root/maint/gnulib/tests/test-printf-frexpl.c

/* */

DEFINITIONS

1. my_ldexp
2. main

   1 /* Test of splitting a 'long double' into fraction and mantissa.
   2    Copyright (C) 2007-2021 Free Software Foundation, Inc.
   3 
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8 
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13 
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16 
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
  18 
  19 #include <config.h>
  20 
  21 #include "printf-frexpl.h"
  22 
  23 #include <float.h>
  24 
  25 #include "fpucw.h"
  26 #include "macros.h"
  27 
  28 /* On MIPS IRIX machines, LDBL_MIN_EXP is -1021, but the smallest reliable
  29    exponent for 'long double' is -964.  Similarly, on PowerPC machines,
  30    LDBL_MIN_EXP is -1021, but the smallest reliable exponent for 'long double'
  31    is -968.  For exponents below that, the precision may be truncated to the
  32    precision used for 'double'.  */
  33 #ifdef __sgi
  34 # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 57)
  35 # define MIN_SUBNORMAL_EXP MIN_NORMAL_EXP
  36 #elif defined __ppc || defined __ppc__ || defined __powerpc || defined __powerpc__
  37 # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 53)
  38 # define MIN_SUBNORMAL_EXP MIN_NORMAL_EXP
  39 #else
  40 # define MIN_NORMAL_EXP LDBL_MIN_EXP
  41 # define MIN_SUBNORMAL_EXP (LDBL_MIN_EXP - 100)
  42 #endif
  43 
  44 static long double
  45 my_ldexp (long double x, int d)
     /*  */
  46 {
  47   for (; d > 0; d--)
  48     x *= 2.0L;
  49   for (; d < 0; d++)
  50     x *= 0.5L;
  51   return x;
  52 }
  53 
  54 int
  55 main ()
     /*  */
  56 {
  57   int i;
  58   long double x;
  59   DECL_LONG_DOUBLE_ROUNDING
  60 
  61   BEGIN_LONG_DOUBLE_ROUNDING ();
  62 
  63   for (i = 1, x = 1.0L; i <= LDBL_MAX_EXP; i++, x *= 2.0L)
  64     {
  65       int exp = -9999;
  66       long double mantissa = printf_frexpl (x, &exp);
  67       ASSERT (exp == i - 1);
  68       ASSERT (mantissa == 1.0L);
  69     }
  70   for (i = 1, x = 1.0L; i >= MIN_NORMAL_EXP; i--, x *= 0.5L)
  71     {
  72       int exp = -9999;
  73       long double mantissa = printf_frexpl (x, &exp);
  74       ASSERT (exp == i - 1);
  75       ASSERT (mantissa == 1.0L);
  76     }
  77   for (; i >= MIN_SUBNORMAL_EXP && x > 0.0L; i--, x *= 0.5L)
  78     {
  79       int exp = -9999;
  80       long double mantissa = printf_frexpl (x, &exp);
  81       ASSERT (exp == LDBL_MIN_EXP - 1);
  82       ASSERT (mantissa == my_ldexp (1.0L, i - LDBL_MIN_EXP));
  83     }
  84 
  85   for (i = 1, x = 1.01L; i <= LDBL_MAX_EXP; i++, x *= 2.0L)
  86     {
  87       int exp = -9999;
  88       long double mantissa = printf_frexpl (x, &exp);
  89       ASSERT (exp == i - 1);
  90       ASSERT (mantissa == 1.01L);
  91     }
  92   for (i = 1, x = 1.01L; i >= MIN_NORMAL_EXP; i--, x *= 0.5L)
  93     {
  94       int exp = -9999;
  95       long double mantissa = printf_frexpl (x, &exp);
  96       ASSERT (exp == i - 1);
  97       ASSERT (mantissa == 1.01L);
  98     }
  99   for (; i >= MIN_SUBNORMAL_EXP && x > 0.0L; i--, x *= 0.5L)
 100     {
 101       int exp = -9999;
 102       long double mantissa = printf_frexpl (x, &exp);
 103       ASSERT (exp == LDBL_MIN_EXP - 1);
 104       ASSERT (mantissa >= my_ldexp (1.0L, i - LDBL_MIN_EXP));
 105       ASSERT (mantissa <= my_ldexp (2.0L, i - LDBL_MIN_EXP));
 106       ASSERT (mantissa == my_ldexp (x, - exp));
 107     }
 108 
 109   for (i = 1, x = 1.73205L; i <= LDBL_MAX_EXP; i++, x *= 2.0L)
 110     {
 111       int exp = -9999;
 112       long double mantissa = printf_frexpl (x, &exp);
 113       ASSERT (exp == i - 1);
 114       ASSERT (mantissa == 1.73205L);
 115     }
 116   for (i = 1, x = 1.73205L; i >= MIN_NORMAL_EXP; i--, x *= 0.5L)
 117     {
 118       int exp = -9999;
 119       long double mantissa = printf_frexpl (x, &exp);
 120       ASSERT (exp == i - 1);
 121       ASSERT (mantissa == 1.73205L);
 122     }
 123   for (; i >= MIN_SUBNORMAL_EXP && x > 0.0L; i--, x *= 0.5L)
 124     {
 125       int exp = -9999;
 126       long double mantissa = printf_frexpl (x, &exp);
 127       ASSERT (exp == LDBL_MIN_EXP - 1);
 128       ASSERT (mantissa >= my_ldexp (1.0L, i - LDBL_MIN_EXP));
 129       ASSERT (mantissa <= my_ldexp (2.0L, i - LDBL_MIN_EXP));
 130       ASSERT (mantissa == my_ldexp (x, - exp));
 131     }
 132 
 133   return 0;
 134 }

/* */