Prevent Hblank HDMAs when the LCD is off

This commit is contained in:
Lior Halphon 2017-02-21 22:33:09 +02:00
parent f4a364c3db
commit c5ce14dad1

View File

@ -315,13 +315,20 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
gb->stat_interrupt_line = false;
if (!(gb->io_registers[GB_IO_LCDC] & 0x80)) {
/* LCD is disabled, do nothing */
/* LCD is disabled, state is constant */
/* When the LCD is off, LY is 0 and STAT mode is 0.
Todo: Verify the LY=LYC flag should be on. */
gb->io_registers[GB_IO_LY] = 0;
gb->io_registers[GB_IO_STAT] &= ~3;
gb->io_registers[GB_IO_STAT] |= 4;
if (gb->hdma_on_hblank) {
gb->hdma_on_hblank = false;
gb->hdma_on = false;
/* Todo: is this correct? */
gb->hdma_steps_left = 0xff;
}
/* Keep sending vblanks to user even if the screen is off */
gb->display_cycles += cycles;