mirror of https://github.com/stella-emu/stella.git
174 lines
4.7 KiB
C++
174 lines
4.7 KiB
C++
//============================================================================
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//
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// SSSS tt lll lll
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// SS SS tt ll ll
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// SS tttttt eeee ll ll aaaa
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// SSSS tt ee ee ll ll aa
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// SS tt eeeeee ll ll aaaaa -- "An Atari 2600 VCS Emulator"
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// SS SS tt ee ll ll aa aa
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// SSSS ttt eeeee llll llll aaaaa
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//
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// Copyright (c) 1995-2017 by Bradford W. Mott, Stephen Anthony
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// and the Stella Team
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//
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// See the file "License.txt" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//============================================================================
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#include "M6532.hxx"
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#include "System.hxx"
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#include "CartFE.hxx"
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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CartridgeFE::CartridgeFE(const BytePtr& image, uInt32 size,
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const Settings& settings)
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: Cartridge(settings),
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myBankOffset(0),
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myLastAccessWasFE(false)
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{
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// Copy the ROM image into my buffer
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memcpy(myImage, image.get(), std::min(8192u, size));
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createCodeAccessBase(8192);
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myStartBank = 0; // For now, we assume this; more research is needed
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeFE::reset()
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{
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bank(myStartBank);
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myLastAccessWasFE = false;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeFE::install(System& system)
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{
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mySystem = &system;
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// The hotspot $01FE is in a mirror of zero-page RAM
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// We need to claim access to it here, and deal with it in peek/poke below
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System::PageAccess access(this, System::PA_READWRITE);
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for(uInt16 addr = 0x180; addr < 0x200; addr += System::PAGE_SIZE)
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mySystem->setPageAccess(addr, access);
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// Map all of the cart accesses to call peek and poke
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access.type = System::PA_READ;
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for(uInt16 addr = 0x1000; addr < 0x2000; addr += System::PAGE_SIZE)
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mySystem->setPageAccess(addr, access);
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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uInt8 CartridgeFE::peek(uInt16 address)
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{
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uInt8 value = (address < 0x200) ? mySystem->m6532().peek(address) :
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myImage[myBankOffset + (address & 0x0FFF)];
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// Check if we hit hotspot
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checkBankSwitch(address, value);
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return value;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeFE::poke(uInt16 address, uInt8 value)
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{
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if(address < 0x200)
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mySystem->m6532().poke(address, value);
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// Check if we hit hotspot
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checkBankSwitch(address, value);
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return false;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeFE::checkBankSwitch(uInt16 address, uInt8 value)
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{
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if(bankLocked())
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return;
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// Did we detect $01FE on the last address bus access?
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// If so, we bankswitch according to the upper 3 bits of the data bus
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// NOTE: see the header file for the significance of 'value & 0x20'
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if(myLastAccessWasFE)
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bank((value & 0x20) ? 0 : 1);
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// On the next cycle, we use the (then) current data bus value to decode
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// the bank to use
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myLastAccessWasFE = address == 0x01FE;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeFE::bank(uInt16 bank)
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{
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if(bankLocked())
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return false;
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myBankOffset = bank << 12;
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return myBankChanged = true;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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uInt16 CartridgeFE::getBank() const
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{
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return myBankOffset >> 12;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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uInt16 CartridgeFE::bankCount() const
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{
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return 2;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeFE::patch(uInt16 address, uInt8 value)
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{
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myImage[myBankOffset + (address & 0x0FFF)] = value;
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return myBankChanged = true;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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const uInt8* CartridgeFE::getImage(uInt32& size) const
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{
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size = 8192;
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return myImage;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeFE::save(Serializer& out) const
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{
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try
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{
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out.putString(name());
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out.putShort(myBankOffset);
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out.putBool(myLastAccessWasFE);
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}
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catch(...)
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{
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cerr << "ERROR: CartridgeFE::save" << endl;
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return false;
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}
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return true;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeFE::load(Serializer& in)
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{
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try
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{
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if(in.getString() != name())
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return false;
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myBankOffset = in.getShort();
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myLastAccessWasFE = in.getBool();
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}
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catch(...)
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{
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cerr << "ERROR: CartridgeF8SC::load" << endl;
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return false;
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}
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return true;
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}
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