mappers/42.c

   1 /* FCE Ultra - NES/Famicom Emulator
   2  *
   3  * Copyright notice for this file:
   4  *  Copyright (C) 2002 Xodnizel
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  19  */
  20
  21 #include "mapinc.h"
  22
  23
  24 static DECLFW(Mapper42_write)
  25 {
  26 // FCEU_printf("%04x:%04x\n",A,V);
  27  switch(A&0xe003)
  28  {
  29   case 0x8000:VROM_BANK8(V);break;
  30   case 0xe000:mapbyte1[0]=V;ROM_BANK8(0x6000,V&0xF);break;
  31   case 0xe001:MIRROR_SET((V>>3)&1);break;
  32   case 0xe002:IRQa=V&2;if(!IRQa) IRQCount=0;X6502_IRQEnd(FCEU_IQEXT);break;
  33  }
  34 }
  35
  36 static void Mapper42IRQ(int a)
  37 {
  38  if(IRQa)
  39  {
  40         IRQCount+=a;
  41         if(IRQCount>=32768) IRQCount-=32768;
  42         if(IRQCount>=24576)
  43          X6502_IRQBegin(FCEU_IQEXT);
  44         else
  45          X6502_IRQEnd(FCEU_IQEXT);
  46  }
  47 }
  48
  49 static void Mapper42_StateRestore(int version)
  50 {
  51     ROM_BANK8(0x6000,mapbyte1[0]&0xF);
  52 }
  53
  54
  55 void Mapper42_init(void)
  56 {
  57   ROM_BANK8(0x6000,0);
  58   ROM_BANK32(~0);
  59   SetWriteHandler(0x6000,0xffff,Mapper42_write);
  60   SetReadHandler(0x6000,0x7fff,CartBR);
  61   MapStateRestore=Mapper42_StateRestore;
  62   MapIRQHook=Mapper42IRQ;
  63 }
  64