/* s_scalbnl.c -- long double version of s_scalbn.c.

 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.

 */

/* @(#)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.

 * ====================================================

 */

#if defined(LIBM_SCCS) && !defined(lint)

static char rcsid[] = "$NetBSD: $";

#endif

/*

 * 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>

#include <math_ldbl_opt.h>

static const long double

twolm54 = 5.55111512312578270212e-17, /* 0x3C90000000000000, 0 */

huge   = 1.0E+300L,

tiny   = 1.0E-300L;

static const double

two54 = 1.80143985094819840000e+16, /* 0x4350000000000000 */

twom54 = 5.55111512312578270212e-17; /* 0x3C90000000000000 */

long double __scalbnl (long double x, int n)

{

	int64_t k,l,hx,lx;

	union { int64_t i; double d; } u;

	double xhi, xlo;

	ldbl_unpack (x, &xhi, &xlo;;

	EXTRACT_WORDS64 (hx, xhi);

	EXTRACT_WORDS64 (lx, xlo);

	k = (hx>>52)&0x7ff;		/* extract exponent */

	l = (lx>>52)&0x7ff;

	if (k==0) {				/* 0 or subnormal x */

	    if ((hx&0x7fffffffffffffffULL)==0) return x; /* +-0 */

	    u.i = hx;

	    u.d *= two54;

	    hx = u.i;

	    k = ((hx>>52)&0x7ff) - 54;

	}

	else if (k==0x7ff) return x+x;		/* NaN or Inf */

	if (n< -50000) return tiny*__copysignl(tiny,x); /*underflow */

	if (n> 50000 || k+n > 0x7fe)

	  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 (k > 0) {				/* normal result */

	    hx = (hx&0x800fffffffffffffULL)|(k<<52);

	    if ((lx & 0x7fffffffffffffffULL) == 0) { /* low part +-0 */

		INSERT_WORDS64 (xhi, hx);

		INSERT_WORDS64 (xlo, lx);

		x = ldbl_pack (xhi, xlo);

		return x;

	    }

	    if (l == 0) { /* low part subnormal */

		u.i = lx;

		u.d *= two54;

		lx = u.i;

		l = ((lx>>52)&0x7ff) - 54;

	    }

	    l = l + n;

	    if (l > 0)

		lx = (lx&0x800fffffffffffffULL)|(l<<52);

	    else if (l <= -54)

		lx = (lx&0x8000000000000000ULL);

	    else {

		l += 54;

		u.i = (lx&0x800fffffffffffffULL)|(l<<52);

		u.d *= twom54;

		lx = u.i;

	    }

	    INSERT_WORDS64 (xhi, hx);

	    INSERT_WORDS64 (xlo, lx);

	    x = ldbl_pack (xhi, xlo);

	    return x;

	}

	if (k <= -54)

	  return tiny*__copysignl(tiny,x); 	/*underflow*/

	k += 54;				/* subnormal result */

	lx &= 0x8000000000000000ULL;

	hx &= 0x800fffffffffffffULL;

	INSERT_WORDS64 (xhi, hx|(k<<52));

	INSERT_WORDS64 (xlo, lx);

	x = ldbl_pack (xhi, xlo);

	return x*twolm54;

}