Emulate DMG LCDC write conflicts correctly. This might vary between individual units.
@@ -18,6 +18,7 @@ typedef enum {
GB_CONFLICT_STAT_DMG,
GB_CONFLICT_PALETTE_DMG,
GB_CONFLICT_PALETTE_CGB,
+ GB_CONFLICT_READ_DMG_LCDC,
} GB_conflict_t;
/* Todo: How does double speed mode affect these? */
@@ -37,7 +38,7 @@ static const GB_conflict_t cgb_conflict_map[0x80] = {
static const GB_conflict_t dmg_conflict_map[0x80] = {
[GB_IO_IF] = GB_CONFLICT_WRITE_CPU,
[GB_IO_LYC] = GB_CONFLICT_READ_OLD,
- [GB_IO_LCDC] = GB_CONFLICT_READ_NEW,
+ [GB_IO_LCDC] = GB_CONFLICT_READ_DMG_LCDC,
[GB_IO_SCY] = GB_CONFLICT_READ_NEW,
[GB_IO_STAT] = GB_CONFLICT_STAT_DMG,
@@ -192,6 +193,17 @@ static void cycle_write(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
gb->pending_cycles = 6;
return;
}
+
+ case GB_CONFLICT_READ_DMG_LCDC: {
+ /* Seems to be affected by screen? Both my DMG (B, blob) and Game Boy Light behave this way though. */
+ uint8_t old_value = GB_read_memory(gb, addr);
+ GB_advance_cycles(gb, gb->pending_cycles - 2);
+ GB_write_memory(gb, addr, old_value | (value & 1));
+ GB_advance_cycles(gb, 1);
+ GB_write_memory(gb, addr, value);
+ gb->pending_cycles = 5;
+ return;
+ }
}
}
