/* FCE Ultra - NES/Famicom Emulator
 *
 * Copyright notice for this file:
 *  Copyright (C) 2012 CaH4e3
 *
 * 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 cregs[4], pregs[2];
static uint8 IRQCount, IRQa;

static SFORMAT StateRegs[] =
{
	{ cregs, 4, "CREG" },
	{ pregs, 2, "PREG" },
	{ &IRQa, 1, "IRQA" },
	{ &IRQCount, 1, "IRQC" },
	{ 0 }
};

static void Sync(void) {
	setprg8(0x8000, pregs[0]);
	setprg8(0xa000, pregs[1]);
	setprg8(0xc000, ~1);
	setprg8(0xe000, ~0);
	setchr2(0x0000, cregs[0]);
	setchr2(0x0800, cregs[1]);
	setchr2(0x1000, cregs[2]);
	setchr2(0x1800, cregs[3]);
}

static DECLFW(M91Write0) {
	cregs[A & 3] = V;
	Sync();
}

static DECLFW(M91Write1) {
	switch (A & 3) {
	case 0:
	case 1: pregs[A & 1] = V; Sync(); break;
	case 2: IRQa = IRQCount = 0; X6502_IRQEnd(FCEU_IQEXT); break;
	case 3: IRQa = 1; X6502_IRQEnd(FCEU_IQEXT); break;
	}
}

static void M91Power(void) {
	Sync();
	SetWriteHandler(0x6000, 0x6fff, M91Write0);
	SetWriteHandler(0x7000, 0x7fff, M91Write1);
	SetReadHandler(0x8000, 0xffff, CartBR);
}

static void M91IRQHook(void) {
	if (IRQCount < 8 && IRQa) {
		IRQCount++;
		if (IRQCount >= 8) {
			X6502_IRQBegin(FCEU_IQEXT);
		}
	}
}

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

void Mapper91_Init(CartInfo *info) {
	info->Power = M91Power;
	GameHBIRQHook = M91IRQHook;
	GameStateRestore = StateRestore;
	AddExState(&StateRegs, ~0, 0, 0);
}