New file, exercising scm_round.

2025-05-20 19:50:24 +02:00 · 2004-04-21 23:53:23 +00:00 · 2004-04-21 23:53:23 +00:00 · 370b8399a8
commit 370b8399a8
parent 6dfc9f1f8f
1 changed files with 122 additions and 0 deletions
--- a/test-suite/standalone/test-round.c
+++ b/test-suite/standalone/test-round.c
@ -0,0 +1,122 @@
+/* Copyright (C) 2004 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "config.h"
+
+#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_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_round (0.0) == 0.0);
+      assert (scm_round (1.0) == 1.0);
+      assert (scm_round (-1.0) == -1.0);
+
+      assert (scm_round (0.5) == 0.0);
+      assert (scm_round (1.5) == 2.0);
+      assert (scm_round (-1.5) == -2.0);
+      assert (scm_round (2.5) == 2.0);
+      assert (scm_round (-2.5) == -2.0);
+      assert (scm_round (3.5) == 4.0);
+      assert (scm_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_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_round (x) == want);
+
+      /* 2^DBL_MANT_DIG-1
+         In the past scm_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_round (x) == x);  /* scm_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_round (x) == x);  /* scm_round should return it unchanged */
+
+      /* 2^64 */
+      x = ldexp (1.0, 64);
+      assert (scm_round (x) == x);
+
+      /* -2^64
+         In the past scm_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_round (x) == x);
+    }
+}
+
+int
+main (int argc, char *argv[])
+{
+  scm_init_guile();
+  test_scm_round ();
+  return 0;
+}