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mmc3 not perfect but closer to working, kirby intro is correct, smb3 is pretty off but doesn't crash

This commit is contained in:
Theron Spiegl 2020-01-18 14:52:09 -06:00
parent 3e598ec9e6
commit 413d9454a4
3 changed files with 23 additions and 18 deletions
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4
src/audio.rs
View File

@ -37,7 +37,7 @@ impl AudioCallback for ApuSampler {
*b = b.split_off(target);
}
} else {
println!("buffer empty!"); // happens when the callback fires twice between video frames
// println!("buffer empty!"); // happens when the callback fires twice between video frames
}
}
}
@ -52,7 +52,7 @@ pub fn initialize(sdl_context: &Sdl, buffer: Arc<Mutex<Vec<f32>>>)
samples: Some(SAMPLES_PER_FRAME)
};
audio_subsystem.open_playback(None, &desired_spec, |spec| {
println!("{:?}", spec);
// println!("{:?}", spec);
ApuSampler{buffer, sample_ratio: APU_SAMPLE_RATE / (SDL_SAMPLE_RATE as f32)}
})
}

32
src/cartridge/mmc3.rs
View File

@ -18,13 +18,14 @@ pub struct Mmc3 {
prg_rom_bank_mode: bool,
// 0: two 2 KB banks at $0000-$0FFF, four 1 KB banks at $1000-$1FFF
// 1: two 2 KB banks at $1000-$1FFF, four 1 KB banks at $0000-$0FFF
chr_rom_bank_mode: bool,
chr_ram_bank: Vec<u8>, // used if cartridge doesn't have any CHR-ROM, 8KB, $0000-$1FFF
}
impl Mmc3 {
pub fn new(cart: Cartridge) -> Self {
let m = cart.mirroring;
// let num_banks = cart.prg_rom_size
Mmc3{
cart: cart,
mirroring: m,
@ -37,6 +38,7 @@ impl Mmc3 {
prg_ram_bank: vec![0; 0x2000],
prg_rom_bank_mode: false,
chr_rom_bank_mode: false,
chr_ram_bank: vec![0; 0x2000],
}
}
@ -51,8 +53,8 @@ impl Mmc3 {
// R6 and R7 will ignore the top two bits, as the MMC3 has only 6 PRG ROM address lines.
// R0 and R1 ignore the bottom bit, as the value written still counts banks in 1KB units but odd numbered banks can't be selected.
self.bank_registers[self.next_bank as usize] = match self.next_bank {
0 | 1 => value & 0b0011_1111,
6 | 7 => value & 0b1111_1110,
0 | 1 => value & 0b1111_1110,
6 | 7 => value & 0b0011_1111,
_ => value,
} as usize;
}
@ -67,7 +69,6 @@ impl Mapper for Mmc3 {
let offset_1k = address % 0x400;
let offset_2k = address % 0x800;
let bank_reg_num = match self.chr_rom_bank_mode {
// look at the value in the bank reg, then depending whether that's a
true => {
match address {
0x0000..=0x03FF => 2,
@ -92,13 +93,11 @@ impl Mapper for Mmc3 {
},
};
let bank_num = self.bank_registers[bank_reg_num];
let chunk_num = bank_num / 8;
let chunk_eighth = (bank_num % 8) * 0x400;
if bank_reg_num == 0 || bank_reg_num == 1 { // dealing with 2K banks of 8K chunks
let chunk_num = bank_num / 4;
let chunk_quarter = (bank_num % 4) * 0x800;
self.cart.chr_rom[chunk_num][chunk_quarter + offset_2k]
self.cart.chr_rom[chunk_num][chunk_eighth + offset_2k]
} else { // dealing with 1K banks of 8K chunks
let chunk_num = bank_num / 8;
let chunk_eighth = (bank_num % 8) * 0x400;
self.cart.chr_rom[chunk_num][chunk_eighth + offset_1k]
}
},
@ -108,7 +107,7 @@ impl Mapper for Mmc3 {
0x8000..=0xFFFF => { // reading from PRG ROM, dealing with 8K banks of 16K chunks
let offset_8k = address % 0x2000;
let num_banks = self.cart.prg_rom_size * 2;
let bank_num = match self.chr_rom_bank_mode {
let bank_num = match self.prg_rom_bank_mode {
true => {
match address {
0x8000..=0x9FFF => num_banks - 2,
@ -129,7 +128,7 @@ impl Mapper for Mmc3 {
},
};
let chunk_num = bank_num / 2;
let chunk_half = (bank_num % 2) * 0x1000;
let chunk_half = (bank_num % 2) * 0x2000;
self.cart.prg_rom[chunk_num][chunk_half + offset_8k]
},
@ -138,11 +137,16 @@ impl Mapper for Mmc3 {
0
},
};
println!("reading 0x{:X} from 0x{:X}", val, address);
val
}
fn write(&mut self, address: usize, value: u8) {
if (0..=0x1FFF).contains(&address) {
if self.cart.chr_rom_size == 0 {
self.chr_ram_bank[address] = value;
}
return
}
match address % 2 == 0 {
true => { // even
match address {
@ -151,7 +155,7 @@ impl Mapper for Mmc3 {
0xA000..=0xBFFF => self.mirroring = if value & 1 == 0 {Mirror::Vertical} else {Mirror::Horizontal},
0xC000..=0xDFFF => self.irq_latch = value,
0xE000..=0xFFFF => self.irq_enable = false,
_ => panic!("oh no"),
_ => println!("bad address written to MMC3: 0x{:X}", address),
}
},
false => { // odd
@ -161,7 +165,7 @@ impl Mapper for Mmc3 {
0xA000..=0xBFFF => self.prg_ram_protect(),
0xC000..=0xDFFF => self.irq_counter = 0, // Writing any value to this register reloads the MMC3 IRQ counter at the NEXT rising edge of the PPU address, presumably at PPU cycle 260 of the current scanline.
0xE000..=0xFFFF => self.irq_enable = true,
_ => panic!("oh no"),
_ => println!("bad address written to MMC3: 0x{:X}", address),
}
},
}

5
src/cpu/mod.rs
View File

@ -84,7 +84,7 @@ impl Cpu {
A: 0, X: 0, Y: 0,
PC: 0,
S: 0xFD,
P: 0x34,
P: 0x24,
clock: 0,
delay: 0,
mapper: mapper,
@ -155,7 +155,8 @@ impl Cpu {
}
self.apu.trigger_irq = false;
// and mapper MMC3
if self.mapper.borrow_mut().check_irq() {
if self.mapper.borrow_mut().check_irq() && (self.P & INTERRUPT_DISABLE_FLAG == 0) {
// println!("firing IRQ from mapper");
self.irq();
}