/*

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

 * 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