cde/programs/dtksh/ksh93/src/lib/libast/sfio/sfputd.c

   1 /* $XConsortium: sfputd.c /main/3 1995/11/01 18:33:55 rswiston $ */
   2 /***************************************************************
   3 *                                                              *
   4 *                      AT&T - PROPRIETARY                      *
   5 *                                                              *
   6 *         THIS IS PROPRIETARY SOURCE CODE LICENSED BY          *
   7 *                          AT&T CORP.                          *
   8 *                                                              *
   9 *                Copyright (c) 1995 AT&T Corp.                 *
  10 *                     All Rights Reserved                      *
  11 *                                                              *
  12 *           This software is licensed by AT&T Corp.            *
  13 *       under the terms and conditions of the license in       *
  14 *       http://www.research.att.com/orgs/ssr/book/reuse        *
  15 *                                                              *
  16 *               This software was created by the               *
  17 *           Software Engineering Research Department           *
  18 *                    AT&T Bell Laboratories                    *
  19 *                                                              *
  20 *               For further information contact                *
  21 *                     gsf@research.att.com                     *
  22 *                                                              *
  23 ***************************************************************/
  24 #include        "sfhdr.h"
  25
  26 /*      Write out a double value in a portable format
  27 **
  28 **      Written by Kiem-Phong Vo (08/05/90)
  29 */
  30
  31 #if __STD_C
  32 _sfputd(Sfio_t* f, reg double v)
  33 #else
  34 _sfputd(f,v)
  35 Sfio_t          *f;
  36 reg double      v;
  37 #endif
  38 {
  39 #define N_ARRAY         (16*sizeof(double))
  40         reg int         n, w;
  41         reg double      x;
  42         reg uchar       *s, *ends;
  43         int             exp;
  44         uchar           c[N_ARRAY];
  45
  46         if(f->mode != SF_WRITE && _sfmode(f,SF_WRITE,0) < 0)
  47                 return -1;
  48         SFLOCK(f,0);
  49
  50         /* get the sign of v */
  51         if(v < 0.)
  52         {       v = -v;
  53                 n = 1;
  54         }
  55         else    n = 0;
  56
  57         /* make the magnitude of v < 1 */
  58         if(v != 0.)
  59                 v = frexp(v,&exp);
  60         else    exp = 0;
  61
  62         /* code the sign of v and exp */
  63         if((w = exp) < 0)
  64         {       n |= 02;
  65                 w = -w;
  66         }
  67
  68         /* write out the signs and the exp */
  69         SFOPEN(f,0);
  70         if(sfputc(f,n) < 0 || (w = sfputu(f,w)) < 0)
  71                 return -1;
  72         SFLOCK(f,0);
  73         w += 1;
  74
  75         s = (ends = &c[0])+sizeof(c);
  76         while(s > ends)
  77         {       /* get 2^SF_PRECIS precision at a time */
  78                 n = (int)(x = ldexp(v,SF_PRECIS));
  79                 *--s = n|SF_MORE;
  80                 if((v = x-n) <= 0.)
  81                         break;
  82         }
  83
  84         /* last byte is not SF_MORE */
  85         ends = &c[0] + sizeof(c) -1;
  86         *ends &= ~SF_MORE;
  87
  88         /* write out coded bytes */
  89         n = ends - s + 1;
  90         w = SFWRITE(f,(Void_t*)s,n) == n ? w+n : -1;
  91
  92         SFOPEN(f,0);
  93         return w;
  94 }