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