/* FCE Ultra - NES/Famicom Emulator
 *
 * Copyright notice for this file:
 *  Copyright (C) 2005 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
 *
 * Gimmick Bootleg (VRC4 mapper)
 */

#include "mapinc.h"

static uint8 prg[4], chr[8], mirr;
static uint8 IRQCount;
static uint8 IRQPre;
static uint8 IRQa;

static SFORMAT StateRegs[] =
{
	{ prg, 4, "PRG" },
	{ chr, 8, "CHR" },
	{ &mirr, 1, "MIRR" },
	{ &IRQCount, 1, "IRQC" },
	{ &IRQPre, 1, "IRQP" },
	{ &IRQa, 1, "IRQA" },
	{ 0 }
};

static void SyncPrg(void) {
	setprg8(0x6000, prg[3]);
	setprg8(0x8000, prg[0]);
	setprg8(0xA000, prg[1]);
	setprg8(0xC000, prg[2]);
	setprg8(0xE000, ~0);
}

static void SyncMirr(void) {
	switch (mirr) {
	case 0: setmirror(MI_V); break;
	case 1: setmirror(MI_H); break;
	case 2: setmirror(MI_0); break;
	case 3: setmirror(MI_1); break;
	}
}

static void SyncChr(void) {
	int i;
	for (i = 0; i < 8; i++)
		setchr1(i << 10, chr[i]);
}

static void StateRestore(int version) {
	SyncPrg();
	SyncChr();
	SyncMirr();
}

static DECLFW(M183Write) {
	if ((A & 0xF800) == 0x6800) {
		prg[3] = A & 0x3F;
		SyncPrg();
	} else if (((A & 0xF80C) >= 0xB000) && ((A & 0xF80C) <= 0xE00C)) {
		int index = (((A >> 11) - 6) | (A >> 3)) & 7;
		chr[index] = (chr[index] & (0xF0 >> (A & 4))) | ((V & 0x0F) << (A & 4));
		SyncChr();
	} else switch (A & 0xF80C) {
		case 0x8800: prg[0] = V; SyncPrg(); break;
		case 0xA800: prg[1] = V; SyncPrg(); break;
		case 0xA000: prg[2] = V; SyncPrg(); break;
		case 0x9800: mirr = V & 3; SyncMirr(); break;
		case 0xF000: IRQCount = ((IRQCount & 0xF0) | (V & 0xF)); break;
		case 0xF004: IRQCount = ((IRQCount & 0x0F) | ((V & 0xF) << 4)); break;
		case 0xF008: IRQa = V; if (!V) IRQPre = 0; X6502_IRQEnd(FCEU_IQEXT); break;
		case 0xF00C: IRQPre = 16; break;
		}
}

static void M183IRQCounter(void) {
	if (IRQa) {
		IRQCount++;
		if ((IRQCount - IRQPre) == 238)
			X6502_IRQBegin(FCEU_IQEXT);
	}
}

static void M183Power(void) {
	IRQPre = IRQCount = IRQa = 0;
	SetReadHandler(0x6000, 0xFFFF, CartBR);
	SetWriteHandler(0x6000, 0xFFFF, M183Write);
	SyncPrg();
	SyncChr();
}

void Mapper183_Init(CartInfo *info) {
	info->Power = M183Power;
	GameHBIRQHook = M183IRQCounter;
	GameStateRestore = StateRestore;
	AddExState(&StateRegs, ~0, 0, 0);
}