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fix(cartridge): improve accuracy of MBC1 with large file sizes

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-09-06 23:37:55 -03:00
parent 44ac0c8ebd
commit e128025208
1 changed files with 13 additions and 25 deletions
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36
src/cartridge.rs
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@ -188,16 +188,16 @@ impl MBC1 {
}
}
fn ram_addr(&self, addr: u16) -> u16 {
fn ram_addr(&self, addr: u16) -> usize {
use RamSize::*;
match self.ram_size {
Unused | One => (addr - 0xA000) % self.ram_size.capacity() as u16,
Unused | One => (addr as usize - 0xA000) % self.ram_size.capacity(),
Four => {
if self.mode {
0x2000 * self.ram_bank as u16 + (addr - 0xA000)
0x2000 * self.ram_bank as usize + (addr as usize - 0xA000)
} else {
addr - 0xA000
addr as usize - 0xA000
}
}
_ => unreachable!("RAM size can not be greater than 32KB on MBC1"),
@ -210,23 +210,15 @@ impl MBCIo for MBC1 {
use MBCResult::*;
match addr {
0x0000..=0x3FFF => {
if self.mode {
0x0000..=0x3FFF if self.mode => {
Address(0x4000 * self.zero_bank() as usize + addr as usize)
} else {
Address(addr as usize)
}
}
0x0000..=0x3FFF => Address(addr as usize),
0x4000..=0x7FFF => {
Address(0x4000 * self.high_bank() as usize + (addr as usize - 0x4000))
}
0xA000..=0xBFFF => {
if self.mem_enabled {
Value(self.memory[self.ram_addr(addr) as usize])
} else {
Value(0xFF)
}
}
0xA000..=0xBFFF if self.mem_enabled => Value(self.memory[self.ram_addr(addr)]),
0xA000..=0xBFFF => Value(0xFF),
_ => unreachable!("A read from {:#06X} should not be handled by MBC1", addr),
}
}
@ -235,18 +227,14 @@ impl MBCIo for MBC1 {
match addr {
0x0000..=0x1FFF => self.mem_enabled = (byte & 0x0F) == 0x0A,
0x2000..=0x3FFF => {
self.rom_bank = if byte == 0x00 {
0x01
} else {
byte & self.rom_size_mask()
};
self.rom_bank &= 0x1F;
let value = byte & 0x1F;
let masked_value = byte & self.rom_size_mask();
self.rom_bank = if value == 0 { 0x01 } else { masked_value };
}
0x4000..=0x5FFF => self.ram_bank = byte & 0x03,
0x6000..=0x7FFF => self.mode = (byte & 0x01) == 0x01,
0xA000..=0xBFFF if self.mem_enabled => {
let ram_addr = self.ram_addr(addr) as usize;
let ram_addr = self.ram_addr(addr);
self.memory[ram_addr] = byte;
}
0xA000..=0xBFFF => {} // Ram isn't enabled, ignored write