JVCMSXMIDI.cc

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