From 6cdbe2629224e6e5b7d10129894d43a65b48b149 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Sat, 10 Jun 2023 10:47:43 +0100
Subject: [PATCH] chore: greatly improved game genie code
---
src/rom.rs | 44 +++++++++++++++++++++++++++++++-------------
1 file changed, 31 insertions(+), 13 deletions(-)
diff --git a/src/rom.rs b/src/rom.rs
index a85c578f..72572236 100644
--- a/src/rom.rs
+++ b/src/rom.rs
@@ -217,6 +217,21 @@ pub struct GameGenieCode {
old_data: u8,
}
+impl GameGenieCode {
+ pub fn description(&self) -> String {
+ format!(
+ "Code: {}, Address: 0x{:04x}, New Data: 0x{:04x}, Old Data: 0x{:04x}",
+ self.code, self.address, self.new_data, self.old_data
+ )
+ }
+}
+
+impl Display for GameGenieCode {
+ fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+ write!(f, "{}", self.description())
+ }
+}
+
/// Structure that defines the ROM and ROM contents
/// of a Game Boy cartridge. Should correctly address
/// the specifics of all the major MBCs (Memory Bank
@@ -236,8 +251,6 @@ pub struct Cartridge {
/// RAM and ROM access on the current cartridge.
mbc: &'static Mbc,
- genie_codes: HashMap<u16, GameGenieCode>,
-
/// The number of ROM banks (of 8KB) that are available
/// to the current cartridge, this is a computed value
/// to allow improved performance.
@@ -264,6 +277,12 @@ pub struct Cartridge {
// that is considered to be non zero (0x0) so that a
// proper safe conversion to UTF-8 string can be done.
title_offset: usize,
+
+ /// Hash map that contains the complete set of Game Genie
+ /// codes that have been registered for the current ROM.
+ /// These codes are going to apply a series of patches to
+ /// the ROM effectively allowing the user to cheat.
+ genie_codes: HashMap<u16, GameGenieCode>,
}
impl Cartridge {
@@ -272,13 +291,13 @@ impl Cartridge {
rom_data: vec![],
ram_data: vec![],
mbc: &NO_MBC,
- genie_codes: HashMap::new(),
rom_bank_count: 0,
ram_bank_count: 0,
rom_offset: 0x4000,
ram_offset: 0x0000,
ram_enabled: false,
title_offset: 0x0143,
+ genie_codes: HashMap::new(),
}
}
@@ -294,14 +313,10 @@ impl Cartridge {
}
pub fn read(&self, addr: u16) -> u8 {
- //if addr == 0x4A17 {
- // println!("cenas");
- // return 0x00;
- //} // @todo hack for gamegenie
-
if self.genie_codes.contains_key(&addr) {
- let game_genie_code = self.genie_codes.get(&addr).unwrap();
- return game_genie_code.new_data;
+ let genie_code = self.genie_codes.get(&addr).unwrap();
+ debugln!("Applying Game Genie code: {}", game_genie_code);
+ return genie_code.new_data;
}
match addr & 0xf000 {
@@ -420,14 +435,17 @@ impl Cartridge {
let new_data_slice = &code[0..=1];
let new_data = u8::from_str_radix(new_data_slice, 16).unwrap();
+ let old_data_slice = format!("{}{}", &code[8..=8], &code[10..=10]);
+ let old_data: u8 = (u8::from_str_radix(old_data_slice.as_str(), 16).unwrap() ^ 0xba) << 2;
+
let address_slice = format!("{}{}{}", &code[6..=6], &code[2..=2], &code[4..=5]);
let address = u16::from_str_radix(address_slice.as_str(), 16).unwrap() ^ 0xf000;
let game_genie_code = GameGenieCode {
code: String::from(code),
- address: address,
- new_data: new_data,
- old_data: new_data,
+ address,
+ new_data,
+ old_data,
};
self.genie_codes.insert(address, game_genie_code);
--
GitLab