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bsnes/Core/timing.c

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#include "gb.h"
#ifdef _WIN32
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0500
#endif
#include <windows.h>
#else
#include <sys/time.h>
#endif
static const unsigned GB_TAC_TRIGGER_BITS[] = {512, 8, 32, 128};
#ifndef GB_DISABLE_TIMEKEEPING
static int64_t get_nanoseconds(void)
{
#ifndef _WIN32
struct timeval now;
gettimeofday(&now, NULL);
return (now.tv_usec) * 1000 + now.tv_sec * 1000000000L;
#else
FILETIME time;
GetSystemTimeAsFileTime(&time);
return (((int64_t)time.dwHighDateTime << 32) | time.dwLowDateTime) * 100L;
#endif
}
static void nsleep(uint64_t nanoseconds)
{
#ifndef _WIN32
struct timespec sleep = {0, nanoseconds};
nanosleep(&sleep, NULL);
#else
HANDLE timer;
LARGE_INTEGER time;
timer = CreateWaitableTimer(NULL, true, NULL);
time.QuadPart = -(nanoseconds / 100L);
SetWaitableTimer(timer, &time, 0, NULL, NULL, false);
WaitForSingleObject(timer, INFINITE);
CloseHandle(timer);
#endif
}
bool GB_timing_sync_turbo(GB_gameboy_t *gb)
{
if (!gb->turbo_dont_skip) {
int64_t nanoseconds = get_nanoseconds();
if (nanoseconds <= gb->last_sync + (1000000000LL * LCDC_PERIOD / GB_get_clock_rate(gb))) {
return true;
}
gb->last_sync = nanoseconds;
}
return false;
}
void GB_timing_sync(GB_gameboy_t *gb)
{
if (gb->turbo) {
gb->cycles_since_last_sync = 0;
return;
}
/* Prevent syncing if not enough time has passed.*/
if (gb->cycles_since_last_sync < LCDC_PERIOD / 3) return;
uint64_t target_nanoseconds = gb->cycles_since_last_sync * 1000000000LL / 2 / GB_get_clock_rate(gb); /* / 2 because we use 8MHz units */
int64_t nanoseconds = get_nanoseconds();
int64_t time_to_sleep = target_nanoseconds + gb->last_sync - nanoseconds;
if (time_to_sleep > 0 && time_to_sleep < LCDC_PERIOD * 1000000000LL / GB_get_clock_rate(gb)) {
nsleep(time_to_sleep);
gb->last_sync += target_nanoseconds;
}
else {
gb->last_sync = nanoseconds;
}
gb->cycles_since_last_sync = 0;
if (gb->update_input_hint_callback) {
gb->update_input_hint_callback(gb);
}
}
#else
bool GB_timing_sync_turbo(GB_gameboy_t *gb)
{
return false;
}
void GB_timing_sync(GB_gameboy_t *gb)
{
}
#endif
static void GB_ir_run(GB_gameboy_t *gb)
{
if (gb->ir_queue_length == 0) return;
if (gb->cycles_since_input_ir_change >= gb->ir_queue[0].delay) {
gb->cycles_since_input_ir_change -= gb->ir_queue[0].delay;
gb->infrared_input = gb->ir_queue[0].state;
gb->ir_queue_length--;
memmove(&gb->ir_queue[0], &gb->ir_queue[1], sizeof(gb->ir_queue[0]) * (gb->ir_queue_length));
}
}
static void advance_tima_state_machine(GB_gameboy_t *gb)
{
if (gb->tima_reload_state == GB_TIMA_RELOADED) {
gb->tima_reload_state = GB_TIMA_RUNNING;
}
else if (gb->tima_reload_state == GB_TIMA_RELOADING) {
gb->io_registers[GB_IO_IF] |= 4;
gb->tima_reload_state = GB_TIMA_RELOADED;
}
}
static void increase_tima(GB_gameboy_t *gb)
{
gb->io_registers[GB_IO_TIMA]++;
if (gb->io_registers[GB_IO_TIMA] == 0) {
gb->io_registers[GB_IO_TIMA] = gb->io_registers[GB_IO_TMA];
gb->tima_reload_state = GB_TIMA_RELOADING;
}
}
static void GB_set_internal_div_counter(GB_gameboy_t *gb, uint32_t value)
{
/* TIMA increases when a specific high-bit becomes a low-bit. */
value &= INTERNAL_DIV_CYCLES - 1;
uint32_t triggers = gb->div_counter & ~value;
if ((gb->io_registers[GB_IO_TAC] & 4) && (triggers & GB_TAC_TRIGGER_BITS[gb->io_registers[GB_IO_TAC] & 3])) {
increase_tima(gb);
}
/* TODO: Can switching to double speed mode trigger an event? */
if (triggers & (gb->cgb_double_speed? 0x2000 : 0x1000)) {
GB_apu_run(gb);
GB_apu_div_event(gb);
}
gb->div_counter = value;
}
static void GB_timers_run(GB_gameboy_t *gb, uint8_t cycles)
{
if (gb->stopped) {
gb->apu.apu_cycles += 4 << !gb->cgb_double_speed;
return;
}
GB_STATE_MACHINE(gb, div, cycles, 1) {
GB_STATE(gb, div, 1);
GB_STATE(gb, div, 2);
GB_STATE(gb, div, 3);
}
GB_set_internal_div_counter(gb, 0);
main:
GB_SLEEP(gb, div, 1, 3);
while (true) {
