Constant nc::types::IOC_NRBITS

pub const IOC_NRBITS: i32

ioctl command encoding: 32 bits total, command in lower 16 bits, size of the parameter structure in the lower 14 bits of the upper 16 bits. Encoding the size of the parameter structure in the ioctl request is useful for catching programs compiled with old versions and to avoid overwriting user space outside the user buffer area. The highest 2 bits are reserved for indicating the ``access mode''. NOTE: This limits the max parameter size to 16kB -1 ! The following is for compatibility across the various Linux platforms. The generic ioctl numbering scheme doesn't really enforce a type field. De facto, however, the top 8 bits of the lower 16 bits are indeed used as a type field, so we might just as well make this explicit here. Please be sure to use the decoding macros below from now on.