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 __scalbnf = scalbnf
31
32 #include "libm.h"
33 #include <float.h> /* FLT_MAX, FLT_MIN */
34 #include <stdlib.h> /* abs */
35
36 static const float twom25f = 2.98023223876953125e-8F;
37 #if defined(__x86)
38 static const float two23f = 8388608.0F;
39 #else
40 /*
41 * v: a non-zero subnormal |x|; returns [-22, 0]
42 */
43 static int
ilogbf_biased(unsigned v)44 ilogbf_biased(unsigned v) {
45 int r = -22;
46
47 if (v & 0xffff0000)
48 r += 16, v >>= 16;
49 if (v & 0xff00)
50 r += 8, v >>= 8;
51 if (v & 0xf0)
52 r += 4, v >>= 4;
53 v <<= 1;
54 return (r + ((0xffffaa50 >> v) & 0x3));
55 }
56 #endif /* defined(__x86) */
57
58 float
scalbnf(float x,int n)59 scalbnf(float x, int n) {
60 int *px = (int *) &x, ix, k;
61
62 ix = *px & ~0x80000000;
63 k = ix >> 23;
64 if (k == 0xff)
65 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
66 return (ix > 0x7f800000 ? x * x : x);
67 #else
68 return (x + x);
69 #endif
70 if (ix == 0 || n == 0)
71 return (x);
72 if (k == 0) {
73 #if defined(__x86)
74 x *= two23f;
75 k = ((*px & ~0x80000000) >> 23) - 23;
76 #else
77 k = ilogbf_biased(ix);
78 *px = (*px & 0x80000000) | (ix << (-k + 1));
79 #endif
80 }
81 if ((unsigned) abs(n) >= 131072) /* cast to unsigned for -2^31 */
82 n >>= 1; /* avoid subsequent integer overflow */
83 k += n;
84 if (k > 0xfe)
85 return (FLT_MAX * copysignf(FLT_MAX, x));
86 if (k <= -25)
87 return (FLT_MIN * copysignf(FLT_MIN, x));
88 if (k > 0) {
89 *px = (*px & ~0x7f800000) | (k << 23);
90 return (x);
91 }
92 k += 25;
93 *px = (*px & ~0x7f800000) | (k << 23);
94 return (x * twom25f);
95 }
96