static INLINE u8 memread(u32 addr)
{
static int n;
//handle dpcm cycle stealing
if(nes->cpu.pcmcycles) {
n = nes->cpu.pcmcycles - 1;
nes->cpu.pcmcycles = 0;
if(addr == 0x4016 || addr == 0x4017) {
if(n--)
memread(addr);
while(n--)
cpu_tick();
}
else {
while(n--)
memread(addr);
}
apu_dpcm_fetch();
}
//increment cycle counter, check irq lines
cpu_tick();
//read data from address
return(cpu_read(addr));
}
static INLINE void memwrite(u32 addr,u8 data)
{
//handle dpcm cycle stealing
if(nes->cpu.pcmcycles)
nes->cpu.pcmcycles--;
//increment cycle counter, check irq lines
cpu_tick();
//write data to its address
cpu_write(addr,data);
}
static void track_free(void* p, size_t size)
{
track_init();
assert(!track.internal);
track.internal = true;
track.stack = pool_track_push(track.stack, POOL_TRACK_FREE);
track.stack = pool_track_push(track.stack, p);
track.stack = pool_track_push(track.stack, (void*)size);
track.stack = pool_track_push(track.stack, (void*)cpu_tick());
track.internal = false;
}
static void track_alloc(void* p, size_t size)
{
track_init();
if(track.internal)
return;
track.internal = true;
track.stack = pool_track_push(track.stack, POOL_TRACK_ALLOC);
track.stack = pool_track_push(track.stack, p);
track.stack = pool_track_push(track.stack, (void*)size);
track.stack = pool_track_push(track.stack, (void*)cpu_tick());
track.internal = false;
}
/**
* Executes a single step
*
* @param emu Reference to the emulator structure
*/
void
emulator_tick(emulator_t* emu)
{
cpu_tick(&emu->cpu);
/* When graphics are emulated, we execute a screen refresh after 34ms has
* passed (30 frames per second) */
uint32_t frame_time = 20;
if (emu->graphics)
{
uint64_t now = emulator_get_time();
if ((now - emu->last_refresh) > frame_time)
{
fb_tick(&emu->fb);
emu->last_refresh = now;
}
}
}
static void track_pull(pool_item_t* p, size_t length, size_t size)
{
track_init();
assert(!track.internal);
track.internal = true;
uint64_t tsc = cpu_tick();
track.stack = pool_track_push(track.stack, POOL_TRACK_PULL_LIST);
track.stack = pool_track_push(track.stack, (void*)length);
track.stack = pool_track_push(track.stack, (void*)size);
track.stack = pool_track_push(track.stack, (void*)tsc);
while(p != NULL)
{
track.stack = pool_track_push(track.stack, POOL_TRACK_PULL);
track.stack = pool_track_push(track.stack, p);
track.stack = pool_track_push(track.stack, (void*)size);
track.stack = pool_track_push(track.stack, (void*)tsc);
p = p->next;
}
track.internal = false;
}
int gb_tick(gb_t *gb)
{
update_joypad(gb);
if (!cpu_tick(gb))
return 0;
if (!lcd_tick(gb))
return 0;
if (++gb->ticks == TICKS_MAX)
{
ERR("Game Over");
return 0;
}
// DMA
if (gb->mem[IO_DMA] != 0xFF)
{
// XXX instant DMA?
memcpy(&gb->mem[0xFE00], &gb->mem[gb->mem[IO_DMA] << 8], 0xA0);
gb->mem[IO_DMA] = 0xFF;
}
if (++gb->ticks_divider == TICKS_DIVIDER)
{
gb->mem[IO_DIV]++;
gb->ticks_divider = 0;
}
if (gb->mem[IO_TAC] & (1 << 2))
{
// timer ON
unsigned int total_ticks;
switch(gb->mem[IO_TAC] & 3)
{
case 0:
total_ticks = 244;
break;
case 1:
total_ticks = 4;
break;
case 2:
total_ticks = 15;
break;
case 3:
total_ticks = 61;
break;
}
if (++gb->ticks_timer >= total_ticks)
{
gb->ticks_timer = 0;
if (gb->mem[IO_TIMA]++ == 0xFF)
{
//overflow
gb->mem[IO_TIMA] = gb->mem[IO_TMA];
cpu_interrupt(gb, 2);
}
}
}
return 1;
}