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Optimized nearbyint for 64-bit.

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Ulrich Drepper 2009-08-25 23:26:16 -07:00
parent e6fd9b2490
commit 77a1e0873f
2 changed files with 88 additions and 0 deletions
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@ -1,5 +1,7 @@
2009-08-25 Ulrich Drepper <drepper@redhat.com>
* sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c: New file
* sysdeps/ieee754/dbl-64/wordsize-64/s_rint.c: New file.
* sysdeps/ieee754/dbl-64/wordsize-64/s_round.c: New file.

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sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c Normal file
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/* Adapted for use as nearbyint by Ulrich Drepper <drepper@cygnus.com>. */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* rint(x)
* Return x rounded to integral value according to the prevailing
* rounding mode.
* Method:
* Using floating addition.
* Exception:
* Inexact flag raised if x not equal to rint(x).
*/
#include <fenv.h>
#include "math.h"
#include "math_private.h"
#ifdef __STDC__
static const double
#else
static double
#endif
TWO52[2]={
4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
};
#ifdef __STDC__
double __nearbyint(double x)
#else
double __nearbyint(x)
double x;
#endif
{
fenv_t env;
int64_t i0,sx;
int32_t j0;
EXTRACT_WORDS64(i0,x);
sx = (i0>>63)&1;
j0 = ((i0>>52)&0x7ff)-0x3ff;
if(j0<52) {
if(j0<0) {
if((i0&UINT64_C(0x7fffffffffffffff))==0) return x;
uint64_t i = i0 & UINT64_C(0xfffffffffffff);
i0 &= UINT64_C(0xfffe000000000000);
i0 |= (((i|-i) >> 12) & UINT64_C(0x8000000000000));
INSERT_WORDS64(x,i0);
feholdexcept (&env);
double w = TWO52[sx]+x;
double t = w-TWO52[sx];
fesetenv (&env);
EXTRACT_WORDS64(i0,t);
INSERT_WORDS64(t,(i0&UINT64_C(0x7fffffffffffffff))|(sx<<63));
return t;
} else {
uint64_t i = UINT64_C(0x000fffffffffffff)>>j0;
if((i0&i)==0) return x; /* x is integral */
i>>=1;
if((i0&i)!=0)
i0 = (i0&(~i))|(UINT64_C(0x4000000000000)>>j0);
}
} else {
if(j0==0x400) return x+x; /* inf or NaN */
else return x; /* x is integral */
}
INSERT_WORDS64(x,i0);
feholdexcept (&env);
double w = TWO52[sx]+x;
double t = w-TWO52[sx];
fesetenv (&env);
return t;
}
weak_alias (__nearbyint, nearbyint)
#ifdef NO_LONG_DOUBLE
strong_alias (__nearbyint, __nearbyintl)
weak_alias (__nearbyint, nearbyintl)
#endif