1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 */
25 /*
26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
28 */
29
30 #pragma weak __ilogbl = ilogbl
31
32 #include "libm.h"
33 #include "xpg6.h" /* __xpg6 */
34
35 #if defined(__sparc)
36 #define ISNORMALL(k, x) (k != 0x7fff) /* assuming k != 0 */
37 #define X86PDNRM(k, x)
38 #define XSCALE_OFFSET 0x406f /* 0x3fff + 112 */
39 static const long double xscale = 5192296858534827628530496329220096.0L;
40 /* 2^112 */
41 #elif defined(__x86)
42 /*
43 * if pseudo-denormal, replace by the equivalent normal
44 */
45 #define X86PDNRM(k, x) if (k == 0 && (((int *) &x)[1] & 0x80000000) != 0) \
46 ((int *) &x)[2] |= k = 1
47 #if defined(HANDLE_UNSUPPORTED) /* assuming k != 0 */
48 #define ISNORMALL(k, x) (k != 0x7fff && (((int *) &x)[1] & 0x80000000) != 0)
49 #else
50 #define ISNORMALL(k, x) (k != 0x7fff)
51 #endif
52 #define XSCALE_OFFSET 0x403e /* 0x3fff + 63 */
53 static const long double xscale = 9223372036854775808.0L; /* 2^63 */
54 #endif
55
56 static int
raise_invalid(int v)57 raise_invalid(int v) { /* SUSv3 requires ilogbl(0,+/-Inf,NaN) raise invalid */
58 #ifndef lint
59 if ((__xpg6 & _C99SUSv3_ilogb_0InfNaN_raises_invalid) != 0) {
60 static const double zero = 0.0;
61 volatile double dummy;
62
63 dummy = zero / zero;
64 }
65 #endif
66 return (v);
67 }
68
69 int
ilogbl(long double x)70 ilogbl(long double x) {
71 int k = XBIASED_EXP(x);
72
73 X86PDNRM(k, x);
74 if (k == 0) {
75 if (ISZEROL(x))
76 return (raise_invalid(0x80000001));
77 else {
78 x *= xscale; /* scale up by 2^112 or 2^63 */
79 return (XBIASED_EXP(x) - XSCALE_OFFSET);
80 }
81 } else if (ISNORMALL(k, x))
82 return (k - 0x3fff);
83 else
84 return (raise_invalid(0x7fffffff));
85 }
86