OXYGENHUB
◆ main openmsx / src / serial / MusicModuleMIDI.cc
2.8 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "MusicModuleMIDI.hh"
2
3 
#include "serialize.hh"
4
5 
namespace openmsx {
6
7 
// MSX interface:
8 
// port R/W
9 
// 0    W    Control Register
10 
// 1    W    Transmit Data Register
11 
// 4    R    Status Register
12 
// 5    R    Receive Data Register
13
14 
// Some existing Music-Module detection routines:
15 
// - fac demo 5: does OUT 0,3 : OUT 0,21 : INP(4) and expects to read 2
16 
// - tetris 2 special edition: does INP(4) and expects to read 0
17 
// - Synthesix: does INP(4), expects 0; OUT 0,3 : OUT 0,21: INP(4) and expects
18 
//   bit 1 to be 1 and bit 2, 3 and 7 to be 0. Then does OUT 5,0xFE : INP(4)
19 
//   and expects bit 1 to be 0.
20 
// I did some _very_basic_ investigation and found the following:
21 
// - after a reset reading from port 4 returns 0
22 
// - after initializing the control register, reading port 4 returns 0 (of
23 
//   course this will change when you start to actually receive/transmit data)
24 
// - writing any value with the lower 2 bits set to 1 returns to the initial
25 
//   state, and reading port 4 again returns 0.
26 
// -  ?INP(4) : OUT0,3 : ?INP(4) : OUT0,21 : ? INP(4) : OUT0,3 :  ?INP(4)
27 
//    outputs: 0, 0, 2, 0
28
29 
MusicModuleMIDI::MusicModuleMIDI(const DeviceConfig& config)
30 
	: MSXDevice(config)
31 
	, mc6850(MSXDevice::getName(), getMotherBoard(), 500000) // 500 kHz
32 
{
33 
	reset(getCurrentTime());
34 
}
35
36 
void MusicModuleMIDI::reset(EmuTime time)
37 
{
38 
	mc6850.reset(time);
39 
}
40
41 
uint8_t MusicModuleMIDI::readIO(uint16_t port, EmuTime /*time*/)
42 
{
43 
	switch (port & 0x1) {
44 
	case 0:
45 
		return mc6850.readStatusReg();
46 
	case 1:
47 
		return mc6850.readDataReg();
48 
	}
49 
	UNREACHABLE;
50 
}
51
52 
uint8_t MusicModuleMIDI::peekIO(uint16_t port, EmuTime /*time*/) const
53 
{
54 
	switch (port & 0x1) {
55 
	case 0:
56 
		return mc6850.peekStatusReg();
57 
	case 1:
58 
		return mc6850.peekDataReg();
59 
	}
60 
	UNREACHABLE;
61 
}
62
63 
void MusicModuleMIDI::writeIO(uint16_t port, uint8_t value, EmuTime time)
64 
{
65 
	switch (port & 0x01) {
66 
	case 0:
67 
		mc6850.writeControlReg(value, time);
68 
		break;
69 
	case 1:
70 
		mc6850.writeDataReg(value, time);
71 
		break;
72 
	}
73 
}
74
75 
// versions 1-3: were for type "MC6850", see that class for details
76 
// version 4: first version for "MusicModuleMIDI"
77 
template<typename Archive>
78 
void MusicModuleMIDI::serialize(Archive& ar, unsigned version)
79 
{
80 
	ar.template serializeBase<MSXDevice>(*this);
81 
	if (ar.versionAtLeast(version, 4)) {
82 
		ar.serialize("MC6850", mc6850);
83 
	} else {
84 
		// MC6850 members were serialized as direct children of the
85 
		// <device> tag, without an intermediate <MC6850> tag.
86 
		mc6850.serialize(ar, version);
87 
	}
88 
}
89 
INSTANTIATE_SERIALIZE_METHODS(MusicModuleMIDI);
90 
REGISTER_MSXDEVICE(MusicModuleMIDI, "MusicModuleMIDI");
91
92 
// For backwards compatiblity, also register this class with the old name (only
93 
// needed for loading from disk). Versions 1-3 use the old name "MC6850",
94 
// version 4 (and above) use the name "MusicModuleMIDI".
95 
static const RegisterInitializerHelper<XmlInputArchive, MusicModuleMIDI> registerbwCompat("MC6850");
96
97 
} // namespace openmsx