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Travis Geiselbrecht9e604862009-06-28 12:24:07 -07001/*
2 * Copyright (c) 2008 Travis Geiselbrecht
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files
6 * (the "Software"), to deal in the Software without restriction,
7 * including without limitation the rights to use, copy, modify, merge,
8 * publish, distribute, sublicense, and/or sell copies of the Software,
9 * and to permit persons to whom the Software is furnished to do so,
10 * subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22 */
23#ifndef __POW2_H
24#define __POW2_H
25
26#include <sys/types.h>
27#include <compiler.h>
28
29/* routines for dealing with power of 2 values for efficiency */
30static inline __ALWAYS_INLINE bool ispow2(uint val)
31{
32 return ((val - 1) & val) == 0;
33}
34
35static inline __ALWAYS_INLINE uint log2(uint val)
36{
37 if (!ispow2(val))
38 return 0; // undefined
39
40 return __builtin_ctz(val);
41}
42
43static inline __ALWAYS_INLINE uint valpow2(uint valp2)
44{
45 return 1 << valp2;
46}
47
48static inline __ALWAYS_INLINE uint divpow2(uint val, uint divp2)
49{
50 return val >> divp2;
51}
52
53static inline __ALWAYS_INLINE uint modpow2(uint val, uint modp2)
54{
55 return val & ((1UL << modp2) - 1);
56}
57
58
59#endif
60