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/* @(#)s_scalbn.c 5.1 93/09/24 */
/*
* ====================================================
* 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 "fdlibm.h"
#ifdef _NEED_FLOAT64
static const __float64
two54 = _F_64(1.80143985094819840000e+16), /* 0x43500000, 0x00000000 */
twom54 = _F_64(5.55111512312578270212e-17); /* 0x3C900000, 0x00000000 */
__float64
scalbln64 (__float64 x, long int n)
{
__int32_t hx,lx;
long int k;
EXTRACT_WORDS(hx,lx,x);
k = (hx&0x7ff00000)>>20; /* extract exponent */
if (k==0) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two54;
GET_HIGH_WORD(hx,x);
k = ((hx&0x7ff00000)>>20) - 54;
if (n< -50000) return __math_uflow(hx < 0); /*underflow*/
}
if (k==0x7ff) return x+x; /* NaN or Inf */
k = k+n;
if (n> 50000 || k > 0x7fe)
return __math_oflow(hx<0); /* overflow */
if (k > 0) /* normal result */
{SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
if (k <= -54)
return __math_uflow(hx < 0); /*underflow*/
k += 54; /* subnormal result */
SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
return check_uflow(x*twom54);
}
_MATH_ALIAS_d_dj(scalbln)
#endif /* _NEED_FLOAT64 */
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