mirror of
https://github.com/0ldsk00l/nestopia.git
synced 2025-04-02 10:31:51 -04:00
264 lines
6.4 KiB
C++
264 lines
6.4 KiB
C++
////////////////////////////////////////////////////////////////////////////////////////
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//
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// Nestopia - NES/Famicom emulator written in C++
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//
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// Copyright (C) 2003-2008 Martin Freij
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//
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// This file is part of Nestopia.
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//
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// Nestopia is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// Nestopia is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Nestopia; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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////////////////////////////////////////////////////////////////////////////////////////
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#include "../NstLog.hpp"
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#include "NstBoard.hpp"
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#include "NstBoardMmc1.hpp"
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#include "../NstFile.hpp"
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namespace Nes
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{
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namespace Core
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{
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namespace Boards
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{
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#ifdef NST_MSVC_OPTIMIZE
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#pragma optimize("s", on)
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#endif
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Mmc1::Mmc1(const Context& c,Revision rev)
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: Board(c), revision(rev)
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{
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switch (rev)
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{
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case REV_A: Log::Flush( "Board: MMC rev. A" NST_LINEBREAK ); break;
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case REV_B1: Log::Flush( "Board: MMC rev. B1" NST_LINEBREAK ); break;
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case REV_B2: Log::Flush( "Board: MMC rev. B2" NST_LINEBREAK ); break;
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case REV_B3: Log::Flush( "Board: MMC rev. B3" NST_LINEBREAK ); break;
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}
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}
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void Mmc1::ResetRegisters()
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{
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serial.buffer = 0;
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serial.shifter = 0;
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regs[CTRL] = CTRL_HARD_RESET;
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regs[CHR0] = 0;
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regs[CHR1] = 0;
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regs[PRG0] = (revision == REV_B3 ? PRG0_WRAM_DISABLED : 0);
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}
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void Mmc1::SubReset(const bool hard)
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{
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Map( 0x8000U, 0xFFFFU, &Mmc1::Poke_8000 );
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serial.ready = cpu.GetClock(Serial::RESET_CYCLES);
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if (hard)
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{
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ResetRegisters();
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for (uint i=0; i < 4; ++i)
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UpdateRegisters( i );
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}
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}
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void Mmc1::SubLoad(State::Loader& state,const dword baseChunk)
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{
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NST_VERIFY( baseChunk == (AsciiId<'M','M','1'>::V) );
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serial.ready = 0;
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if (baseChunk == AsciiId<'M','M','1'>::V)
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{
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while (const dword chunk = state.Begin())
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{
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if (chunk == AsciiId<'R','E','G'>::V)
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{
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State::Loader::Data<4+2> data( state );
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for (uint i=0; i < 4; ++i)
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regs[i] = data[i] & 0x1F;
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serial.buffer = data[4] & 0x1F;
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serial.shifter = NST_MIN(data[5],5);
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}
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state.End();
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}
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}
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}
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void Mmc1::SubSave(State::Saver& state) const
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{
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const byte data[4+2] =
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{
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regs[0],
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regs[1],
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regs[2],
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regs[3],
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serial.buffer,
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serial.shifter
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};
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state.Begin( AsciiId<'M','M','1'>::V ).Begin( AsciiId<'R','E','G'>::V ).Write( data ).End().End();
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}
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#ifdef NST_MSVC_OPTIMIZE
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#pragma optimize("", on)
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#endif
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void Mmc1::Save(File& file) const
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{
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uint offset = (board.GetWram() == SIZE_16K) ? SIZE_8K : 0; // SOROM
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if (board.HasBattery() && board.GetSavableWram())
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file.Save( File::BATTERY, wrk.Source().Mem(offset), board.GetSavableWram() );
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}
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void Mmc1::Load(File& file)
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{
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uint offset = (board.GetWram() == SIZE_16K) ? SIZE_8K : 0; // SOROM
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if (board.HasBattery() && board.GetSavableWram())
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file.Load( File::BATTERY, wrk.Source().Mem(offset), board.GetSavableWram() );
