From 41c9be12ed724b792f870ccecfff2adc699caaa6 Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Fri, 3 Jan 2020 19:52:15 -0800
Subject: match changes in arch to have Resulty decode, instead of Option

---
 src/lib.rs | 46 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 7dc4872..523a8df 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,8 @@ extern crate yaxpeax_arch;
 
 use yaxpeax_arch::{Arch, Decoder, LengthedInstruction};
 
+use std::fmt;
+
 #[derive(Debug)]
 pub enum Opcode {
     NOP
@@ -29,24 +31,51 @@ impl LengthedInstruction for Instruction {
     }
 }
 
+#[derive(Debug, PartialEq)]
+pub enum DecodeError {
+    ExhaustedInput,
+    InvalidOpcode,
+    InvalidOperand,
+}
+
+impl fmt::Display for DecodeError {
+    fn fmt(&self, f:  &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            DecodeError::ExhaustedInput => write!(f, "exhausted input"),
+            DecodeError::InvalidOpcode => write!(f, "invalid opcode"),
+            DecodeError::InvalidOperand => write!(f, "invalid operand"),
+        }
+    }
+}
+
+impl yaxpeax_arch::DecodeError for DecodeError {
+    fn data_exhausted(&self) -> bool { self == &DecodeError::ExhaustedInput }
+    fn bad_opcode(&self) -> bool { self == &DecodeError::InvalidOpcode }
+    fn bad_operand(&self) -> bool { self == &DecodeError::InvalidOperand }
+}
+
+impl yaxpeax_arch::Instruction for Instruction {
+    // TODO: this is wrong!!
+    fn well_defined(&self) -> bool { true }
+}
+
 #[derive(Default, Debug)]
 pub struct InstDecoder {}
 
 impl Decoder<Instruction> for InstDecoder {
-    fn decode<T: IntoIterator<Item=u8>>(&self, bytes: T) -> Option<Instruction> {
+    type Error = DecodeError;
+
+    fn decode<T: IntoIterator<Item=u8>>(&self, bytes: T) -> Result<Instruction, Self::Error> {
         let mut blank = Instruction { opcode: Opcode::NOP };
-        match self.decode_into(&mut blank, bytes) {
-            Some(_) => Some(blank),
-            None => None
-        }
+        self.decode_into(&mut blank, bytes).map(|_: ()| blank)
     }
-    fn decode_into<T: IntoIterator<Item=u8>>(&self, instr: &mut Instruction, bytes: T) -> Option<()> {
+    fn decode_into<T: IntoIterator<Item=u8>>(&self, instr: &mut Instruction, bytes: T) -> Result<(), Self::Error> {
         match bytes.into_iter().next() {
             Some(0x00) => {
                 instr.opcode = Opcode::NOP;
-                Some(())
+                Ok(())
             },
-            _ => None
+            _ => Err(DecodeError::ExhaustedInput)
         }
     }
 }
@@ -62,6 +91,7 @@ pub struct PIC24;
 impl Arch for PIC24 {
     type Address = u32;
     type Instruction = Instruction;
+    type DecodeError = DecodeError;
     type Decoder = InstDecoder;
     type Operand = ();
 }
-- 
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