_IOC_TYPEBITS      39 include/asm-generic/ioctl.h #define _IOC_TYPEMASK	((1 << _IOC_TYPEBITS)-1)
_IOC_TYPEBITS      45 include/asm-generic/ioctl.h #define _IOC_SIZESHIFT	(_IOC_TYPESHIFT+_IOC_TYPEBITS)