NinjaTap.cc

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#include "NinjaTap.hh"
#include "JoystickPort.hh"
#include "enumerate.hh"
#include "ranges.hh"
#include "serialize.hh"
 
// See this (long) MRC thread for a detailed discussion on NinjaTap, including
// an electric schema.
//   https://www.msx.org/forum/msx-talk/hardware/ninja-tap
 
namespace openmsx {
 
NinjaTap::NinjaTap(PluggingController& pluggingController_, std::string name_)
        : JoyTap(pluggingController_, std::move(name_))
{
        ranges::fill(buf, 0xFF);
}
 
std::string_view NinjaTap::getDescription() const
{
        return "MSX Ninja Tap device";
}
 
 
void NinjaTap::plugHelper(Connector& /*connector*/, EmuTime::param time)
{
        createPorts("Ninja Tap port", time);
}
 
uint8_t NinjaTap::read(EmuTime::param /*time*/)
{
        return status;
}
 
void NinjaTap::write(uint8_t value, EmuTime::param time)
{
        // bit 0 -> pin 6
        // bit 1 -> pin 7
        // bit 2 -> pin 8
        if (value & 2) {
                // pin7 = 1 :  read mode
                if (!(value & 1) && (previous & 1)) {
                        // pin 6 1->0 :  query joysticks
                        // TODO does output change?
                        for (auto [i, slave] : enumerate(slaves)) {
                                uint8_t t = slave->read(time);
                                buf[i] = ((t & 0x0F) << 4) |
                                         ((t & 0x30) >> 4) |
                                         0x0C;
                        }
                }
                if (!(value & 4) && (previous & 4)) {
                        // pin 8 1->0 :  shift values
                        // TODO what about b4 and b5?
                        uint8_t t = 0;
                        for (auto [i, b] : enumerate(buf)) {
                                if (b & 1) t |= (1 << i);
                                b >>= 1;
                        }
                        status = (status & ~0x0F) | t;
                }
        }
 
        // pin7 (b5) is always the inverse of pin8
        // See Danjovic's post from 08-10-2022, 06:58
        //    https://www.msx.org/forum/msx-talk/hardware/ninja-tap?page=7
        if (value & 4) {
                status &= ~0x20;
        } else {
                status |= 0x20;
        }
 
        previous = value;
}
 
 
template<typename Archive>
void NinjaTap::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<JoyTap>(*this);
        ar.serialize("status",   status,
                     "previous", previous,
                     "buf",      buf);
}
INSTANTIATE_SERIALIZE_METHODS(NinjaTap);
REGISTER_POLYMORPHIC_INITIALIZER(Pluggable, NinjaTap, "NinjaTap");
 
} // namespace openmsx