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authorUlrich Drepper <drepper@gmail.com>2011-10-23 21:31:21 -0400
committerUlrich Drepper <drepper@gmail.com>2011-10-23 21:31:21 -0400
commitbb3129bd2503bd3339b5418cca4eef97f16128b6 (patch)
tree7e9be9794da39afb721794298196eeb941fc160a /sysdeps
parent0275fff8a105d5963df43b27df769487adac25ac (diff)
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Optimized remquo for 64-bit platforms
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c112
1 files changed, 112 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c
new file mode 100644
index 0000000000..011401ebca
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c
@@ -0,0 +1,112 @@
+/* Compute remainder and a congruent to the quotient.
+ Copyright (C) 1997, 2011 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 zero = 0.0;
+
+
+double
+__remquo (double x, double y, int *quo)
+{
+ int64_t hx, hy;
+ uint64_t sx, qs;
+ int cquo;
+
+ EXTRACT_WORDS64 (hx, x);
+ EXTRACT_WORDS64 (hy, y);
+ sx = hx & UINT64_C(0x8000000000000000);
+ qs = sx ^ (hy & UINT64_C(0x8000000000000000));
+ hy &= UINT64_C(0x7fffffffffffffff);
+ hx &= UINT64_C(0x7fffffffffffffff);
+
+ /* Purge off exception values. */
+ if (__builtin_expect (hy == 0, 0))
+ return (x * y) / (x * y); /* y = 0 */
+ if (__builtin_expect (hx >= UINT64_C(0x7ff0000000000000) /* x not finite */
+ || hy > UINT64_C(0x7ff0000000000000), 0))/* y is NaN */
+ return (x * y) / (x * y);
+
+ if (hy <= UINT64_C(0x7fbfffffffffffff))
+ x = __ieee754_fmod (x, 8 * y); /* now x < 8y */
+
+ if (__builtin_expect (hx == hy, 0))
+ {
+ *quo = qs ? -1 : 1;
+ return zero * x;
+ }
+
+ INSERT_WORDS64 (x, hx);
+ INSERT_WORDS64 (y, hy);
+ cquo = 0;
+
+ if (x >= 4 * y)
+ {
+ x -= 4 * y;
+ cquo += 4;
+ }
+ if (x >= 2 * y)
+ {
+ x -= 2 * y;
+ cquo += 2;
+ }
+
+ if (hy < UINT64_C(0x0020000000000000))
+ {
+ if (x + x > y)
+ {
+ x -= y;
+ ++cquo;
+ if (x + x >= y)
+ {
+ x -= y;
+ ++cquo;
+ }
+ }
+ }
+ else
+ {
+ double y_half = 0.5 * y;
+ if (x > y_half)
+ {
+ x -= y;
+ ++cquo;
+ if (x >= y_half)
+ {
+ x -= y;
+ ++cquo;
+ }
+ }
+ }
+
+ *quo = qs ? -cquo : cquo;
+
+ if (sx)
+ x = -x;
+ return x;
+}
+weak_alias (__remquo, remquo)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__remquo, __remquol)
+weak_alias (__remquo, remquol)
+#endif