1 files changed, 119 insertions, 0 deletions
diff --git a/gnulib-tests/test-printf-frexp.c b/gnulib-tests/test-printf-frexp.c
new file mode 100644
index 0000000..01b34a5
--- /dev/null
+++ b/gnulib-tests/test-printf-frexp.c
@@ -0,0 +1,119 @@
+/* Test of splitting a double into fraction and mantissa.
+   Copyright (C) 2007-2022 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 <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+#include <config.h>
+
+#include "printf-frexp.h"
+
+#include <float.h>
+
+#include "macros.h"
+
+static double
+my_ldexp (double x, int d)
+{
+  for (; d > 0; d--)
+    x *= 2.0;
+  for (; d < 0; d++)
+    x *= 0.5;
+  return x;
+}
+
+int
+main ()
+{
+  int i;
+  /* The use of 'volatile' guarantees that excess precision bits are dropped
+     when dealing with denormalized numbers.  It is necessary on x86 systems
+     where double-floats are not IEEE compliant by default, to avoid that the
+     results become platform and compiler option dependent.  'volatile' is a
+     portable alternative to gcc's -ffloat-store option.  */
+  volatile double x;
+
+  for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == i - 1);
+      ASSERT (mantissa == 1.0);
+    }
+  for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == i - 1);
+      ASSERT (mantissa == 1.0);
+    }
+  for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == DBL_MIN_EXP - 1);
+      ASSERT (mantissa == my_ldexp (1.0, i - DBL_MIN_EXP));
+    }
+
+  for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == i - 1);
+      ASSERT (mantissa == 1.01);
+    }
+  for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == i - 1);
+      ASSERT (mantissa == 1.01);
+    }
+  for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == DBL_MIN_EXP - 1);
+      ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
+      ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
+      ASSERT (mantissa == my_ldexp (x, - exp));
+    }
+
+  for (i = 1, x = 1.73205; i <= DBL_MAX_EXP; i++, x *= 2.0)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == i - 1);
+      ASSERT (mantissa == 1.73205);
+    }
+  for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == i - 1);
+      ASSERT (mantissa == 1.73205);
+    }
+  for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5)
+    {
+      int exp = -9999;
+      double mantissa = printf_frexp (x, &exp);
+      ASSERT (exp == DBL_MIN_EXP - 1);
+      ASSERT (mantissa >= my_ldexp (1.0, i - DBL_MIN_EXP));
+      ASSERT (mantissa <= my_ldexp (2.0, i - DBL_MIN_EXP));
+      ASSERT (mantissa == my_ldexp (x, - exp));
+    }
+
+  return 0;
+}