mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-24 22:10:13 +00:00
9e97f239ea
Remove the wordsize-64 implementations by merging them into the main dbl-64 directory. The second patch just moves all wordsize-64 files and removes a few wordsize-64 uses in comments and Implies files. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
61 lines
1.8 KiB
C
61 lines
1.8 KiB
C
/*
|
|
* ====================================================
|
|
* 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
/*
|
|
* scalbn (double x, int n)
|
|
* scalbn(x,n) returns x* 2**n computed by exponent
|
|
* manipulation rather than by actually performing an
|
|
* exponentiation or a multiplication.
|
|
*/
|
|
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
static const double
|
|
two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
|
|
twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
|
|
huge = 1.0e+300,
|
|
tiny = 1.0e-300;
|
|
|
|
double
|
|
__scalbln (double x, long int n)
|
|
{
|
|
int64_t ix;
|
|
int64_t k;
|
|
EXTRACT_WORDS64(ix,x);
|
|
k = (ix >> 52) & 0x7ff; /* extract exponent */
|
|
if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
|
|
if ((ix & UINT64_C(0xfffffffffffff))==0) return x; /* +-0 */
|
|
x *= two54;
|
|
EXTRACT_WORDS64(ix,x);
|
|
k = ((ix >> 52) & 0x7ff) - 54;
|
|
}
|
|
if (__builtin_expect(k==0x7ff, 0)) return x+x; /* NaN or Inf */
|
|
if (__builtin_expect(n< -50000, 0))
|
|
return tiny*copysign(tiny,x); /*underflow*/
|
|
if (__builtin_expect(n> 50000 || k+n > 0x7fe, 0))
|
|
return huge*copysign(huge,x); /* overflow */
|
|
/* Now k and n are bounded we know that k = k+n does not
|
|
overflow. */
|
|
k = k+n;
|
|
if (__builtin_expect(k > 0, 1)) /* normal result */
|
|
{INSERT_WORDS64(x,(ix&UINT64_C(0x800fffffffffffff))|(k<<52));
|
|
return x;}
|
|
if (k <= -54)
|
|
return tiny*copysign(tiny,x); /*underflow*/
|
|
k += 54; /* subnormal result */
|
|
INSERT_WORDS64(x,(ix&INT64_C(0x800fffffffffffff))|(k<<52));
|
|
return x*twom54;
|
|
}
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__scalbln, __scalblnl)
|
|
#endif
|