1 files changed, 62 insertions, 0 deletions
diff --git a/tests/test-modf.h b/tests/test-modf.h
new file mode 100644
index 0000000..589c725
--- /dev/null
+++ b/tests/test-modf.h
@@ -0,0 +1,62 @@
+/* Test of modf*() function family.
+   Copyright (C) 2012-2015 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+static void
+test_function (void)
+{
+  int i;
+  const DOUBLE TWO_MANT_DIG =
+    /* Assume MANT_DIG <= 5 * 31.
+       Use the identity
+         n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5).  */
+    (DOUBLE) (1U << ((MANT_DIG - 1) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5))
+    * (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5));
+
+  /* Randomized tests.  */
+  for (i = 0; i < SIZEOF (RANDOM); i++)
+    {
+      DOUBLE x = RANDOM[i]; /* 0.0 <= x < 1.0 */
+      DOUBLE y;
+      DOUBLE z;
+
+      y = MODF (x, &z);
+      ASSERT (z == L_(0.0));
+      ASSERT (y == x);
+
+      y = MODF (- x, &z);
+      ASSERT (z == L_(0.0));
+      ASSERT (y == - x);
+
+      y = MODF (L_(1.0) + x, &z);
+      ASSERT (z == L_(1.0));
+      y -= x;
+      ASSERT (y >= - L_(1.0) / TWO_MANT_DIG);
+      ASSERT (y <= L_(1.0) / TWO_MANT_DIG);
+
+      y = MODF (- L_(1.0) - x, &z);
+      ASSERT (z == - L_(1.0));
+      y -= - x;
+      ASSERT (y >= - L_(1.0) / TWO_MANT_DIG);
+      ASSERT (y <= L_(1.0) / TWO_MANT_DIG);
+    }
+}
+
+volatile DOUBLE x;
+DOUBLE y;
+DOUBLE z;