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 <limits.h>
28#include <math.h>
29#include <math_private.h>
30
31int __ieee754_ilogbl (_Float128 x)
32{
33 int64_t hx,lx;
34 int ix;
35
36 GET_LDOUBLE_WORDS64(hx,lx,x);
37 hx &= 0x7fffffffffffffffLL;
38 if(hx <= 0x0001000000000000LL) {
39 if((hx|lx)==0)
40 return FP_ILOGB0; /* ilogbl(0) = FP_ILOGB0 */
41 else /* subnormal x */
42 if(hx==0) {
43 for (ix = -16431; lx>0; lx<<=1) ix -=1;
44 } else {
45 for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1;
46 }
47 return ix;
48 }
49 else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff;
50 else if (FP_ILOGBNAN != INT_MAX) {
51 /* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */
52 if (((hx^0x7fff000000000000LL)|lx) == 0)
53 return INT_MAX;
54 }
55 return FP_ILOGBNAN;
56}
57