94 lines
2.9 KiB
Rust
94 lines
2.9 KiB
Rust
use super::mbc::MBC;
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pub struct MBC1 {
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rom: Box<[u8]>,
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ram: Box<[u8]>,
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bank_no: u8,
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ram_rtc_enabled: bool,
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ram_bank_no: u8,
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rom_banks: u16,
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bank_mode: u8,
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bank_no_high: u8,
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}
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impl MBC1 {
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pub fn new(rom: Box<[u8]>, ram: Box<[u8]>) -> MBC1 {
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MBC1 {
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rom: rom,
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ram: ram,
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bank_no: 0,
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ram_rtc_enabled: false,
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ram_bank_no: 0,
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rom_banks: 0,
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bank_mode: 0,
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bank_no_high: 0,
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}
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}
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}
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impl MBC for MBC1 {
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fn read_byte(&self, addr: u16) -> u8 {
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match addr {
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0x0000 ... 0x3FFF => self.rom[addr as usize],
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0x4000 ... 0x7FFF => {
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let addr = addr - 0x4000;
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// println!("BankNo: {:02X}", self.bank_no);
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let abs_addr: usize = addr as usize + self.bank_no as usize * 0x4000;
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let val: u8 = self.rom[abs_addr];
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val
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},
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0xA000 ... 0xBFFF => {
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// TODO: Safty checks? Or let rust handle this?
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let addr = addr - 0xA000;
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if self.ram_bank_no < 4 {
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println!("Access [{:02X}] {:04X}", self.ram_bank_no, addr);
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self.ram[self.ram_bank_no as usize * 0x2000 + addr as usize]
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} else {
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println!("Ignoring RTC read");
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0
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}
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}
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_ => {
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panic!("Cartride: Unable to read from {:04X}", addr);
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}
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}
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}
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fn write_byte(&mut self, addr: u16, val: u8) {
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match addr {
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0x0000 ... 0x1FFF => {
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match val {
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0x0A => self.ram_rtc_enabled = true,
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0x00 => self.ram_rtc_enabled = false,
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_ => println!("Unknown MBC value {:02X} for {:04X}", val, addr)
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}
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},
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0x2000 ... 0x3FFF => self.bank_no = val & 0x7F,
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0x4000 ... 0x5FFF => {
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// RAM bank select
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match val {
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0x00 ... 0x03 => self.ram_bank_no = 0, //val,
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0x08 ... 0x0C => self.ram_bank_no = val, // RTC clock values, TODO
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_ => panic!("Unknown MBC1 RAM BANK NO: {:02X}", val)
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}
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},
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0x6000 ... 0x7FFF => {
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// Latch clock data, ignore.
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},
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0xA000 ... 0xBFFF => {
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// TODO: Safty checks? Or let rust handle this?
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let addr = addr - 0xA000;
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if self.ram_bank_no < 4 {
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self.ram[self.ram_bank_no as usize * 0x2000 + addr as usize] = val;
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} else {
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println!("Ignoring RTC write");
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}
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}
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_ => panic!("MBC1: Writing {:02X} to {:04X} not supported", val, addr),
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}
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}
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}
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