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

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This commit is contained in:
Joseph Myers
2012-09-14 20:18:49 +00:00
parent 01e80428f7
commit 784761bee3
4 changed files with 154 additions and 30 deletions
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stdio-common/tst-printf-round.c Normal file
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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"