1/* s_ilogbl.c -- long double version of s_ilogb.c.
2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#if defined(LIBM_SCCS) && !defined(lint)
17static char rcsid[] = "NetBSD: ";
18#endif
19
20/* ilogbl(long double x)
21 * return the binary exponent of non-zero x
22 * ilogbl(0) = FP_ILOGB0
23 * ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)
24 * ilogbl(+-Inf) = INT_MAX (no signal is raised)
25 */
26
27#include <math.h>
28#include "quadmath-imp.h"
29#ifndef FP_ILOGB0
30# define FP_ILOGB0 INT_MIN
31#endif
32#ifndef FP_ILOGBNAN
33# define FP_ILOGBNAN INT_MAX
34#endif
35
36int ilogbq (__float128 x)
37{
38	int64_t hx,lx;
39	int ix;
40
41	GET_FLT128_WORDS64(hx,lx,x);
42	hx &= 0x7fffffffffffffffLL;
43	if(hx <= 0x0001000000000000LL) {
44	    if((hx|lx)==0)
45		{ errno = EDOM; feraiseexcept (FE_INVALID); return FP_ILOGB0; }	/* ilogbl(0) = FP_ILOGB0 */
46	    else			/* subnormal x */
47		if(hx==0) {
48		    for (ix = -16431; lx>0; lx<<=1) ix -=1;
49		} else {
50		    for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1;
51		}
52	    return ix;
53	}
54	else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff;
55	else if (FP_ILOGBNAN != INT_MAX) {
56	    /* ISO C99 requires ilogbl(+-Inf) == INT_MAX.  */
57	    if (((hx^0x7fff000000000000LL)|lx) == 0)
58		{ errno = EDOM; feraiseexcept (FE_INVALID); return INT_MAX; }
59	}
60	{ errno = EDOM; feraiseexcept (FE_INVALID); return FP_ILOGBNAN; }
61}
62