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 __scalblnl = scalblnl
31
32 #include "libm.h"
33 #include <float.h> /* LDBL_MAX, LDBL_MIN */
34
35 #if defined(__sparc)
36 #define XSET_EXP(k, x) ((int *) &x)[0] = (((int *) &x)[0] & ~0x7fff0000) | \
37 (k << 16)
38 #define ISINFNANL(k, x) (k == 0x7fff)
39 #define XTWOT_OFFSET 113
40 static const long double xtwot = 10384593717069655257060992658440192.0L,
41 /* 2^113 */
42 twomtm1 = 4.814824860968089632639944856462318296E-35L; /* 2^-114 */
43 #elif defined(__x86)
44 #define XSET_EXP(k, x) ((int *) &x)[2] = (((int *) &x)[2] & ~0x7fff) | k
45 #if defined(HANDLE_UNSUPPORTED)
46 #define ISINFNANL(k, x) (k == 0x7fff || \
47 (k != 0 && (((int *) &x)[1] & 0x80000000) == 0))
48 #else
49 #define ISINFNANL(k, x) (k == 0x7fff)
50 #endif
51 #define XTWOT_OFFSET 64
52 static const long double xtwot = 18446744073709551616.0L, /* 2^64 */
53 twomtm1 = 2.7105054312137610850186E-20L; /* 2^-65 */
54 #endif
55
56 long double
scalblnl(long double x,long n)57 scalblnl(long double x, long n) {
58 int k = XBIASED_EXP(x);
59
60 if (ISINFNANL(k, x))
61 return (x + x);
62 if (ISZEROL(x) || n == 0)
63 return (x);
64 if (k == 0) {
65 x *= xtwot;
66 k = XBIASED_EXP(x) - XTWOT_OFFSET;
67 }
68 k += (int) n;
69 if (n > 50000 || k > 0x7ffe)
70 return (LDBL_MAX * copysignl(LDBL_MAX, x));
71 if (n < -50000 || k <= -XTWOT_OFFSET - 1)
72 return (LDBL_MIN * copysignl(LDBL_MIN, x));
73 if (k > 0) {
74 XSET_EXP(k, x);
75 return (x);
76 }
77 k += XTWOT_OFFSET + 1;
78 XSET_EXP(k, x);
79 return (x * twomtm1);
80 }
81