merge mapper code from FCEUX

[fceu.git] / mappers / 50.c

/* 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 void Mapper50IRQ(int a)
{
 if(IRQa)
 {
        if(IRQCount<4096)
         IRQCount+=a;
        else
        {
         IRQa=0;
         X6502_IRQBegin(FCEU_IQEXT);
        }
 }
}

static void M50Restore(int version)
{
 setprg8(0xc000,mapbyte1[0]);
}

static DECLFW(M50W)
{
 if((A&0xD060)==0x4020)
 {
  if(A&0x100)
  {
   IRQa=V&1;
   if(!IRQa) IRQCount=0;
   X6502_IRQEnd(FCEU_IQEXT);
  }
  else
  {
   V=((V&1)<<2)|((V&2)>>1)|((V&4)>>1)|(V&8);
   mapbyte1[0]=V;
   setprg8(0xc000,V);
  }
 }
}

void Mapper50_init(void)
{
  SetWriteHandler(0x4020,0x5fff,M50W);
  SetReadHandler(0x6000,0xffff,CartBR);
  MapStateRestore=M50Restore;
  MapIRQHook=Mapper50IRQ;

  setprg8(0x6000,0xF);
  setprg8(0x8000,0x8);
  setprg8(0xa000,0x9);
  setprg8(0xc000,0x0);
  setprg8(0xe000,0xB);
}