Subversion Repositories HelenOS

Rev

Rev 1702 | Rev 1787 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
771 palkovsky 1
/*
2
 * Copyright (C) 2006 Ondrej 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
 
1702 cejka 29
 /** @addtogroup generic   
30
 * @{
31
 */
32
/** @file
33
 */
34
 
771 palkovsky 35
#ifndef _BITOPS_H_
36
#define _BITOPS_H_
37
 
38
#include <typedefs.h>
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
 */
1780 jermar 45
static inline int fnzb32(uint32_t arg)
771 palkovsky 46
{
47
    int n = 0;
48
 
772 palkovsky 49
    if (arg >> 16) { arg >>= 16;n += 16;}
50
    if (arg >> 8) { arg >>= 8; n += 8;}
51
    if (arg >> 4) { arg >>= 4; n += 4;}
52
    if (arg >> 2) { arg >>= 2; n+=2;}
53
    if (arg >> 1) { arg >>= 1; n+=1;}
771 palkovsky 54
    return n;
55
}
56
 
1780 jermar 57
static inline int fnzb64(uint64_t arg)
771 palkovsky 58
{
59
    int n = 0;
60
 
772 palkovsky 61
    if (arg >> 32) { arg >>= 32;n += 32;}
1780 jermar 62
    return n + fnzb32((uint32_t) arg);
771 palkovsky 63
}
64
 
65
#define fnzb(x) fnzb32(x)
66
 
67
#endif
1702 cejka 68
 
69
 /** @}
70
 */
71