Make printf respect the rounding mode for decimal output (bug 5044).

1 files changed, 110 insertions, 0 deletions

diff --git a/stdio-common/tst-printf-round.c b/stdio-common/tst-printf-round.c
new file mode 100644
index 0000000000..2bd46079ac
--- /dev/null
+++ b/stdio-common/tst-printf-round.c
@@ -0,0 +1,110 @@
+/* Test for correct rounding of printf floating-point output.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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.
+
+   The GNU C 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 the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <fenv.h>
+#include <stdio.h>
+#include <string.h>
+
+struct dec_test {
+  double d;
+  const char *fmt;
+  const char *rd, *rn, *rz, *ru;
+};
+
+static const struct dec_test dec_tests[] = {
+  { 1.5, "%.0f", "1", "2", "1", "2" },
+  { -1.5, "%.0f", "-2", "-2", "-1", "-1" },
+  { 2.5, "%.0f", "2", "2", "2", "3" },
+  { -2.5, "%.0f", "-3", "-2", "-2", "-2" },
+  { 1.4999, "%.0f", "1", "1", "1", "2" },
+  { -1.4999, "%.0f", "-2", "-1", "-1", "-1" },
+  { 1.5001, "%.0f", "1", "2", "1", "2" },
+  { -1.5001, "%.0f", "-2", "-2", "-1", "-1" },
+  { 2.4999, "%.0f", "2", "2", "2", "3" },
+  { -2.4999, "%.0f", "-3", "-2", "-2", "-2" },
+  { 2.5001, "%.0f", "2", "3", "2", "3" },
+  { -2.5001, "%.0f", "-3", "-3", "-2", "-2" },
+  { 1.0 / 3.0, "%f", "0.333333", "0.333333", "0.333333", "0.333334" },
+  { -1.0 / 3.0, "%f", "-0.333334", "-0.333333", "-0.333333", "-0.333333" },
+  { 0.2500001, "%.2e", "2.50e-01", "2.50e-01", "2.50e-01", "2.51e-01" },
+  { -0.2500001, "%.2e", "-2.51e-01", "-2.50e-01", "-2.50e-01", "-2.50e-01" },
+  { 1000001.0, "%.1e", "1.0e+06", "1.0e+06", "1.0e+06", "1.1e+06" },
+  { -1000001.0, "%.1e", "-1.1e+06", "-1.0e+06", "-1.0e+06", "-1.0e+06" },
+};
+
+static int
+test_dec_in_one_mode (double d, const char *fmt, const char *expected,
+		      const char *mode_name)
+{
+  char buf[100];
+  int ret = snprintf (buf, sizeof buf, fmt, d);
+  if (ret <= 0 || ret >= (int) sizeof buf)
+    {
+      printf ("snprintf for %a returned %d\n", d, ret);
+      return 1;
+    }
+  if (strcmp (buf, expected) == 0)
+    return 0;
+  else
+    {
+      printf ("snprintf (\"%s\", %a) returned \"%s\" not \"%s\" (%s)\n",
+	      fmt, d, buf, expected, mode_name);
+      return 1;
+    }
+}
+
+static int
+do_test (void)
+{
+  int save_round_mode = fegetround ();
+  int result = 0;
+
+  for (size_t i = 0; i < sizeof (dec_tests) / sizeof (dec_tests[0]); i++)
+    {
+      result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt,
+				      dec_tests[i].rn, "default rounding mode");
+#ifdef FE_DOWNWARD
+      if (!fesetround (FE_DOWNWARD))
+	{
+	  result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt,
+					  dec_tests[i].rd, "FE_DOWNWARD");
+	  fesetround (save_round_mode);
+	}
+#endif
+#ifdef FE_TOWARDZERO
+      if (!fesetround (FE_TOWARDZERO))
+	{
+	  result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt,
+					  dec_tests[i].rz, "FE_TOWARDZERO");
+	  fesetround (save_round_mode);
+	}
+#endif
+#ifdef FE_UPWARD
+      if (!fesetround (FE_UPWARD))
+	{
+	  result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt,
+					  dec_tests[i].ru, "FE_UPWARD");
+	  fesetround (save_round_mode);
+	}
+#endif
+    }
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"