fceugx/source/fceultra/boards/vrc7.cpp

/* FCE Ultra - NES/Famicom Emulator
 *
 * Copyright notice for this file:
 *  Copyright (C) 2009 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
 */

#include "mapinc.h"

static uint8 prg[3], chr[8], mirr;
static uint8 IRQLatch, IRQa, IRQd;
static uint32 IRQCount, CycleCount;

static SFORMAT StateRegs[]=
{
  {prg, 3, "PRG"},
  {chr, 8, "CHR"},
  {&mirr, 1, "MIRR"},
  {&IRQa, 1, "IRQA"},
  {&IRQd, 1, "IRQD"},
  {&IRQLatch, 1, "IRQC"},
  {&IRQCount, 4, "IRQC"},
  {&CycleCount, 4, "CYCC"},
  {0}
};

static void Sync(void)
{
  uint8 i;
  setprg8(0x8000,prg[0]);
  setprg8(0xa000,prg[1]);
  setprg8(0xc000,prg[2]);
  setprg8(0xe000,~0);
  for(i=0; i<8; i++)
    setchr1(i<<10,chr[i]);
  switch(mirr&3)
  {
    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 DECLFW(UNLVRC7Write)
{
  switch(A&0xF008)
  {
    case 0x8000: prg[0]=V; Sync(); break;
    case 0x8008: prg[1]=V; Sync(); break;
    case 0x9000: prg[2]=V; Sync(); break;
    case 0xa000: chr[0]=V; Sync(); break;
    case 0xa008: chr[1]=V; Sync(); break;
    case 0xb000: chr[2]=V; Sync(); break;
    case 0xb008: chr[3]=V; Sync(); break;
    case 0xc000: chr[4]=V; Sync(); break;
    case 0xc008: chr[5]=V; Sync(); break;
    case 0xd000: chr[6]=V; Sync(); break;
    case 0xd008: chr[7]=V; Sync(); break;
    case 0xe000: mirr=V; Sync(); break;
    case 0xe008:
      IRQLatch=V;
      X6502_IRQEnd(FCEU_IQEXT);
      break;
    case 0xf000:
      IRQa=V&2;
      IRQd=V&1;
      if(V&2)
        IRQCount=IRQLatch;
      CycleCount=0;
      X6502_IRQEnd(FCEU_IQEXT);
      break;
    case 0xf008:
      if(IRQd)
        IRQa=1;
      else
        IRQa=0;
      X6502_IRQEnd(FCEU_IQEXT);
      break;
  }
}

static void UNLVRC7Power(void)
{
  Sync();
  SetReadHandler(0x8000,0xFFFF,CartBR);
  SetWriteHandler(0x8000,0xFFFF,UNLVRC7Write);
}

static void UNLVRC7IRQHook(int a)
{
  if(IRQa)
  {
    CycleCount+=a*3;
    while(CycleCount>=341)
    {
      CycleCount-=341;
      IRQCount++;
      if(IRQCount==248)
      {
        X6502_IRQBegin(FCEU_IQEXT);
        IRQCount=IRQLatch;
      }
    }
  }
}

static void StateRestore(int version)
{
  Sync();
}

void UNLVRC7_Init(CartInfo *info)
{
  info->Power=UNLVRC7Power;
  MapIRQHook=UNLVRC7IRQHook;
  GameStateRestore=StateRestore;
  AddExState(&StateRegs, ~0, 0, 0);
}