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