1 /* $NetBSD: popcount64.c,v 1.6 2011/08/21 21:25:04 dholland 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 1.6 2011/08/21 21:25:04 dholland 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 /* 47 * If uint64_t is larger than size_t, the follow assumes that 48 * splitting into 32bit halfes is faster. 49 * 50 * The native pocount64 version is based on the same ideas as popcount32(3), 51 * see popcount32.c for comments. 52 */ 53 54 #if SIZE_MAX < 0xffffffffffffffffULL 55 unsigned int 56 popcount64(uint64_t v) 57 { 58 return popcount32((uint32_t)(v >> 32)) + 59 popcount32((uint32_t)(v & 0xffffffffULL)); 60 } 61 #else 62 unsigned int 63 popcount64(uint64_t v) 64 { 65 unsigned int c; 66 67 v = v - ((v >> 1) & 0x5555555555555555ULL); 68 v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL); 69 v = ((v + (v >> 4)) & 0x0f0f0f0f0f0f0f0fULL) * 0x0101010101010101ULL; 70 c = v >> 56; 71 72 return c; 73 } 74 #endif 75 76 #if ULONG_MAX == 0xffffffffffffffffULL 77 __strong_alias(popcountl, popcount64) 78 #endif 79 80 #if ULLONG_MAX == 0xffffffffffffffffULL 81 __strong_alias(popcountll, popcount64) 82 #endif 83 84