MSXE6Timer.cc

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#include "MSXE6Timer.hh"
#include "serialize.hh"
 
namespace openmsx {
 
MSXE6Timer::MSXE6Timer(const DeviceConfig& config)
        : MSXDevice(config)
        , reference(getCurrentTime())
{
}
 
void MSXE6Timer::reset(EmuTime::param time)
{
        reference.reset(time);
}
 
void MSXE6Timer::writeIO(word /*port*/, byte /*value*/, EmuTime::param time)
{
        /*
        The Clock class rounds down time to its clock resolution.
        This is correct for the E6 timer, verified by running the following
        program in R800 mode:
                org &HC000
                di
                ld c,&HE6
        loop:
                out (&HE6),a
                in d,(c)
                jp z,loop
                ei
                ret
        It returns with D=1.
        */
        reference.advance(time);
}
 
byte MSXE6Timer::readIO(word port, EmuTime::param time)
{
        return peekIO(port, time);
}
 
byte MSXE6Timer::peekIO(word port, EmuTime::param time) const
{
        auto counter = reference.getTicksTill(time);
        return (port & 1) ? ((counter >> 8) & 0xFF) : (counter & 0xFF);
}
 
template<typename Archive>
void MSXE6Timer::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<MSXDevice>(*this);
        ar.serialize("reference", reference);
}
INSTANTIATE_SERIALIZE_METHODS(MSXE6Timer);
REGISTER_MSXDEVICE(MSXE6Timer, "E6Timer");
 
} // namespace openmsx