FreeBSD/Linux Kernel Cross Reference
sys/include/asm-i386/ioctl.h

     /* $Id: ioctl.h,v 1.5 1993/07/19 21:53:50 root Exp root $
      *
      * linux/ioctl.h for Linux by H.H. Bergman.
      */
     
     #ifndef _ASMI386_IOCTL_H
     #define _ASMI386_IOCTL_H
     
     /* 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 i386 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.
     */
    #define _IOC_NRBITS     8
    #define _IOC_TYPEBITS   8
    #define _IOC_SIZEBITS   14
    #define _IOC_DIRBITS    2
    
    #define _IOC_NRMASK     ((1 << _IOC_NRBITS)-1)
    #define _IOC_TYPEMASK   ((1 << _IOC_TYPEBITS)-1)
    #define _IOC_SIZEMASK   ((1 << _IOC_SIZEBITS)-1)
    #define _IOC_DIRMASK    ((1 << _IOC_DIRBITS)-1)
    
    #define _IOC_NRSHIFT    0
    #define _IOC_TYPESHIFT  (_IOC_NRSHIFT+_IOC_NRBITS)
    #define _IOC_SIZESHIFT  (_IOC_TYPESHIFT+_IOC_TYPEBITS)
    #define _IOC_DIRSHIFT   (_IOC_SIZESHIFT+_IOC_SIZEBITS)
    
    /*
     * Direction bits.
     */
    #define _IOC_NONE       0U
    #define _IOC_WRITE      1U
    #define _IOC_READ       2U
    
    #define _IOC(dir,type,nr,size) \
            (((dir)  << _IOC_DIRSHIFT) | \
             ((type) << _IOC_TYPESHIFT) | \
             ((nr)   << _IOC_NRSHIFT) | \
             ((size) << _IOC_SIZESHIFT))
    
    /* used to create numbers */
    #define _IO(type,nr)            _IOC(_IOC_NONE,(type),(nr),0)
    #define _IOR(type,nr,size)      _IOC(_IOC_READ,(type),(nr),sizeof(size))
    #define _IOW(type,nr,size)      _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
    #define _IOWR(type,nr,size)     _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
    
    /* used to decode ioctl numbers.. */
    #define _IOC_DIR(nr)            (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
    #define _IOC_TYPE(nr)           (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
    #define _IOC_NR(nr)             (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
    #define _IOC_SIZE(nr)           (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
    
    /* ...and for the drivers/sound files... */
    
    #define IOC_IN          (_IOC_WRITE << _IOC_DIRSHIFT)
    #define IOC_OUT         (_IOC_READ << _IOC_DIRSHIFT)
    #define IOC_INOUT       ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
    #define IOCSIZE_MASK    (_IOC_SIZEMASK << _IOC_SIZESHIFT)
    #define IOCSIZE_SHIFT   (_IOC_SIZESHIFT)
    
    #endif /* _ASMI386_IOCTL_H */

Cache object: 717c6588f708b9a888d0635b59154ff0