lib/libc/i386/gen/signbitl.c

   1 /*      $NetBSD: signbitl.c,v 1.1 2004/01/15 19:43:45 kleink Exp $      */
   2 /*      $DragonFly: src/lib/libc/i386/gen/signbitl.c,v 1.1 2005/07/26 21:15:19 joerg Exp $ */
   3
   4 /*-
   5  * Copyright (c) 2003 The NetBSD Foundation, Inc.
   6  * All rights reserved.
   7  *
   8  * This code is derived from software contributed to The NetBSD Foundation
   9  * by Klaus Klein.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. All advertising materials mentioning features or use of this software
  20  *    must display the following acknowledgement:
  21  *        This product includes software developed by the NetBSD
  22  *        Foundation, Inc. and its contributors.
  23  * 4. Neither the name of The NetBSD Foundation nor the names of its
  24  *    contributors may be used to endorse or promote products derived
  25  *    from this software without specific prior written permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  37  * POSSIBILITY OF SUCH DAMAGE.
  38  */
  39
  40 #include <machine/ieee.h>
  41 #include <math.h>
  42
  43 /*
  44  * 7.12.3.6 signbit - determine whether the sign of an argument is negative
  45  *          IEEE 754 compatible 80-bit extended-precision Intel 386 version
  46  */
  47 int
  48 __signbitl(long double x)
  49 {
  50         union ieee_ext_u u;
  51
  52         u.extu_ld = x;
  53
  54         return (u.extu_ext.ext_sign == 1);
  55 }