use super::Mapper;
use crate::cartridge::Mirroring;
use crate::cartridge::mappers::{decode_mirroring, encode_mirroring};
use crate::savestate::{SaveStateError, StateReader, StateWriter};
const PRG_BANK_8K: usize = 0x2000;
const CHR_BANK_2K: usize = 0x0800;
const CHR_BANK_1K: usize = 0x0400;
enum ChrMemory {
Rom(Vec<u8>),
Ram(Vec<u8>),
}
pub(super) struct Taito0190 {
prg_rom: Vec<u8>,
chr: ChrMemory,
regs: [u8; 8],
mirroring: Mirroring,
is_48: bool,
irq_latch: u8,
irq_counter: u16,
irq_enabled: bool,
}
impl Taito0190 {
pub(super) fn new(
prg_rom: Vec<u8>,
chr_rom: Vec<u8>,
mirroring: Mirroring,
is_48: bool,
) -> Self {
let chr = if chr_rom.is_empty() {
ChrMemory::Ram(vec![0; 0x2000])
} else {
ChrMemory::Rom(chr_rom)
};
Self {
prg_rom,
chr,
regs: [0; 8],
mirroring,
is_48,
irq_latch: 0,
irq_counter: 0,
irq_enabled: false,
}
}
fn prg_bank_count_8k(&self) -> usize {
self.prg_rom.len() / PRG_BANK_8K
}
fn chr_bank_count_2k(&self) -> usize {
match &self.chr {
ChrMemory::Rom(r) => (r.len() / CHR_BANK_2K).max(1),
ChrMemory::Ram(r) => (r.len() / CHR_BANK_2K).max(1),
}
}
fn chr_bank_count_1k(&self) -> usize {
match &self.chr {
ChrMemory::Rom(r) => (r.len() / CHR_BANK_1K).max(1),
ChrMemory::Ram(r) => (r.len() / CHR_BANK_1K).max(1),
}
}
}
impl Mapper for Taito0190 {
fn cpu_read(&mut self, addr: u16) -> Option<u8> {
match addr {
0x8000..=0x9FFF => {
let bank = self.regs[0] as usize % self.prg_bank_count_8k();
let offset = bank * PRG_BANK_8K + (addr as usize - 0x8000);
Some(self.prg_rom[offset % self.prg_rom.len()])
}
0xA000..=0xBFFF => {
let bank = self.regs[1] as usize % self.prg_bank_count_8k();
let offset = bank * PRG_BANK_8K + (addr as usize - 0xA000);
Some(self.prg_rom[offset % self.prg_rom.len()])
}
0xC000..=0xDFFF => {
let second_last = self.prg_bank_count_8k().saturating_sub(2);
let offset = second_last * PRG_BANK_8K + (addr as usize - 0xC000);
Some(self.prg_rom[offset % self.prg_rom.len()])
}
0xE000..=0xFFFF => {
let last = self.prg_bank_count_8k().saturating_sub(1);
let offset = last * PRG_BANK_8K + (addr as usize - 0xE000);
Some(self.prg_rom[offset % self.prg_rom.len()])
}
_ => None,
}
}
fn cpu_write(&mut self, addr: u16, data: u8) -> bool {
if self.is_48 && addr >= 0xC000 {
match addr & 0xF003 {
0xC000 => {
self.irq_latch = data;
}
0xC001 => {
self.irq_counter = self.irq_latch as u16;
}
0xC002 => {
self.irq_enabled = true;
}
0xC003 => {
self.irq_enabled = false;
}
0xE000 => {
self.mirroring = if ((data >> 6) & 1) != 0 {
Mirroring::Horizontal
} else {
Mirroring::Vertical
};
}
_ => return false,
}
return true;
}
match addr & 0xF003 {
0x8000 => {
self.regs[0] = data & 0x3F;
if !self.is_48 {
self.mirroring = if ((data >> 6) & 1) != 0 {
Mirroring::Horizontal
} else {
Mirroring::Vertical
};
}
}
0x8001 => {
