Mapper31.java

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package com.grapeshot.halfnes.mappers;

import com.grapeshot.halfnes.utils;

/**
 *
 * @author Andrew
 */
public class Mapper31 extends Mapper {

    //mapper for NSF compilations, based on BNROM with NSF type bankswitch
    //written in about 20mins so i could listen to 2a03puritans
    public boolean nsfBanking;
    public int[] nsfBanks = {00, 00, 00, 00, 00, 00, 00, 0xff};

    @Override
    public void loadrom() throws BadMapperException {
        // needs to be in every mapper. Fill with initial cfg
        super.loadrom();
        setBanks();
    }

    @Override
    public void cartWrite(final int addr, final int data) {
        if (addr >= 0x6000 && addr < 0x8000) {
            //default no-mapper operation just writes if in PRG RAM range
            prgram[addr & 0x1fff] = data;
        } else if ((addr >= 0x5000) && (addr < 0x6000)) {
            nsfBanks[addr & 7] = data;
            //System.err.println(addr - 0x5ff8 + " " + data);
            setBanks();
        } else {
            System.err.println("write to " + utils.hex(addr) + " goes nowhere");
        }
    }

    @Override
    public 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) {

            int fuuu = prg_map[((addr & 0x7fff)) >> 10] + (addr & 1023);
            return prg[fuuu];
        } else if (addr >= 0x6000 && hasprgram) {

            return prgram[addr & 0x1fff];
        } else if ((addr >= 0x5000)) {
            return nsfBanks[addr & 7];
        }
        System.err.println("reading open bus " + utils.hex(addr));
        return addr >> 8; //open bus
    }

    private void setBanks() {
        for (int i = 0; i < prg_map.length; ++i) {
            prg_map[i] = (4096 * nsfBanks[i / 4]) + (1024 * (i % 4));
            if ((prg_map[i]) >= prg.length) {
//                System.err.println("broken banks");
                prg_map[i] &= ((this.prgsize) - 1);
            }
        }
    }

}