/// <summary>
/// this is what causes the whole thing to run.
/// </summary>
public static void step()
{
// interrupt master flag enabled
// and MMU interrupt enabled && MM interrupt flag
if (Z80._r.ime && MMU._ie != 0 && MMU._if != 0)
{
// don't halt, disable master interrupt flag
Z80._halt = false; Z80._r.ime = false;
// if interrupt enable bit 1 set and interrupt flag 1 set
if (((MMU._ie & 1) != 0) && ((MMU._if & 1) != 0))
{
// clear interrupt flag 1, trigger reset to 0x40
MMU._if &= 0xFE; Z80._ops.RST40();
}
}
else
{
// halted - do nothing
if (Z80._halt)
{
Z80._r.m = 1;
}
else
{
Z80._r.r = (Z80._r.r + 1) & 127;
Z80._map[MMU.rb(Z80._r.pc++)]();
// wrap PC to 16 bits
//Z80._r.pc &= 0xFF; // handled in PC setter
}
}
Z80._clock.m += Z80._r.m; Z80._clock.t += (Z80._r.m * 4);
GPU.checkline();
if (Z80._stop)
{
pause();
}
//dbgupdate();
}
public static void frame()
{
// a frame takes 17556 clock cycles to render. we're stuck here until it's complete.
var fclock = Z80._clock.m + 17556;
//var brk = document.getElementById('breakpoint').value;
//var t0 = new Date();
do
{
// if halted, do nothing and increment m
if (Z80._halt)
{
Z80._r.m = 1;
}
else
{
// Z80._r.r = (Z80._r.r+1) & 127;
// increment and execute PC
Z80._map[MMU.rb(Z80._r.pc++)]();
// wrap PC to 16 bits - now handled in PC setter
//Z80._r.pc &= 65535;
}
// if interrupt master enabled and any interrupts enabled and any interrupts triggered
if (Z80._r.ime && MMU._ie != 0 && MMU._if != 0)
{
// disable interrupts
Z80._halt = false; Z80._r.ime = false;
// get fired interrupts that are enabled
var ifired = MMU._ie & MMU._if;
// interrupts get triggered according to priority (see page 40)
if ((ifired & (1 << 0)) != 0)
{
MMU._if &= 0xFE; Z80._ops.RST40();
} // V-Blank
else if ((ifired & (1 << 1)) != 0)
{
MMU._if &= 0xFD; Z80._ops.RST48();
} // LCDC (see STAT)
else if ((ifired & (1 << 2)) != 0)
{
MMU._if &= 0xFB; Z80._ops.RST50();
} // Timer Overflow
else if ((ifired & (1 << 3)) != 0)
{
MMU._if &= 0xF7; Z80._ops.RST58();
} // Serial I/O Complete
else if ((ifired & (1 << 4)) != 0)
{
MMU._if &= 0xEF; Z80._ops.RST60();
} // P10-P13 transition H => L
else
{
Z80._r.ime = true;
} // otherwise, re-enable IME
}
//jsGB.dbgtrace();
Z80._clock.m += Z80._r.m;
GPU.checkline();
TIMER.inc();
//if ((brk && parseInt(brk, 16) == Z80._r.pc) || Z80._stop)
//{
// jsGB.pause();
// break;
//}
} while (Z80._clock.m < fclock);
//var t1 = new Date();
//document.getElementById('fps').innerHTML = Math.round(10000 / (t1 - t0)) / 10;
}