/**
* Opcode #0x76.
*
* HALT
*
* @param \GameBoy\Core $core
* @throws Exception
*/
public static function opcode118(Core $core)
{
if ($core->untilEnable == 1) {
/*VBA-M says this fixes Torpedo Range (Seems to work):
Involves an edge case where an EI is placed right before a HALT.
EI in this case actually is immediate, so we adjust (Hacky?).*/
$core->programCounter = $core->nswtuw($core->programCounter - 1);
} else {
if (!$core->halt && !$core->IME && !$core->cGBC && ($core->memory[0xff0f] & $core->memory[0xffff] & 0x1f) > 0) {
$core->skipPCIncrement = true;
}
$core->halt = true;
while ($core->halt && ($core->stopEmulator & 1) === 0) {
/*We're hijacking the main interpreter loop to do this dirty business
in order to not slow down the main interpreter loop code with halt state handling.*/
$bitShift = 0;
$testbit = 1;
$interrupts = $core->memory[0xffff] & $core->memory[0xff0f];
while ($bitShift < 5) {
//Check to see if an interrupt is enabled AND requested.
if (($testbit & $interrupts) === $testbit) {
$core->halt = false;
//Get out of halt state if in halt state.
return;
//Let the main interrupt handler compute the interrupt.
}
$testbit = 1 << ++$bitShift;
}
$core->CPUTicks = 1;
//1 machine cycle under HALT...
//Timing:
$core->updateCore();
}
//Throw an error on purpose to exit out of the loop.
throw new Exception('HALT_OVERRUN');
}
}
