wasm_interp: implement call and return instructions

crates/wasm_module/src/lib.rs

@@ -642,6 +642,22 @@ impl From<u8> for ValueType {
     }
 }
 
+impl Parse<()> for ValueType {
+    fn parse(_: (), bytes: &[u8], cursor: &mut usize) -> Result<Self, ParseError> {
+        let byte = u8::parse((), bytes, cursor)?;
+        Ok(ValueType::from(byte))
+    }
+}
+
+// A group of local variable declarations
+impl Parse<()> for (u32, ValueType) {
+    fn parse(_: (), bytes: &[u8], cursor: &mut usize) -> Result<Self, ParseError> {
+        let count = u32::parse((), bytes, cursor)?;
+        let ty = ValueType::parse((), bytes, cursor)?;
+        Ok((count, ty))
+    }
+}
+
 /// Wasm memory alignment for load/store instructions.
 /// Rust representation matches Wasm encoding.
 /// It's an error to specify alignment higher than the "natural" alignment of the instruction