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More accurate internal bus behavior

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This commit is contained in:
Lior Halphon 2022-02-06 13:02:15 +02:00
parent 4e27558ac2
commit 97c758ba75
2 changed files with 13 additions and 9 deletions
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13
Core/display.c
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@ -482,6 +482,11 @@ static inline uint8_t oam_read(GB_gameboy_t *gb, uint8_t addr)
static void add_object_from_index(GB_gameboy_t *gb, unsigned index)
{
if (likely(!GB_is_dma_active(gb) || gb->halted || gb->stopped)) {
gb->mode2_y_bus = oam_read(gb, index * 4);
gb->mode2_x_bus = oam_read(gb, index * 4 + 1);
}
if (gb->n_visible_objs == 10) return;
/* TODO: It appears that DMA blocks PPU access to OAM, but it needs verification. */
@ -498,11 +503,7 @@ static void add_object_from_index(GB_gameboy_t *gb, unsigned index)
if (unlikely(gb->oam_ppu_blocked)) {
return;
}
if (likely(!GB_is_dma_active(gb) || gb->halted || gb->stopped)) {
gb->mode2_y_bus = oam_read(gb, index * 4);
gb->mode2_x_bus = oam_read(gb, index * 4 + 1);
}
bool height_16 = (gb->io_registers[GB_IO_LCDC] & 4) != 0;
signed y = gb->mode2_y_bus - 16;
/* This reverse sorts the visible objects by location and priority */
@ -1657,7 +1658,7 @@ void GB_display_run(GB_gameboy_t *gb, unsigned cycles, bool force)
dma_sync(gb, &cycles);
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->mode2_y_bus = 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)
);

9
Core/gb.h
View File

@ -597,7 +597,12 @@ struct GB_gameboy_internal_s {
uint8_t objects_x[10];
uint8_t objects_y[10];
uint8_t object_tile_data[2];
uint8_t object_flags;
uint8_t mode2_y_bus;
// They're the same bus
union {
uint8_t mode2_x_bus;
uint8_t object_flags;
};
uint8_t n_visible_objs;
uint8_t oam_search_index;
uint8_t accessed_oam_row;
@ -621,8 +626,6 @@ struct GB_gameboy_internal_s {
uint16_t last_tile_index_address;
bool cgb_repeated_a_frame;
uint8_t data_for_sel_glitch;
uint8_t mode2_y_bus;
uint8_t mode2_x_bus;
)
/* Unsaved data. This includes all pointers, as well as everything that shouldn't be on a save state */