refactor 2 electric boogaloo

common/src/instructions/errors.rs

@@ -0,0 +1,54 @@
+//! All the errors that may be returned from [`instructions`].
+
+use crate::prelude::*;
+
+#[derive(Debug)]
+/// Error type for parsing register numbers.
+pub enum RegisterParseError {
+    InvalidIndex(u8),
+}
+
+impl std::fmt::Display for RegisterParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::InvalidIndex(idx) => write!(f, "invalid index given ({idx})"),
+        }
+    }
+}
+
+impl std::error::Error for RegisterParseError {}
+
+/// A list of errors that can be returned when decoding instructions.
+#[derive(Debug)]
+pub enum InstructionDecodeError {
+    /// Some field was incorrect. Returns an error for debugging purposes.
+    InvalidArgument(ArgsDecodeError),
+    /// Some opcode was invalid. Returns the offending opcode for debugging purposes etc.
+    InvalidOpcode(u8),
+}
+
+impl From<ArgsDecodeError> for InstructionDecodeError {
+    fn from(err: ArgsDecodeError) -> Self {
+        Self::InvalidArgument(err)
+    }
+}
+
+impl std::fmt::Display for InstructionDecodeError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::InvalidOpcode(code) => write!(f, "invalid opcode, got {code:x}")?,
+            Self::InvalidArgument(err) => write!(f, "invalid arguments, got an error {err}")?,
+        }
+
+        Ok(())
+    }
+}
+
+impl std::error::Error for InstructionDecodeError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::InvalidArgument(err) => Some(err),
+            _ => None,
+        }
+    }
+}