| 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 |
| 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 |
| 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 | #endif /* !popcount64 */ |
| 89 | |