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fix mmc1 reg#3 masking to prohibit >= 16 PRG banks (except for the typical SOROM/SUROM chr bank magic)

This commit is contained in:
zeromus 2015-11-02 20:00:53 +00:00
parent 95890b21ea
commit 8efa68b7af
1 changed files with 14 additions and 13 deletions
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27
trunk/src/boards/mmc1.cpp
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@ -73,37 +73,38 @@ static void MMC1CHR(void) {
}
static void MMC1PRG(void) {
uint8 offs = DRegs[1] & 0x10;
uint8 offs_16banks = DRegs[1] & 0x10;
uint8 prg_reg = DRegs[3] & 0xF; //homebrewers arent allowed to use more banks on MMC1. use another mapper.
if (MMC1PRGHook16) {
switch (DRegs[0] & 0xC) {
case 0xC:
MMC1PRGHook16(0x8000, (DRegs[3] + offs));
MMC1PRGHook16(0xC000, 0xF + offs);
MMC1PRGHook16(0x8000, (prg_reg + offs_16banks));
MMC1PRGHook16(0xC000, 0xF + offs_16banks);
break;
case 0x8:
MMC1PRGHook16(0xC000, (DRegs[3] + offs));
MMC1PRGHook16(0x8000, offs);
MMC1PRGHook16(0xC000, (prg_reg + offs_16banks));
MMC1PRGHook16(0x8000, offs_16banks);
break;
case 0x0:
case 0x4:
MMC1PRGHook16(0x8000, ((DRegs[3] & ~1) + offs));
MMC1PRGHook16(0xc000, ((DRegs[3] & ~1) + offs + 1));
MMC1PRGHook16(0x8000, ((prg_reg & ~1) + offs_16banks));
MMC1PRGHook16(0xc000, ((prg_reg & ~1) + offs_16banks + 1));
break;
}
} else {
switch (DRegs[0] & 0xC) {
case 0xC:
setprg16(0x8000, (DRegs[3] + offs));
setprg16(0xC000, 0xF + offs);
setprg16(0x8000, (prg_reg + offs_16banks));
setprg16(0xC000, 0xF + offs_16banks);
break;
case 0x8:
setprg16(0xC000, (DRegs[3] + offs));
setprg16(0x8000, offs);
setprg16(0xC000, (prg_reg + offs_16banks));
setprg16(0x8000, offs_16banks);
break;
case 0x0:
case 0x4:
setprg16(0x8000, ((DRegs[3] & ~1) + offs));
setprg16(0xc000, ((DRegs[3] & ~1) + offs + 1));
setprg16(0x8000, ((prg_reg & ~1) + offs_16banks));
setprg16(0xc000, ((prg_reg & ~1) + offs_16banks + 1));
break;
}
}