/* 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.

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

 */

/*

 * 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 <math_ldbl_opt.h>

#include <fix-int-fp-convert-zero.h>

long double

__logbl (long double x)

{

  int64_t hx, hxs, rhx;

  double xhi, xlo;

  ldbl_unpack (x, &xhi, &xlo;;

  EXTRACT_WORDS64 (hx, xhi);

  hxs = hx;

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

  if (hx == 0)

    return -1.0 / fabs (x);

  if (hx >= 0x7ff0000000000000LL)

    return x * x;

  if (__glibc_unlikely ((rhx = hx >> 52) == 0))

    {

      /* POSIX specifies that denormal number is treated as

         though it were normalized.  */

      rhx -= __builtin_clzll (hx) - 12;

    }

  else if ((hx & 0x000fffffffffffffLL) == 0)

    {

      /* If the high part is a power of 2, and the low part is nonzero

	 with the opposite sign, the low part affects the

	 exponent.  */

      int64_t lx;

      EXTRACT_WORDS64 (lx, xlo);

      if ((hxs ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0)

	rhx--;

    }

  if (FIX_INT_FP_CONVERT_ZERO && rhx == 1023)

    return 0.0L;

  return (long double) (rhx - 1023);

}

#ifndef __logbl

long_double_symbol (libm, __logbl, logbl);

#endif