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 __log10l = log10l
36 * Let log10_2hi = leading 98(SPARC)/49(x86) bits of log10(2) and
37 * log10_2lo = log10(2) - log10_2hi,
38 * ivln10 = 1/log(10) rounded.
43 * LOG10(x) := n*log10_2hi + (n*log10_2lo + ivln10*log(x))
46 * For fear of destroying log10(10**n)=n, the rounding mode is
47 * set to Round-to-Nearest.
50 * log10(x) is NaN with signal if x < 0;
51 * log10(+INF) is +INF with no signal; log10(0) is -INF with signal;
52 * log10(NaN) is that NaN with no signal;
53 * log10(10**N) = N for N=0,1,...,22.
56 * The hexadecimal values are the intended ones for the following constants.
57 * The decimal values may be used, provided that the compiler will convert
58 * from decimal to binary accurately enough to produce the hexadecimal values
63 #include "longdouble.h"
66 #define __swapRD __swap87RD
68 extern enum fp_direction_type
__swapRD(enum fp_direction_type
);
70 static const long double
72 ivln10
= 4.342944819032518276511289189166050822944e-0001L,
75 log10_2hi
= 3.010299956639803653501985536422580480576e-01L,
76 log10_2lo
= 8.298635403410822349787106337291183585413e-16L;
77 #elif defined(__sparc)
78 log10_2hi
= 3.010299956639811952137388947242098603469e-01L,
79 log10_2lo
= 2.831664213089468167896664371953210945664e-31L;
81 #error Unknown Architecture!
85 log10l(long double x
) {
87 enum fp_direction_type rd
;
91 return (x
+ fabsl(x
)); /* x is +-INF or NaN */
96 rd
= __swapRD(fp_nearest
);
99 z
= y
* log10_2lo
+ ivln10
* logl(x
);
101 if (rd
!= fp_nearest
)
104 } else if (x
== zero
) /* -INF */
105 return (-one
/ zero
);
106 else /* x <0, return NaN */
107 return (zero
/ zero
);