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GB: Improve emulation of DMG-on-CGB register reads

This commit is contained in:
Vicki Pfau 2020-11-20 02:38:37 -08:00
parent d5e434c684
commit e050a2ae3d
3 changed files with 26 additions and 27 deletions
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23
src/gb/io.c
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@ -104,6 +104,7 @@ static const uint8_t _registerMask[] = {
[GB_REG_BCPS] = 0x40,
[GB_REG_OPRI] = 0xFE,
[GB_REG_SVBK] = 0xF8,
[GB_REG_UNK75] = 0x8F,
[GB_REG_IE] = 0xE0,
};
@ -531,12 +532,9 @@ void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
goto success;
}
failed:
mLOG(GB_IO, STUB, "Writing to unknown register FF%02X:%02X", address, value);
if (address >= GB_SIZE_IO) {
mLOG(GB_IO, GAME_ERROR, "Writing to unknown register FF%02X:%02X", address, value);
return;
}
break;
}
success:
gb->memory.io[address] = value;
}
@ -662,9 +660,6 @@ uint8_t GBIORead(struct GB* gb, unsigned address) {
case GB_REG_WX:
// Handled transparently by the registers
break;
default:
if (gb->model >= GB_MODEL_CGB) {
switch (address) {
case GB_REG_KEY1:
case GB_REG_VBK:
case GB_REG_HDMA1:
@ -677,16 +672,20 @@ uint8_t GBIORead(struct GB* gb, unsigned address) {
case GB_REG_OCPS:
case GB_REG_OCPD:
case GB_REG_SVBK:
case GB_REG_UNK72:
case GB_REG_UNK73:
case GB_REG_UNK75:
// Handled transparently by the registers
goto success;
default:
if (gb->model < GB_MODEL_CGB) {
// In DMG mode, these all get initialized to 0xFF during reset
// But in DMG-on-CGB mode, they get initialized by the CGB reset so they can be non-zero
mLOG(GB_IO, GAME_ERROR, "Reading from CGB register FF%02X in DMG mode", address);
}
break;
}
}
default:
mLOG(GB_IO, STUB, "Reading from unknown register FF%02X", address);
return 0xFF;
}
success:
return gb->memory.io[address] | _registerMask[address];
}