AfterburnerMapper.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;
import java.util.Arrays;

/**
 *
 * @author Andrew
 */
public class AfterburnerMapper extends Mapper {
    //the Afterburner mapper is special in that it uses ROM name tables

    private int bank = 0x0;
    boolean useromnt = false;
    int romnt1, romnt2;

    @Override
    public void loadrom() throws BadMapperException {
        //needs to be in every mapper. Fill with initial cfg
        super.loadrom();
        //movable bank, should really be random. eh, effort
        for (int i = 0; i < 16; ++i) {
            prg_map[i] = (1024 * i) & (prgsize - 1);
        }
        //fixed bank
        for (int i = 1; i <= 16; ++i) {
            prg_map[32 - i] = prgsize - (1024 * i);
        }
        for (int i = 0; i < 8; ++i) {
            chr_map[i] = (1024 * i) & (chrsize - 1);
        }
    }

    @Override
    public final void cartWrite(int addr, int data) {
        if (addr < 0x8000 || addr > 0xffff) {
            super.cartWrite(addr, data);
            return;
        } else if (addr <= 0x8fff) {
            setppubank(2, 0, data);
        } else if (addr <= 0x9fff) {
            setppubank(2, 2, data);
        } else if (addr <= 0xafff) {
            setppubank(2, 4, data);
        } else if (addr <= 0xbfff) {
            setppubank(2, 6, data);
        } else if (addr <= 0xcfff) {
            romnt1 = data | 0x80;
        } else if (addr <= 0xdfff) {
            romnt2 = data | 0x80;
        } else if (addr <= 0xefff) {
            useromnt = ((data & (utils.BIT4)) != 0);
            setmirroring(((data & (utils.BIT0)) != 0) ? MirrorType.H_MIRROR : MirrorType.V_MIRROR);
        } else if (addr <= 0xffff) {
            bank = data & 0xf;
            //remap PRG bank (1st bank switchable, 2nd bank mapped to LAST bank)
            for (int i = 0; i < 16; ++i) {
                prg_map[i] = (1024 * (i + 16 * bank)) & (prgsize - 1);
            }
        }
    }

    private void setppubank(int banksize, int bankpos, int banknum) {
//        System.err.println(banksize + ", " + bankpos + ", "+ banknum);
        for (int i = 0; i < banksize; ++i) {
            chr_map[i + bankpos] = (1024 * ((banksize * banknum) + i)) % chrsize;
        }
    }

    public int ppuRead(int addr) {
        if (addr < 0x2000) {
            return chr[chr_map[addr >> 10] + (addr & 1023)];
        } else {
            switch (addr & 0xc00) {
                case 0:
                    return (useromnt ? chr[(addr & 0x3ff) + (romnt1 * 1024)] : nt0[addr & 0x3ff]);
                case 0x400:
                    return (useromnt ? chr[(addr & 0x3ff) + (romnt2 * 1024)] : nt1[addr & 0x3ff]);
                case 0x800:
                    return (useromnt ? chr[(addr & 0x3ff) + (romnt2 * 1024)] : nt2[addr & 0x3ff]);
                case 0xc00:
                default:
                    if (addr >= 0x3f00) {
                        addr &= 0x1f;
                        if (addr >= 0x10 && ((addr & 3) == 0)) {
                            addr -= 0x10;
                        }
                        return ppu.pal[addr];
                    } else {
                        return (useromnt ? chr[(addr & 0x3ff) + (romnt1 * 1024)] : nt3[addr & 0x3ff]);
                    }
            }
        }
    }
}