openMSX
RomHalnote.cc
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1 /*
2  * HALNOTE mapper
3  *
4  * This info is extracted from the romMapperHalnote.c source in blueMSX,
5  * implemented by white_cat.
6  *
7  * This is a 1024kB mapper, it's divided in 128 pages of 8kB. The last 512kB
8  * can also be mapped as 256 pages of 2kB. There is 16kB SRAM.
9  *
10  * Main bankswitch registers:
11  * bank 0, region: [0x4000-0x5FFF], switch addr: 0x4FFF
12  * bank 1, region: [0x6000-0x7FFF], switch addr: 0x6FFF
13  * bank 2, region: [0x8000-0x9FFF], switch addr: 0x8FFF
14  * bank 3, region: [0xA000-0xBFFF], switch addr: 0xAFFF
15  * Sub-bankswitch registers:
16  * bank 0, region: [0x7000-0x77FF], switch addr: 0x77FF
17  * bank 1, region: [0x7800-0x7FFF], switch addr: 0x7FFF
18  * Note that the two sub-banks overlap with main bank 1!
19  *
20  * The upper bit (0x80) of the first two main bankswitch registers are special:
21  * bank 0, bit7 SRAM enabled in [0x0000-0x3FFF] (1=enabled)
22  * bank 1, bit7 submapper enabled in [0x7000-0x7FFF] (1=enabled)
23  * If enabled, the submapper shadows (part of) main bank 1.
24  */
25 
26 #include "RomHalnote.hh"
27 #include "CacheLine.hh"
28 #include "SRAM.hh"
29 #include "MSXException.hh"
30 #include "one_of.hh"
31 #include "serialize.hh"
32 #include "xrange.hh"
33 #include <memory>
34 
35 namespace openmsx {
36 
37 RomHalnote::RomHalnote(const DeviceConfig& config, Rom&& rom_)
38  : Rom8kBBlocks(config, std::move(rom_))
39 {
40  if (rom.getSize() != 0x100000) {
41  throw MSXException(
42  "Rom for HALNOTE mapper must be exactly 1MB in size.");
43  }
44  sram = std::make_unique<SRAM>(getName() + " SRAM", 0x4000, config);
45  reset(EmuTime::dummy());
46 }
47 
48 void RomHalnote::reset(EmuTime::param /*time*/)
49 {
50  subBanks[0] = subBanks[1] = 0;
51  sramEnabled = false;
52  subMapperEnabled = false;
53 
54  setUnmapped(0);
55  setUnmapped(1);
56  for (auto i : xrange(2, 6)) {
57  setRom(i, 0);
58  }
59  setUnmapped(6);
60  setUnmapped(7);
61 }
62 
63 const byte* RomHalnote::getReadCacheLine(word address) const
64 {
65  if (subMapperEnabled && (0x7000 <= address) && (address < 0x8000)) {
66  // sub-mapper
67  int subBank = address < 0x7800 ? 0 : 1;
68  return &rom[0x80000 + subBanks[subBank] * 0x800 + (address & 0x7FF)];
69  } else {
70  // default mapper implementation
71  return Rom8kBBlocks::getReadCacheLine(address);
72  }
73 }
74 byte RomHalnote::readMem(word address, EmuTime::param /*time*/)
75 {
76  // all reads are cacheable, reuse that implementation
77  return *RomHalnote::getReadCacheLine(address);
78 }
79 
80 void RomHalnote::writeMem(word address, byte value, EmuTime::param /*time*/)
81 {
82  if (address < 0x4000) {
83  // SRAM region
84  if (sramEnabled) {
85  sram->write(address, value);
86  }
87  } else if (address < 0xC000) {
88  if (address == one_of(0x77FF, 0x7FFF)) {
89  // sub-mapper bank switch region
90  int subBank = address < 0x7800 ? 0 : 1;
91  if (subBanks[subBank] != value) {
92  subBanks[subBank] = value;
93  if (subMapperEnabled) {
95  0x7000 + subBank * 0x800, 0x800);
96  }
97  }
98  } else if ((address & 0x1FFF) == 0x0FFF) {
99  // normal bank switch region
100  int bank = address >> 13; // 2-5
101  setRom(bank, value);
102  if (bank == 2) {
103  // sram enable/disable
104  bool newSramEnabled = (value & 0x80) != 0;
105  if (newSramEnabled != sramEnabled) {
106  sramEnabled = newSramEnabled;
107  if (sramEnabled) {
108  setBank(0, &(*sram)[0x0000], value);
