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      1 /*	$NetBSD: fd_set.h,v 1.8 2024/05/12 10:34:56 rillig Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  *
     31  *	from: @(#)types.h	8.4 (Berkeley) 1/21/94
     32  */
     33 
     34 #ifndef _SYS_FD_SET_H_
     35 #define	_SYS_FD_SET_H_
     36 
     37 #include <sys/cdefs.h>
     38 #include <sys/featuretest.h>
     39 #include <machine/int_types.h>
     40 
     41 /*
     42  * Implementation dependent defines, hidden from user space.
     43  * POSIX does not specify them.
     44  */
     45 
     46 typedef	__uint32_t	__fd_mask;
     47 
     48 /* 32 = 2 ^ 5 */
     49 #define	__NFDBITS	(32)
     50 #define	__NFDSHIFT	(5)
     51 #define	__NFDMASK	(__NFDBITS - 1)
     52 
     53 /*
     54  * Select uses bit fields of file descriptors.  These macros manipulate
     55  * such bit fields.  Note: FD_SETSIZE may be defined by the user.
     56  */
     57 
     58 #ifndef	FD_SETSIZE
     59 #define	FD_SETSIZE	256
     60 #endif
     61 
     62 #define	__NFD_LEN(a)	(((a) + (__NFDBITS - 1)) / __NFDBITS)
     63 #define	__NFD_SIZE	__NFD_LEN(FD_SETSIZE)
     64 #define	__NFD_BYTES(a)	(__NFD_LEN(a) * sizeof(__fd_mask))
     65 
     66 typedef	struct fd_set {
     67 	__fd_mask	fds_bits[__NFD_SIZE];
     68 } fd_set;
     69 
     70 #define	FD_SET(n, p)	\
     71     ((p)->fds_bits[(unsigned)(n) >> __NFDSHIFT] |= (1U << ((n) & __NFDMASK)))
     72 #define	FD_CLR(n, p)	\
     73     ((p)->fds_bits[(unsigned)(n) >> __NFDSHIFT] &= ~(1U << ((n) & __NFDMASK)))
     74 #define	FD_ISSET(n, p)	\
     75     ((p)->fds_bits[(unsigned)(n) >> __NFDSHIFT] & (1U << ((n) & __NFDMASK)))
     76 #if __GNUC_PREREQ__(2, 95)
     77 #define	FD_ZERO(p)	(void)__builtin_memset((p), 0, sizeof(*(p)))
     78 #else
     79 #define	FD_ZERO(p)	do {						\
     80 	fd_set *__fds = (p);						\
     81 	unsigned int __i;						\
     82 	for (__i = 0; __i < __NFD_SIZE; __i++)				\
     83 		__fds->fds_bits[__i] = 0;				\
     84 	} while (0)
     85 #endif /* GCC 2.95 */
     86 
     87 /*
     88  * Expose our internals if we are not required to hide them.
     89  */
     90 #if defined(_NETBSD_SOURCE)
     91 
     92 #define	fd_mask		__fd_mask
     93 #define	NFDBITS		__NFDBITS
     94 
     95 #if __GNUC_PREREQ__(2, 95)
     96 #define	FD_COPY(f, t)	(void)__builtin_memcpy((t), (f), sizeof(*(f)))
     97 #else
     98 #define	FD_COPY(f, t)	do {						\
     99 	fd_set *__f = (f), *__t = (t);					\
    100 	unsigned int __i;						\
    101 	for (__i = 0; __i < __NFD_SIZE; __i++)				\
    102 		__t->fds_bits[__i] = __f->fds_bits[__i];		\
    103 	} while (0)
    104 #endif /* GCC 2.95 */
    105 
    106 #endif /* _NETBSD_SOURCE */
    107 
    108 #endif /* _SYS_FD_SET_H_ */
    109