1 /* ilogbq.c -- __float128 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)
17 static char rcsid[] = "$NetBSD: $";
18 #endif
19
20 /* ilogbl(__float128 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 <errno.h>
30 #include "quadmath-imp.h"
31
32 #ifndef FP_ILOGB0
33 # define FP_ILOGB0 INT_MIN
34 #endif
35 #ifndef FP_ILOGBNAN
36 # define FP_ILOGBNAN INT_MAX
37 #endif
38
39 int
ilogbq(__float128 x)40 ilogbq (__float128 x)
41 {
42 int64_t hx,lx;
43 int ix;
44
45 GET_FLT128_WORDS64(hx,lx,x);
46 hx &= 0x7fffffffffffffffLL;
47 if(hx <= 0x0001000000000000LL) {
48 if((hx|lx)==0)
49 {
50 errno = EDOM;
51 #ifdef USE_FENV_H
52 feraiseexcept (FE_INVALID);
53 #endif
54 return FP_ILOGB0; /* ilogbl(0) = FP_ILOGB0 */
55 }
56 else /* subnormal x */
57 if(hx==0) {
58 for (ix = -16431; lx>0; lx<<=1) ix -=1;
59 } else {
60 for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1;
61 }
62 return ix;
63 }
64 else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff;
65 else if (FP_ILOGBNAN != INT_MAX) {
66 /* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */
67 if (((hx^0x7fff000000000000LL)|lx) == 0)
68 {
69 errno = EDOM;
70 #ifdef USE_FENV_H
71 feraiseexcept (FE_INVALID);
72 #endif
73 return INT_MAX;
74 }
75 }
76
77 errno = EDOM;
78 #ifdef USE_FENV_H
79 feraiseexcept (FE_INVALID);
80 #endif
81 return FP_ILOGBNAN;
82 }
83