FreeBSD/Linux Kernel Cross Reference
sys/sys/fd_set.h

     /*-
      * Copyright (c) 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)select.h    8.2 (Berkeley) 1/4/94
     * $FreeBSD: src/sys/sys/select.h,v 1.6.2.1 2000/05/05 03:50:02 jlemon Exp $
     * $DragonFly: src/sys/sys/fd_set.h,v 1.3 2008/05/30 08:07:22 corecode Exp $
     */
    
    #ifndef _SYS_FD_SET_H_
    #define _SYS_FD_SET_H_
    
    /*
     * Select uses bit masks of file descriptors in longs.  These macros
     * manipulate such bit fields (the filesystem macros use chars).
     * FD_SETSIZE may be defined by the user, but the default here should
     * be enough for most uses.
     */
    #ifndef FD_SETSIZE
    #define FD_SETSIZE      1024
    #endif
    
    #define __NBBY          8               /* number of bits in a byte */
    
    typedef unsigned long   __fd_mask;
    #define __NFDBITS ((unsigned int)sizeof(__fd_mask) * __NBBY)    /* bits per mask */
    
    #ifndef __howmany
    #define __howmany(x, y) (((x) + ((y) - 1)) / (y))
    #endif
    
    typedef struct fd_set {
            __fd_mask fds_bits[__howmany(FD_SETSIZE, __NFDBITS)];
    } fd_set;
    
    #define _fdset_mask(n)  ((__fd_mask)1 << ((n) % __NFDBITS))
    #define FD_SET(n, p)    ((p)->fds_bits[(n)/__NFDBITS] |= _fdset_mask(n))
    #define FD_CLR(n, p)    ((p)->fds_bits[(n)/__NFDBITS] &= ~_fdset_mask(n))
    #define FD_ISSET(n, p)  ((p)->fds_bits[(n)/__NFDBITS] & _fdset_mask(n))
    #define FD_ZERO(p)      __builtin_memset((p), 0, sizeof(*(p)))
    
    
    /*
     * Expose classic BSD names if we're not running in conformance mode.
     */
    #ifdef __BSD_VISIBLE
    
    #define fd_mask __fd_mask
    #define NFDBITS __NFDBITS
    #ifndef howmany
    #define howmany(a, b)   __howmany(a, b)
    #endif
    
    #define FD_COPY(f, t)   __builtin_memcpy((t), (f), sizeof(*(f)))
    
    #endif /* __BSD_VISIBLE */
    
    #endif /* _SYS_FD_SET_H_ */

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