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) 1995-2014 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 // $Id: CartFE.cxx 2838 2014-01-17 23:34:03Z stephena $
18 //============================================================================
19
20 #include <cassert>
21 #include <cstring>
22
23 #include "System.hxx"
24 #include "CartFE.hxx"
25
26 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
CartridgeFE(const uInt8 * image,uInt32 size,const Settings & settings)27 CartridgeFE::CartridgeFE(const uInt8* image, uInt32 size, const Settings& settings)
28 : Cartridge(settings),
29 myLastAddress1(0),
30 myLastAddress2(0),
31 myLastAddressChanged(false)
32 {
33 // Copy the ROM image into my buffer
34 memcpy(myImage, image, MIN(8192u, size));
35
36 // We use System::PageAccess.codeAccessBase, but don't allow its use
37 // through a pointer, since the address space of FE carts can change
38 // at the instruction level, and PageAccess is normally defined at an
39 // interval of 64 bytes
40 //
41 // Instead, access will be through the getAccessFlags and setAccessFlags
42 // methods below
43 createCodeAccessBase(8192);
44 }
45
46 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
~CartridgeFE()47 CartridgeFE::~CartridgeFE()
48 {
49 }
50
51 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
reset()52 void CartridgeFE::reset()
53 {
54 }
55
56 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
install(System & system)57 void CartridgeFE::install(System& system)
58 {
59 mySystem = &system;
60 uInt16 shift = mySystem->pageShift();
61 uInt16 mask = mySystem->pageMask();
62
63 // Make sure the system we're being installed in has a page size that'll work
64 assert((0x1000 & mask) == 0);
65
66 System::PageAccess access(0, 0, 0, this, System::PA_READ);
67
68 // Map all of the accesses to call peek and poke
69 for(uInt32 i = 0x1000; i < 0x2000; i += (1 << shift))
70 mySystem->setPageAccess(i >> shift, access);
71 }
72
73 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
peek(uInt16 address)74 uInt8 CartridgeFE::peek(uInt16 address)
75 {
76 // The bank is determined by A13 of the processor
77 // We keep track of the two most recent accesses to determine which bank
78 // we're in, and when the values actually changed
79 myLastAddress2 = myLastAddress1;
80 myLastAddress1 = address;
81 myLastAddressChanged = true;
82
83 return myImage[(address & 0x0FFF) + (((address & 0x2000) == 0) ? 4096 : 0)];
84 }
85
86 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
poke(uInt16,uInt8)87 bool CartridgeFE::poke(uInt16, uInt8)
88 {
89 return false;
90 }
91
92 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
getAccessFlags(uInt16 address)93 uInt8 CartridgeFE::getAccessFlags(uInt16 address)
94 {
95 return myCodeAccessBase[(address & 0x0FFF) +
96 (((address & 0x2000) == 0) ? 4096 : 0)];
97 }
98
99 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
setAccessFlags(uInt16 address,uInt8 flags)100 void CartridgeFE::setAccessFlags(uInt16 address, uInt8 flags)
101 {
102 myCodeAccessBase[(address & 0x0FFF) +
103 (((address & 0x2000) == 0) ? 4096 : 0)] |= flags;
104 }
105
106 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bank(uInt16)107 bool CartridgeFE::bank(uInt16)
108 {
109 // Doesn't support bankswitching in the normal sense
110 return false;
111 }
112
113 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bank() const114 uInt16 CartridgeFE::bank() const
115 {
116 // The current bank depends on the last address accessed
117 return ((myLastAddress1 & 0x2000) == 0) ? 1 : 0;
118 }
119
120 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bankCount() const121 uInt16 CartridgeFE::bankCount() const
122 {
123 return 2;
124 }
125
126 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bankChanged()127 bool CartridgeFE::bankChanged()
128 {
129 if(myLastAddressChanged)
130 {
131 // A bankswitch occurs when the addresses transition from state to another
132 myBankChanged = ((myLastAddress1 & 0x2000) == 0) !=
133 ((myLastAddress2 & 0x2000) == 0);
134 myLastAddressChanged = false;
135 }
136 else
137 myBankChanged = false;
138
139 // In any event, let the base class know about it
140 return Cartridge::bankChanged();
141 }
142
143
144 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
patch(uInt16 address,uInt8 value)145 bool CartridgeFE::patch(uInt16 address, uInt8 value)
146 {
147 myImage[(address & 0x0FFF) + (((address & 0x2000) == 0) ? 4096 : 0)] = value;
148 return myBankChanged = true;
149 }
150
151 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
getImage(int & size) const152 const uInt8* CartridgeFE::getImage(int& size) const
153 {
154 size = 8192;
155 return myImage;
156 }
157
158 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
save(Serializer & out) const159 bool CartridgeFE::save(Serializer& out) const
160 {
161 out.putString(name());
162 out.putShort(myLastAddress1);
163 out.putShort(myLastAddress2);
164
165 return true;
166 }
167
168 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
load(Serializer & in)169 bool CartridgeFE::load(Serializer& in)
170 {
171 if(in.getString() != name())
172 return false;
173
174 myLastAddress1 = in.getShort();
175 myLastAddress2 = in.getShort();
176
177 return true;
178 }
179