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/* Copyright (C) 2004, 2006, 2008 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <assert.h>
#include <math.h>
#include <stdio.h>
#if HAVE_FENV_H
#include <fenv.h>
#endif
#include <libguile.h>
#define numberof(x) (sizeof (x) / sizeof ((x)[0]))
static void
test_scm_c_round ()
{
/* FE constants are defined only where supported, in particular for
instance some ARM systems have been seen with only a couple of modes */
static const int modes[] = {
0,
#ifdef FE_TONEAREST
FE_TONEAREST,
#endif
#ifdef FE_UPWARD
FE_UPWARD,
#endif
#ifdef FE_DOWNWARD
FE_DOWNWARD,
#endif
#ifdef FE_TOWARDZERO
FE_TOWARDZERO,
#endif
};
double x, want;
int i;
for (i = 0; i < numberof (modes); i++)
{
/* First iteration is the default rounding mode, ie. no call to
fesetround. Subsequent iterations are the FE modes from the
table. */
if (i != 0)
{
#if HAVE_FESETROUND
fesetround (modes[i]);
#endif
}
assert (scm_c_round (0.0) == 0.0);
assert (scm_c_round (1.0) == 1.0);
assert (scm_c_round (-1.0) == -1.0);
assert (scm_c_round (0.5) == 0.0);
assert (scm_c_round (1.5) == 2.0);
assert (scm_c_round (-1.5) == -2.0);
assert (scm_c_round (2.5) == 2.0);
assert (scm_c_round (-2.5) == -2.0);
assert (scm_c_round (3.5) == 4.0);
assert (scm_c_round (-3.5) == -4.0);
/* 2^(DBL_MANT_DIG-1)-1+0.5 */
x = ldexp (1.0, DBL_MANT_DIG - 1) - 1.0 + 0.5;
want = ldexp (1.0, DBL_MANT_DIG - 1);
assert (scm_c_round (x) == want);
/* -(2^(DBL_MANT_DIG-1)-1+0.5) */
x = - (ldexp (1.0, DBL_MANT_DIG - 1) - 1.0 + 0.5);
want = - ldexp (1.0, DBL_MANT_DIG - 1);
assert (scm_c_round (x) == want);
/* 2^DBL_MANT_DIG-1
In the past scm_c_round had incorrectly incremented this value, due
to the way that x+0.5 would round upwards (in the usual default
nearest-even mode on most systems). */
x = ldexp (1.0, DBL_MANT_DIG) - 1.0;
assert (x == floor (x)); /* should be an integer already */
assert (scm_c_round (x) == x); /* scm_c_round should return it unchanged */
/* -(2^DBL_MANT_DIG-1) */
x = - (ldexp (1.0, DBL_MANT_DIG) - 1.0);
assert (x == floor (x)); /* should be an integer already */
assert (scm_c_round (x) == x); /* scm_c_round should return it unchanged */
/* 2^64 */
x = ldexp (1.0, 64);
assert (scm_c_round (x) == x);
/* -2^64
In the past scm_c_round had incorrectely gone to the next highest
representable value in FE_UPWARD, due to x+0.5 rounding. */
x = - ldexp (1.0, 64);
assert (scm_c_round (x) == x);
}
}
static void
tests (void *data, int argc, char **argv)
{
test_scm_c_round ();
}
int
main (int argc, char *argv[])
{
scm_boot_guile (argc, argv, tests, NULL);
return 0;
}
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