contrib/openbsd_libm/src/s_frexpl.c

   1 /*      $OpenBSD: s_frexpl.c,v 1.1 2008/12/09 20:00:35 martynas Exp $   */
   2 /*-
   3  * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD: src/lib/msun/src/s_frexpl.c,v 1.1 2005/03/07 04:54:51 das Exp $
  28  */
  29
  30 #include <sys/types.h>
  31 #include <machine/ieee.h>
  32 #include <float.h>
  33 #include <math.h>
  34
  35 #if LDBL_MAX_EXP != 0x4000
  36 #error "Unsupported long double format"
  37 #endif
  38
  39 long double
  40 frexpl(long double x, int *ex)
  41 {
  42         struct ieee_ext *p = (struct ieee_ext *)&x;
  43
  44         switch (p->ext_exp) {
  45         case 0:         /* 0 or subnormal */
  46                 if ((p->ext_fracl
  47 #ifdef EXT_FRACLMBITS
  48                         | p->ext_fraclm
  49 #endif /* EXT_FRACLMBITS */
  50 #ifdef EXT_FRACHMBITS
  51                         | p->ext_frachm
  52 #endif /* EXT_FRACHMBITS */
  53                         | p->ext_frach) == 0) {
  54                         *ex = 0;
  55                 } else {
  56                         x *= 0x1.0p514;
  57                         *ex = p->ext_exp - 0x4200;
  58                         p->ext_exp = 0x3ffe;
  59                 }
  60                 break;
  61         case 0x7fff:    /* infinity or NaN; value of *ex is unspecified */
  62                 break;
  63         default:        /* normal */
  64                 *ex = p->ext_exp - 0x3ffe;
  65                 p->ext_exp = 0x3ffe;
  66                 break;
  67         }
  68
  69         return x;
  70 }