lib/libm/src/s_frexpl.c

   1 /*-
   2  * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/lib/msun/src/s_frexpl.c,v 1.1 2005/03/07 04:54:51 das Exp $
  27  */
  28
  29 #include <float.h>
  30 #include <math.h>
  31
  32 #include "fpmath.h"
  33
  34 #if LDBL_MAX_EXP != 0x4000
  35 #error "Unsupported long double format"
  36 #endif
  37
  38 long double
  39 frexpl(long double x, int *ex)
  40 {
  41         union IEEEl2bits u;
  42
  43         u.e = x;
  44         switch (u.bits.exp) {
  45         case 0:         /* 0 or subnormal */
  46                 if ((u.bits.manl | u.bits.manh) == 0) {
  47                         *ex = 0;
  48                 } else {
  49                         u.e *= 0x1.0p514;
  50                         *ex = u.bits.exp - 0x4200;
  51                         u.bits.exp = 0x3ffe;
  52                 }
  53                 break;
  54         case 0x7fff:    /* infinity or NaN; value of *ex is unspecified */
  55                 break;
  56         default:        /* normal */
  57                 *ex = u.bits.exp - 0x3ffe;
  58                 u.bits.exp = 0x3ffe;
  59                 break;
  60         }
  61         return (u.e);
  62 }