Replace example by a sinusoid generator

examples/basic.rs

@@ -3,8 +3,25 @@ extern crate cpal;
 fn main() {
     let mut channel = cpal::Channel::new();
 
+    let mut data_source =
+        std::iter::iterate(0.0f32, |f| f + 0.03)
+            .map(|angle| {
+                use std::num::FloatMath;
+                use std::num::Int;
+
+                let angle = angle.sin();
+
+                let max: u16 = Int::max_value();
+                let value = (max as f32 / 2.0) + (angle * (max as f32 / 2.0));
+                value as u16
+            })
+            .map(|v| (v, v));
+
     loop {
         let mut buffer = channel.append_data::<(u16, u16)>();
-        buffer[0] = std::rand::random();
+
+        for value in buffer.iter_mut() {
+            *value = data_source.next().unwrap();
+        }
     }
 }