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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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53
stdio-common/printf_fp.c
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@@ -39,6 +39,8 @@
#include <unistd.h>
#include <stdlib.h>
#include <wchar.h>
#include <stdbool.h>
#include <rounding-mode.h>
#ifdef COMPILE_WPRINTF
# define CHAR_T wchar_t
@@ -197,9 +199,6 @@ ___printf_fp (FILE *fp,
/* Temporary bignum value. */
MPN_VAR(tmp);
/* Digit which is result of last hack_digit() call. */
wchar_t digit;
/* The type of output format that will be used: 'e'/'E' or 'f'. */
int type;
@@ -955,34 +954,31 @@ ___printf_fp (FILE *fp,
}
/* Do rounding. */
digit = hack_digit ();
if (digit > L'4')
wchar_t last_digit = wcp[-1] != decimalwc ? wcp[-1] : wcp[-2];
wchar_t next_digit = hack_digit ();
bool more_bits;
if (next_digit != L'0' && next_digit != L'5')
more_bits = true;
else if (fracsize == 1 && frac[0] == 0)
/* Rest of the number is zero. */
more_bits = false;
else if (scalesize == 0)
{
/* Here we have to see whether all limbs are zero since no
normalization happened. */
size_t lcnt = fracsize;
while (lcnt >= 1 && frac[lcnt - 1] == 0)
--lcnt;
more_bits = lcnt > 0;
}
else
more_bits = true;
int rounding_mode = get_rounding_mode ();
if (round_away (is_neg, (last_digit - L'0') & 1, next_digit >= L'5',
more_bits, rounding_mode))
{
wchar_t *wtp = wcp;
if (digit == L'5'
&& ((*(wcp - 1) != decimalwc && (*(wcp - 1) & 1) == 0)
|| ((*(wcp - 1) == decimalwc && (*(wcp - 2) & 1) == 0))))
{
/* This is the critical case. */
if (fracsize == 1 && frac[0] == 0)
/* Rest of the number is zero -> round to even.
(IEEE 754-1985 4.1 says this is the default rounding.) */
goto do_expo;
else if (scalesize == 0)
{
/* Here we have to see whether all limbs are zero since no
normalization happened. */
size_t lcnt = fracsize;
while (lcnt >= 1 && frac[lcnt - 1] == 0)
--lcnt;
if (lcnt == 0)
/* Rest of the number is zero -> round to even.
(IEEE 754-1985 4.1 says this is the default rounding.) */
goto do_expo;
}
}
if (fracdig_no > 0)
{
/* Process fractional digits. Terminate if not rounded or
@@ -1076,7 +1072,6 @@ ___printf_fp (FILE *fp,
}
}
do_expo:
/* Now remove unnecessary '0' at the end of the string. */
while (fracdig_no > fracdig_min + added_zeros && *(wcp - 1) == L'0')
{