mappers/21.c

   1 /* FCE Ultra - NES/Famicom Emulator
   2  *
   3  * Copyright notice for this file:
   4  *  Copyright (C) 2002 Ben Parnell
   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "mapinc.h"
  22
  23 #define K4buf mapbyte2
  24 #define K4IRQ mapbyte1[1]
  25 #define K4sel mapbyte1[0]
  26
  27 static int acount=0;
  28
  29 DECLFW(Mapper21_write)
  30 {
  31         A|=((A>>5)&0xF);
  32
  33         if((A&0xF000)==0xA000)
  34         {
  35           ROM_BANK8(0xA000,V);
  36           X6502_Rebase();
  37         }
  38         else if((A&0xF000)==0x8000)
  39         {
  40          if(K4sel&2)
  41           ROM_BANK8(0xC000,V);
  42          else
  43           ROM_BANK8(0x8000,V);
  44          X6502_Rebase();
  45         }
  46         else if(A>=0xb000 && A<=0xefff)
  47         {
  48           A&=0xF006;
  49           {
  50            int x=((A>>2)&1)|((A-0xB000)>>11);
  51
  52            K4buf[x]&=(0xF0)>>((A&2)<<1);
  53            K4buf[x]|=(V&0xF)<<((A&2)<<1);
  54            VROM_BANK1(x<<10,K4buf[x]);
  55           }
  56
  57         }
  58         else switch(A&0xF006)
  59         {
  60          case 0x9000:
  61                      switch(V&0x3)
  62                      {
  63                       case 0:MIRROR_SET(0);break;
  64                       case 1:MIRROR_SET(1);break;
  65                       case 2:onemir(0);break;
  66                       case 3:onemir(1);break;
  67                      }
  68                      break;
  69          case 0x9006:
  70          case 0x9004:
  71          case 0x9002:if((K4sel&2)!=(V&2))
  72                      {
  73                       uint8 swa;
  74                       swa=PRGBankList[0];
  75                       ROM_BANK8(0x8000,PRGBankList[2]);
  76                       ROM_BANK8(0xc000,swa);
  77                       X6502_Rebase();
  78                      }
  79                      K4sel=V;
  80                      break;
  81          case 0xf000:IRQLatch&=0xF0;IRQLatch|=V&0xF;break;
  82          case 0xf002:IRQLatch&=0x0F;IRQLatch|=V<<4;break;
  83          case 0xf004:IRQCount=IRQLatch;
  84                      IRQa=V&2;K4IRQ=V&1;break;
  85          case 0xf006:IRQa=K4IRQ;break;
  86  }
  87 }
  88 static void FP_FASTAPASS(1) KonamiIRQHook(int a)
  89 {
  90   #define LCYCS 114
  91   if(IRQa)
  92    {
  93     acount+=a;
  94     if(acount>=LCYCS)
  95     {
  96      doagainbub:acount-=LCYCS;IRQCount++;
  97      if(IRQCount&0x100) {TriggerIRQ();IRQCount=IRQLatch;}
  98      if(acount>=LCYCS) goto doagainbub;
  99     }
 100  }
 101 }
 102
 103 void Mapper21_init(void)
 104 {
 105         SetWriteHandler(0x8000,0xffff,Mapper21_write);
 106         MapIRQHook=KonamiIRQHook;
 107 }