_IOC_SIZEMASK
#define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
#define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
#define EVIOC_MASK_SIZE(nr) ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
#define INFO_FL_CLEAR_MASK (_IOC_SIZEMASK << 16)
cmd &= ~(_IOC_SIZEMASK << _IOC_SIZESHIFT);
#define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
#define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)