path: root/src/mapper.rs

#![allow(dead_code)]
extern crate core;
use core::cell::UnsafeCell;
use memory::{VMem, CPUBus};
use cartridge::{Cartridge, BankType, MirrorType};

pub trait Mapper : VMem {
    fn get_cart(&self) -> &Cartridge;
    fn tick(&mut self, _bus: &CPUBus) {}
}

pub struct RefMapper<'a> {
    mapper: UnsafeCell<&'a mut Mapper>
}

impl<'a> RefMapper<'a> {
    pub fn new(mapper: &'a mut Mapper) -> Self {
        RefMapper { mapper: UnsafeCell::new(mapper) }
    }

    #[inline(always)]
    pub fn get_mut(&self) -> &'a mut Mapper {
        unsafe { *self.mapper.get() }
    }
}

impl<'a> core::ops::Deref for RefMapper<'a> {
    type Target = &'a mut Mapper;
    #[inline(always)]
    fn deref(&self) -> &&'a mut Mapper {
        unsafe { &*self.mapper.get() }
    }
}

pub struct Mapper1<'a, C> where C: Cartridge {
    cart: C,
    prg_banks: [&'a [u8]; 2],
    chr_banks: [&'a mut [u8]; 2],
    sram: &'a mut [u8],
    ctl_reg: u8,
    load_reg: u8,
    prg_nbank: usize, /* num of 16k PRG ROM banks */
    chr_nbank: usize /* num of 8k PRG ROM banks */
}

impl<'a, C> VMem for Mapper1<'a, C> where C: Cartridge {
    fn read(&self, addr: u16) -> u8 {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_banks[(addr >> 12) & 1][addr & 0xfff],
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000],
            /* [0x8000..0xffff] */
            _ => self.prg_banks[(addr >> 14) & 1][addr & 0x3fff]
        }
    }

    fn write(&mut self, addr: u16, data: u8) {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_banks[(addr >> 12) & 1][addr & 0xfff] = data,
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000] = <