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