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More accurate OAM access timings

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This commit is contained in:
Lior Halphon 2022-01-14 15:07:50 +02:00
parent ec012cf9f8
commit 4ce8e77796
2 changed files with 40 additions and 30 deletions
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64
Core/display.c
View File

@ -485,12 +485,14 @@ static void add_object_from_index(GB_gameboy_t *gb, unsigned index)
if (y <= gb->current_line && y + (height_16? 16 : 8) > gb->current_line) {
unsigned j = 0;
for (; j < gb->n_visible_objs; j++) {
if (gb->obj_comparators[j] <= objects[index].x) break;
if (gb->objects_x[j] <= objects[index].x) break;
}
memmove(gb->visible_objs + j + 1, gb->visible_objs + j, gb->n_visible_objs - j);
memmove(gb->obj_comparators + j + 1, gb->obj_comparators + j, gb->n_visible_objs - j);
memmove(gb->objects_x + j + 1, gb->objects_x + j, gb->n_visible_objs - j);
memmove(gb->objects_y + j + 1, gb->objects_y + j, gb->n_visible_objs - j);
gb->visible_objs[j] = index;
gb->obj_comparators[j] = objects[index].x;
gb->objects_x[j] = objects[index].x;
gb->objects_y[j] = objects[index].y;
gb->n_visible_objs++;
}
}
@ -842,25 +844,30 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb)
}
}
static uint16_t get_object_line_address(GB_gameboy_t *gb, const object_t *object)
static uint8_t oam_read(GB_gameboy_t *gb, uint8_t addr)
{
/* TODO: what does the PPU read if DMA is active? */
if (gb->oam_ppu_blocked) {
static const object_t blocked = {0xFF, 0xFF, 0xFF, 0xFF};
object = &blocked;
if (unlikely(gb->oam_ppu_blocked)) {
return 0xFF;
}
if (unlikely(GB_is_dma_active(gb))) {
}
return gb->oam[addr];
}
static uint16_t get_object_line_address(GB_gameboy_t *gb, uint8_t y, uint8_t tile, uint8_t flags)
{
bool height_16 = (gb->io_registers[GB_IO_LCDC] & 4) != 0; /* Todo: Which T-cycle actually reads this? */
uint8_t tile_y = (gb->current_line - object->y) & (height_16? 0xF : 7);
uint8_t tile_y = (gb->current_line - y) & (height_16? 0xF : 7);
if (object->flags & 0x40) { /* Flip Y */
if (flags & 0x40) { /* Flip Y */
tile_y ^= height_16? 0xF : 7;
}
/* Todo: I'm not 100% sure an access to OAM can't trigger the OAM bug while we're accessing this */
uint16_t line_address = (height_16? object->tile & 0xFE : object->tile) * 0x10 + tile_y * 2;
uint16_t line_address = (height_16? tile & 0xFE : tile) * 0x10 + tile_y * 2;
if (gb->cgb_mode && (object->flags & 0x8)) { /* Use VRAM bank 2 */
if (gb->cgb_mode && (flags & 0x8)) { /* Use VRAM bank 2 */
line_address += 0x2000;
}
return line_address;
@ -932,7 +939,7 @@ static void render_line(GB_gameboy_t *gb)
const object_t *object = &objects[object_index];
gb->n_visible_objs--;
uint16_t line_address = get_object_line_address(gb, object);
uint16_t line_address = get_object_line_address(gb, object->y, object->tile, object->flags);
uint8_t data0 = gb->vram[line_address];
uint8_t data1 = gb->vram[line_address + 1];
if (gb->n_visible_objs == 0) {
@ -1096,7 +1103,7 @@ static void render_line_sgb(GB_gameboy_t *gb)
const object_t *object = &objects[gb->visible_objs[gb->n_visible_objs - 1]];
gb->n_visible_objs--;
uint16_t line_address = get_object_line_address(gb, object);
uint16_t line_address = get_object_line_address(gb, object->y, object->tile, object->flags);
uint8_t data0 = gb->vram[line_address];
uint8_t data1 = gb->vram[line_address + 1];
if (object->flags & 0x20) {
