121 lines
4.1 KiB
Rust
121 lines
4.1 KiB
Rust
use std::str::from_utf8;
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use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
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use super::arm7tdmi::{bus::Bus, Addr};
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/// From GBATEK
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///
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/// 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).
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///
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/// Header Overview
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/// Address Bytes Expl.
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/// 000h 4 ROM Entry Point (32bit ARM branch opcode, eg. "B rom_start")
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/// 004h 156 Nintendo Logo (compressed bitmap, required!)
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/// 0A0h 12 Game Title (uppercase ascii, max 12 characters)
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/// 0ACh 4 Game Code (uppercase ascii, 4 characters)
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/// 0B0h 2 Maker Code (uppercase ascii, 2 characters)
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/// 0B2h 1 Fixed value (must be 96h, required!)
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/// 0B3h 1 Main unit code (00h for current GBA models)
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/// 0B4h 1 Device type (usually 00h) (bit7=DACS/debug related)
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/// 0B5h 7 Reserved Area (should be zero filled)
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/// 0BCh 1 Software version (usually 00h)
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/// 0BDh 1 Complement check (header checksum, required!)
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/// 0BEh 2 Reserved Area (should be zero filled)
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/// --- Additional Multiboot Header Entries ---
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/// 0C0h 4 RAM Entry Point (32bit ARM branch opcode, eg. "B ram_start")
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/// 0C4h 1 Boot mode (init as 00h - BIOS overwrites this value!)
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/// 0C5h 1 Slave ID Number (init as 00h - BIOS overwrites this value!)
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/// 0C6h 26 Not used (seems to be unused)
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/// 0E0h 4 JOYBUS Entry Pt. (32bit ARM branch opcode, eg. "B joy_start")
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///
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#[derive(Debug)]
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pub struct CartridgeHeader {
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// rom_entry_point: Addr,
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game_title: String,
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game_code: String,
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maker_code: String,
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software_version: u8,
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checksum: u8,
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// ram_entry_point: Addr,
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// joybus_entry_point: Addr,
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}
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impl CartridgeHeader {
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fn parse(bytes: &[u8]) -> CartridgeHeader {
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// let (_, rom_entry_point) = le_u32(bytes).unwrap();
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let game_title = from_utf8(&bytes[0xa0..0xac]).unwrap();
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let game_code = from_utf8(&bytes[0xac..0xb0]).unwrap();
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let maker_code = from_utf8(&bytes[0xb0..0xb2]).unwrap();
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// let (_, ram_entry_point) = le_u32(&bytes[0xc0..]).unwrap();
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// let (_, joybus_entry_point) = le_u32(&bytes[0xc0..]).unwrap();
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CartridgeHeader {
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// rom_entry_point: rom_entry_point,
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game_title: String::from(game_title),
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game_code: String::from(game_code),
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maker_code: String::from(maker_code),
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software_version: bytes[0xbc],
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checksum: bytes[0xbd],
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// ram_entry_point: ram_entry_point,
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// joybus_entry_point: joybus_entry_point,
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}
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}
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}
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#[derive(Debug)]
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pub struct Cartridge {
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pub header: CartridgeHeader,
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bytes: Box<[u8]>,
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}
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impl Cartridge {
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const MIN_SIZE: usize = 4 * 1024 * 1024;
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pub fn new(mut rom_bin: Vec<u8>) -> Cartridge {
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if rom_bin.len() < Cartridge::MIN_SIZE {
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rom_bin.resize_with(Cartridge::MIN_SIZE, Default::default);
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}
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let header = CartridgeHeader::parse(&rom_bin);
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Cartridge {
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header: header,
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bytes: rom_bin.into_boxed_slice(),
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}
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}
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}
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impl Bus for Cartridge {
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fn read_32(&self, addr: Addr) -> u32 {
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(&self.bytes[addr as usize..])
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.read_u32::<LittleEndian>()
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.unwrap()
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}
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fn read_16(&self, addr: Addr) -> u16 {
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(&self.bytes[addr as usize..])
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.read_u16::<LittleEndian>()
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.unwrap()
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}
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fn read_8(&self, addr: Addr) -> u8 {
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(&self.bytes[addr as usize..])[0]
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}
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fn write_32(&mut self, addr: Addr, value: u32) {
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(&mut self.bytes[addr as usize..])
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.write_u32::<LittleEndian>(value)
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.unwrap()
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}
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fn write_16(&mut self, addr: Addr, value: u16) {
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(&mut self.bytes[addr as usize..])
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.write_u16::<LittleEndian>(value)
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.unwrap()
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}
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fn write_8(&mut self, addr: Addr, value: u8) {
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(&mut self.bytes[addr as usize..]).write_u8(value).unwrap()
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}
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}
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