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path: root/stdio-common/tst-printf-round.c
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/* 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"