prepare for fix

src/engine/platform/sound/gb/gb.h

@@ -9,6 +9,7 @@
 #include "gb_struct_def.h"
 
 #include "apu.h"
+#include "timing.h"
 
 #define GB_STRUCT_VERSION 13
 

src/engine/platform/sound/gb/timing.c

@@ -0,0 +1,407 @@
+#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 * 1200000000LL / GB_get_clock_rate(gb)) { // +20% to be more forgiving
+        nsleep(time_to_sleep);
+        gb->last_sync += target_nanoseconds;
+    }
+    else {
+        if (time_to_sleep < 0 && -time_to_sleep < LCDC_PERIOD * 1200000000LL / GB_get_clock_rate(gb)) {
+            // We're running a bit too slow, but the difference is small enough,
+            // just skip this sync and let it even out
+            return;
+        }
+        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
+
+#define IR_DECAY 31500
+#define IR_THRESHOLD 19900
+#define IR_MAX IR_THRESHOLD * 2 + IR_DECAY
+
+static void GB_ir_run(GB_gameboy_t *gb, uint32_t cycles)
+{
+    if (gb->model == GB_MODEL_AGB) return;
+    if (gb->infrared_input || gb->cart_ir || (gb->io_registers[GB_IO_RP] & 1)) {
+        gb->ir_sensor += cycles;
+        if (gb->ir_sensor > IR_MAX) {
+            gb->ir_sensor = IR_MAX;
+        }
+        
+        gb->effective_ir_input = gb->ir_sensor >= IR_THRESHOLD && gb->ir_sensor <= IR_THRESHOLD + IR_DECAY;
+    }
+    else {
+        if (gb->ir_sensor <= cycles) {
+            gb->ir_sensor = 0;
+        }
+        else {
+            gb->ir_sensor -= cycles;
+        }
+        gb->effective_ir_input = false;
+    }
+    
+}
+
+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, uint16_t value)
+{
+    /* TIMA increases when a specific high-bit becomes a low-bit. */
+    value &= INTERNAL_DIV_CYCLES - 1;
+    uint16_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? */
+    uint16_t apu_bit = gb->cgb_double_speed? 0x2000 : 0x1000;
+    if (triggers & apu_bit) {
+        GB_apu_run(gb);
+        GB_apu_div_event(gb);
+    }
+    else {
+        uint16_t secondary_triggers = ~gb->div_counter & value;
+        if (secondary_triggers & apu_bit) {
+            GB_apu_run(gb);
+            GB_apu_div_secondary_event(gb);
+        }
+    }
+    gb->div_counter = value;
+}
+
+static void GB_timers_run(GB_gameboy_t *gb, uint8_t cycles)
+{
+    if (gb->stopped) {
+        if (GB_is_cgb(gb)) {
+            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->printer.command_state || gb->printer.bits_received) {
+        gb->printer.idle_time += 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;
+    
+}
+
+static void GB_rtc_run(GB_gameboy_t *gb, uint8_t cycles)
+{
+    if (gb->cartridge_type->mbc_type != GB_HUC3 && !gb->cartridge_type->has_rtc) return;
+    gb->rtc_cycles += cycles;
+    time_t current_time = 0;
+    
+    switch (gb->rtc_mode) {
+        case GB_RTC_MODE_SYNC_TO_HOST:
+            // Sync in a 1/32s resolution
+            if (gb->rtc_cycles < GB_get_unmultiplied_clock_rate(gb) / 16) return;
+            gb->rtc_cycles -= GB_get_unmultiplied_clock_rate(gb) / 16;
+            current_time = time(NULL);
+            break;
+        case GB_RTC_MODE_ACCURATE:
+            if (gb->cartridge_type->mbc_type != GB_HUC3 && (gb->rtc_real.high & 0x40)) {
+                gb->rtc_cycles -= cycles;
+                return;
+            }
+            if (gb->rtc_cycles < GB_get_unmultiplied_clock_rate(gb) * 2) return;
+            gb->rtc_cycles -= GB_get_unmultiplied_clock_rate(gb) * 2;
+            current_time = gb->last_rtc_second + 1;
+            break;
+    }
+
+    if (gb->cartridge_type->mbc_type == GB_HUC3) {
+        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;
+    }
+    bool running = false;
+    if (gb->cartridge_type->mbc_type == GB_TPP1) {
+        running = gb->tpp1_mr4 & 0x4;
+    }
+    else {
+        running = (gb->rtc_real.high & 0x40) == 0;
+    }
+    
+    if (running) { /* is timer running? */
+        while (gb->last_rtc_second + 60 * 60 * 24 < current_time) {
+            gb->last_rtc_second += 60 * 60 * 24;
+            if (gb->cartridge_type->mbc_type == GB_TPP1) {
+                if (++gb->rtc_real.tpp1.weekday == 7) {
+                    gb->rtc_real.tpp1.weekday = 0;
+                    if (++gb->rtc_real.tpp1.weeks == 0) {
+                        gb->tpp1_mr4 |= 8; /* Overflow bit */
+                    }
+                }
+            }
+            else 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;
+            }
+        }
+        
+        while (gb->last_rtc_second < current_time) {
+            gb->last_rtc_second++;
+            if (++gb->rtc_real.seconds != 60) continue;
+            gb->rtc_real.seconds = 0;
+            
+            if (++gb->rtc_real.minutes != 60) continue;
+            gb->rtc_real.minutes = 0;
+            
+            if (gb->cartridge_type->mbc_type == GB_TPP1) {
+                if (++gb->rtc_real.tpp1.hours != 24) continue;
+                gb->rtc_real.tpp1.hours = 0;
+                if (++gb->rtc_real.tpp1.weekday != 7) continue;
+                gb->rtc_real.tpp1.weekday = 0;
+                if (++gb->rtc_real.tpp1.weeks == 0) {
+                    gb->tpp1_mr4 |= 8; /* Overflow bit */
+                }
+            }
+            else {
+                if (++gb->rtc_real.hours != 24) continue;
+                gb->rtc_real.hours = 0;
+                
+                if (++gb->rtc_real.days != 0) continue;
+                
+                if (gb->rtc_real.high & 1) { /* Bit 8 of days*/
+                    gb->rtc_real.high |= 0x80; /* Overflow bit */
+                }
+                
+                gb->rtc_real.high ^= 1;
+            }
+        }
+    }
+}
+
+
+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
+    if (gb->io_registers[GB_IO_LCDC] & 0x80) {
+        gb->double_speed_alignment += cycles;
+    }
+    gb->hdma_cycles += cycles;
+    gb->apu_output.sample_cycles += cycles;
+    gb->cycles_since_last_sync += cycles;
+    gb->cycles_since_run += cycles;
+    
+    gb->rumble_on_cycles += gb->rumble_strength & 3;
+    gb->rumble_off_cycles += (gb->rumble_strength & 3) ^ 3;
+        
+    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, cycles);
+    GB_rtc_run(gb, cycles);
+}
+
+/* 
+   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);
+        }
+    }
+}

