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◆ main openmsx / src / serial / JVCMSXMIDI.cc
1.9 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "JVCMSXMIDI.hh"
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#include "serialize.hh"
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namespace openmsx {
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// MSX interface:
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// port R/W
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// 0    R    DIN sync input. Bit0 stop/start, bit 1: clock pulse (NOT EMULATED)
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// 2    W    Control Register
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// 3    W    Transmit Data Register
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// 2    R    Status Register
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// 3    R    Receive Data Register
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// See information provided by gflorez here:
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// https://www.msx.org/forum/msx-talk/hardware/jvc-msx-midi-interface?page=1#comment-377145
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// Some existing JVC MSX-MIDI detection routines:
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// - Synthesix (copied from MusicModule): does INP(2), expects 0; OUT 2,3 : OUT
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//   2,21: INP(2) and expects bit 1 to be 1 and bit 2, 3 and 7 to be 0. Then does
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//   OUT 3,0xFE : INP(2) and expects bit 1 to be 0.
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JVCMSXMIDI::JVCMSXMIDI(const DeviceConfig& config)
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	: MSXDevice(config)
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	, mc6850(MSXDevice::getName(), getMotherBoard(), 2000000) // 2 MHz
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{
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	reset(getCurrentTime());
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}
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void JVCMSXMIDI::reset(EmuTime time)
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{
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	mc6850.reset(time);
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}
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uint8_t JVCMSXMIDI::readIO(uint16_t port, EmuTime /*time*/)
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{
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	switch (port & 0x7) {
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	case 0:
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		return 0x00; // NOT IMPLEMENTED
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	case 2:
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		return mc6850.readStatusReg();
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	case 3:
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		return mc6850.readDataReg();
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	}
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	return 0xFF;
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}
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uint8_t JVCMSXMIDI::peekIO(uint16_t port, EmuTime /*time*/) const
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{
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	switch (port & 0x7) {
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	case 0:
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		return 0x00; // NOT IMPLEMENTED
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	case 2:
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		return mc6850.peekStatusReg();
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	case 3:
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		return mc6850.peekDataReg();
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	}
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	return 0xFF;
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}
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void JVCMSXMIDI::writeIO(uint16_t port, uint8_t value, EmuTime time)
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{
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	switch (port & 0x7) {
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	case 2:
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		mc6850.writeControlReg(value, time);
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		break;
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	case 3:
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		mc6850.writeDataReg(value, time);
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		break;
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	}
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}
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// version 1: initial version
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template<typename Archive>
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void JVCMSXMIDI::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<MSXDevice>(*this);
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	ar.serialize("MC6850", mc6850);
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}
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INSTANTIATE_SERIALIZE_METHODS(JVCMSXMIDI);
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REGISTER_MSXDEVICE(JVCMSXMIDI, "JVCMSXMIDI");
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} // namespace openmsx