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diff --git a/test-suite/standalone/test-round.c b/test-suite/standalone/test-round.c
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+/* Copyright 2004,2006,2008-2009,2011,2014,2018
+ Free Software Foundation, Inc.
+
+ This file is part of Guile.
+
+ Guile 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 3 of the License, or
+ (at your option) any later version.
+
+ Guile 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 Guile. If not, see
+ <https://www.gnu.org/licenses/>. */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#undef NDEBUG
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+
+#if HAVE_FENV_H
+# if defined __GNUC__ && defined __GLIBC__
+/* In Glibc 2.17, <bits/fenv.h> defines `feraiseexcept' as an inline
+ without declaring it first, so ignore the warning. */
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wmissing-prototypes"
+# endif
+# include <fenv.h>
+# if defined __GNUC__ && defined __GLIBC__
+# pragma GCC diagnostic pop
+# endif
+#elif defined HAVE_MACHINE_FPU_H
+/* On Tru64 5.1b, the declaration of fesetround(3) is in <machine/fpu.h>.
+ On NetBSD, this header has to be included along with <sys/types.h>. */
+# ifdef HAVE_SYS_TYPES_H
+# include <sys/types.h>
+# endif
+# include <machine/fpu.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)
+ {
+#ifdef 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;
+}