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Halt during DMA with objects

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This commit is contained in:
Lior Halphon 2022-01-23 21:05:29 +02:00
parent 0ab7bf7749
commit aa5a279116
2 changed files with 42 additions and 30 deletions
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57
Core/display.c
View File

@ -465,34 +465,55 @@ void GB_lcd_off(GB_gameboy_t *gb)
}
}
static inline uint8_t oam_read(GB_gameboy_t *gb, uint8_t addr)
{
if (unlikely(gb->oam_ppu_blocked)) {
return 0xFF;
}
if (unlikely(gb->dma_current_dest <= 0xa0 && gb->dma_current_dest > 0)) { // TODO: what happens in the last and first M cycles?
return gb->oam[((gb->dma_current_dest - 1 + (gb->halted || gb->stopped)) & ~1) | (addr & 1)];
}
return gb->oam[addr];
}
static void add_object_from_index(GB_gameboy_t *gb, unsigned index)
{
if (gb->n_visible_objs == 10) return;
/* TODO: It appears that DMA blocks PPU access to OAM, but it needs verification. */
if (GB_is_dma_active(gb)) {
return;
if (unlikely(GB_is_dma_active(gb))) {
if (!gb->halted && !gb->stopped) {
return;
}
if (gb->model < GB_MODEL_CGB_E) {
return;
}
/* CGB-0 to CGB-D: Halted DMA still blocks Mode 2;
Pre-CGB: Unit specific behavior, some units read FFs, some units read using
several different corruption pattterns. For simplicity, we emulate
FFs. */
}
if (gb->oam_ppu_blocked) {
if (unlikely(gb->oam_ppu_blocked)) {
return;
}
/* This reverse sorts the visible objects by location and priority */
object_t *objects = (object_t *) &gb->oam;
uint8_t oam_y = oam_read(gb, index * 4);
uint8_t oam_x = oam_read(gb, index * 4) + 1;
bool height_16 = (gb->io_registers[GB_IO_LCDC] & 4) != 0;
signed y = objects[index].y - 16;
signed y = oam_y - 16;
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->objects_x[j] <= objects[index].x) break;
if (gb->objects_x[j] <= oam_x) break;
}
memmove(gb->visible_objs + j + 1, gb->visible_objs + 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->objects_x[j] = objects[index].x;
gb->objects_y[j] = objects[index].y;
gb->objects_x[j] = oam_y;
gb->objects_y[j] = oam_y;
gb->n_visible_objs++;
}
}
@ -680,24 +701,25 @@ static inline uint8_t vram_read(GB_gameboy_t *gb, uint16_t addr)
/* TODO: AGS has its own, very different pattern, but AGS is not currently a supported model */
/* TODO: Research this when researching odd modes */
/* TODO: probably not 100% on the first few reads during halt/stop modes*/
unsigned offset = 1 - (gb->halted || gb->stopped);
if (GB_is_cgb(gb)) {
if (gb->dma_ppu_vram_conflict) {
addr = (gb->dma_ppu_vram_conflict_addr & 0x1FFF) | (addr & 0x2000);
}
else if (gb->dma_cycles_modulo && !gb->halted && !gb->stopped) {
addr &= 0x2000;
addr |= ((gb->dma_current_src - 1) & 0x1FFF);
addr |= ((gb->dma_current_src - offset) & 0x1FFF);
}
else {
addr &= 0x2000 | ((gb->dma_current_src - 1) & 0x1FFF);
addr &= 0x2000 | ((gb->dma_current_src - offset) & 0x1FFF);
gb->dma_ppu_vram_conflict_addr = addr;
gb->dma_ppu_vram_conflict = !gb->halted && !gb->stopped;
}
}
else {
addr |= ((gb->dma_current_src - 1) & 0x1FFF);
addr |= ((gb->dma_current_src - offset) & 0x1FFF);
}
gb->oam[gb->dma_current_dest - 1] = gb->vram[(addr & 0x1FFF) | (gb->cgb_vram_bank? 0x2000 : 0)];
gb->oam[gb->dma_current_dest - offset] = gb->vram[(addr & 0x1FFF) | (gb->cgb_vram_bank? 0x2000 : 0)];
}
return gb->vram[addr];
}
@ -875,17 +897,6 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb, unsigned *cycles)
}
}
static inline uint8_t oam_read(GB_gameboy_t *gb, uint8_t addr)
{
if (unlikely(gb->oam_ppu_blocked)) {
return 0xFF;
}
if (unlikely(gb->dma_current_dest <= 0xa0 && gb->dma_current_dest > 0)) { // TODO: what happens in the last and first M cycles?
return gb->oam[((gb->dma_current_dest - 1) & ~1) | (addr & 1)];
}
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? */

15
Core/sm83_cpu.c
View File

@ -354,6 +354,9 @@ static void enter_stop_mode(GB_gameboy_t *gb)
static void leave_stop_mode(GB_gameboy_t *gb)
{
gb->stopped = false;
// TODO: verify this
gb->dma_cycles = 4;
GB_dma_run(gb);
gb->oam_ppu_blocked = false;
gb->vram_ppu_blocked = false;
gb->cgb_palettes_ppu_blocked = false;
@ -373,8 +376,6 @@ static void stop(GB_gameboy_t *gb, uint8_t opcode)
// When entering with IF&IE, the 2nd byte of STOP is actually executed
if (!exit_by_joyp) {
if (!immediate_exit) {
// TODO: verify this!
gb->dma_cycles = 4;
GB_dma_run(gb);
}
enter_stop_mode(gb);
@ -419,8 +420,6 @@ static void stop(GB_gameboy_t *gb, uint8_t opcode)
if (immediate_exit) {
leave_stop_mode(gb);
if (!interrupt_pending) {
// TODO: verify this!
gb->dma_cycles = 4;
GB_dma_run(gb);
gb->halted = true;
gb->just_halted = true;
@ -1024,9 +1023,6 @@ static void halt(GB_gameboy_t *gb, uint8_t opcode)
}
}
else {
// TODO: verify the timing!
gb->dma_cycles = 4;
GB_dma_run(gb);
gb->halted = true;
}
gb->just_halted = true;
@ -1625,12 +1621,17 @@ void GB_cpu_run(GB_gameboy_t *gb)
/* Wake up from HALT mode without calling interrupt code. */
if (gb->halted && !effective_ime && interrupt_queue) {
gb->halted = false;
gb->dma_cycles = 4;
GB_dma_run(gb);
gb->speed_switch_halt_countdown = 0;
}
/* Call interrupt */
else if (effective_ime && interrupt_queue) {
gb->halted = false;
// TODO: verify the timing!
gb->dma_cycles = 4;
GB_dma_run(gb);
gb->speed_switch_halt_countdown = 0;
uint16_t call_addr = gb->pc;