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◆ main openmsx / src / video / ADVram.cc
2.1 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "ADVram.hh"
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#include "VDP.hh"
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#include "VDPVRAM.hh"
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#include "MSXException.hh"
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#include "serialize.hh"
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#include <algorithm>
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namespace openmsx {
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ADVram::ADVram(const DeviceConfig& config)
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	: MSXDevice(config)
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	, hasEnable(config.getChildDataAsBool("hasEnable", true))
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{
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}
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void ADVram::init()
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{
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	MSXDevice::init();
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	const auto& refs = getReferences();
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	if (refs.size() != 1) {
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		throw MSXException("Invalid ADVRAM configuration: "
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		                   "need reference to VDP device.");
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	}
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	vdp = dynamic_cast<VDP*>(refs[0]);
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	if (!vdp) {
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		throw MSXException("Invalid ADVRAM configuration: device '",
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		                   refs[0]->getName(), "' is not a VDP device.");
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	}
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	vram = &vdp->getVRAM();
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	mask = std::min(vram->getSize(), 128u * 1024) - 1;
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	reset(EmuTime::dummy());
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}
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void ADVram::reset(EmuTime /*time*/)
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{
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	// TODO figure out exactly what happens during reset
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	baseAddr = 0;
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	planar = false;
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	enabled = !hasEnable;
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}
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uint8_t ADVram::readIO(uint16_t port, EmuTime /*time*/)
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{
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	// ADVram only gets 'read's from 0x9A
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	if (hasEnable) {
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		enabled = ((port & 0x8000) != 0);
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		planar  = ((port & 0x4000) != 0);
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	} else {
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		planar  = ((port & 0x0100) != 0);
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	}
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	return 0xFF;
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}
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void ADVram::writeIO(uint16_t /*port*/, uint8_t value, EmuTime /*time*/)
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{
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	// set mapper register
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	baseAddr = (value & 0x07) << 14;
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}
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unsigned ADVram::calcAddress(uint16_t address) const
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{
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	unsigned addr = (address & 0x3FFF) | baseAddr;
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	if (planar) {
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		addr = ((addr & 1) << 16) | (addr >> 1);
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	}
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	return addr & mask;
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}
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uint8_t ADVram::readMem(uint16_t address, EmuTime time)
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{
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	return enabled ? vram->cpuRead(calcAddress(address), time) : 0xFF;
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}
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void ADVram::writeMem(uint16_t address, uint8_t value, EmuTime time)
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{
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	if (enabled) {
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		vram->cpuWrite(calcAddress(address), value, time);
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	}
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}
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template<typename Archive>
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void ADVram::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<MSXDevice>(*this);
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	ar.serialize("baseAddr", baseAddr,
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	             "enabled",  enabled,
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	             "planar",   planar);
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}
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INSTANTIATE_SERIALIZE_METHODS(ADVram);
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REGISTER_MSXDEVICE(ADVram, "ADVRAM");
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} // namespace openmsx