Action52Mapper.java

/*
 * HalfNES by Andrew Hoffman
 * Licensed under the GNU GPL Version 3. See LICENSE file
 */
package com.grapeshot.halfnes.mappers;

import com.grapeshot.halfnes.utils;

/**
 *
 * @author Andrew
 */
public class Action52Mapper extends Mapper {

    int[] ram = new int[4];
    int prgchip = 0;
    int prgpage = 0;
    int chrpage = 0;
    boolean prgmode = false;

    @Override
    public void loadrom() throws BadMapperException {
        super.loadrom();
        cartWrite(0x8000, 0);
    }

    @Override
    public final void cartWrite(final int addr, final int data) {
        if (addr <= 0x5fff) {
            ram[addr & 3] = data & 0xf;
        } else if (addr >= 0x8000) {
            chrpage = ((addr & 0xf) << 2) + (data & 3);
            prgmode = ((addr & (utils.BIT5)) != 0);
            prgpage = (addr >> 6) & 0x1f;
            prgchip = (addr >> 11) & 3;
            setmirroring((((addr & (utils.BIT13)) != 0)) ? MirrorType.H_MIRROR : MirrorType.V_MIRROR);
            for (int i = 0; i < 8; ++i) {
                chr_map[i] = (1024 * (chrpage * 8 + i)) % chrsize;
            }
            int off = 0;
            switch (prgchip) {
                case 0:
                    off = 0;
                    break;
                case 1:
                    off = 0x080000;
                    break;
                case 3:
                    off = 0x100000;
                    break;
                default:
                    System.err.println("Who knows.");
            }
            if (prgmode) {
                for (int i = 0; i < 16; ++i) {
                    prg_map[i] = ((1024 * ((16 * prgpage) + i)) + off) % prgsize;
                    prg_map[i + 16] = ((1024 * ((16 * prgpage) + i)) + off) % prgsize;
                }
            } else {
                for (int i = 0; i < 32; ++i) {
                    prg_map[i] = ((1024 * ((32 * (prgpage >> 1)) + i)) + off) % prgsize;
                }
            }
        }
    }

    @Override
    public final int cartRead(final int addr) {
        // by default has wram at 0x6000 and cartridge at 0x8000-0xfff
        // but some mappers have different so override for those
        if (addr >= 0x8000) {
            return prg[prg_map[((addr & 0x7fff)) >> 10] + (addr & 1023)];
        } else if (addr < 0x6000) {
            return ram[addr & 3] & 0xf;
        }
        return addr >> 8; //open bus
    }

    public void reset() {
        cartWrite(0x8000, 0);
    }
}