xref: /freebsd/sys/sys/bitcount.h (revision 81ad6265)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1982, 1986, 1991, 1993, 1994
5  *	The Regents of the University of California.  All rights reserved.
6  * (c) UNIX System Laboratories, Inc.
7  * All or some portions of this file are derived from material licensed
8  * to the University of California by American Telephone and Telegraph
9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10  * the permission of UNIX System Laboratories, Inc.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  *	@(#)types.h	8.6 (Berkeley) 2/19/95
37  * $FreeBSD$
38  */
39 
40 #ifndef _SYS_BITCOUNT_H_
41 #define	_SYS_BITCOUNT_H_
42 
43 #include <sys/_types.h>
44 
45 #ifdef __POPCNT__
46 #define	__bitcount64(x)	__builtin_popcountll((__uint64_t)(x))
47 #define	__bitcount32(x)	__builtin_popcount((__uint32_t)(x))
48 #define	__bitcount16(x)	__builtin_popcount((__uint16_t)(x))
49 #define	__bitcountl(x)	__builtin_popcountl((unsigned long)(x))
50 #define	__bitcount(x)	__builtin_popcount((unsigned int)(x))
51 #else
52 /*
53  * Population count algorithm using SWAR approach
54  * - "SIMD Within A Register".
55  */
56 static __inline __uint16_t
57 __bitcount16(__uint16_t _x)
58 {
59 
60 	_x = (_x & 0x5555) + ((_x & 0xaaaa) >> 1);
61 	_x = (_x & 0x3333) + ((_x & 0xcccc) >> 2);
62 	_x = (_x + (_x >> 4)) & 0x0f0f;
63 	_x = (_x + (_x >> 8)) & 0x00ff;
64 	return (_x);
65 }
66 
67 static __inline __uint32_t
68 __bitcount32(__uint32_t _x)
69 {
70 
71 	_x = (_x & 0x55555555) + ((_x & 0xaaaaaaaa) >> 1);
72 	_x = (_x & 0x33333333) + ((_x & 0xcccccccc) >> 2);
73 	_x = (_x + (_x >> 4)) & 0x0f0f0f0f;
74 	_x = (_x + (_x >> 8));
75 	_x = (_x + (_x >> 16)) & 0x000000ff;
76 	return (_x);
77 }
78 
79 #ifdef __LP64__
80 static __inline __uint64_t
81 __bitcount64(__uint64_t _x)
82 {
83 
84 	_x = (_x & 0x5555555555555555) + ((_x & 0xaaaaaaaaaaaaaaaa) >> 1);
85 	_x = (_x & 0x3333333333333333) + ((_x & 0xcccccccccccccccc) >> 2);
86 	_x = (_x + (_x >> 4)) & 0x0f0f0f0f0f0f0f0f;
87 	_x = (_x + (_x >> 8));
88 	_x = (_x + (_x >> 16));
89 	_x = (_x + (_x >> 32)) & 0x000000ff;
90 	return (_x);
91 }
92 
93 #define	__bitcountl(x)	__bitcount64((unsigned long)(x))
94 #else
95 static __inline __uint64_t
96 __bitcount64(__uint64_t _x)
97 {
98 
99 	return (__bitcount32(_x >> 32) + __bitcount32(_x));
100 }
101 
102 #define	__bitcountl(x)	__bitcount32((unsigned long)(x))
103 #endif
104 #define	__bitcount(x)	__bitcount32((unsigned int)(x))
105 #endif
106 
107 #endif /* !_SYS_BITCOUNT_H_ */
108