OXYGENHUB
◆ main openmsx / src / fdc / TurboRFDC.cc
6.6 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
/*
2 
 * Based on code from NLMSX written by Frits Hilderink
3 
 *
4 
 * Despite the name, the class implements MSX connection to TC8566AF FDC for
5 
 * any MSX that uses it. To make reuse possible, it implements two sets of
6 
 * I/O configurations, one is used on turboR, the other on other machines with
7 
 * this FDC.
8 
 * There's also a mapper mechanism implemented. It's only used on the turboR,
9 
 * but all other machines only have a 16kB diskROM, so it's practically
10 
 * ineffective there. The mapper has 0x7FF0 as switch address. (Thanks to
11 
 * NYYRIKKI for this info.)
12 
 */
13
14 
#include "TurboRFDC.hh"
15
16 
#include "CacheLine.hh"
17 
#include "MSXCPU.hh"
18 
#include "MSXException.hh"
19 
#include "Rom.hh"
20 
#include "serialize.hh"
21
22 
#include "narrow.hh"
23
24 
namespace openmsx {
25
26 
[[nodiscard]] static TurboRFDC::Type parseType(const DeviceConfig& config)
27 
{
28 
	auto ioRegs = config.getChildData("io_regs", {});
29 
	if (ioRegs == "7FF2") {
30 
		return TurboRFDC::Type::R7FF2;
31 
	} else if (ioRegs == "7FF8") {
32 
		return TurboRFDC::Type::R7FF8;
33 
	} else if (ioRegs.empty()) {
34 
		// for backwards compatibility
35 
		return TurboRFDC::Type::BOTH;
36 
	} else {
37 
		throw MSXException(
38 
			"Invalid 'io_regs' specification: expected one of "
39 
			"'7FF2' or '7FF8', but got: ", ioRegs);
40 
	}
41 
}
42
43 
TurboRFDC::TurboRFDC(DeviceConfig& config)
44 
	: MSXFDC(config)
45 
	, controller(getScheduler(), drives, getCliComm(), getCurrentTime())
46 
	, romBlockDebug(*this, std::span{&bank, 1}, 0x4000, 0x4000, 14)
47 
	, memory(subspan<0x4000>(*rom))
48 
	, blockMask(narrow_cast<byte>((rom->size() / 0x4000) - 1))
49 
	, type(parseType(config))
50 
{
51 
	auto size = rom->size();
52 
	if ((size % 0x4000) != 0) {
53 
		throw MSXException("TurboRFDC rom size must be a multiple of 16kB");
54 
	}
55 
	if (size == 0) {
56 
		throw MSXException("TurboRFDC rom size too small");
57 
	}
58 
	if ((size / 0x4000) > 256) {
59 
		throw MSXException("TurboRFDC rom size too large");
60 
	}
61 
	reset(getCurrentTime());
62 
}
63
64 
void TurboRFDC::reset(EmuTime time)
65 
{
66 
	setBank(0);
67 
	controller.reset(time);
68 
}
69
70 
byte TurboRFDC::readMem(uint16_t address, EmuTime time_)
71 
{
72 
	EmuTime time = time_;
73 
	if (0x3FF0 <= (address & 0x3FFF)) {
74 
		// Reading or writing to this region takes 1 extra clock
75 
		// cycle. But only in R800 mode. Verified on a real turboR
76 
		// machine, it happens for all 16 positions in this region
77 
		// and both for reading and writing.
78 
		time = getCPU().waitCyclesR800(time, 1);
79 
		if (type != Type::R7FF8) { // turboR or BOTH
80 
			switch (address & 0xF) {
81 
			case 0x1: {
82 
				byte result = 0x33;
83 
				if (controller.diskChanged(0)) result &= ~0x10;
84 
				if (controller.diskChanged(1)) result &= ~0x20;
85 
				return result;
86 
			}
87 
			case 0x4: return controller.readStatus(time);
88 
			case 0x5: return controller.readDataPort(time);
89 
			}
90 
		}
91 
		if (type != Type::R7FF2) { // non-turboR or BOTH
92 
			switch (address & 0xF) {
93 
			case 0xA: return controller.readStatus(time);
94 
			case 0xB: return controller.readDataPort(time);
95 
			}
96
97 
		}
98 
	}
99 
	// all other stuff is handled by peekMem()
100 
	return TurboRFDC::peekMem(address, time);
101 
}
102
103
104 
byte TurboRFDC::peekMem(uint16_t address, EmuTime time) const
105 
{
106 
	if (0x3FF0 <= (address & 0x3FFF)) {
107 
		// note: this implementation requires that the handled
108 
		//    addresses for the MSX2 and TURBOR variants don't overlap
109 
		if (type != Type::R7FF8) { // turboR or BOTH
110 
			switch (address & 0xF) {
111 
			case 0x0: return bank;
112 
			case 0x1: {
113 
				// bit 0  FD2HD1  High Density detect drive 1
114 
				// bit 1  FD2HD2  High Density detect drive 2
115 
				// bit 4  FDCHG1  Disk Change detect on drive 1
116 
				// bit 5  FDCHG2  Disk Change detect on drive 2
117 
				// active low
118 
				byte result = 0x33;
119 
				if (controller.peekDiskChanged(0)) result &= ~0x10;
120 
				if (controller.peekDiskChanged(1)) result &= ~0x20;
121 
				return result;
122 
			}
123 
			case 0x4: return controller.peekStatus();
124 
			case 0x5: return controller.peekDataPort(time);
125 
			}
126 
		}
127 
		if (type != Type::R7FF2) { // non-turboR or BOTH
128 
			switch (address & 0xF) {
129 
			case 0xA: return controller.peekStatus();
130 
			case 0xB: return controller.peekDataPort(time);
131 
			}
132 
		}
133 
		switch (address & 0xF) {
134 
		// TODO Any idea what these 4 are? I've confirmed that on a
135 
		// real FS-A1GT I get these values, though the ROM dumps
136 
		// contain 0xFF in these locations. When looking at the ROM
137 
		// content via the 'RomPanasonic' mapper in slot 3-3, you can
138 
		// see that the ROM dumps are correct (these 4 values are not
139 
		// part of the ROM).
