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authorMike Frysinger <vapier@gentoo.org>2005-11-03 23:57:25 +0000
committerMike Frysinger <vapier@gentoo.org>2005-11-03 23:57:25 +0000
commitea8e9b58cc284de51f163abf762c0504880a4041 (patch)
treef296281888098f7a6bed1eb0dfe46424c6535847 /libm/s_round.c
parentabc27c85d619d917d411080a24373f98fe5d88ac (diff)
add implementations from glibc for the round functions
Diffstat (limited to 'libm/s_round.c')
-rw-r--r--libm/s_round.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/libm/s_round.c b/libm/s_round.c
new file mode 100644
index 000000000..b2d009520
--- /dev/null
+++ b/libm/s_round.c
@@ -0,0 +1,92 @@
+/* Round double to integer away from zero.
+ Copyright (C) 1997 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+ 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <math.h>
+
+#include "math_private.h"
+
+
+static const double huge = 1.0e300;
+
+
+double
+round (double x)
+{
+ int32_t i0, j0;
+ u_int32_t i1;
+
+ EXTRACT_WORDS (i0, i1, x);
+ j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
+ if (j0 < 20)
+ {
+ if (j0 < 0)
+ {
+ if (huge + x > 0.0)
+ {
+ i0 &= 0x80000000;
+ if (j0 == -1)
+ i0 |= 0x3ff00000;
+ i1 = 0;
+ }
+ }
+ else
+ {
+ u_int32_t i = 0x000fffff >> j0;
+ if (((i0 & i) | i1) == 0)
+ /* X is integral. */
+ return x;
+ if (huge + x > 0.0)
+ {
+ /* Raise inexact if x != 0. */
+ i0 += 0x00080000 >> j0;
+ i0 &= ~i;
+ i1 = 0;
+ }
+ }
+ }
+ else if (j0 > 51)
+ {
+ if (j0 == 0x400)
+ /* Inf or NaN. */
+ return x + x;
+ else
+ return x;
+ }
+ else
+ {
+ u_int32_t i = 0xffffffff >> (j0 - 20);
+ if ((i1 & i) == 0)
+ /* X is integral. */
+ return x;
+
+ if (huge + x > 0.0)
+ {
+ /* Raise inexact if x != 0. */
+ u_int32_t j = i1 + (1 << (51 - j0));
+ if (j < i1)
+ i0 += 1;
+ i1 = j;
+ }
+ i1 &= ~i;
+ }
+
+ INSERT_WORDS (x, i0, i1);
+ return x;
+}