/* s_logbl.c -- long double version of s_logb.c.

 * Conversion to long double by Ulrich Drepper,

 * Cygnus Support, drepper@cygnus.com.

 */

/*

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

 * 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.

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

 */

/*

 * long double logbl(x)

 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.

 * Use ilogb instead.

 */

#include <math.h>

#include <math_private.h>

long double

__logbl (long double x)

{

  int32_t es, lx, ix;

  GET_LDOUBLE_WORDS (es, ix, lx, x);

  es &= 0x7fff;			/* exponent */

  if ((es | ix | lx) == 0)

    return -1.0 / fabsl (x);

  if (es == 0x7fff)

    return x * x;

  if (es == 0)			/* IEEE 754 logb */

    {

      /* POSIX specifies that denormal number is treated as

         though it were normalized.  */

      if (ix == 0)

	es = -(__builtin_clz (lx) + 32);

      else

	es = -__builtin_clz (ix);

    }

  return (long double) (es - 16383);

}

weak_alias (__logbl, logbl)