src/engine/platform/sound/gb/timing.h

@@ -0,0 +1,40 @@
+#ifndef timing_h
+#define timing_h
+#include "gb_struct_def.h"
+
+#ifdef GB_INTERNAL
+void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles);
+void GB_emulate_timer_glitch(GB_gameboy_t *gb, uint8_t old_tac, uint8_t new_tac);
+bool GB_timing_sync_turbo(GB_gameboy_t *gb); /* Returns true if should skip frame */
+void GB_timing_sync(GB_gameboy_t *gb);
+
+enum {
+    GB_TIMA_RUNNING = 0,
+    GB_TIMA_RELOADING = 1,
+    GB_TIMA_RELOADED = 2
+};
+
+
+#define GB_SLEEP(gb, unit, state, cycles) do {\
+    (gb)->unit##_cycles -= (cycles) * __state_machine_divisor; \
+    if ((gb)->unit##_cycles <= 0) {\
+        (gb)->unit##_state = state;\
+        return;\
+        unit##state:; \
+    }\
+} while (0)
+
+#define GB_STATE_MACHINE(gb, unit, cycles, divisor) \
+static const int __state_machine_divisor = divisor;\
+(gb)->unit##_cycles += cycles; \
+if ((gb)->unit##_cycles <= 0) {\
+    return;\
+}\
+switch ((gb)->unit##_state)
+#endif
+
+#define GB_STATE(gb, unit, state) case state: goto unit##state
+
+#define GB_UNIT(unit) int32_t unit##_cycles, unit##_state
+
+#endif /* timing_h */