nestopia/source/core/board/NstBoardMmc1.cpp
2021-02-15 08:01:46 -05:00

264 lines
6.4 KiB
C++

////////////////////////////////////////////////////////////////////////////////////////
//
// Nestopia - NES/Famicom emulator written in C++
//
// Copyright (C) 2003-2008 Martin Freij
//
// This file is part of Nestopia.
//
// Nestopia 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.
//
// Nestopia 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 Nestopia; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
////////////////////////////////////////////////////////////////////////////////////////
#include "../NstLog.hpp"
#include "NstBoard.hpp"
#include "NstBoardMmc1.hpp"
#include "../NstFile.hpp"
namespace Nes
{
namespace Core
{
namespace Boards
{
#ifdef NST_MSVC_OPTIMIZE
#pragma optimize("s", on)
#endif
Mmc1::Mmc1(const Context& c,Revision rev)
: Board(c), revision(rev)
{
switch (rev)
{
case REV_A: Log::Flush( "Board: MMC rev. A" NST_LINEBREAK ); break;
case REV_B1: Log::Flush( "Board: MMC rev. B1" NST_LINEBREAK ); break;
case REV_B2: Log::Flush( "Board: MMC rev. B2" NST_LINEBREAK ); break;
case REV_B3: Log::Flush( "Board: MMC rev. B3" NST_LINEBREAK ); break;
}
}
void Mmc1::ResetRegisters()
{
serial.buffer = 0;
serial.shifter = 0;
regs[CTRL] = CTRL_HARD_RESET;
regs[CHR0] = 0;
regs[CHR1] = 0;
regs[PRG0] = (revision == REV_B3 ? PRG0_WRAM_DISABLED : 0);
}
void Mmc1::SubReset(const bool hard)
{
Map( 0x8000U, 0xFFFFU, &Mmc1::Poke_8000 );
serial.ready = cpu.GetClock(Serial::RESET_CYCLES);
if (hard)
{
ResetRegisters();
for (uint i=0; i < 4; ++i)
UpdateRegisters( i );
}
}
void Mmc1::SubLoad(State::Loader& state,const dword baseChunk)
{
NST_VERIFY( baseChunk == (AsciiId<'M','M','1'>::V) );
serial.ready = 0;
if (baseChunk == AsciiId<'M','M','1'>::V)
{
while (const dword chunk = state.Begin())
{
if (chunk == AsciiId<'R','E','G'>::V)
{
State::Loader::Data<4+2> data( state );
for (uint i=0; i < 4; ++i)
regs[i] = data[i] & 0x1F;
serial.buffer = data[4] & 0x1F;
serial.shifter = NST_MIN(data[5],5);
}
state.End();
}
}
}
void Mmc1::SubSave(State::Saver& state) const
{
const byte data[4+2] =
{
regs[0],
regs[1],
regs[2],
regs[3],
serial.buffer,
serial.shifter
};
state.Begin( AsciiId<'M','M','1'>::V ).Begin( AsciiId<'R','E','G'>::V ).Write( data ).End().End();
}
#ifdef NST_MSVC_OPTIMIZE
#pragma optimize("", on)
#endif
void Mmc1::Save(File& file) const
{
uint offset = (board.GetWram() == SIZE_16K) ? SIZE_8K : 0; // SOROM
if (board.HasBattery() && board.GetSavableWram())
file.Save( File::BATTERY, wrk.Source().Mem(offset), board.GetSavableWram() );
}
void Mmc1::Load(File& file)
{
uint offset = (board.GetWram() == SIZE_16K) ? SIZE_8K : 0; // SOROM
if (board.HasBattery() && board.GetSavableWram())
file.Load( File::BATTERY, wrk.Source().Mem(offset), board.GetSavableWram() );
}
void Mmc1::UpdatePrg()
{
prg.SwapBanks<SIZE_16K,0x0000>
(
(regs[CHR0] & 0x10U) | ((regs[PRG0] | 0x0U) & ((regs[CTRL] & uint(CTRL_PRG_SWAP_16K)) ? (regs[CTRL] & uint(CTRL_PRG_SWAP_LOW)) ? 0xF : 0x0 : 0xE)),
(regs[CHR0] & 0x10U) | ((regs[PRG0] & 0xFU) | ((regs[CTRL] & uint(CTRL_PRG_SWAP_16K)) ? (regs[CTRL] & uint(CTRL_PRG_SWAP_LOW)) ? 0xF : 0x0 : 0x1))
);
}
void Mmc1::UpdateWrk()
{
const dword size = board.GetWram();
if (revision != REV_A)
{
const uint enable = ~uint(regs[PRG0]) & PRG0_WRAM_DISABLED;
wrk.Source().SetSecurity( enable, enable && size );
}
if (size >= SIZE_16K)
wrk.SwapBank<SIZE_8K,0x0000>( regs[CHR0] >> (2 + (size == SIZE_16K)) );
}
void Mmc1::UpdateChr() const
{
ppu.Update();
const uint mode = regs[CTRL] >> 4 & 0x1U;
chr.SwapBanks<SIZE_4K,0x0000>
(
regs[CHR0] & (0x1E | mode),
(regs[CHR0+mode] & 0x1FU) | (mode^1)
);
}
void Mmc1::UpdateNmt()
{
static const byte lut[4][4] =
{
{0,0,0,0},
{1,1,1,1},
{0,1,0,1},
{0,0,1,1}
};
ppu.SetMirroring( lut[regs[CTRL] & uint(CTRL_MIRRORING)] );
}
void Mmc1::UpdateRegisters(const uint index)
{
NST_ASSERT( index < 4 );
if (index != CHR1)
{
UpdatePrg();
UpdateWrk();
}
if (index != PRG0)
{
if (index == CTRL)
UpdateNmt();
UpdateChr();
}
}
NES_POKE_AD(Mmc1,8000)
{
if (cpu.GetCycles() >= serial.ready)
{
if (!(data & Serial::RESET_BIT))
{
serial.buffer |= (data & 0x1) << serial.shifter++;
if (serial.shifter != 5)
return;
serial.shifter = 0;
data = serial.buffer;
serial.buffer = 0;
address = address >> 13 & 0x3;
if (regs[address] != data)
{
regs[address] = data;
UpdateRegisters( address );
}
}
else
{
serial.ready = cpu.GetCycles() + cpu.GetClock(Serial::RESET_CYCLES);
serial.buffer = 0;
serial.shifter = 0;
if ((regs[CTRL] & uint(CTRL_WRITE_RESET)) != CTRL_WRITE_RESET)
{
regs[CTRL] |= uint(CTRL_WRITE_RESET);
UpdateRegisters( CTRL );
}
}
}
else
{
// looks like there's some protection from rapid writes on register
// reset, otherwise games like 'AD&D Hillsfar' and 'Bill & Ted' will break
NST_DEBUG_MSG("MMC1 PRG write ignored!");
}
}
void Mmc1::Sync(Event event,Input::Controllers* controllers)
{
if (event == EVENT_END_FRAME)
{
if (serial.ready <= cpu.GetFrameCycles())
serial.ready = 0;
else
serial.ready -= cpu.GetFrameCycles();
}
Board::Sync( event, controllers );
}
}
}
}