From fca2c0b86a234d88bf2ea799eb37776a2eafcf32 Mon Sep 17 00:00:00 2001
From: LongHairedHacker <sebastian@sebastians-site.de>
Date: Sun, 24 May 2020 20:47:22 +0200
Subject: [PATCH] Added multipliers

---
 src/lib.rs      |   1 +
 src/multiply.rs | 113 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 src/multiply.rs

diff --git a/src/lib.rs b/src/lib.rs
index 51dd74e..b4509fb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,4 @@
 mod amdemod;
 mod firfilter;
 mod resamplers;
+mod multiply;
diff --git a/src/multiply.rs b/src/multiply.rs
new file mode 100644
index 0000000..1712239
--- /dev/null
+++ b/src/multiply.rs
@@ -0,0 +1,113 @@
+use num::traits::Num;
+use std::iter::FromIterator;
+
+pub struct Multiply<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    iterator_a: Box<dyn Iterator<Item = NumType> + 'a>,
+    iterator_b: Box<dyn Iterator<Item = NumType> + 'a>,
+}
+
+impl<'a, NumType> Multiply<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    pub fn from<I>(iterator_a: I, iterator_b: I) -> Multiply<'a, NumType>
+    where
+        I: Iterator<Item = NumType> + 'a,
+    {
+        Multiply {
+            iterator_a: Box::new(iterator_a),
+            iterator_b: Box::new(iterator_b),
+        }
+    }
+}
+
+impl<'a, NumType> Iterator for Multiply<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    type Item = NumType;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let value_a = match self.iterator_a.next() {
+            Some(a) => a,
+            None => return None,
+        };
+
+        let value_b = match self.iterator_b.next() {
+            Some(b) => b,
+            None => return None,
+        };
+
+        Some(value_a * value_b)
+    }
+}
+
+pub struct MultiplyConst<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    factor: NumType,
+    iterator: Box<dyn Iterator<Item = NumType> + 'a>,
+}
+
+impl<'a, NumType> MultiplyConst<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    pub fn from<I>(iterator: I, factor: NumType) -> MultiplyConst<'a, NumType>
+    where
+        I: Iterator<Item = NumType> + 'a,
+    {
+        MultiplyConst {
+            factor: factor,
+            iterator: Box::new(iterator),
+        }
+    }
+}
+
+impl<'a, NumType> Iterator for MultiplyConst<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    type Item = NumType;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let value = match self.iterator.next() {
+            Some(x) => x,
+            None => return None,
+        };
+
+        return Some(value * self.factor);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn multiply_test() {
+        let test_a = vec![1_f32, 2_f32, 3_f32];
+        let test_b = vec![4_f32, 5_f32, 6_f32, 7_f32];
+
+        let result = Multiply::from(test_a.into_iter(), test_b.into_iter());
+
+        let result_data = Vec::from_iter(result);
+        assert_eq!(result_data.len(), 3);
+        assert_eq!(result_data, [4_f32, 10_f32, 18_f32]);
+    }
+
+    #[test]
+    fn multiplyconst_test() {
+        let test_a = vec![1_f32, 2_f32, 3_f32];
+
+        let result = MultiplyConst::from(test_a.into_iter(), 5_f32);
+
+        let result_data = Vec::from_iter(result);
+        assert_eq!(result_data.len(), 3);
+        assert_eq!(result_data, [5_f32, 10_f32, 15_f32]);
+    }
+}