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

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

 */

/*

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

 * 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

/*

 * 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>

#include <libm-alias-ldouble.h>

_Float128

__logbl (_Float128 x)

{

  int64_t lx, hx, ex;

  GET_LDOUBLE_WORDS64 (hx, lx, x);

  hx &= 0x7fffffffffffffffLL;	/* high |x| */

  if ((hx | lx) == 0)

    return -1.0 / fabsl (x);

  if (hx >= 0x7fff000000000000LL)

    return x * x;

  if ((ex = hx >> 48) == 0)	/* IEEE 754 logb */

    {

      /* POSIX specifies that denormal number is treated as

         though it were normalized.  */

      int ma;

      if (hx == 0)

	ma = __builtin_clzll (lx) + 64;

      else

	ma = __builtin_clzll (hx);

      ex -= ma - 16;

    }

  return (_Float128) (ex - 16383);

}

libm_alias_ldouble (__logb, logb)