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authorJoseph Myers <joseph@codesourcery.com>2012-09-12 23:36:19 +0000
committerJoseph Myers <joseph@codesourcery.com>2012-09-12 23:36:19 +0000
commit6c9b0f68267cf365d060d4e51e7cb8f61498b875 (patch)
tree7527c31f9593972fa3781f570b1712ba79d4a556 /include
parent19fcedd5fcaab4355adf62350224ce53797f0f5a (diff)
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Make strtod respect the rounding mode (bug 14518).
Diffstat (limited to 'include')
-rw-r--r--include/rounding-mode.h65
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 */