() {
             let pos = (self.pos + self.coeffs.len() - i) % self.coeffs.len();
-            result += self.state[pos] * self.coeffs[i];
+            result = result + (self.state[pos] * self.coeffs[i].clone());
         }
 
         Some(result)
     }
 }
+
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fir_avg_test() {
+        let test_data = vec![0_f32, 1_f32, 2_f32, 3_f32, 4_f32, 5_f32, 6_f32, 7_f32];
+
+        let upsampler = FIRFilter::from(test_data.into_iter(), &[0.5_f32, 0.5_f32]);
+
+        let result_data = Vec::from_iter(upsampler);
+        assert_eq!(result_data.len(), 8);
+        assert_eq!(
+            result_data,
+            [0.0_f32, 0.5_f32, 1.5_f32, 2.5_f32, 3.5_f32, 4.5_f32, 5.5_f32, 6.5_f32]
+        );
+    }
+}