test-suite/standalone/test-round.c

   1 /* Copyright (C) 2004, 2006, 2008, 2009, 2011, 2014 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19 #if HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #undef NDEBUG
  24
  25 #include <assert.h>
  26 #include <math.h>
  27 #include <stdio.h>
  28
  29 #if HAVE_FENV_H
  30 # if defined __GNUC__ && defined __GLIBC__
  31 /* In Glibc 2.17, <bits/fenv.h> defines `feraiseexcept' as an inline
  32    without declaring it first, so ignore the warning.  */
  33 #   pragma GCC diagnostic push
  34 #   pragma GCC diagnostic ignored "-Wmissing-prototypes"
  35 # endif
  36 # include <fenv.h>
  37 # if defined __GNUC__ && defined __GLIBC__
  38 #   pragma GCC diagnostic pop
  39 # endif
  40 #elif defined HAVE_MACHINE_FPU_H
  41 /* On Tru64 5.1b, the declaration of fesetround(3) is in <machine/fpu.h>.
  42    On NetBSD, this header has to be included along with <sys/types.h>.  */
  43 # ifdef HAVE_SYS_TYPES_H
  44 #  include <sys/types.h>
  45 # endif
  46 # include <machine/fpu.h>
  47 #endif
  48
  49 #include <libguile.h>
  50
  51
  52 #define numberof(x)  (sizeof (x) / sizeof ((x)[0]))
  53
  54 static void
  55 test_scm_c_round ()
  56 {
  57   /* FE constants are defined only where supported, in particular for
  58      instance some ARM systems have been seen with only a couple of modes */
  59   static const int modes[] = {
  60     0,
  61 #ifdef FE_TONEAREST
  62     FE_TONEAREST,
  63 #endif
  64 #ifdef FE_UPWARD
  65     FE_UPWARD,
  66 #endif
  67 #ifdef FE_DOWNWARD
  68     FE_DOWNWARD,
  69 #endif
  70 #ifdef FE_TOWARDZERO
  71     FE_TOWARDZERO,
  72 #endif
  73   };
  74
  75   double  x, want;
  76   int  i;
  77
  78   for (i = 0; i < numberof (modes); i++)
  79     {
  80       /* First iteration is the default rounding mode, ie. no call to
  81          fesetround.  Subsequent iterations are the FE modes from the
  82          table.  */
  83       if (i != 0)
  84         {
  85 #ifdef HAVE_FESETROUND
  86           fesetround (modes[i]);
  87 #endif
  88         }
  89
  90       assert (scm_c_round (0.0) == 0.0);
  91       assert (scm_c_round (1.0) == 1.0);
  92       assert (scm_c_round (-1.0) == -1.0);
  93
  94       assert (scm_c_round (0.5) == 0.0);
  95       assert (scm_c_round (1.5) == 2.0);
  96       assert (scm_c_round (-1.5) == -2.0);
  97       assert (scm_c_round (2.5) == 2.0);
  98       assert (scm_c_round (-2.5) == -2.0);
  99       assert (scm_c_round (3.5) == 4.0);
 100       assert (scm_c_round (-3.5) == -4.0);
 101
 102       /* 2^(DBL_MANT_DIG-1)-1+0.5 */
 103       x = ldexp (1.0, DBL_MANT_DIG - 1) - 1.0 + 0.5;
 104       want = ldexp (1.0, DBL_MANT_DIG - 1);
 105       assert (scm_c_round (x) == want);
 106
 107       /* -(2^(DBL_MANT_DIG-1)-1+0.5) */
 108       x = - (ldexp (1.0, DBL_MANT_DIG - 1) - 1.0 + 0.5);
 109       want = - ldexp (1.0, DBL_MANT_DIG - 1);
 110       assert (scm_c_round (x) == want);
 111
 112       /* 2^DBL_MANT_DIG-1
 113          In the past scm_c_round had incorrectly incremented this value, due
 114          to the way that x+0.5 would round upwards (in the usual default
 115          nearest-even mode on most systems).  */
 116       x = ldexp (1.0, DBL_MANT_DIG) - 1.0;
 117       assert (x == floor (x));      /* should be an integer already */
 118       assert (scm_c_round (x) == x);  /* scm_c_round should return it unchanged */
 119
 120       /* -(2^DBL_MANT_DIG-1) */
 121       x = - (ldexp (1.0, DBL_MANT_DIG) - 1.0);
 122       assert (x == floor (x));      /* should be an integer already */
 123       assert (scm_c_round (x) == x);  /* scm_c_round should return it unchanged */
 124
 125       /* 2^64 */
 126       x = ldexp (1.0, 64);
 127       assert (scm_c_round (x) == x);
 128
 129       /* -2^64
 130          In the past scm_c_round had incorrectely gone to the next highest
 131          representable value in FE_UPWARD, due to x+0.5 rounding.  */
 132       x = - ldexp (1.0, 64);
 133       assert (scm_c_round (x) == x);
 134     }
 135 }
 136
 137 static void
 138 tests (void *data, int argc, char **argv)
 139 {
 140   test_scm_c_round ();
 141 }
 142
 143 int
 144 main (int argc, char *argv[])
 145 {
 146   scm_boot_guile (argc, argv, tests, NULL);
 147   return 0;
 148 }