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1 | /* FCE Ultra - NES/Famicom Emulator |
2 | * |
3 | * Copyright notice for this file: |
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4 | * Copyright (C) 2002 Xodnizel |
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5 | * |
6 | * This program is free software; you can redistribute it and/or modify |
7 | * it under the terms of the GNU General Public License as published by |
8 | * the Free Software Foundation; either version 2 of the License, or |
9 | * (at your option) any later version. |
10 | * |
11 | * This program is distributed in the hope that it will be useful, |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | * GNU General Public License for more details. |
15 | * |
16 | * You should have received a copy of the GNU General Public License |
17 | * along with this program; if not, write to the Free Software |
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18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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19 | */ |
20 | |
21 | #include "mapinc.h" |
22 | |
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23 | //16 bits of ram in total |
24 | //only use bottom 4 bits as ram though |
25 | static uint8 mapper228_ram[4]; |
26 | |
27 | static SFORMAT StateRegs[]= |
28 | { |
29 | { mapper228_ram, 4, "MAPPER_RAM" }, |
30 | { 0 } |
31 | }; |
32 | |
33 | static DECLFR(Mapper228_read) |
34 | { |
35 | return mapper228_ram[A & 3] & 0xF; |
36 | } |
37 | |
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38 | static DECLFW(Mapper228_write) |
39 | { |
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40 | uint32 page, pagel, pageh; |
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41 | |
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42 | //write to ram |
43 | if (A < 0x6000) |
44 | { |
45 | mapper228_ram[A & 3] = V; |
46 | return; |
47 | } |
48 | MIRROR_SET((A >> 13) & 1); |
49 | page = (A >> 7) & 0x3F; |
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50 | |
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51 | if( (page & 0x30) == 0x30) |
52 | page -= 0x10; |
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53 | |
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54 | pagel = pageh = (page << 1) + (((A >> 6) & 1) & ((A >> 5) & 1)); |
55 | pageh += ((A >> 5) & 1) ^ 1; |
56 | |
57 | ROM_BANK16(0x8000,pagel); |
58 | ROM_BANK16(0xC000,pageh); |
59 | VROM_BANK8( (V&0x3) | ((A&0xF)<<2) ); |
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60 | } |
61 | |
62 | static void A52Reset(void) |
63 | { |
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64 | Mapper228_write(0x8000, 0); |
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65 | } |
66 | |
67 | void Mapper228_init(void) |
68 | { |
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69 | MapperReset=A52Reset; |
70 | A52Reset(); |
71 | SetWriteHandler(0x8000, 0xFFFF, Mapper228_write); |
72 | SetWriteHandler(0x4020, 0x5FFF, Mapper228_write); |
73 | SetReadHandler (0x4020, 0x5FFF, Mapper228_read); |
74 | AddExState(StateRegs, ~0, 0, 0); |
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75 | } |
76 | |