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.
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.
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]
23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
30 #pragma weak __ilogb = ilogb
33 #include "xpg6.h" /* __xpg6 */
36 static const double two52
= 4503599627370496.0;
39 * v: high part of a non-zero subnormal |x|; w: low part of |x|
42 ilogb_subnormal(unsigned v
, unsigned w
) {
56 return (r
+ ((0xffffaa50 >> v
) & 0x3));
58 #endif /* defined(__x86) */
61 raise_invalid(int v
) { /* SUSv3 requires ilogb(0,+/-Inf,NaN) raise invalid */
63 if ((__xpg6
& _C99SUSv3_ilogb_0InfNaN_raises_invalid
) != 0) {
64 static const double zero
= 0.0;
65 volatile double dummy
;
75 int *px
= (int *) &x
, k
= px
[HIWORD
] & ~0x80000000;
78 if ((px
[LOWORD
] | k
) == 0)
79 return (raise_invalid(0x80000001));
83 return (((px
[HIWORD
] & 0x7ff00000) >> 20) - 1075);
85 return (ilogb_subnormal(k
, px
[LOWORD
]));
88 } else if (k
< 0x7ff00000)
89 return ((k
>> 20) - 1023);
91 return (raise_invalid(0x7fffffff));