/* FCE Ultra - NES/Famicom Emulator
 *
 * Copyright notice for this file:
 *  Copyright (C) 2002 Ben Parnell
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "mapinc.h"

#define K4buf mapbyte2
#define K4IRQ mapbyte1[1]
#define K4sel mapbyte1[0]

static int acount=0;

DECLFW(Mapper21_write)
{
	A|=((A>>5)&0xF);

	if((A&0xF000)==0xA000)
	  ROM_BANK8(0xA000,V);
	else if((A&0xF000)==0x8000)
	{
         if(K4sel&2)
          ROM_BANK8(0xC000,V);
         else
          ROM_BANK8(0x8000,V);
 	}
	else if(A>=0xb000 && A<=0xefff)
	{
	  A&=0xF006;
          {
           int x=((A>>2)&1)|((A-0xB000)>>11);

           K4buf[x]&=(0xF0)>>((A&2)<<1);
           K4buf[x]|=(V&0xF)<<((A&2)<<1);
           VROM_BANK1(x<<10,K4buf[x]);
          }
 
	}
	else switch(A&0xF006)
        {
	 case 0x9000:
        	     switch(V&0x3)
	             {
        	      case 0:MIRROR_SET(0);break;
	              case 1:MIRROR_SET(1);break;
	              case 2:onemir(0);break;
	              case 3:onemir(1);break;
         	     }
	             break;
	 case 0x9006:
	 case 0x9004:
	 case 0x9002:if((K4sel&2)!=(V&2))
        	     {
             	      uint8 swa;
	              swa=PRGBankList[0];
         	      ROM_BANK8(0x8000,PRGBankList[2]);
	              ROM_BANK8(0xc000,swa);
         	     }
	             K4sel=V;
        	     break;
	 case 0xf000:IRQLatch&=0xF0;IRQLatch|=V&0xF;break;
         case 0xf002:IRQLatch&=0x0F;IRQLatch|=V<<4;break;
	 case 0xf004:IRQCount=IRQLatch;
	             IRQa=V&2;K4IRQ=V&1;break;
	 case 0xf006:IRQa=K4IRQ;break;
 }
}
static void FP_FASTAPASS(1) KonamiIRQHook(int a)
{
  if(IRQa)
   {
    acount+=(a<<1)+a;
    if(acount>=342)
    {
     doagainbub:acount-=342;IRQCount++;
     if(IRQCount&0x100) {TriggerIRQ();IRQCount=IRQLatch;}
     if(acount>=342) goto doagainbub;
    }
 }
}

void Mapper21_init(void)
{
        SetWriteHandler(0x8000,0xffff,Mapper21_write);
        MapIRQHook=KonamiIRQHook;
}
