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Emulate the FIFO insertion glitch (WX variant)

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This commit is contained in:
Lior Halphon 2020-02-29 17:06:08 +02:00
parent 955860b463
commit 39b999a68b
2 changed files with 12 additions and 1 deletions
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11
Core/display.c
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@ -524,6 +524,7 @@ static void render_pixel_if_possible(GB_gameboy_t *gb)
} }
gb->position_in_line++; gb->position_in_line++;
gb->window_is_being_fetched = false;
} }
/* All verified CGB timings are based on CGB CPU E. CGB CPUs >= D are known to have /* All verified CGB timings are based on CGB CPU E. CGB CPUs >= D are known to have
@ -960,9 +961,19 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
fifo_clear(&gb->bg_fifo); fifo_clear(&gb->bg_fifo);
gb->fetcher_state = 0; gb->fetcher_state = 0;
window_got_activated = true; window_got_activated = true;
gb->window_is_being_fetched = true;
} }
} }
} }
if (!GB_is_cgb(gb) && gb->wx_triggered && !gb->window_is_being_fetched &&
gb->fetcher_state == 0 && gb->io_registers[GB_IO_WX] == (uint8_t) (gb->position_in_line + 7) ) {
// Insert a pixel right at the FIFO's end
gb->bg_fifo.read_end--;
gb->bg_fifo.read_end &= GB_FIFO_LENGTH - 1;
gb->bg_fifo.fifo[gb->bg_fifo.read_end] = (GB_fifo_item_t){0,};
gb->window_is_being_fetched = false;
}
/* Handle objects */ /* Handle objects */
/* When the sprite enabled bit is off, this proccess is skipped entirely on the DMG, but not on the CGB. /* When the sprite enabled bit is off, this proccess is skipped entirely on the DMG, but not on the CGB.

2
Core/gb.h
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@ -500,7 +500,7 @@ struct GB_gameboy_internal_s {
uint8_t current_tile_attributes; uint8_t current_tile_attributes;
uint8_t current_tile_data[2]; uint8_t current_tile_data[2];
uint8_t fetcher_state; uint8_t fetcher_state;
GB_PADDING(bool,bg_fifo_paused); bool window_is_being_fetched;
GB_PADDING(bool,oam_fifo_paused); GB_PADDING(bool,oam_fifo_paused);
bool wx_triggered; bool wx_triggered;
uint8_t visible_objs[10]; uint8_t visible_objs[10];