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}
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void Mmc1::UpdatePrg()
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{
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prg.SwapBanks<SIZE_16K,0x0000>
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(
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(regs[CHR0] & 0x10U) | ((regs[PRG0] | 0x0U) & ((regs[CTRL] & uint(CTRL_PRG_SWAP_16K)) ? (regs[CTRL] & uint(CTRL_PRG_SWAP_LOW)) ? 0xF : 0x0 : 0xE)),
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(regs[CHR0] & 0x10U) | ((regs[PRG0] & 0xFU) | ((regs[CTRL] & uint(CTRL_PRG_SWAP_16K)) ? (regs[CTRL] & uint(CTRL_PRG_SWAP_LOW)) ? 0xF : 0x0 : 0x1))
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);
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}
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void Mmc1::UpdateWrk()
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{
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const dword size = board.GetWram();
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if (revision != REV_A)
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{
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const uint enable = ~uint(regs[PRG0]) & PRG0_WRAM_DISABLED;
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wrk.Source().SetSecurity( enable, enable && size );
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}
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if (size >= SIZE_16K)
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wrk.SwapBank<SIZE_8K,0x0000>( regs[CHR0] >> (2 + (size == SIZE_16K)) );
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}
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void Mmc1::UpdateChr() const
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{
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ppu.Update();
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const uint mode = regs[CTRL] >> 4 & 0x1U;
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chr.SwapBanks<SIZE_4K,0x0000>
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(
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regs[CHR0] & (0x1E | mode),
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(regs[CHR0+mode] & 0x1FU) | (mode^1)
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);
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}
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void Mmc1::UpdateNmt()
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{
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static const byte lut[4][4] =
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{
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{0,0,0,0},
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{1,1,1,1},
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{0,1,0,1},
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{0,0,1,1}
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};
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ppu.SetMirroring( lut[regs[CTRL] & uint(CTRL_MIRRORING)] );
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}
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void Mmc1::UpdateRegisters(const uint index)
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{
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NST_ASSERT( index < 4 );
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if (index != CHR1)
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{
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UpdatePrg();
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UpdateWrk();
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}
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if (index != PRG0)
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{
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if (index == CTRL)
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UpdateNmt();
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UpdateChr();
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}
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}
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NES_POKE_AD(Mmc1,8000)
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{
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if (cpu.GetCycles() >= serial.ready)
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{
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if (!(data & Serial::RESET_BIT))
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{
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serial.buffer |= (data & 0x1) << serial.shifter++;
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if (serial.shifter != 5)
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return;
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serial.shifter = 0;
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data = serial.buffer;
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serial.buffer = 0;
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address = address >> 13 & 0x3;
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if (regs[address] != data)
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{
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regs[address] = data;
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UpdateRegisters( address );
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}
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}
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else
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{
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serial.ready = cpu.GetCycles() + cpu.GetClock(Serial::RESET_CYCLES);
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serial.buffer = 0;
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serial.shifter = 0;
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if ((regs[CTRL] & uint(CTRL_WRITE_RESET)) != CTRL_WRITE_RESET)
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{
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regs[CTRL] |= uint(CTRL_WRITE_RESET);
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UpdateRegisters( CTRL );
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}
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}
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}
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else
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{
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// looks like there's some protection from rapid writes on register
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// reset, otherwise games like 'AD&D Hillsfar' and 'Bill & Ted' will break
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NST_DEBUG_MSG("MMC1 PRG write ignored!");
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}
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}
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void Mmc1::Sync(Event event,Input::Controllers* controllers)
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{
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if (event == EVENT_END_FRAME)
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{
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if (serial.ready <= cpu.GetFrameCycles())
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serial.ready = 0;
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else
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serial.ready -= cpu.GetFrameCycles();
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}
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Board::Sync( event, controllers );
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}
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}
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}
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}
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