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Add optimized 64-bit frexp

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Ulrich Drepper 2011-10-17 22:30:44 -04:00
parent 228a984d54
commit 1004d1821e
2 changed files with 69 additions and 0 deletions
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2011-10-17 Ulrich Drepper <drepper@gmail.com>
* sysdeps/ieee754/dbl-64/wordsize-64/s_frexp.c: New file.
* sysdeps/x86_64/fpu/math_private.h: Relax asm requirements for
recently added interfaces.
* sysdeps/x86_64/fpu/bits/mathinline.h: Likewise.

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sysdeps/ieee754/dbl-64/wordsize-64/s_frexp.c Normal file
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/* Copyright (C) 2011 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
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 <inttypes.h>
#include "math.h"
#include "math_private.h"
/*
* for non-zero, finite x
* x = frexp(arg,&exp);
* return a double fp quantity x such that 0.5 <= |x| <1.0
* and the corresponding binary exponent "exp". That is
* arg = x*2^exp.
* If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
* with *exp=0.
*/
double
__frexp (double x, int *eptr)
{
int64_t ix;
EXTRACT_WORDS64 (ix, x);
int32_t ex = 0x7ff & (ix >> 52);
int e = 0;
if (__builtin_expect (ex != 0x7ff && x != 0.0, 1))
{
/* Not zero and finite. */
e = ex - 1022;
if (__builtin_expect (ex == 0, 0))
{
/* Subnormal. */
x *= 0x1p54;
EXTRACT_WORDS64 (ix, x);
ex = 0x7ff & (ix >> 52);
e = ex - 1022 - 54;
}
ix = (ix & INT64_C (0x800fffffffffffff)) | INT64_C (0x3fe0000000000000);
INSERT_WORDS64 (x, ix);
}
*eptr = e;
return x;
}
weak_alias (__frexp, frexp)
#ifdef NO_LONG_DOUBLE
strong_alias (__frexp, __frexpl)
weak_alias (__frexp, frexpl)
#endif