Subversion Repositories HelenOS

Rev

Rev 3022 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
771 palkovsky 1
/*
2071 jermar 2
 * Copyright (c) 2006 Ondrej Palkovsky
771 palkovsky 3
 * All rights reserved.
4
 *
5
 * Redistribution and use in source and binary forms, with or without
6
 * modification, are permitted provided that the following conditions
7
 * are met:
8
 *
9
 * - Redistributions of source code must retain the above copyright
10
 *   notice, this list of conditions and the following disclaimer.
11
 * - Redistributions in binary form must reproduce the above copyright
12
 *   notice, this list of conditions and the following disclaimer in the
13
 *   documentation and/or other materials provided with the distribution.
14
 * - The name of the author may not be used to endorse or promote products
15
 *   derived from this software without specific prior written permission.
16
 *
17
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
 */
28
 
4668 trochtova 29
/** @addtogroup generic
1702 cejka 30
 * @{
31
 */
32
/** @file
33
 */
34
 
2015 jermar 35
#ifndef LIBC_BITOPS_H_
36
#define LIBC_BITOPS_H_
771 palkovsky 37
 
2541 jermar 38
#include <sys/types.h>
771 palkovsky 39
 
40
 
1310 jermar 41
/** Return position of first non-zero bit from left (i.e. [log_2(arg)]).
771 palkovsky 42
 *
43
 * If number is zero, it returns 0
44
 */
4668 trochtova 45
static inline unsigned int fnzb32(uint32_t arg)
771 palkovsky 46
{
4668 trochtova 47
    unsigned int n = 0;
48
 
2004 decky 49
    if (arg >> 16) {
50
        arg >>= 16;
51
        n += 16;
52
    }
53
 
54
    if (arg >> 8) {
55
        arg >>= 8;
56
        n += 8;
57
    }
58
 
59
    if (arg >> 4) {
60
        arg >>= 4;
61
        n += 4;
62
    }
63
 
64
    if (arg >> 2) {
65
        arg >>= 2;
66
        n += 2;
67
    }
68
 
69
    if (arg >> 1) {
70
        arg >>= 1;
71
        n += 1;
72
    }
73
 
771 palkovsky 74
    return n;
75
}
76
 
4668 trochtova 77
static inline unsigned int fnzb64(uint64_t arg)
771 palkovsky 78
{
4668 trochtova 79
    unsigned int n = 0;
80
 
2004 decky 81
    if (arg >> 32) {
82
        arg >>= 32;
83
        n += 32;
84
    }
85
 
4668 trochtova 86
    return (n + fnzb32((uint32_t) arg));
771 palkovsky 87
}
88
 
4668 trochtova 89
static inline unsigned int fnzb(size_t arg)
90
{
91
    return fnzb64(arg);
92
}
771 palkovsky 93
 
94
#endif
1702 cejka 95
 
1819 decky 96
/** @}
1702 cejka 97
 */