mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 14:01:20 +00:00
66 lines
2.2 KiB
C
66 lines
2.2 KiB
C
/* Handle floating-point rounding mode within libc.
|
|
Copyright (C) 2012-2023 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#ifndef _ROUNDING_MODE_H
|
|
#define _ROUNDING_MODE_H 1
|
|
|
|
#include <fenv.h>
|
|
#include <stdbool.h>
|
|
#include <stdlib.h>
|
|
|
|
/* Get the architecture-specific definition of how to determine the
|
|
rounding mode in libc. This header must also define the FE_*
|
|
macros for any standard rounding modes the architecture does not
|
|
have in <fenv.h>, to arbitrary distinct values. */
|
|
#include <get-rounding-mode.h>
|
|
|
|
/* Return true if a number should be rounded away from zero in
|
|
rounding mode MODE, false otherwise. NEGATIVE is true if the
|
|
number is negative, false otherwise. LAST_DIGIT_ODD is true if the
|
|
last digit of the truncated value (last bit for binary) is odd,
|
|
false otherwise. HALF_BIT is true if the number is at least half
|
|
way from the truncated value to the next value with the
|
|
least-significant digit in the same place, false otherwise.
|
|
MORE_BITS is true if the number is not exactly equal to the
|
|
truncated value or the half-way value, false otherwise. */
|
|
|
|
static bool
|
|
round_away (bool negative, bool last_digit_odd, bool half_bit, bool more_bits,
|
|
int mode)
|
|
{
|
|
switch (mode)
|
|
{
|
|
case FE_DOWNWARD:
|
|
return negative && (half_bit || more_bits);
|
|
|
|
case FE_TONEAREST:
|
|
return half_bit && (last_digit_odd || more_bits);
|
|
|
|
case FE_TOWARDZERO:
|
|
return false;
|
|
|
|
case FE_UPWARD:
|
|
return !negative && (half_bit || more_bits);
|
|
|
|
default:
|
|
abort ();
|
|
}
|
|
}
|
|
|
|
#endif /* rounding-mode.h */
|