109  setBank(1, &(*sram)[0x2000], value);
110  } else {
111  setUnmapped(0);
112  setUnmapped(1);
113  }
114  // 'R' is already handled
115  invalidateDeviceWCache(0x0000, 0x4000);
116  }
117  } else if (bank == 3) {
118  // sub-mapper enable/disable
119  subMapperEnabled = (value & 0x80) != 0;
120  if (subMapperEnabled) {
121  invalidateDeviceRCache(0x7000, 0x1000);
122  }
123  }
124  }
125  }
126 }
127 
129 {
130  if (address < 0x4000) {
131  // SRAM region
132  if (sramEnabled) {
133  return nullptr;
134  }
135  } else if (address < 0xC000) {
136  if ((address & CacheLine::HIGH) == one_of(0x77FF & CacheLine::HIGH,
137  0x7FFF & CacheLine::HIGH)) {
138  // sub-mapper bank switch region
139  return nullptr;
140  } else if ((address & 0x1FFF & CacheLine::HIGH) ==
141  (0x0FFF & CacheLine::HIGH)) {
142  // normal bank switch region
143  return nullptr;
144  }
145  }
146  return unmappedWrite;
147 }
148 
149 template<typename Archive>
150 void RomHalnote::serialize(Archive& ar, unsigned /*version*/)
151 {
152  ar.template serializeBase<Rom8kBBlocks>(*this);
153  ar.serialize("subBanks", subBanks,
154  "sramEnabled", sramEnabled,
155  "subMapperEnabled", subMapperEnabled);
156 
157 }
160 
161 } // namespace openmsx
Definition: one_of.hh:7
void invalidateDeviceRCache()
Definition: MSXDevice.hh:210
void invalidateDeviceWCache()
Definition: MSXDevice.hh:211
virtual const std::string & getName() const
Returns a human-readable name for this device.
Definition: MSXDevice.cc:376
static byte unmappedWrite[0x10000]
Definition: MSXDevice.hh:302
void setBank(byte region, const byte *adr, int block)
Sets the memory visible for reading in a certain region.
Definition: RomBlocks.cc:78
std::unique_ptr< SRAM > sram
Definition: RomBlocks.hh:84
void setRom(byte region, unsigned block)
Selects a block of the ROM image for reading in a certain region.
Definition: RomBlocks.cc:105
const byte * getReadCacheLine(word address) const override
Test that the memory in the interval [start, start + CacheLine::SIZE) is cacheable for reading.
Definition: RomBlocks.cc:72
void setUnmapped(byte region)
Select 'unmapped' memory for this region.
Definition: RomBlocks.cc:92
byte * getWriteCacheLine(word address) const override
Test that the memory in the interval [start, start + CacheLine::SIZE) is cacheable for writing.
Definition: RomHalnote.cc:128
void reset(EmuTime::param time) override
This method is called on reset.
Definition: RomHalnote.cc:48
RomHalnote(const DeviceConfig &config, Rom &&rom)
Definition: RomHalnote.cc:37
const byte * getReadCacheLine(word address) const override
Test that the memory in the interval [start, start + CacheLine::SIZE) is cacheable for reading.
Definition: RomHalnote.cc:63
void writeMem(word address, byte value, EmuTime::param time) override
Write a given byte to a given location at a certain time to this device.
Definition: RomHalnote.cc:80
void serialize(Archive &ar, unsigned version)
Definition: RomHalnote.cc:150
byte readMem(word address, EmuTime::param time) override
Read a byte from a location at a certain time from this device.
Definition: RomHalnote.cc:74
unsigned getSize() const
Definition: Rom.hh:34
constexpr unsigned HIGH
Definition: CacheLine.hh:10
This file implemented 3 utility functions:
Definition: Autofire.cc:9
REGISTER_MSXDEVICE(ChakkariCopy, "ChakkariCopy")
uint16_t word
16 bit unsigned integer
Definition: openmsx.hh:29
#define INSTANTIATE_SERIALIZE_METHODS(CLASS)
Definition: serialize.hh:998
constexpr auto xrange(T e)
Definition: xrange.hh:155