lib/libm/src/s_frexpl.c

   1 /*      $NetBSD: s_frexpl.c,v 1.3 2013/02/12 21:40:19 martin Exp $      */
   2
   3 /*-
   4  * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $FreeBSD: src/lib/msun/src/s_frexpl.c,v 1.1 2005/03/07 04:54:51 das Exp $
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __RCSID("$NetBSD: s_frexpl.c,v 1.3 2013/02/12 21:40:19 martin Exp $");
  33
  34 #include <machine/ieee.h>
  35 #include <float.h>
  36 #include <math.h>
  37
  38 #include "math_private.h"
  39
  40 #ifdef __HAVE_LONG_DOUBLE
  41 #if LDBL_MAX_EXP != 0x4000
  42 #error "Unsupported long double format"
  43 #endif
  44
  45 long double
  46 frexpl(long double x, int *ex)
  47 {
  48         union ieee_ext_u u;
  49
  50         u.extu_ld = x;
  51         switch (u.extu_ext.ext_exp) {
  52         case 0:         /* 0 or subnormal */
  53                 if ((u.extu_ext.ext_fracl | u.extu_ext.ext_frach) == 0) {
  54                         *ex = 0;
  55                 } else {
  56                         u.extu_ld *= 0x1.0p514;
  57                         *ex = u.extu_ext.ext_exp - 0x4200;
  58                         u.extu_ext.ext_exp = 0x3ffe;
  59                 }
  60                 break;
  61         case 0x7fff:    /* infinity or NaN; value of *ex is unspecified */
  62                 break;
  63         default:        /* normal */
  64                 *ex = u.extu_ext.ext_exp - 0x3ffe;
  65                 u.extu_ext.ext_exp = 0x3ffe;
  66                 break;
  67         }
  68         return (u.extu_ld);
  69 }
  70 #endif