self.regs[1] = data & 0x3F;
}
0x8002 => {
self.regs[2] = data;
}
0x8003 => {
self.regs[3] = data;
}
0xA000 => {
self.regs[4] = data;
}
0xA001 => {
self.regs[5] = data;
}
0xA002 => {
self.regs[6] = data;
}
0xA003 => {
self.regs[7] = data;
}
_ => return false,
}
true
}
fn ppu_read(&mut self, addr: u16) -> Option<u8> {
if !matches!(addr, 0x0000..=0x1FFF) {
return None;
}
let offset = addr as usize;
let max_2k = self.chr_bank_count_2k();
let max_1k = self.chr_bank_count_1k();
match &mut self.chr {
ChrMemory::Rom(chr_rom) => {
let bank = match offset {
0x0000..=0x07FF => self.regs[2] as usize % max_2k,
0x0800..=0x0FFF => self.regs[3] as usize % max_2k,
0x1000..=0x13FF => self.regs[4] as usize % max_1k,
0x1400..=0x17FF => self.regs[5] as usize % max_1k,
0x1800..=0x1BFF => self.regs[6] as usize % max_1k,
_ => self.regs[7] as usize % max_1k,
};
let base = match offset {
0x0000..=0x07FF => bank * CHR_BANK_2K,
0x0800..=0x0FFF => bank * CHR_BANK_2K,
_ => bank * CHR_BANK_1K,
};
let sub_offset = match offset {
0x0000..=0x0FFF => offset & 0x07FF,
_ => offset & 0x03FF,
};
Some(chr_rom[(base + sub_offset) % chr_rom.len()])
}
ChrMemory::Ram(chr_ram) => Some(chr_ram[offset]),
}
}
fn ppu_write(&mut self, addr: u16, data: u8) -> bool {
if !matches!(addr, 0x0000..=0x1FFF) {
return false;
}
if let ChrMemory::Ram(chr_ram) = &mut self.chr {
chr_ram[addr as usize] = data;
}
true
}
fn mirroring(&self) -> Mirroring {
self.mirroring
}
fn irq_line(&self) -> bool {
self.is_48 && self.irq_enabled && self.irq_counter == 0xFF
}
fn tick_cpu_cycle(&mut self) {
if !self.is_48 || !self.irq_enabled {
return;
}
self.irq_counter = self.irq_counter.wrapping_add(1);
}
fn save_state(&self, writer: &mut StateWriter) {
writer.write_bytes(&self.regs);
writer.write_bool(self.is_48);
writer.write_u8(encode_mirroring(self.mirroring));
if self.is_48 {
writer.write_u8(self.irq_latch);
writer.write_u16(self.irq_counter);
writer.write_bool(self.irq_enabled);
}
match &self.chr {
ChrMemory::Rom(_) => writer.write_bool(false),
ChrMemory::Ram(chr_ram) => {
writer.write_bool(true);
writer.write_bytes(chr_ram);
}
}
}
fn load_state(&mut self, reader: &mut StateReader<'_>) -> Result<(), SaveStateError> {
reader.read_bytes_into(&mut self.regs)?;
self.is_48 = reader.read_bool()?;
self.mirroring = decode_mirroring(reader.read_u8()?)?;
if self.is_48 {
self.irq_latch = reader.read_u8()?;
self.irq_counter = reader.read_u16()?;
self.irq_enabled = reader.read_bool()?;
}
let has_chr_ram = reader.read_bool()?;
match (&mut self.chr, has_chr_ram) {
(ChrMemory::Ram(chr_ram), true) => reader.read_bytes_into(chr_ram)?,
(ChrMemory::Rom(_), false) => {}
_ => {
return Err(SaveStateError::InvalidData(
"CHR RAM mismatch for Taito TC0190 save state",
));
}
}
Ok(())
}
}