VDPIODelay.cc

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#include "VDPIODelay.hh"
#include "MSXCPU.hh"
#include "MSXCPUInterface.hh"
#include "DummyDevice.hh"
#include "serialize.hh"
#include "xrange.hh"
#include <cassert>
 
namespace openmsx {
 
VDPIODelay::VDPIODelay(const DeviceConfig& config, MSXCPUInterface& cpuInterface)
        : MSXDevice(config)
        , cpu(getCPU()) // used frequently, so cache it
        , lastTime(EmuTime::zero())
{
        for (auto port : xrange(byte(0x98), byte(0x9c))) {
                getInDevicePtr (port) = &cpuInterface.getDummyDevice();
                getOutDevicePtr(port) = &cpuInterface.getDummyDevice();
        }
}
 
const MSXDevice& VDPIODelay::getInDevice(byte port) const
{
        assert((0x98 <= port) && (port <= 0x9B));
        return *inDevices[port - 0x98];
}
 
MSXDevice*& VDPIODelay::getInDevicePtr(byte port)
{
        assert((0x98 <= port) && (port <= 0x9B));
        return inDevices[port - 0x98];
}
 
MSXDevice*& VDPIODelay::getOutDevicePtr(byte port)
{
        assert((0x98 <= port) && (port <= 0x9B));
        return outDevices[port - 0x98];
}
 
byte VDPIODelay::readIO(word port, EmuTime::param time)
{
        delay(time);
        return getInDevicePtr(byte(port))->readIO(byte(port), lastTime.getTime());
}
 
byte VDPIODelay::peekIO(word port, EmuTime::param time) const
{
        return getInDevice(byte(port)).peekIO(byte(port), time);
}
 
void VDPIODelay::writeIO(word port, byte value, EmuTime::param time)
{
        delay(time);
        getOutDevicePtr(byte(port))->writeIO(byte(port), value, lastTime.getTime());
}
 
void VDPIODelay::delay(EmuTime::param time)
{
        if (cpu.isR800Active()) {
                // Number of cycles based on measurements on real HW.
                // See doc/turbor-vdp-io-timing.ods for details.
                lastTime += 62; // 8us
                if (time < lastTime.getTime()) {
                        cpu.wait(lastTime.getTime());
                        return;
                }
        }
        lastTime.advance(time);
}
 
template<typename Archive>
void VDPIODelay::serialize(Archive& ar, unsigned /*version*/)
{
        ar.serialize("lastTime", lastTime);
}
INSTANTIATE_SERIALIZE_METHODS(VDPIODelay);
 
} // namespace openmsx