lib/libc/arch/x86_64/gen/isinfl.c

   1 /*      $NetBSD: isinfl.c,v 1.6 2007/02/02 23:19:25 christos Exp $      */
   2
   3 /*
   4  * Copyright (c) 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This software was developed by the Computer Systems Engineering group
   8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
   9  * contributed to Berkeley.
  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. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * from: Header: isinf.c,v 1.1 91/07/08 19:03:34 torek Exp
  36  */
  37
  38 #include <sys/cdefs.h>
  39 #if defined(LIBC_SCCS) && !defined(lint)
  40 #if 0
  41 static char sccsid[] = "@(#)isinf.c     8.1 (Berkeley) 6/4/93";
  42 #else
  43 __RCSID("$NetBSD: isinfl.c,v 1.6 2007/02/02 23:19:25 christos Exp $");
  44 #endif
  45 #endif /* LIBC_SCCS and not lint */
  46
  47 #include <machine/ieee.h>
  48 #include <math.h>
  49
  50 /*
  51  * 7.12.3.3 isinf - test for infinity
  52  *          IEEE 754 compatible 80-bit extended-precision Intel 386 version
  53  */
  54 int
  55 __isinfl(long double x)
  56 {
  57         union ieee_ext_u u;
  58
  59         u.extu_ld = x;
  60
  61         return (u.extu_ext.ext_exp == EXT_EXP_INFNAN &&
  62              u.extu_ext.ext_frach == 0x80000000 && u.extu_ext.ext_fracl == 0);
  63 }