glibc/sysdeps/i386/bits/select.h

/* Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#ifndef _SYS_SELECT_H
#error "Never use <bits/select.h> directly; include <sys/select.h> instead."
#endif


#if defined __GNUC__ && __GNUC__ >= 2

# define __FD_ZERO(fdsetp) \
  __asm__ __volatile__ ("cld; rep; stosl"				      \
			: "=m" (((__fd_mask *)				      \
				 (fdsetp))[__FDELT (__FD_SETSIZE)])	      \
			: "a" (0), "c" (sizeof (__fd_set)		      \
					/ sizeof (__fd_mask)),		      \
			  "D" ((__fd_set *) (fdsetp))			      \
			:"cx","di")
# define __FD_SET(fd, fdsetp) \
  __asm__ __volatile__ ("btsl %1,%0"					      \
			: "=m" (((__fd_mask *) (fdsetp))[__FDELT (fd)])	      \
			: "r" (((int) (fd)) % __NFDBITS)		      \
			: "cc")
# define __FD_CLR(fd, fdsetp) \
  __asm__ __volatile__ ("btrl %1,%0"					      \
			: "=m" (((__fd_mask *) (fdsetp))[__FDELT (fd)])	      \
			: "r" (((int) (fd)) % __NFDBITS)		      \
			: "cc")
# define __FD_ISSET(fd, fdsetp) \
  (__extension__							      \
   ({register char __result;						      \
     __asm__ __volatile__ ("btl %1,%2 ; setcb %b0"			      \
			   : "=q" (__result)				      \
			   : "r" (((int) (fd)) % __NFDBITS),		      \
			     "m" (((__fd_mask *) (fdsetp))[__FDELT (fd)])     \
			   : "cc");					      \
     __result; }))

#else	/* ! GNU CC */

/* We don't use `memset' because this would require a prototype and
   the array isn't too big.  */
# define __FD_ZERO(set)  \
  do {									      \
    unsigned int __i;							      \
    __fd_mask *__arr = (set);						      \
    for (__i = 0; __i < sizeof (__fd_set) / sizeof (__fd_mask); ++__i)	      \
      __arr->fds_bits[__i] = 0;						      \
  } while (0)
# define __FD_SET(d, set)	((set)->fds_bits[__FDELT (d)] |= __FDMASK (d))
# define __FD_CLR(d, set)	((set)->fds_bits[__FDELT (d)] &= ~__FDMASK (d))
# define __FD_ISSET(d, set)	((set)->fds_bits[__FDELT (d)] & __FDMASK (d))

#endif	/* GNU CC */