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Emulate DMG LCDC write conflicts correctly. This might vary between individual units.

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This commit is contained in:
Lior Halphon 2020-02-21 02:55:07 +02:00
parent 0290e70445
commit a8f63aea3c
1 changed files with 13 additions and 1 deletions
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14
Core/sm83_cpu.c
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@ -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;
}
}
}