WebSVN – HelenOS – Diff – /trunk/kernel/generic/include/bitops.h


/*
 * Copyright (c) 2006 Ondrej Palkovsky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/** @addtogroup generic
 * @{
 */
/** @file
 */
 
#ifndef KERN_BITOPS_H_
#define KERN_BITOPS_H_
 
#include <typedefs.h>
 
 
/** Return position of first non-zero bit from left (i.e. [log_2(arg)]).
 *
 * If number is zero, it returns 0
 */
static inline int fnzb32(uint32_t arg)
{
    int n = 0;
 
    if (arg >> 16) {
        arg >>= 16;
        n += 16;
    }
   
    if (arg >> 8) {
        arg >>= 8;
        n += 8;
    }
   
    if (arg >> 4) {
        arg >>= 4;
        n += 4;
    }
   
    if (arg >> 2) {
        arg >>= 2;
        n += 2;
    }
   
    if (arg >> 1) {
        arg >>= 1;
        n += 1;
    }
   
    return n;
}
 
static inline int fnzb64(uint64_t arg)
{
    int n = 0;
 
    if (arg >> 32) {
        arg >>= 32;
        n += 32;
    }
   
    return n + fnzb32((uint32_t) arg);
}
 
#define fnzb(x) fnzb32(x)
 
#endif
 
/** @}
 */
 

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

Subversion Repositories HelenOS

(root)/trunk/kernel/generic/include/bitops.h – Rev 2004 → 2071