port more from osmocom

cellular/src/jitter.rs

@@ -0,0 +1,41 @@
+type Sample = f64;
+
+#[derive(Clone)]
+pub struct Jitter {
+    pub buffer: Vec<Sample>,
+    pub read_pos: usize,
+    pub write_pos: usize,
+    pub size: usize,
+}
+
+impl Jitter {
+    pub fn new(size: usize) -> Self {
+        Jitter {
+            buffer: vec![0.0; size],
+            read_pos: 0,
+            write_pos: 0,
+            size,
+        }
+    }
+
+    pub fn write(&mut self, samples: &[Sample]) {
+        for &sample in samples {
+            self.buffer[self.write_pos] = sample;
+            self.write_pos = (self.write_pos + 1) % self.size;
+        }
+    }
+
+    pub fn read(&mut self, output: &mut [Sample]) -> usize {
+        let mut count = 0;
+        for i in 0..output.len() {
+            if self.read_pos != self.write_pos {
+                output[i] = self.buffer[self.read_pos];
+                self.read_pos = (self.read_pos + 1) % self.size;
+                count += 1;
+            } else {
+                break;
+            }
+        }
+        count
+    }
+}