From 709d2a2639ba172fb6408a7470f8248085000d8e Mon Sep 17 00:00:00 2001
From: Marco Thomas <github@marcothms.de>
Date: Wed, 2 Jul 2025 17:16:01 +0900
Subject: [PATCH] fix(interpreter): fix safeguard for memory `write_raw()`

---
 src/interpreter/memory.rs | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/interpreter/memory.rs b/src/interpreter/memory.rs
index e8e8eea..ac7e90b 100644
--- a/src/interpreter/memory.rs
+++ b/src/interpreter/memory.rs
@@ -20,14 +20,18 @@ impl Memory {
     /// Safely writes a [`ImmediateOperand`] into an index of memory.
     /// Warning: Does access at `addr`, not `DS:addr`!
     pub fn write_raw(&mut self, addr: Word, val: ImmediateOperand) -> Result<(), InterpreterError> {
-        if (addr + 1) as usize > MEMORY_SIZE {
-            return Err(InterpreterError::MemoryOutOfBound(addr));
-        } else {
-            match val {
-                ImmediateOperand::Byte(b) => {
+        match val {
+            ImmediateOperand::Byte(b) => {
+                if addr as usize > MEMORY_SIZE {
+                    return Err(InterpreterError::MemoryOutOfBound(addr));
+                } else {
                     self.raw[addr as usize] = b;
                 }
-                ImmediateOperand::Word(w) => {
+            }
+            ImmediateOperand::Word(w) => {
+                if (addr + 1) as usize > MEMORY_SIZE {
+                    return Err(InterpreterError::MemoryOutOfBound(addr));
+                } else {
                     let [low, high] = w.to_le_bytes();
                     self.raw[addr as usize] = low;
                     self.raw[(addr + 1) as usize] = high;