fceugx/source/fceultra/boards/117.cpp

/* FCE Ultra - NES/Famicom Emulator
 *
 * Copyright notice for this file:
 *  Copyright (C) 2002 Xodnizel
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "mapinc.h"

static uint8 prgreg[4], chrreg[8], mirror;
static uint8 IRQa, IRQCount, IRQLatch;

static SFORMAT StateRegs[] =
{
	{ &IRQa, 1, "IRQA" },
	{ &IRQCount, 1, "IRQC" },
	{ &IRQLatch, 1, "IRQL" },
	{ prgreg, 4, "PREG" },
	{ chrreg, 8, "CREG" },
	{ &mirror, 1, "MREG" },
	{ 0 }
};

static void Sync(void) {
	setprg8(0x8000, prgreg[0]);
	setprg8(0xa000, prgreg[1]);
	setprg8(0xc000, prgreg[2]);
	setprg8(0xe000, prgreg[3]);
	int i;
	for (i = 0; i < 8; i++)
		setchr1(i << 10, chrreg[i]);
	setmirror(mirror ^ 1);
}

static DECLFW(M117Write) {
	if (A < 0x8004) {
		prgreg[A & 3] = V;
		Sync();
	} else if ((A >= 0xA000) && (A <= 0xA007)) {
		chrreg[A & 7] = V;
		Sync();
	} else switch (A) {
		case 0xc001: IRQLatch = V; break;
		case 0xc003: IRQCount = IRQLatch; IRQa |= 2; break;
		case 0xe000: IRQa &= ~1; IRQa |= V & 1; X6502_IRQEnd(FCEU_IQEXT); break;
		case 0xc002: X6502_IRQEnd(FCEU_IQEXT); break;
		case 0xd000: mirror = V & 1;
		}
}

static void M117Power(void) {
	prgreg[0] = ~3; prgreg[1] = ~2; prgreg[2] = ~1; prgreg[3] = ~0;
	Sync();
	SetReadHandler(0x8000, 0xFFFF, CartBR);
	SetWriteHandler(0x8000, 0xFFFF, M117Write);
}

static void M117IRQHook(void) {
	if (IRQa == 3 && IRQCount) {
		IRQCount--;
		if (!IRQCount) {
			IRQa &= 1;
			X6502_IRQBegin(FCEU_IQEXT);
		}
	}
}

static void StateRestore(int version) {
	Sync();
}

void Mapper117_Init(CartInfo *info) {
	info->Power = M117Power;
	GameHBIRQHook = M117IRQHook;
	GameStateRestore = StateRestore;
	AddExState(&StateRegs, ~0, 0, 0);
}