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rustboyadvance-ng/src/cartridge.rs

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use std::str::from_utf8;
use crate::arm7tdmi::{
bus::{Bus, MemoryAccess, MemoryAccessWidth},
Addr,
};
use crate::sysbus::WaitState;
/// From GBATEK
///
/// The first 192 bytes at 8000000h-80000BFh in ROM are used as cartridge header. The same header is also used for Multiboot images at 2000000h-20000BFh (plus some additional multiboot entries at 20000C0h and up).
///
/// Header Overview
/// Address Bytes Expl.
/// 000h 4 ROM Entry Point (32bit ARM branch opcode, eg. "B rom_start")
/// 004h 156 Nintendo Logo (compressed bitmap, required!)
/// 0A0h 12 Game Title (uppercase ascii, max 12 characters)
/// 0ACh 4 Game Code (uppercase ascii, 4 characters)
/// 0B0h 2 Maker Code (uppercase ascii, 2 characters)
/// 0B2h 1 Fixed value (must be 96h, required!)
/// 0B3h 1 Main unit code (00h for current GBA models)
/// 0B4h 1 Device type (usually 00h) (bit7=DACS/debug related)
/// 0B5h 7 Reserved Area (should be zero filled)
/// 0BCh 1 Software version (usually 00h)
/// 0BDh 1 Complement check (header checksum, required!)
/// 0BEh 2 Reserved Area (should be zero filled)
/// --- Additional Multiboot Header Entries ---
/// 0C0h 4 RAM Entry Point (32bit ARM branch opcode, eg. "B ram_start")
/// 0C4h 1 Boot mode (init as 00h - BIOS overwrites this value!)
/// 0C5h 1 Slave ID Number (init as 00h - BIOS overwrites this value!)
/// 0C6h 26 Not used (seems to be unused)
/// 0E0h 4 JOYBUS Entry Pt. (32bit ARM branch opcode, eg. "B joy_start")
///
#[derive(Debug)]
pub struct CartridgeHeader {
// rom_entry_point: Addr,
game_title: String,
game_code: String,
maker_code: String,
software_version: u8,
checksum: u8,
// ram_entry_point: Addr,
// joybus_entry_point: Addr,
}
impl CartridgeHeader {
fn parse(bytes: &[u8]) -> CartridgeHeader {
// let (_, rom_entry_point) = le_u32(bytes).unwrap();
let game_title = from_utf8(&bytes[0xa0..0xac]).unwrap();
let game_code = from_utf8(&bytes[0xac..0xb0]).unwrap();
let maker_code = from_utf8(&bytes[0xb0..0xb2]).unwrap();
// let (_, ram_entry_point) = le_u32(&bytes[0xc0..]).unwrap();
// let (_, joybus_entry_point) = le_u32(&bytes[0xc0..]).unwrap();
CartridgeHeader {
// rom_entry_point: rom_entry_point,
game_title: String::from(game_title),
game_code: String::from(game_code),
maker_code: String::from(maker_code),
software_version: bytes[0xbc],
checksum: bytes[0xbd],
// ram_entry_point: ram_entry_point,
// joybus_entry_point: joybus_entry_point,
}
}
}
#[derive(Debug)]
pub struct Cartridge {
pub header: CartridgeHeader,
bytes: Box<[u8]>,
ws: WaitState,
}
impl Cartridge {
pub fn new(gamepak: Vec<u8>) -> Cartridge {
let header = CartridgeHeader::parse(&gamepak);
Cartridge {
header: header,
bytes: gamepak.into_boxed_slice(),
ws: WaitState::new(5, 5, 8),
}
}
}
impl Bus for Cartridge {
fn get_bytes(&self, addr: Addr) -> &[u8] {
&self.bytes[addr as usize..]
}
fn get_bytes_mut(&mut self, addr: Addr) -> &mut [u8] {
&mut self.bytes[addr as usize..]
}
fn get_cycles(&self, _addr: Addr, access: MemoryAccess) -> usize {
match access.1 {
MemoryAccessWidth::MemoryAccess8 => self.ws.access8,
MemoryAccessWidth::MemoryAccess16 => self.ws.access16,
MemoryAccessWidth::MemoryAccess32 => self.ws.access32,
}
}
}