140 
		// This MRC post indicates that also on non-turbor machines
141 
		// you see these 4 values (bluemsx' post of 10-03-2013, 10:15):
142 
		//   http://www.msx.org/forum/msx-talk/development/finally-have-feature-request-openmsx?page=3
143 
		case 0xC: return 0xFC;
144 
		case 0xD: return 0xFC;
145 
		case 0xE: return 0xFF;
146 
		case 0xF: return 0x3F;
147 
		default:  return 0xFF; // other regs in this region
148 
		}
149 
	} else if ((0x4000 <= address) && (address < 0x8000)) {
150 
		return memory[address & 0x3FFF];
151 
	} else {
152 
		return 0xFF;
153 
	}
154 
}
155
156 
const byte* TurboRFDC::getReadCacheLine(uint16_t start) const
157 
{
158 
	if ((start & 0x3FF0) == (0x3FF0 & CacheLine::HIGH)) {
159 
		return nullptr;
160 
	} else if ((0x4000 <= start) && (start < 0x8000)) {
161 
		return &memory[start & 0x3FFF];
162 
	} else {
163 
		return unmappedRead.data();
164 
	}
165 
}
166
167 
void TurboRFDC::writeMem(uint16_t address, byte value, EmuTime time_)
168 
{
169 
	EmuTime time = time_;
170 
	if (0x3FF0 <= (address & 0x3FFF)) {
171 
		// See comment in readMem().
172 
		time = getCPU().waitCyclesR800(time, 1);
173 
	}
174 
	if (address == 0x7FF0) {
175 
		setBank(value);
176 
	} else {
177 
		if (type != Type::R7FF8) { // turboR or BOTH
178 
			switch (address & 0x3FFF) {
179 
			case 0x3FF2:
180 
				controller.writeControlReg0(value, time);
181 
				break;
182 
			case 0x3ff3:
183 
				controller.writeControlReg1(value, time);
184 
				break;
185 
			case 0x3FF5:
186 
				controller.writeDataPort(value, time);
187 
				break;
188 
			}
189 
		}
190 
		if (type != Type::R7FF2) { // non-turboR or BOTH
191 
			switch (address & 0x3FFF) {
192 
			case 0x3FF8:
193 
				controller.writeControlReg0(value, time);
194 
				break;
195 
			case 0x3FF9:
196 
				controller.writeControlReg1(value, time);
197 
				break;
198 
			case 0x3FFB:
199 
				controller.writeDataPort(value, time);
200 
				break;
201 
			}
202 
		}
203 
	}
204 
}
205
206 
void TurboRFDC::setBank(byte value)
207 
{
208 
	invalidateDeviceRCache(0x4000, 0x4000);
209 
	bank = value & blockMask;
210 
	memory = subspan<0x4000>(*rom, 0x4000 * bank);
211 
}
212
213 
byte* TurboRFDC::getWriteCacheLine(uint16_t address)
214 
{
215 
	if ((address == (0x7FF0 & CacheLine::HIGH)) ||
216 
	    ((address & 0x3FF0) == (0x3FF0 & CacheLine::HIGH))) {
217 
		return nullptr;
218 
	} else {
219 
		return unmappedWrite.data();
220 
	}
221 
}
222
223
224 
template<typename Archive>
225 
void TurboRFDC::serialize(Archive& ar, unsigned /*version*/)
226 
{
227 
	ar.template serializeBase<MSXFDC>(*this);
228 
	ar.serialize("TC8566AF", controller,
229 
	             "bank",     bank);
230 
	if constexpr (Archive::IS_LOADER) {
231 
		setBank(bank);
232 
	}
233 
}
234 
INSTANTIATE_SERIALIZE_METHODS(TurboRFDC);
235 
REGISTER_MSXDEVICE(TurboRFDC, "TurboRFDC");
236
237 
} // namespace openmsx