paoda
/
gb
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

fix(cartridge): reimplement apply_rom_size_bitmask

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-03-26 20:18:49 -05:00
parent a82e3d3372
commit a6d5553035
1 changed files with 14 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
src/cartridge.rs
View File

@ -114,18 +114,12 @@ impl MBC1 {
fn calc_high_bank_number(&self) -> u8 {
use BankCount::*;
let less_than_mb = self.apply_rom_size_bitmask(self.rom_bank);
match self.bank_count {
None | Four | Eight | Sixteen | ThirtyTwo => self.apply_rom_size_bitmask(self.rom_bank),
SixtyFour => {
let mut num = self.apply_rom_size_bitmask(self.rom_bank);
num &= !(0x01 << 5);
num | ((self.ram_bank & 0x01) << 5)
}
OneHundredTwentyEight => {
let mut num = self.apply_rom_size_bitmask(self.rom_bank);
num &= !(0x03 << 5);
num | ((self.ram_bank) << 5)
}
None | Four | Eight | Sixteen | ThirtyTwo => less_than_mb,
SixtyFour => (less_than_mb & !(0x01 << 5)) | (self.ram_bank & 0x01) << 5,
OneHundredTwentyEight => (less_than_mb & !(0b11 << 5)) | (self.ram_bank & 0b11) << 5,
_ => unreachable!("{:?} is not a valid MBC1 BankCount", self.bank_count),
}
}
@ -135,7 +129,8 @@ impl MBC1 {
let err_bc = self.bank_count; // Bank Count, but with a shorter name
match self.bank_count {
let result = match self.bank_count {
None => byte, // FIXME: I don't think this is the correct behaviour
Four => byte & 0b00000011,
Eight => byte & 0b00000111,
Sixteen => byte & 0b00001111,
@ -143,7 +138,12 @@ impl MBC1 {
SixtyFour => byte & 0b00011111,
OneHundredTwentyEight => byte & 0b00011111,
_ => unreachable!("{:?} does not have a rom size bitmask in MBC1", err_bc),
};
if result == 0 {
return 1;
}
result
}
fn calc_ram_address(&self, addr: u16) -> u16 {
@ -198,10 +198,6 @@ impl MemoryBankController for MBC1 {
0x0000..=0x1FFF => self.ram_enabled = (byte & 0x0F) == 0x0A,
0x2000..=0x3FFF => {
self.rom_bank = self.apply_rom_size_bitmask(byte);
if self.rom_bank == 0 {
self.rom_bank = 1;
}
}
0x4000..=0x5FFF => self.ram_bank = byte & 0b11,
0x6000..=0x7FFF => self.mode = (byte & 0x01) == 0x01,
@ -323,10 +319,10 @@ impl Default for BankCount {
impl BankCount {
// https://hacktix.github.io/GBEDG/mbcs/#rom-size
pub fn to_rom_size(&self) -> u32 {
pub fn to_byte_count(self) -> u32 {
use BankCount::*;
match *self {
match self {
None => 32_768,
Four => 65_536,
Eight => 131_072,