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/* s_scalbnl.c -- long double version of s_scalbn.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.
* ====================================================
*/
/*
* scalbnl (long double x, int n)
* scalbnl(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 long double
two63 = 0x1p63L,
twom64 = 0x1p-64L,
huge = 1.0e+4900L,
tiny = 1.0e-4900L;
long double
__scalblnl (long double x, long int n)
{
int32_t k,es,hx,lx;
GET_LDOUBLE_WORDS(es,hx,lx,x);
k = es&0x7fff; /* extract exponent */
if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two63;
GET_LDOUBLE_EXP(es,x);
k = (es&0x7fff) - 63;
}
if (__builtin_expect(k==0x7fff, 0)) return x+x; /* NaN or Inf */
if (__builtin_expect(n< -50000, 0))
return tiny*copysignl(tiny,x);
if (__builtin_expect(n> 50000 || k+n > 0x7ffe, 0))
return huge*copysignl(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 */
{SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;}
if (k <= -64)
return tiny*copysignl(tiny,x); /*underflow*/
k += 64; /* subnormal result */
SET_LDOUBLE_EXP(x,(es&0x8000)|k);
return x*twom64;
}
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