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author | Joseph Myers <joseph@codesourcery.com> | 2012-09-12 23:36:19 +0000 |
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committer | Joseph Myers <joseph@codesourcery.com> | 2012-09-12 23:36:19 +0000 |
commit | 6c9b0f68267cf365d060d4e51e7cb8f61498b875 (patch) | |
tree | 7527c31f9593972fa3781f570b1712ba79d4a556 /include/rounding-mode.h | |
parent | 19fcedd5fcaab4355adf62350224ce53797f0f5a (diff) | |
download | glibc-6c9b0f68267cf365d060d4e51e7cb8f61498b875.zip glibc-6c9b0f68267cf365d060d4e51e7cb8f61498b875.tar.gz glibc-6c9b0f68267cf365d060d4e51e7cb8f61498b875.tar.bz2 |
Make strtod respect the rounding mode (bug 14518).
Diffstat (limited to 'include/rounding-mode.h')
-rw-r--r-- | include/rounding-mode.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/include/rounding-mode.h b/include/rounding-mode.h new file mode 100644 index 0000000..bde41e7 --- /dev/null +++ b/include/rounding-mode.h @@ -0,0 +1,65 @@ +/* Handle floating-point rounding mode within libc. + 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/>. */ + +#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 inline 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 */ |