/*      $NetBSD: fd_set.h,v 1.8 2024/05/12 10:34:56 rillig Exp $        */

/*-
 * 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. 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.
 *
 *      from: @(#)types.h       8.4 (Berkeley) 1/21/94
 */

#ifndef _SYS_FD_SET_H_
#define _SYS_FD_SET_H_

#include <sys/cdefs.h>
#include <sys/featuretest.h>
#include <machine/int_types.h>

/*
 * Implementation dependent defines, hidden from user space.
 * POSIX does not specify them.
 */

typedef __uint32_t      __fd_mask;

/* 32 = 2 ^ 5 */
#define __NFDBITS       (32)
#define __NFDSHIFT      (5)
#define __NFDMASK       (__NFDBITS - 1)

/*
 * Select uses bit fields of file descriptors.  These macros manipulate
 * such bit fields.  Note: FD_SETSIZE may be defined by the user.
 */

#ifndef FD_SETSIZE
#define FD_SETSIZE      256
#endif

#define __NFD_LEN(a)    (((a) + (__NFDBITS - 1)) / __NFDBITS)
#define __NFD_SIZE      __NFD_LEN(FD_SETSIZE)
#define __NFD_BYTES(a)  (__NFD_LEN(a) * sizeof(__fd_mask))

typedef struct fd_set {
        __fd_mask       fds_bits[__NFD_SIZE];
} fd_set;

#define FD_SET(n, p)    \
    ((p)->fds_bits[(unsigned)(n) >> __NFDSHIFT] |= (1U << ((n) & __NFDMASK)))
#define FD_CLR(n, p)    \
    ((p)->fds_bits[(unsigned)(n) >> __NFDSHIFT] &= ~(1U << ((n) & __NFDMASK)))
#define FD_ISSET(n, p)  \
    ((p)->fds_bits[(unsigned)(n) >> __NFDSHIFT] & (1U << ((n) & __NFDMASK)))
#if __GNUC_PREREQ__(2, 95)
#define FD_ZERO(p)      (void)__builtin_memset((p), 0, sizeof(*(p)))
#else
#define FD_ZERO(p)      do {                                            \
        fd_set *__fds = (p);                                            \
        unsigned int __i;                                               \
        for (__i = 0; __i < __NFD_SIZE; __i++)                          \
                __fds->fds_bits[__i] = 0;                               \
        } while (0)
#endif /* GCC 2.95 */

/*
 * Expose our internals if we are not required to hide them.
 */
#if defined(_NETBSD_SOURCE)

#define fd_mask         __fd_mask
#define NFDBITS         __NFDBITS

#if __GNUC_PREREQ__(2, 95)
#define FD_COPY(f, t)   (void)__builtin_memcpy((t), (f), sizeof(*(f)))
#else
#define FD_COPY(f, t)   do {                                            \
        fd_set *__f = (f), *__t = (t);                                  \
        unsigned int __i;                                               \
        for (__i = 0; __i < __NFD_SIZE; __i++)                          \
                __t->fds_bits[__i] = __f->fds_bits[__i];                \
        } while (0)
#endif /* GCC 2.95 */

#endif /* _NETBSD_SOURCE */

#endif /* _SYS_FD_SET_H_ */