advance_tima_state_machine(gb);
GB_set_internal_div_counter(gb, gb->div_counter + 4);
gb->apu.apu_cycles += 4 << !gb->cgb_double_speed;
GB_SLEEP(gb, div, 2, 4);
}
/* Todo: This is ugly to allow compatibility with 0.11 save states. Fix me when breaking save compatibility */
{
div3:
/* Compensate for lack of prefetch emulation, as well as DIV's internal initial value */
GB_set_internal_div_counter(gb, 8);
goto main;
}
}
static void advance_serial(GB_gameboy_t *gb, uint8_t cycles)
{
if (gb->serial_length == 0) {
gb->serial_cycles += cycles;
return;
}
while (cycles > gb->serial_length) {
advance_serial(gb, gb->serial_length);
cycles -= gb->serial_length;
}
uint16_t previous_serial_cycles = gb->serial_cycles;
gb->serial_cycles += cycles;
if ((gb->serial_cycles & gb->serial_length) != (previous_serial_cycles & gb->serial_length)) {
gb->serial_count++;
if (gb->serial_count == 8) {
gb->serial_length = 0;
gb->serial_count = 0;
gb->io_registers[GB_IO_SC] &= ~0x80;
gb->io_registers[GB_IO_IF] |= 8;
}
gb->io_registers[GB_IO_SB] <<= 1;
if (gb->serial_transfer_bit_end_callback) {
gb->io_registers[GB_IO_SB] |= gb->serial_transfer_bit_end_callback(gb);
}
else {
gb->io_registers[GB_IO_SB] |= 1;
}
if (gb->serial_length) {
/* Still more bits to send */
if (gb->serial_transfer_bit_start_callback) {
gb->serial_transfer_bit_start_callback(gb, gb->io_registers[GB_IO_SB] & 0x80);
}
}
}
return;
}
void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
{
gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF; // Sort of hacky, but too many cross-component interactions to do it right
// Affected by speed boost
gb->dma_cycles += cycles;
GB_timers_run(gb, cycles);
if (!gb->stopped) {
advance_serial(gb, cycles); // TODO: Verify what happens in STOP mode
}
gb->debugger_ticks += cycles;
if (!gb->cgb_double_speed) {
cycles <<= 1;
}
// Not affected by speed boost
gb->double_speed_alignment += cycles;
gb->hdma_cycles += cycles;
gb->apu_output.sample_cycles += cycles;
gb->cycles_since_ir_change += cycles;
gb->cycles_since_input_ir_change += cycles;
gb->cycles_since_last_sync += cycles;
gb->cycles_since_run += cycles;
if (gb->rumble_state) {
gb->rumble_on_cycles++;
}
else {
gb->rumble_off_cycles++;
}
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);
}
/*
This glitch is based on the expected results of mooneye-gb rapid_toggle test.
This glitch happens because how TIMA is increased, see GB_set_internal_div_counter.
According to GiiBiiAdvance, GBC's behavior is different, but this was not tested or implemented.
*/
void GB_emulate_timer_glitch(GB_gameboy_t *gb, uint8_t old_tac, uint8_t new_tac)
{
/* Glitch only happens when old_tac is enabled. */
if (!(old_tac & 4)) return;
unsigned old_clocks = GB_TAC_TRIGGER_BITS[old_tac & 3];
unsigned new_clocks = GB_TAC_TRIGGER_BITS[new_tac & 3];
/* The bit used for overflow testing must have been 1 */
if (gb->div_counter & old_clocks) {
/* And now either the timer must be disabled, or the new bit used for overflow testing be 0. */
if (!(new_tac & 4) || gb->div_counter & new_clocks) {
increase_tima(gb);
}
}
}
void GB_rtc_run(GB_gameboy_t *gb)
{
if (gb->cartridge_type->mbc_type == GB_HUC3) {
time_t current_time = time(NULL);
while (gb->last_rtc_second / 60 < current_time / 60) {
gb->last_rtc_second += 60;
gb->huc3_minutes++;
if (gb->huc3_minutes == 60 * 24) {
gb->huc3_days++;
gb->huc3_minutes = 0;
}
}
return;
}
if ((gb->rtc_real.high & 0x40) == 0) { /* is timer running? */
time_t current_time = time(NULL);
while (gb->last_rtc_second < current_time) {
gb->last_rtc_second++;
if (++gb->rtc_real.seconds == 60) {
gb->rtc_real.seconds = 0;
if (++gb->rtc_real.minutes == 60) {
gb->rtc_real.minutes = 0;
if (++gb->rtc_real.hours == 24) {
gb->rtc_real.hours = 0;
if (++gb->rtc_real.days == 0) {
if (gb->rtc_real.high & 1) { /* Bit 8 of days*/
gb->rtc_real.high |= 0x80; /* Overflow bit */
}
gb->rtc_real.high ^= 1;
}
}
}
}
}
}
}
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