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 __scalblnf = scalblnf
31
32 #include "libm.h"
33 #include <float.h> /* FLT_MAX, FLT_MIN */
34
35 static const float twom25f = 2.98023223876953125e-8F;
36 #if defined(__x86)
37 static const float two23f = 8388608.0F;
38 #else
39 /*
40 * v: a non-zero subnormal |x|; returns [-22, 0]
41 */
42 static int
ilogbf_biased(unsigned v)43 ilogbf_biased(unsigned v) {
44 int r = -22;
45
46 if (v & 0xffff0000)
47 r += 16, v >>= 16;
48 if (v & 0xff00)
49 r += 8, v >>= 8;
50 if (v & 0xf0)
51 r += 4, v >>= 4;
52 v <<= 1;
53 return (r + ((0xffffaa50 >> v) & 0x3));
54 }
55 #endif /* defined(__x86) */
56
57 float
scalblnf(float x,long n)58 scalblnf(float x, long n) {
59 int *px = (int *) &x, ix, k;
60
61 ix = *px & ~0x80000000;
62 k = ix >> 23;
63 if (k == 0xff)
64 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
65 return (ix > 0x7f800000 ? x * x : x);
66 #else
67 return (x + x);
68 #endif
69 if (ix == 0 || n == 0)
70 return (x);
71 if (k == 0) {
72 #if defined(__x86)
73 x *= two23f;
74 k = ((*px & ~0x80000000) >> 23) - 23;
75 #else
76 k = ilogbf_biased(ix);
77 *px = (*px & 0x80000000) | (ix << (-k + 1));
78 #endif
79 }
80 k += (int) n;
81 if (n > 5000 || k > 0xfe)
82 return (FLT_MAX * copysignf(FLT_MAX, x));
83 if (n < -5000 || k <= -25)
84 return (FLT_MIN * copysignf(FLT_MIN, x));
85 if (k > 0) {
86 *px = (*px & ~0x7f800000) | (k << 23);
87 return (x);
88 }
89 k += 25;
90 *px = (*px & ~0x7f800000) | (k << 23);
91 return (x * twom25f);
92 }
93