ArkanoidPad.cc

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#include "ArkanoidPad.hh"
#include "MSXEventDistributor.hh"
#include "StateChangeDistributor.hh"
#include "Event.hh"
#include "StateChange.hh"
#include "serialize.hh"
#include "serialize_meta.hh"
#include <algorithm>
 
// Implemented mostly according to the info here: http://www.msx.org/forumtopic7661.html
// This is absolutely not accurate, but good enough to make the pad work in the
// Arkanoid games.
 
// The hardware works with a 556 dual timer that's unemulated here, it requires
// short delays at each shift, and a long delay at latching. Too short delays
// will cause garbage reads, and too long delays at shifting will eventually
// cause the shift register bits to return to 0.
 
namespace openmsx {
 
constexpr int POS_MIN = 55; // measured by hap
constexpr int POS_MAX = 325; // measured by hap
constexpr int POS_CENTER = 236; // approx. middle used by games
constexpr int SCALE = 2;
 
 
class ArkanoidState final : public StateChange
{
public:
        ArkanoidState() = default; // for serialize
        ArkanoidState(EmuTime::param time_, int delta_, bool press_, bool release_)
                : StateChange(time_)
                , delta(delta_), press(press_), release(release_) {}
        [[nodiscard]] int  getDelta()   const { return delta; }
        [[nodiscard]] bool getPress()   const { return press; }
        [[nodiscard]] bool getRelease() const { return release; }
 
        template<typename Archive> void serialize(Archive& ar, unsigned /*version*/)
        {
                ar.template serializeBase<StateChange>(*this);
                ar.serialize("delta",   delta,
                             "press",   press,
                             "release", release);
        }
private:
        int delta;
        bool press, release;
};
REGISTER_POLYMORPHIC_CLASS(StateChange, ArkanoidState, "ArkanoidState");
 
ArkanoidPad::ArkanoidPad(MSXEventDistributor& eventDistributor_,
                         StateChangeDistributor& stateChangeDistributor_)
        : eventDistributor(eventDistributor_)
        , stateChangeDistributor(stateChangeDistributor_)
        , shiftreg(0) // the 9 bit shift degrades to 0
        , dialpos(POS_CENTER)
        , buttonStatus(0x3E)
        , lastValue(0)
{
}
 
ArkanoidPad::~ArkanoidPad()
{
        if (isPluggedIn()) {
                ArkanoidPad::unplugHelper(EmuTime::dummy());
        }
}
 
 
// Pluggable
std::string_view ArkanoidPad::getName() const
{
        return "arkanoidpad";
}
 
std::string_view ArkanoidPad::getDescription() const
{
        return "Arkanoid pad";
}
 
void ArkanoidPad::plugHelper(Connector& /*connector*/, EmuTime::param /*time*/)
{
        eventDistributor.registerEventListener(*this);
        stateChangeDistributor.registerListener(*this);
}
 
void ArkanoidPad::unplugHelper(EmuTime::param /*time*/)
{
        stateChangeDistributor.unregisterListener(*this);
        eventDistributor.unregisterEventListener(*this);
}
 
// JoystickDevice
byte ArkanoidPad::read(EmuTime::param /*time*/)
{
        return buttonStatus | ((shiftreg & 0x100) >> 8);
}
 
void ArkanoidPad::write(byte value, EmuTime::param /*time*/)
{
        byte diff = lastValue ^ value;
        lastValue = value;
 
        if (diff & value & 0x4) {
                // pin 8 from low to high: copy dial position into shift reg
                shiftreg = dialpos;
        }
        if (diff & value & 0x1) {
                // pin 6 from low to high: shift the shift reg
                shiftreg = (shiftreg << 1) | (shiftreg & 1); // bit 0's value is 'shifted in'
        }
}
 
// MSXEventListener
void ArkanoidPad::signalMSXEvent(const Event& event,
                                 EmuTime::param time) noexcept
{
        visit(overloaded{
                [&](const MouseMotionEvent& e) {
                        int newPos = std::min(POS_MAX,
                                        std::max(POS_MIN,
                                                dialpos + e.getX() / SCALE));
                        int delta = newPos - dialpos;
                        if (delta != 0) {
                                stateChangeDistributor.distributeNew<ArkanoidState>(
                                        time, delta, false, false);
                        }
                },
                [&](const MouseButtonDownEvent& /*e*/) {
                        // any button will press the Arkanoid Pad button
                        if (buttonStatus & 2) {
                                stateChangeDistributor.distributeNew<ArkanoidState>(
                                        time, 0, true, false);
                        }
                },
                [&](const MouseButtonUpEvent& /*e*/) {
                        // any button will unpress the Arkanoid Pad button
                        if (!(buttonStatus & 2)) {
                                stateChangeDistributor.distributeNew<ArkanoidState>(
                                        time, 0, false, true);
                        }
                },
                [](const EventBase&) { /*ignore */}
        }, event);
}
 
// StateChangeListener
void ArkanoidPad::signalStateChange(const StateChange& event)
{
        const auto* as = dynamic_cast<const ArkanoidState*>(&event);
        if (!as) return;
 
        dialpos += as->getDelta();
        if (as->getPress())   buttonStatus &= ~2;
        if (as->getRelease()) buttonStatus |=  2;
}
 
void ArkanoidPad::stopReplay(EmuTime::param time) noexcept
{
        // TODO Get actual mouse button(s) state. Is it worth the trouble?
        int delta = POS_CENTER - dialpos;
        bool release = (buttonStatus & 2) == 0;
        if ((delta != 0) || release) {
                stateChangeDistributor.distributeNew<ArkanoidState>(
                        time, delta, false, release);
        }
}
 
 
// version 1: Initial version, the variables dialpos and buttonStatus were not
//            serialized.
// version 2: Also serialize the above variables, this is required for
//            record/replay, see comment in Keyboard.cc for more details.
template<typename Archive>
void ArkanoidPad::serialize(Archive& ar, unsigned version)
{
        ar.serialize("shiftreg",  shiftreg,
                     "lastValue", lastValue);
        if (ar.versionAtLeast(version, 2)) {
                ar.serialize("dialpos",      dialpos,
                             "buttonStatus", buttonStatus);
        }
        if constexpr (Archive::IS_LOADER) {
                if (isPluggedIn()) {
                        plugHelper(*getConnector(), EmuTime::dummy());
                }
        }
}
INSTANTIATE_SERIALIZE_METHODS(ArkanoidPad);
REGISTER_POLYMORPHIC_INITIALIZER(Pluggable, ArkanoidPad, "ArkanoidPad");
 
} // namespace openmsx