1//============================================================================
2//
3// SSSS tt lll lll
4// SS SS tt ll ll
5// SS tttttt eeee ll ll aaaa
6// SSSS tt ee ee ll ll aa
7// SS tt eeeeee ll ll aaaaa -- "An Atari 2600 VCS Emulator"
8// SS SS tt ee ll ll aa aa
9// SSSS ttt eeeee llll llll aaaaa
10//
11// Copyright (c) 1995-2019 by Bradford W. Mott, Stephen Anthony
12// and the Stella Team
13//
14// See the file "License.txt" for information on usage and redistribution of
15// this file, and for a DISCLAIMER OF ALL WARRANTIES.
16//============================================================================
17
18#include "CompuMate.hxx"
19#include "System.hxx"
20#include "M6532.hxx"
21#include "CartCM.hxx"
22
23// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
24CartridgeCM::CartridgeCM(const ByteBuffer& image, size_t size,
25 const string& md5, const Settings& settings)
26 : Cartridge(settings, md5),
27 mySWCHA(0xFF), // portA is all 1's
28 myBankOffset(0)
29{
30 // Copy the ROM image into my buffer
31 std::copy_n(image.get(), std::min(myImage.size(), size), myImage.begin());
32 createCodeAccessBase(myImage.size());
33}
34
35// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
36void CartridgeCM::reset()
37{
38 initializeRAM(myRAM.data(), myRAM.size());
39
40 // On powerup, the last bank of ROM is enabled and RAM is disabled
41 mySWCHA = 0xFF;
42 initializeStartBank(mySWCHA & 0x3);
43
44 // Upon reset we switch to the startup bank
45 bank(startBank());
46}
47
48// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
49void CartridgeCM::install(System& system)
50{
51 mySystem = &system;
52
53 // Mirror all access in RIOT; by doing so we're taking responsibility
54 // for that address space in peek and poke below.
55 mySystem->m6532().installDelegate(system, *this);
56
57 // Install pages for the startup bank
58 bank(startBank());
59}
60
61// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
62uInt8 CartridgeCM::peek(uInt16 address)
63{
64 // NOTE: This does not handle accessing cart ROM/RAM, however, this method
65 // should never be called for ROM/RAM because of the way page accessing
66 // has been setup (it will only ever be called for RIOT reads)
67 return mySystem->m6532().peek(address);
68}
69
70// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
71bool CartridgeCM::poke(uInt16 address, uInt8 value)
72{
73 // NOTE: This could be called for RIOT writes or cart ROM writes
74 // In the latter case, the write is ignored
75 if(!(address & 0x1000))
76 {
77 // RIOT mirroring, check bankswitch
78 if(address == 0x280)
79 {
80 mySWCHA = value;
81 bank(mySWCHA & 0x3);
82 if(myCompuMate)
83 {
84 uInt8& column = myCompuMate->column();
85 if(value & 0x20)
86 column = 0;
87 if(value & 0x40)
88 column = (column + 1) % 10;
89 }
90 }
91 mySystem->m6532().poke(address, value);
92 }
93 return myBankChanged;
94}
95
96// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
97uInt8 CartridgeCM::column() const
98{
99 return myCompuMate->column();
100}
101
102// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
103bool CartridgeCM::bank(uInt16 bank)
104{
105 if(bankLocked()) return false;
106
107 // Remember what bank we're in
108 myBankOffset = bank << 12;
109
110 // Although this scheme contains four 4K ROM banks and one 2K RAM bank,
111 // it's easier to think of things in terms of 2K slices, as follows:
112 //
113 // The lower 2K of cart address space always points to the lower 2K of the
114 // current ROM bank
115 // The upper 2K of cart address space can point to either the 2K of RAM or
116 // the upper 2K of the current ROM bank
117
118 System::PageAccess access(this, System::PageAccessType::READ);
119
120 // Lower 2K (always ROM)
121 for(uInt16 addr = 0x1000; addr < 0x1800; addr += System::PAGE_SIZE)
122 {
123 access.directPeekBase = &myImage[myBankOffset + (addr & 0x0FFF)];
124 access.codeAccessBase = &myCodeAccessBase[myBankOffset + (addr & 0x0FFF)];
125 mySystem->setPageAccess(addr, access);
126 }
127
128 // Upper 2K (RAM or ROM)
129 for(uInt16 addr = 0x1800; addr < 0x2000; addr += System::PAGE_SIZE)
130 {
131 access.type = System::PageAccessType::READWRITE;
132
133 if(mySWCHA & 0x10)
134 {
135 access.directPeekBase = &myImage[myBankOffset + (addr & 0x0FFF)];
136 access.codeAccessBase = &myCodeAccessBase[myBankOffset + (addr & 0x0FFF)];
137 }
138 else
139 {
140 access.directPeekBase = &myRAM[addr & 0x7FF];
141 access.codeAccessBase = &myCodeAccessBase[myBankOffset + (addr & 0x07FF)];
142 }
143
144 if((mySWCHA & 0x30) == 0x20)
145 access.directPokeBase = &myRAM[addr & 0x7FF];
146 else
147 access.directPokeBase = nullptr;
148
149 mySystem->setPageAccess(addr, access);
150 }
151
152 return myBankChanged = true;
153}
154
155// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
156uInt16 CartridgeCM::getBank(uInt16) const
157{
158 return myBankOffset >> 12;
159}
160
161// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
162uInt16 CartridgeCM::bankCount() const
163{
164 // We report 4 banks (of ROM), even though RAM can overlap the upper 2K
165 // of cart address space at some times
166 // However, this RAM isn't enabled in the normal way that bankswitching
167 // works, so it is ignored here
168 return 4;
169}
170
171// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
172bool CartridgeCM::patch(uInt16 address, uInt8 value)
173{
174 if((mySWCHA & 0x30) == 0x20)
175 myRAM[address & 0x7FF] = value;
176 else
177 myImage[myBankOffset + address] = value;
178
179 return myBankChanged = true;
180}
181
182// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
183const uInt8* CartridgeCM::getImage(size_t& size) const
184{
185 size = myImage.size();
186 return myImage.data();
187}
188
189// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
190bool CartridgeCM::save(Serializer& out) const
191{
192 try
193 {
194 out.putShort(myBankOffset);
195 out.putByte(mySWCHA);
196 out.putByte(myCompuMate->column());
197 out.putByteArray(myRAM.data(), myRAM.size());
198 }
199 catch(...)
200 {
201 cerr << "ERROR: CartridgeCM::save" << endl;
202 return false;
203 }
204
205 return true;
206}
207
208// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
209bool CartridgeCM::load(Serializer& in)
210{
211 try
212 {
213 myBankOffset = in.getShort();
214 mySWCHA = in.getByte();
215 myCompuMate->column() = in.getByte();
216 in.getByteArray(myRAM.data(), myRAM.size());
217 }
218 catch(...)
219 {
220 cerr << "ERROR: CartridgeCM::load" << endl;
221 return false;
222 }
223
224 // Remember what bank we were in
225 bank(myBankOffset >> 12);
226
227 return true;
228}
229