SG1000JoystickIO.cc

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#include "SG1000JoystickIO.hh"
#include "MSXMotherBoard.hh"
#include "JoystickPort.hh"
#include "serialize.hh"
 
namespace openmsx {
 
// MSXDevice
SG1000JoystickIO::SG1000JoystickIO(const DeviceConfig& config)
        : MSXDevice(config)
 
{
        MSXMotherBoard& motherBoard = getMotherBoard();
        auto time = getCurrentTime();
        for (unsigned i = 0; i < 2; i++) {
                ports[i] = &motherBoard.getJoystickPort(i);
                // Clear strobe bit, or MSX joysticks will stay silent.
                ports[i]->write(0xFB, time);
        }
}
 
byte SG1000JoystickIO::readIO(word port, EmuTime::param time)
{
        return peekIO(port, time);
}
 
byte SG1000JoystickIO::peekIO(word port, EmuTime::param time) const
{
        // Joystick hardware cannot detect when it's being read, so using the
        // read() method for peeking should be safe.
        if (port & 1) {
                byte joy2 = ports[1]->read(time) & 0x3F;
                return 0xF0 | (joy2 >> 2);
        } else {
                byte joy1 = ports[0]->read(time) & 0x3F;
                byte joy2 = ports[1]->read(time) & 0x3F;
                return joy1 | (joy2 << 6);
        }
}
 
 
template<typename Archive>
void SG1000JoystickIO::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<MSXDevice>(*this);
}
INSTANTIATE_SERIALIZE_METHODS(SG1000JoystickIO);
REGISTER_MSXDEVICE(SG1000JoystickIO, "SG1000Joystick");
 
} // namespace openmsx