@ -1251,7 +1258,6 @@ void GB_display_run(GB_gameboy_t *gb, unsigned cycles, bool force)
}
return;
}
object_t *objects = (object_t *) &gb->oam;
GB_BATCHABLE_STATE_MACHINE(gb, display, cycles, 2, !force) {
GB_STATE(gb, display, 1);
@ -1558,14 +1564,14 @@ void GB_display_run(GB_gameboy_t *gb, unsigned cycles, bool force)
while (gb->n_visible_objs != 0 &&
(gb->position_in_line < 160 || gb->position_in_line >= (uint8_t)(-8)) &&
gb->obj_comparators[gb->n_visible_objs - 1] < (uint8_t)(gb->position_in_line + 8)) {
gb->objects_x[gb->n_visible_objs - 1] < (uint8_t)(gb->position_in_line + 8)) {
gb->n_visible_objs--;
}
gb->during_object_fetch = true;
while (gb->n_visible_objs != 0 &&
(gb->io_registers[GB_IO_LCDC] & 2 || GB_is_cgb(gb)) &&
gb->obj_comparators[gb->n_visible_objs - 1] == (uint8_t)(gb->position_in_line + 8)) {
gb->objects_x[gb->n_visible_objs - 1] == (uint8_t)(gb->position_in_line + 8)) {
while (gb->fetcher_state < 5 || fifo_size(&gb->bg_fifo) == 0) {
advance_fetcher_state_machine(gb);
@ -1578,7 +1584,7 @@ void GB_display_run(GB_gameboy_t *gb, unsigned cycles, bool force)
/* Todo: Measure if penalty occurs before or after waiting for the fetcher. */
if (gb->extra_penalty_for_object_at_0 != 0) {
if (gb->obj_comparators[gb->n_visible_objs - 1] == 0) {
if (gb->objects_x[gb->n_visible_objs - 1] == 0) {
gb->cycles_for_line += gb->extra_penalty_for_object_at_0;
GB_SLEEP(gb, display, 28, gb->extra_penalty_for_object_at_0);
gb->extra_penalty_for_object_at_0 = 0;
@ -1605,7 +1611,12 @@ void GB_display_run(GB_gameboy_t *gb, unsigned cycles, bool force)
goto abort_fetching_object;
}
gb->object_low_line_address = get_object_line_address(gb, &objects[gb->visible_objs[gb->n_visible_objs - 1]]);
gb->object_low_line_address = get_object_line_address(gb,
gb->objects_y[gb->n_visible_objs - 1],
oam_read(gb, gb->visible_objs[gb->n_visible_objs - 1] * 4 + 2),
gb->object_flags = oam_read(gb, gb->visible_objs[gb->n_visible_objs - 1] * 4 + 3)
);
gb->cycles_for_line++;
GB_SLEEP(gb, display, 39, 1);
@ -1617,23 +1628,20 @@ void GB_display_run(GB_gameboy_t *gb, unsigned cycles, bool force)
gb->cycles_for_line++;
GB_SLEEP(gb, display, 40, 1);
const object_t *object = &objects[gb->visible_objs[gb->n_visible_objs - 1]];
uint16_t line_address = get_object_line_address(gb, object);
uint8_t palette = (object->flags & 0x10) ? 1 : 0;
uint8_t palette = (gb->object_flags & 0x10) ? 1 : 0;
if (gb->cgb_mode) {
palette = object->flags & 0x7;
palette = gb->object_flags & 0x7;
}
fifo_overlay_object_row(&gb->oam_fifo,
gb->vram_ppu_blocked? 0xFF : gb->vram[gb->object_low_line_address],
gb->vram_ppu_blocked? 0xFF : gb->vram[line_address + 1],
gb->vram_ppu_blocked? 0xFF : gb->vram[gb->object_low_line_address + 1],
palette,
object->flags & 0x80,
gb->object_flags & 0x80,
gb->object_priority == GB_OBJECT_PRIORITY_INDEX? gb->visible_objs[gb->n_visible_objs - 1] : 0,
object->flags & 0x20);
gb->object_flags & 0x20);
gb->data_for_sel_glitch = gb->vram_ppu_blocked? 0xFF : gb->vram[line_address + 1];
gb->data_for_sel_glitch = gb->vram_ppu_blocked? 0xFF : gb->vram[gb->object_low_line_address + 1];
gb->n_visible_objs--;
}

4
Core/gb.h
View File

@ -599,7 +599,9 @@ struct GB_gameboy_internal_s {
bool wx166_glitch;
bool wx_triggered;
uint8_t visible_objs[10];
uint8_t obj_comparators[10];
uint8_t objects_x[10];
uint8_t objects_y[10];
uint8_t object_flags;
uint8_t n_visible_objs;
uint8_t oam_search_index;
uint8_t accessed_oam_row;