Max/SameBoy
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Accurate emulation of (most aspects of) stop mode

Browse Source
This commit is contained in:
Lior Halphon 2019-06-07 13:53:50 +03:00
parent 4c34e0a6e0
commit 64879f5b02
6 changed files with 136 additions and 105 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

190
Core/apu.c
View File

@ -407,105 +407,107 @@ void GB_apu_run(GB_gameboy_t *gb)
gb->apu.apu_cycles = 0;
if (!cycles) return;
/* To align the square signal to 1MHz */
gb->apu.lf_div ^= cycles & 1;
gb->apu.noise_channel.alignment += cycles;
if (likely(!gb->stopped || GB_is_cgb(gb))) {
/* To align the square signal to 1MHz */
gb->apu.lf_div ^= cycles & 1;
gb->apu.noise_channel.alignment += cycles;
if (gb->apu.square_sweep_calculate_countdown) {
if (gb->apu.square_sweep_calculate_countdown > cycles) {
gb->apu.square_sweep_calculate_countdown -= cycles;
}
else {
/* APU bug: sweep frequency is checked after adding the sweep delta twice */
gb->apu.new_sweep_sample_legnth = new_sweep_sample_legnth(gb);
if (gb->apu.new_sweep_sample_legnth > 0x7ff) {
gb->apu.is_active[GB_SQUARE_1] = false;
update_sample(gb, GB_SQUARE_1, 0, gb->apu.square_sweep_calculate_countdown - cycles);
gb->apu.sweep_enabled = false;
}
gb->apu.sweep_decreasing |= gb->io_registers[GB_IO_NR10] & 8;
gb->apu.square_sweep_calculate_countdown = 0;
}
}
UNROLL
for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (gb->apu.is_active[i]) {
uint8_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.square_channels[i].sample_countdown)) {
cycles_left -= gb->apu.square_channels[i].sample_countdown + 1;
gb->apu.square_channels[i].sample_countdown = (gb->apu.square_channels[i].sample_length ^ 0x7FF) * 2 + 1;
gb->apu.square_channels[i].current_sample_index++;
gb->apu.square_channels[i].current_sample_index &= 0x7;
update_square_sample(gb, i);
}
if (cycles_left) {
gb->apu.square_channels[i].sample_countdown -= cycles_left;
}
}
}
gb->apu.wave_channel.wave_form_just_read = false;
if (gb->apu.is_active[GB_WAVE]) {
uint8_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.wave_channel.sample_countdown)) {
cycles_left -= gb->apu.wave_channel.sample_countdown + 1;
gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length ^ 0x7FF;
gb->apu.wave_channel.current_sample_index++;
gb->apu.wave_channel.current_sample_index &= 0x1F;
gb->apu.wave_channel.current_sample =
gb->apu.wave_channel.wave_form[gb->apu.wave_channel.current_sample_index];
update_sample(gb, GB_WAVE,
gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift,
cycles - cycles_left);
gb->apu.wave_channel.wave_form_just_read = true;
}
if (cycles_left) {
gb->apu.wave_channel.sample_countdown -= cycles_left;
gb->apu.wave_channel.wave_form_just_read = false;
}
}
if (gb->apu.is_active[GB_NOISE]) {
uint8_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.noise_channel.sample_countdown)) {
cycles_left -= gb->apu.noise_channel.sample_countdown + 1;
gb->apu.noise_channel.sample_countdown = gb->apu.noise_channel.sample_length * 4 + 3;
/* Step LFSR */
unsigned high_bit_mask = gb->apu.noise_channel.narrow ? 0x4040 : 0x4000;
/* Todo: is this formula is different on a GBA? */
bool new_high_bit = (gb->apu.noise_channel.lfsr ^ (gb->apu.noise_channel.lfsr >> 1) ^ 1) & 1;
gb->apu.noise_channel.lfsr >>= 1;
if (new_high_bit) {
gb->apu.noise_channel.lfsr |= high_bit_mask;
if (gb->apu.square_sweep_calculate_countdown) {
if (gb->apu.square_sweep_calculate_countdown > cycles) {
gb->apu.square_sweep_calculate_countdown -= cycles;
}
else {
/* This code is not redundent, it's relevant when switching LFSR widths */
gb->apu.noise_channel.lfsr &= ~high_bit_mask;
/* APU bug: sweep frequency is checked after adding the sweep delta twice */
gb->apu.new_sweep_sample_legnth = new_sweep_sample_legnth(gb);
if (gb->apu.new_sweep_sample_legnth > 0x7ff) {
