Optimize note_type_id to use 7 bits

src/note_type.rs

@@ -0,0 +1,47 @@
+pub struct NoteTypeId(u8);
+
+impl NoteTypeId {
+    // Constructor that checks if the value fits within 7 bits
+    pub fn new(id: u8) -> Result<Self, &'static str> {
+        if id > 0x7F { // 0x7F = 0b01111111 (7 bits)
+            return Err("NoteTypeId must fit in 7 bits");
+        }
+        Ok(Self(id))
+    }
+
+    // Serialization to bytes (1 byte instead of 32)
+    pub fn to_bytes(&self) -> [u8; 1] {
+        [self.0]
+    }
+
+    // Deserialization from bytes
+    pub fn from_bytes(bytes: [u8; 1]) -> Result<Self, &'static str> {
+        Self::new(bytes[0])
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_note_type_id_validation() {
+        // Valid values (7 bits)
+        assert!(NoteTypeId::new(0).is_ok());
+        assert!(NoteTypeId::new(127).is_ok());
+
+        // Invalid values (>7 bits)
+        assert!(NoteTypeId::new(128).is_err());
+        assert!(NoteTypeId::new(255).is_err());
+    }
+
+    #[test]
+    fn test_serialization() {
+        let id = NoteTypeId::new(42).unwrap();
+        let bytes = id.to_bytes();
+        assert_eq!(bytes.len(), 1);
+
+        let decoded = NoteTypeId::from_bytes(bytes).unwrap();
+        assert_eq!(decoded.0, 42);
+    }
+}