85 lines
2.1 KiB
Text
85 lines
2.1 KiB
Text
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/*
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* This file is part of libsidplayfp, a SID player engine.
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*
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* Copyright 2011-2013 Leandro Nini <drfiemost@users.sourceforge.net>
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* Copyright 2007-2010 Antti Lankila
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* Copyright 2000 Simon White
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*
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* This program 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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* This program 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 this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "mmu.h"
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namespace libsidplayfp
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{
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class Bank;
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MMU::MMU(EventContext *context, Bank* ioBank) :
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context(*context),
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loram(false),
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hiram(false),
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charen(false),
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ioBank(ioBank),
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zeroRAMBank(this, &ramBank)
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{
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cpuReadMap[0] = &zeroRAMBank;
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cpuWriteMap[0] = &zeroRAMBank;
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for (int i = 1; i < 16; i++)
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{
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cpuReadMap[i] = &ramBank;
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cpuWriteMap[i] = &ramBank;
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}
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}
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void MMU::setCpuPort(int state)
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{
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loram = (state & 1) != 0;
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hiram = (state & 2) != 0;
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charen = (state & 4) != 0;
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updateMappingPHI2();
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}
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void MMU::updateMappingPHI2()
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{
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cpuReadMap[0xe] = cpuReadMap[0xf] = hiram ? (Bank*)&kernalRomBank : &ramBank;
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cpuReadMap[0xa] = cpuReadMap[0xb] = (loram && hiram) ? (Bank*)&basicRomBank : &ramBank;
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if (charen && (loram || hiram))
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{
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cpuReadMap[0xd] = cpuWriteMap[0xd] = ioBank;
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}
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else
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{
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cpuReadMap[0xd] = (!charen && (loram || hiram)) ? (Bank*)&characterRomBank : &ramBank;
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cpuWriteMap[0xd] = &ramBank;
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}
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}
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void MMU::reset()
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{
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ramBank.reset();
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zeroRAMBank.reset();
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// Reset the ROMs to undo the hacks applied
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kernalRomBank.reset();
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basicRomBank.reset();
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updateMappingPHI2();
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}
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}
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