mirror of https://github.com/bsnes-emu/bsnes.git
288 lines
8.3 KiB
C
288 lines
8.3 KiB
C
#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 int GB_TAC_TRIGGER_BITS[] = {512, 8, 32, 128};
|
|
|
|
#ifndef 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 / 4) 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;
|
|
}
|
|
#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)
|
|
{
|
|
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)
|
|
{
|
|
// Affected by speed boost
|
|
gb->dma_cycles += cycles;
|
|
|
|
GB_timers_run(gb, cycles);
|
|
advance_serial(gb, cycles);
|
|
|
|
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;
|
|
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 int old_clocks = GB_TAC_TRIGGER_BITS[old_tac & 3];
|
|
unsigned int 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->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;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|