usr/src/lib/libast/common/sfio/sfdlen.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #include        "sfhdr.h"
  23
  24 /*      Return the length of a double value if coded in a portable format
  25 **
  26 **      Written by Kiem-Phong Vo
  27 */
  28
  29 #if __STD_C
  30 int _sfdlen(Sfdouble_t v)
  31 #else
  32 int _sfdlen(v)
  33 Sfdouble_t      v;
  34 #endif
  35 {
  36 #define N_ARRAY         (16*sizeof(Sfdouble_t))
  37         reg int         n, w;
  38         Sfdouble_t      x;
  39         int             exp;
  40
  41         if(v < 0)
  42                 v = -v;
  43
  44         /* make the magnitude of v < 1 */
  45         if(v != 0.)
  46                 v = frexpl(v,&exp);
  47         else    exp = 0;
  48
  49         for(w = 1; w <= N_ARRAY; ++w)
  50         {       /* get 2^SF_PRECIS precision at a time */
  51                 n = (int)(x = ldexpl(v,SF_PRECIS));
  52                 v = x-n;
  53                 if(v <= 0.)
  54                         break;
  55         }
  56
  57         return 1 + sfulen(exp) + w;
  58 }