/* s_ilogbl.c -- long double version of s_ilogb.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

/* ilogbl(long double x)

 * return the binary exponent of non-zero x

 * ilogbl(0) = FP_ILOGB0

 * ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)

 * ilogbl(+-Inf) = INT_MAX (no signal is raised)

 */

#include <limits.h>

#include <math.h>

#include <math_private.h>

#include <math_ldbl_opt.h>

int __ieee754_ilogbl(long double x)

{

	int64_t hx, hxs;

	int ix;

	double xhi, xlo;

	ldbl_unpack (x, &xhi, &xlo;;

	EXTRACT_WORDS64 (hx, xhi);

	hxs = hx;

	hx &= 0x7fffffffffffffffLL;

	if(hx <= 0x0010000000000000LL) {

	    if(hx==0)

		return FP_ILOGB0;	/* ilogbl(0) = FP_ILOGB0 */

	    else			/* subnormal x */

		for (ix = -1022, hx<<=11; hx>0; hx<<=1) ix -=1;

	    return ix;

	}

	else if (hx < 0x7ff0000000000000LL)

	  {

	    int hexp = (hx >> 52) - 0x3ff;

	    /* 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.  */

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

	      {

		int64_t lx;

		EXTRACT_WORDS64 (lx, xlo);

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

		  hexp--;

	      }

	    return hexp;

	  }

	else if (FP_ILOGBNAN != INT_MAX) {

	    /* ISO C99 requires ilogbl(+-Inf) == INT_MAX.  */

	    if (hx==0x7ff0000000000000LL)

		return INT_MAX;

	}

	return FP_ILOGBNAN;

}