From bcc9ec7e4870ff5e92c17406fa97ad1cfc47bac0 Mon Sep 17 00:00:00 2001
From: klangner <klangner@gmail.com>
Date: Tue, 30 Jan 2024 14:29:07 +0100
Subject: [PATCH] Added frequency shifter

---
 src/core/freq_shift.rs | 47 ++++++++++++++++++++++++++++++++++++++++++
 src/core/mod.rs        |  3 ++-
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 src/core/freq_shift.rs

diff --git a/src/core/freq_shift.rs b/src/core/freq_shift.rs
new file mode 100644
index 0000000..dde0afb
--- /dev/null
+++ b/src/core/freq_shift.rs
@@ -0,0 +1,47 @@
+//! Node for shifting frequency of a giveen signal
+//! 
+
+use anyhow::Result;
+use num_complex::Complex32;
+use crate::node::ProcessNode;
+
+use super::generator::Sine;
+
+
+/// Multiply buffer sample by constant value
+/// 
+/// Example
+/// 
+/// ```
+/// use dsp::num_complex::Complex32;
+/// use dsp::node::ProcessNode;
+/// use dsp::core::generator::Sine;
+/// use dsp::core::freq_shift::FrequencyShift;
+/// 
+/// let mut node = FrequencyShift::new(30., 1024);
+/// let input_buffer = vec![Complex32::default(); 1024];
+/// let mut output_buffer = vec![Complex32::default(); 1024];
+/// let source = Sine::new(10., 1024);
+/// node.process_buffer(&input_buffer, &mut output_buffer);
+/// ```
+pub struct FrequencyShift {
+    offset_signal: Sine,
+}
+
+impl FrequencyShift {
+    pub fn new(freq_offset: f32, sample_rate: usize) -> Self {
+        let offset_signal = Sine::new(freq_offset as f32, sample_rate);
+        Self {offset_signal}
+    }
+}
+
+impl ProcessNode<Complex32, Complex32> for FrequencyShift {
+    fn process_buffer(&mut self, input_buffer: &[Complex32], output_buffer: &mut [Complex32]) -> Result<()> {
+        let n = usize::min(input_buffer.len(), output_buffer.len());
+        for i in 0..n {
+            output_buffer[i] = self.offset_signal.next().unwrap() * input_buffer[i]; 
+        }
+        
+        Ok(())
+    }
+}
diff --git a/src/core/mod.rs b/src/core/mod.rs
index 4fec1ca..240c7ca 100644
--- a/src/core/mod.rs
+++ b/src/core/mod.rs
@@ -8,4 +8,5 @@ pub mod generator;
 pub mod fft;
 pub mod file;
 pub mod multiply;
-pub mod network;
\ No newline at end of file
+pub mod network;
+pub mod freq_shift;
\ No newline at end of file