gb->apu.is_active[GB_SQUARE_1] = false;
update_sample(gb, GB_SQUARE_1, 0, gb->apu.square_sweep_calculate_countdown - cycles);
gb->apu.sweep_enabled = false;
}
gb->apu.sweep_decreasing |= gb->io_registers[GB_IO_NR10] & 8;
gb->apu.square_sweep_calculate_countdown = 0;
}
gb->apu.current_lfsr_sample = gb->apu.noise_channel.lfsr & 1;
if (gb->model == GB_MODEL_CGB_C) {
/* Todo: This was confirmed to happen on a CGB-C. This may or may not happen on pre-CGB models.
Because this degrades audio quality, and testing this on a pre-CGB device requires audio records,
I'll assume these devices are innocent until proven guilty.
Also happens on CGB-B, but not on CGB-D.
*/
gb->apu.current_lfsr_sample &= gb->apu.previous_lfsr_sample;
}
gb->apu.previous_lfsr_sample = gb->apu.noise_channel.lfsr & 1;
update_sample(gb, GB_NOISE,
gb->apu.current_lfsr_sample ?
gb->apu.noise_channel.current_volume : 0,
0);
}
if (cycles_left) {
gb->apu.noise_channel.sample_countdown -= cycles_left;
UNROLL
for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (gb->apu.is_active[i]) {
uint8_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.square_channels[i].sample_countdown)) {
cycles_left -= gb->apu.square_channels[i].sample_countdown + 1;
gb->apu.square_channels[i].sample_countdown = (gb->apu.square_channels[i].sample_length ^ 0x7FF) * 2 + 1;
gb->apu.square_channels[i].current_sample_index++;
gb->apu.square_channels[i].current_sample_index &= 0x7;
update_square_sample(gb, i);
}
if (cycles_left) {
gb->apu.square_channels[i].sample_countdown -= cycles_left;
}
}
}
gb->apu.wave_channel.wave_form_just_read = false;
if (gb->apu.is_active[GB_WAVE]) {
uint8_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.wave_channel.sample_countdown)) {
cycles_left -= gb->apu.wave_channel.sample_countdown + 1;
gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length ^ 0x7FF;
gb->apu.wave_channel.current_sample_index++;
gb->apu.wave_channel.current_sample_index &= 0x1F;
gb->apu.wave_channel.current_sample =
gb->apu.wave_channel.wave_form[gb->apu.wave_channel.current_sample_index];
update_sample(gb, GB_WAVE,
gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift,
cycles - cycles_left);
gb->apu.wave_channel.wave_form_just_read = true;
}
if (cycles_left) {
gb->apu.wave_channel.sample_countdown -= cycles_left;
gb->apu.wave_channel.wave_form_just_read = false;
}
}
if (gb->apu.is_active[GB_NOISE]) {
uint8_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.noise_channel.sample_countdown)) {
cycles_left -= gb->apu.noise_channel.sample_countdown + 1;
gb->apu.noise_channel.sample_countdown = gb->apu.noise_channel.sample_length * 4 + 3;
/* Step LFSR */
unsigned high_bit_mask = gb->apu.noise_channel.narrow ? 0x4040 : 0x4000;
/* Todo: is this formula is different on a GBA? */
bool new_high_bit = (gb->apu.noise_channel.lfsr ^ (gb->apu.noise_channel.lfsr >> 1) ^ 1) & 1;
gb->apu.noise_channel.lfsr >>= 1;
if (new_high_bit) {
gb->apu.noise_channel.lfsr |= high_bit_mask;
}
else {
/* This code is not redundent, it's relevant when switching LFSR widths */
gb->apu.noise_channel.lfsr &= ~high_bit_mask;
}
gb->apu.current_lfsr_sample = gb->apu.noise_channel.lfsr & 1;
if (gb->model == GB_MODEL_CGB_C) {
/* Todo: This was confirmed to happen on a CGB-C. This may or may not happen on pre-CGB models.
Because this degrades audio quality, and testing this on a pre-CGB device requires audio records,
I'll assume these devices are innocent until proven guilty.
Also happens on CGB-B, but not on CGB-D.
*/
gb->apu.current_lfsr_sample &= gb->apu.previous_lfsr_sample;
}
gb->apu.previous_lfsr_sample = gb->apu.noise_channel.lfsr & 1;
update_sample(gb, GB_NOISE,
gb->apu.current_lfsr_sample ?
gb->apu.noise_channel.current_volume : 0,
0);
}
if (cycles_left) {
gb->apu.noise_channel.sample_countdown -= cycles_left;
}
}
}

