Add a note about ControlBuffer size restrictions

It only works by chance.

Signed-off-by: Petr Horacek <[email protected]>

Author: phoracek

eurorack/src/system/control_buffer.rs

@@ -25,6 +25,9 @@ impl<const N: usize> ControlBuffer<N> {
     }
 
     pub fn traveled(&self) -> f32 {
+        // NOTE: This does not panic only thanks to the release mode
+        // wrapping around instead of exploding on underflow.
+        // XXX: This works only if N is power of 2.
         let newest = (self.pointer - 1).rem_euclid(N);
         let oldest = self.pointer;
         (self.buffer[newest] - self.buffer[oldest]).abs()

eurorack/src/system/pot.rs

@@ -17,6 +17,7 @@ pub struct Pot<A, P> {
     pin: P,
     input_range: (f32, f32),
     toleration: f32,
+    // XXX: ControlBuffer sizes must be power of 2.
     position_filter: ControlBuffer<8>,
     movement_detector: ControlBuffer<124>,
     _adc: PhantomData<A>,