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 exp10l = __exp10l
31
32 #include "libm.h"
33 #include "longdouble.h"
34
35 /*
36 * exp10l(x)
37 * n = nint(x*(log10/log2)) ;
38 * exp10(x) = 10**x = exp(x*ln(10)) = exp(n*ln2+(x*ln10-n*ln2))
39 * = 2**n*exp(ln10*(x-n*log2/log10)))
40 * If x is an integer <= M then use repeat multiplication. For
41 * 10**M is the largest representable integer, where
42 * M = 10 single precision (24 bits)
43 * M = 22 double precision (53 bits)
44 * M = 48 quadruple precision (113 bits)
45 */
46
47 #define TINY 1.0e-20L /* single: 1e-5, double: 1e-10, quad: 1e-20 */
48 #define LG10OVT 4933.L /* single: 39, double: 309, quad: 4933 */
49 #define LG10UFT -4966.L /* single: -45, double: -323, quad: -4966 */
50 #define M 48
51 /* logt2hi : last 32 bits is zero for quad prec */
52 #define LOGT2HI 0.30102999566398119521373889472420986034688L
53 #define LOGT2LO 2.831664213089468167896664371953e-31L
54
55 static const long double
56 zero = 0.0L,
57 tiny = TINY * TINY,
58 one = 1.0L,
59 lg10 = 3.321928094887362347870319429489390175865e+0000L,
60 ln10 = 2.302585092994045684017991454684364207601e+0000L,
61 logt2hi = LOGT2HI,
62 logt2lo = LOGT2LO,
63 lg10ovt = LG10OVT,
64 lg10uft = LG10UFT;
65
66 long double
67 exp10l(long double x) {
68 long double t, tenp;
69 int k;
70
71 if (!finitel(x)) {
72 if (isnanl(x) || x > zero)
73 return (x + x);
74 else
75 return (zero);
76 }
77 if (fabsl(x) < tiny)
78 return (one + x);
79 if (x <= lg10ovt)
80 if (x >= lg10uft) {
81 k = (int) x;
82 tenp = 10.0L;
83 /* x is a small +integer */
84 if (0 <= k && k <= M && (long double) k == x) {
85 t = one;
86 if (k & 1)
87 t *= tenp;
88 k >>= 1;
89 while (k) {
90 tenp *= tenp;
91 if (k & 1)
92 t *= tenp;
93 k >>= 1;
94 }
95 return (t);
96 }
97 t = anintl(x * lg10);
98 return (scalbnl(expl(ln10 * ((x - t * logt2hi) -
99 t * logt2lo)), (int) t));
100 } else
101 return (scalbnl(one, -50000)); /* underflow */
102 else
103 return (scalbnl(one, 50000)); /* overflow */
104 }