blob: 83f01eaeae605129f513f3943d8e459ec9e67caf (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
/*===================================================================*/
/* */
/* Mapper 25 (Konami VRC4 type B) */
/* */
/*===================================================================*/
BYTE Map25_Bank_Selector;
BYTE Map25_VBank[16];
BYTE Map25_IRQ_Count;
BYTE Map25_IRQ_State;
BYTE Map25_IRQ_Latch;
/*-------------------------------------------------------------------*/
/* Initialize Mapper 25 */
/*-------------------------------------------------------------------*/
void Map25_Init()
{
int nPage;
/* Initialize Mapper */
MapperInit = Map25_Init;
/* Write to Mapper */
MapperWrite = Map25_Write;
/* Write to SRAM */
MapperSram = Map0_Sram;
/* Write to APU */
MapperApu = Map0_Apu;
/* Read from APU */
MapperReadApu = Map0_ReadApu;
/* Callback at VSync */
MapperVSync = Map0_VSync;
/* Callback at HSync */
MapperHSync = Map25_HSync;
/* Callback at PPU */
MapperPPU = Map0_PPU;
/* Callback at Rendering Screen ( 1:BG, 0:Sprite ) */
MapperRenderScreen = Map0_RenderScreen;
/* Set SRAM Banks */
SRAMBANK = SRAM;
/* Set ROM Banks */
ROMBANK0 = ROMPAGE( 0 );
ROMBANK1 = ROMPAGE( 1 );
ROMBANK2 = ROMLASTPAGE( 1 );
ROMBANK3 = ROMLASTPAGE( 0 );
/* Reset VBank Registers */
for (nPage = 0; nPage < 16; nPage++)
Map25_VBank[ nPage ] = 0x00;
/* Set up wiring of the interrupt pin */
K6502_Set_Int_Wiring( 1, 1 );
}
/*-------------------------------------------------------------------*/
/* Mapper 25 Write Function */
/*-------------------------------------------------------------------*/
void Map25_Write( WORD wAddr, BYTE byData )
{
int nBank;
switch ( wAddr )
{
case 0x8000:
/* Set ROM Banks */
byData %= ( NesHeader.byRomSize << 1 );
if ( Map25_Bank_Selector )
{
ROMBANK2 = ROMPAGE( byData );
} else {
ROMBANK0 = ROMPAGE( byData );
}
break;
case 0x9000:
/* Name Table Mirroring */
switch (byData & 0x03)
{
case 0:
InfoNES_Mirroring( 1 ); /* Vertical */
break;
case 1:
InfoNES_Mirroring( 0 ); /* Horizontal */
break;
case 2:
InfoNES_Mirroring( 2 ); /* One Screen 0x2000 */
break;
case 3:
InfoNES_Mirroring( 3 ); /* One Screen 0x2400 */
break;
}
break;
case 0x9002:
/* TODO: SaveRAM Toggle */
/* $8000 Switching Mode */
Map25_Bank_Selector = byData & 0x02;
break;
case 0xa000:
/* Set ROM Banks */
byData %= ( NesHeader.byRomSize << 1 );
ROMBANK1 = ROMPAGE( byData );
break;
default:
/* Set PPU Banks */
switch ( wAddr & 0xfffc)
{
case 0xb000:
Map25_VBank[ 0 + ( wAddr & 0x0003 ) ] = byData & 0x0f;
nBank = 0 + ( wAddr & 0x0001 );
Map25_Sync_Vrom( nBank );
break;
case 0xc000:
Map25_VBank[ 4 + ( wAddr & 0x0003 ) ] = byData & 0x0f;
nBank = 2 + ( wAddr & 0x0001 );
Map25_Sync_Vrom( nBank );
break;
case 0xd000:
Map25_VBank[ 8 + ( wAddr & 0x0003 ) ] = byData & 0x0f;
nBank = 4 + ( wAddr & 0x0001 );
Map25_Sync_Vrom( nBank );
break;
case 0xe000:
Map25_VBank[ 12 + ( wAddr & 0x0003 ) ] = byData & 0x0f;
nBank = 6 + ( wAddr & 0x0001 );
Map25_Sync_Vrom( nBank );
break;
case 0xf000:
switch ( wAddr & 0x0003 )
{
case 0:
case 1:
Map25_IRQ_Latch = byData;
break;
case 2:
Map25_IRQ_State = ( byData & 0x01 ) ? Map25_IRQ_State : 0x00;
Map25_IRQ_State = ( byData & 0x02 ) ? 0x01 : Map25_IRQ_State;
Map25_IRQ_Count = Map25_IRQ_Latch;
break;
case 3:
Map25_IRQ_State = ( Map25_IRQ_State << 1 ) | ( Map25_IRQ_State & 1 );
break;
}
break;
}
break;
}
}
/*-------------------------------------------------------------------*/
/* Mapper 25 Sync VROM Function */
/*-------------------------------------------------------------------*/
void Map25_Sync_Vrom( int nBank )
{
BYTE byValue;
byValue = Map25_VBank[ ( nBank << 1 ) - ( nBank & 0x01 ) ];
byValue |= Map25_VBank[ ( nBank << 1 ) - ( nBank & 0x01 ) + 2] << 4;
byValue %= ( NesHeader.byVRomSize << 3 );
PPUBANK[ nBank ] = VROMPAGE( byValue );
InfoNES_SetupChr();
}
/*-------------------------------------------------------------------*/
/* Mapper 25 H-Sync Function */
/*-------------------------------------------------------------------*/
void Map25_HSync()
{
/*
* Callback at HSync
*
*/
if ( ( Map25_IRQ_State & 0x02 ) && ( ++Map25_IRQ_Count == 0 ) )
{
IRQ_REQ;
Map25_IRQ_Count = Map25_IRQ_Latch;
}
}
|
