GameBoy\Cbopcode::cbopcode20 PHP Method

    private static function cbopcode20(Core $core)
    {
        $newFCarry = ($core->registersHL & 0x8000) == 0x8000;
        $core->registersHL = ($core->registersHL << 1 & 0xfe00) + ($core->FCarry ? 0x100 : 0) + ($core->registersHL & 0xff);
        $core->FCarry = $newFCarry;
        $core->FHalfCarry = $core->FSubtract = false;
        $core->FZero = $core->registersHL <= 0xff;
    }