84 lines
2.4 KiB
C++
84 lines
2.4 KiB
C++
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/******************************************************************************/
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/* Mednafen Sega Saturn Emulation Module */
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/******************************************************************************/
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/* extram.cpp - Extended RAM(1MiB and 4MiB) cart emulation
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** Copyright (C) 2016-2017 Mednafen Team
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**
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** This program is free software; you can redistribute it and/or
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** modify it under the terms of the GNU General Public License
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** as published by the Free Software Foundation; either version 2
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** of the License, or (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software Foundation, Inc.,
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** 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "common.h"
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#include "extram.h"
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namespace MDFN_IEN_SS
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{
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static uint16 ExtRAM[0x200000];
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static size_t ExtRAM_Mask;
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static uint8 Cart_ID;
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template<typename T, bool IsWrite>
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static MDFN_HOT void ExtRAM_RW_DB(uint32 A, uint16* DB)
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{
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const uint32 mask = (sizeof(T) == 2) ? 0xFFFF : (0xFF << (((A & 1) ^ 1) << 3));
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uint16* const ptr = (uint16*)((uint8*)ExtRAM + (A & ExtRAM_Mask));
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//printf("Barf %zu %d: %08x\n", sizeof(T), IsWrite, A);
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if(IsWrite)
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*ptr = (*ptr & ~mask) | (*DB & mask);
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else
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*DB = *ptr;
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}
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static MDFN_HOT void CartID_Read_DB(uint32 A, uint16* DB)
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{
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if((A & ~1) == 0x04FFFFFE)
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*DB = Cart_ID;
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}
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static MDFN_COLD void Reset(bool powering_up)
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{
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if(powering_up)
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memset(ExtRAM, 0, sizeof(ExtRAM)); // TODO: Test.
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}
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void CART_ExtRAM_Init(CartInfo* c, bool R4MiB)
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{
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if(R4MiB)
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{
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Cart_ID = 0x5C;
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ExtRAM_Mask = 0x3FFFFE;
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}
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else
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{
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Cart_ID = 0x5A;
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ExtRAM_Mask = 0x27FFFE;
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}
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SS_SetPhysMemMap(0x02400000, 0x025FFFFF, ExtRAM + (0x000000 / sizeof(uint16)), (R4MiB ? 0x200000 : 0x080000), true);
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SS_SetPhysMemMap(0x02600000, 0x027FFFFF, ExtRAM + (0x200000 / sizeof(uint16)), (R4MiB ? 0x200000 : 0x080000), true);
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c->CS01_SetRW8W16(0x02400000, 0x027FFFFF,
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ExtRAM_RW_DB<uint16, false>,
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ExtRAM_RW_DB<uint8, true>,
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ExtRAM_RW_DB<uint16, true>);
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c->CS01_SetRW8W16(/*0x04FFFFFE*/0x04F00000, 0x04FFFFFF, CartID_Read_DB);
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c->Reset = Reset;
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}
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}
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