15
Core/display.c
View File

@ -137,13 +137,13 @@ static void display_vblank(GB_gameboy_t *gb)
if (!gb->disable_rendering && ((!(gb->io_registers[GB_IO_LCDC] & 0x80) || gb->stopped) || gb->frame_skip_state == GB_FRAMESKIP_LCD_TURNED_ON)) {
/* LCD is off, set screen to white or black (if LCD is on in stop mode) */
if (gb->sgb) {
uint8_t color = (gb->io_registers[GB_IO_LCDC] & 0x80) && gb->stopped ? 0x3 : 0x0;
uint8_t color = (gb->io_registers[GB_IO_LCDC] & 0x80) && gb->stopped && GB_is_cgb(gb) ? 0x3 : 0x0;
for (unsigned i = 0; i < WIDTH * LINES; i++) {
gb->sgb->screen_buffer[i] = color;
}
}
else {
uint32_t color = (gb->io_registers[GB_IO_LCDC] & 0x80) && gb->stopped ?
uint32_t color = (gb->io_registers[GB_IO_LCDC] & 0x80) && gb->stopped && GB_is_cgb(gb) ?
gb->rgb_encode_callback(gb, 0, 0, 0) :
gb->rgb_encode_callback(gb, 0xFF, 0xFF, 0xFF);
for (unsigned i = 0; i < WIDTH * LINES; i++) {
@ -555,6 +555,15 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb)
*/
void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
{
/* The PPU does not advance while in STOP mode on the DMG */
if (gb->stopped && !GB_is_cgb(gb)) {
gb->cycles_in_stop_mode += cycles;
if (gb->cycles_in_stop_mode >= LCDC_PERIOD) {
gb->cycles_in_stop_mode -= LCDC_PERIOD;
display_vblank(gb);
}
return;
}
GB_object_t *objects = (GB_object_t *) &gb->oam;
GB_STATE_MACHINE(gb, display, cycles, 2) {
@ -696,7 +705,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
for (gb->oam_search_index = 0; gb->oam_search_index < 40; gb->oam_search_index++) {
if (GB_is_cgb(gb)) {
add_object_from_index(gb, gb->oam_search_index);
/* The CGB does not care about the accessed OAM row as there's no OAM bug*/
/* The CGB does not care about the accessed OAM row as there's no OAM bug */
}
GB_SLEEP(gb, display, 8, 2);
if (!GB_is_cgb(gb)) {

1
Core/gb.h
View File

@ -478,6 +478,7 @@ struct GB_gameboy_internal_s {
bool lyc_interrupt_line;
bool cgb_palettes_blocked;
uint8_t current_lcd_line; // The LCD can go out of sync since the vsync signal is skipped in some cases.
uint32_t cycles_in_stop_mode;
);
/* Unsaved data. This includes all pointers, as well as everything that shouldn't be on a save state */

1
Core/joypad.c
View File

@ -56,7 +56,6 @@ void GB_update_joyp(GB_gameboy_t *gb)
if (previous_state != (gb->io_registers[GB_IO_JOYP] & 0xF)) {
/* The joypad interrupt DOES occur on CGB (Tested on CGB-CPU-06), unlike what some documents say. */
gb->io_registers[GB_IO_IF] |= 0x10;
gb->stopped = false;
}
gb->io_registers[GB_IO_JOYP] |= 0xC0;

20
Core/sm83_cpu.c
View File

@ -234,7 +234,15 @@ static void stop(GB_gameboy_t *gb, uint8_t opcode)
}
else {
gb->stopped = true;
if ((gb->io_registers[GB_IO_JOYP] & 0xF) != 0xF) {
/* HW Bug? When STOP is executed while a button is down, the CPU halts forever
yet the other hardware keeps running. */
gb->interrupt_enable = 0;
gb->halted = true;
}
else {
gb->stopped = true;
}
}
/* Todo: is PC being actually read? */
@ -1389,7 +1397,15 @@ void GB_cpu_run(GB_gameboy_t *gb)
return;
}
if (gb->stopped) {
GB_advance_cycles(gb, 64);
GB_advance_cycles(gb, 4);
if ((gb->io_registers[GB_IO_JOYP] & 0xF) != 0xF) {
gb->stopped = false;
/* The CPU takes more time to wake up then the other components */
for (unsigned i = 0x800; i--;) {
GB_advance_cycles(gb, 0x40);
}
GB_advance_cycles(gb, 8);
}
return;
}

12
Core/timing.c
View File

@ -210,8 +210,10 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
// Affected by speed boost
gb->dma_cycles += cycles;
GB_timers_run(gb, cycles);
advance_serial(gb, cycles);
if (!gb->stopped) {
GB_timers_run(gb, cycles);
advance_serial(gb, cycles); // TODO: Verify what happens in STOP mode
}
gb->debugger_ticks += cycles;
@ -227,8 +229,10 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
gb->cycles_since_input_ir_change += cycles;
gb->cycles_since_last_sync += cycles;
gb->cycles_since_run += cycles;
GB_dma_run(gb);
GB_hdma_run(gb);
if (!gb->stopped) { // TODO: Verify what happens in STOP mode
GB_dma_run(gb);
GB_hdma_run(gb);
}
GB_apu_run(gb);
GB_display_run(gb, cycles);
GB_ir_run(gb);