From 5ef4e8c792950b4131f8e9bc1f80f3f4a0c0910b Mon Sep 17 00:00:00 2001
From: Alex Janka <alex@alexjanka.com>
Date: Tue, 7 Feb 2023 10:08:34 +1100
Subject: [PATCH] mbc trait

---
 src/processor/memory/rom.rs      | 21 +++++++++-----------
 src/processor/memory/rom/mbcs.rs | 34 ++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 12 deletions(-)
 create mode 100644 src/processor/memory/rom/mbcs.rs

diff --git a/src/processor/memory/rom.rs b/src/processor/memory/rom.rs
index 5715854..fbd2ef4 100644
--- a/src/processor/memory/rom.rs
+++ b/src/processor/memory/rom.rs
@@ -1,16 +1,13 @@
 use crate::processor::memory::Address;
 use std::str::from_utf8_unchecked;
 
-#[derive(Debug)]
-enum MBC {
-    ROM,
-    MBC1,
-}
+use self::mbcs::{MBC, MBC1, NONE};
+
+mod mbcs;
 
 pub struct ROM {
     title: String,
-    data: Vec<u8>,
-    mbc: MBC,
+    mbc: Box<dyn MBC>,
 }
 
 impl ROM {
@@ -27,12 +24,12 @@ impl ROM {
         let _sgb_flag = data[0x146];
         let _rom_size = data[0x148];
         let _ram_size = data[0x149];
-        let mbc = match data[0x147] {
-            0x00 => MBC::ROM,
-            0x01 => MBC::MBC1,
+        let mbc: Box<dyn MBC> = match data[0x147] {
+            0x00 => Box::new(NONE { data }),
+            0x01 => Box::new(MBC1 { data }),
             _ => panic!("unimplemented mbc: {:#X}", data[0x147]),
         };
-        Self { title, data, mbc }
+        Self { title, mbc }
     }
 
     pub fn get_title(&self) -> &String {
@@ -40,6 +37,6 @@ impl ROM {
     }
 
     pub(super) fn get(&self, address: Address) -> u8 {
-        self.data[address as usize]
+        self.mbc.get(address)
     }
 }
diff --git a/src/processor/memory/rom/mbcs.rs b/src/processor/memory/rom/mbcs.rs
new file mode 100644
index 0000000..8e09a73
--- /dev/null
+++ b/src/processor/memory/rom/mbcs.rs
@@ -0,0 +1,34 @@
+use crate::processor::memory::Address;
+
+pub(super) trait MBC {
+    fn get(&self, address: Address) -> u8;
+    fn set(&mut self, address: Address, data: u8);
+}
+
+pub(super) struct NONE {
+    pub(super) data: Vec<u8>,
+}
+
+impl MBC for NONE {
+    fn get(&self, address: Address) -> u8 {
+        self.data[address as usize]
+    }
+
+    fn set(&mut self, address: Address, data: u8) {
+        return;
+    }
+}
+
+pub(super) struct MBC1 {
+    pub(super) data: Vec<u8>,
+}
+
+impl MBC for MBC1 {
+    fn get(&self, address: Address) -> u8 {
+        self.data[address as usize]
+    }
+
+    fn set(&mut self, address: Address, data: u8) {
+        return;
+    }
+}