fceugx/source/fceultra/boards/BMW8544.cpp
2018-08-13 09:05:50 -06:00

80 lines
2.7 KiB
C++

/* FCE Ultra - NES/Famicom Emulator
*
* Copyright notice for this file:
* Copyright (C) 2015 CaH4e3
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* "Dragon Fighter" protected MMC3 based custom mapper board
* mostly hacky implementation, I can't verify if this mapper can read a RAM of the
* console or watches the bus writes somehow.
*
*/
#include "mapinc.h"
#include "mmc3.h"
static void UNLBMW8544PW(uint32 A, uint8 V) {
if(A == 0x8000)
setprg8(A,EXPREGS[0] & 0x1F); // the real hardware has this bank overrided with it's own register,
else // but MMC3 prg swap still works and you can actually change bank C000 at the same time if use 0x46 cmd
setprg8(A,V);
}
static void UNLBMW8544CW(uint32 A, uint8 V) {
if(A == 0x0000)
setchr2(0x0000,(V >> 1) ^ EXPREGS[1]);
else if (A == 0x0800)
setchr2(0x0800,(V >> 1) | ((EXPREGS[2] & 0x40) << 1));
else if (A == 0x1000)
setchr4(0x1000, EXPREGS[2] & 0x3F);
}
static DECLFW(UNLBMW8544ProtWrite) {
if(!(A & 1)) {
EXPREGS[0] = V;
FixMMC3PRG(MMC3_cmd);
}
}
static DECLFR(UNLBMW8544ProtRead) {
if(!fceuindbg) {
if(!(A & 1)) {
if((EXPREGS[0] & 0xE0) == 0xC0) {
EXPREGS[1] = ARead[0x6a](0x6a); // program can latch some data from the BUS, but I can't say how exactly,
} else { // without more euipment and skills ;) probably here we can try to get any write
EXPREGS[2] = ARead[0xff](0xff); // before the read operation
}
FixMMC3CHR(MMC3_cmd & 0x7F); // there are more different behaviour of the board isn't used by game itself, so unimplemented here and
} // actually will break the current logic ;)
}
return 0;
}
static void UNLBMW8544Power(void) {
GenMMC3Power();
SetWriteHandler(0x6000, 0x6FFF, UNLBMW8544ProtWrite);
SetReadHandler(0x6000, 0x6FFF, UNLBMW8544ProtRead);
}
void UNLBMW8544_Init(CartInfo *info) {
GenMMC3_Init(info, 128, 256, 0, 0);
pwrap = UNLBMW8544PW;
cwrap = UNLBMW8544CW;
info->Power = UNLBMW8544Power;
AddExState(EXPREGS, 3, 0, "EXPR");
}