1 /* $NetBSD: popcount64.c,v 1.8 2015/05/29 19:39:41 matt Exp $ */
2 /*-
3 * Copyright (c) 2009 The NetBSD Foundation, Inc.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to The NetBSD Foundation
7 * by Joerg Sonnenberger.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
24 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
30 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __RCSID("$NetBSD: popcount64.c,v 1.8 2015/05/29 19:39:41 matt Exp $");
36
37 #if !defined(_KERNEL) && !defined(_STANDALONE)
38 #include <limits.h>
39 #include <stdint.h>
40 #include <strings.h>
41 #else
42 #include <lib/libkern/libkern.h>
43 #include <machine/limits.h>
44 #endif
45
46 #ifndef popcount64 // might be defined to use a __builtin
47
48 /*
49 * If uint64_t is larger than size_t, the follow assumes that
50 * splitting into 32bit halves is faster.
51 *
52 * The native pocount64 version is based on the same ideas as popcount32(3),
53 * see popcount32.c for comments.
54 */
55
56 #if SIZE_MAX < 0xffffffffffffffffULL
57 unsigned int
popcount64(uint64_t v)58 popcount64(uint64_t v)
59 {
60 return popcount32((uint32_t)(v >> 32)) +
61 popcount32((uint32_t)(v & 0xffffffffULL));
62 }
63 #else
64 unsigned int
popcount64(uint64_t v)65 popcount64(uint64_t v)
66 {
67 unsigned int c;
68
69 v = v - ((v >> 1) & (uint64_t)0x5555555555555555ULL);
70 v = (v & (uint64_t)0x3333333333333333ULL) +
71 ((v >> 2) & (uint64_t)0x3333333333333333ULL);
72 v = ((v + (v >> 4)) & (uint64_t)0x0f0f0f0f0f0f0f0fULL) *
73 (uint64_t)0x0101010101010101ULL;
74 c = (unsigned int)(v >> 56);
75
76 return c;
77 }
78 #endif
79
80 #if ULONG_MAX == 0xffffffffffffffffULL
81 __strong_alias(popcountl, popcount64)
82 #endif
83
84 #if ULLONG_MAX == 0xffffffffffffffffULL
85 __strong_alias(popcountll, popcount64)
86 #endif
87
88 #if defined(__minix)
89 __strong_alias(popcountti2, popcount64)
90 #endif /* defined(__minix) */
91
92 #endif /* !popcount64 */
93