Make strtod respect the rounding mode (bug 14518).

1 files changed, 65 insertions, 0 deletions

diff --git a/include/rounding-mode.h b/include/rounding-mode.h
new file mode 100644
index 0000000000..bde41e7b1e
--- /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 */