/* $NetBSD: popcount64.c,v 1.8 2015/05/29 19:39:41 matt Exp $ */
/*-
* Copyright (c) 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Joerg Sonnenberger.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``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
* COPYRIGHT HOLDERS OR CONTRIBUTORS 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.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: popcount64.c,v 1.8 2015/05/29 19:39:41 matt Exp $");
#ifndef popcount64 // might be defined to use a __builtin
/*
* If uint64_t is larger than size_t, the follow assumes that
* splitting into 32bit halves is faster.
*
* The native pocount64 version is based on the same ideas as popcount32(3),
* see popcount32.c for comments.
*/
#if SIZE_MAX < 0xffffffffffffffffULL
unsigned int
popcount64(uint64_t v)
{
return popcount32((uint32_t)(v >> 32)) +
popcount32((uint32_t)(v & 0xffffffffULL));
}
#else
unsigned int
popcount64(uint64_t v)
{
unsigned int c;
v = v - ((v >> 1) & (uint64_t)0x5555555555555555ULL);
v = (v & (uint64_t)0x3333333333333333ULL) +
((v >> 2) & (uint64_t)0x3333333333333333ULL);
v = ((v + (v >> 4)) & (uint64_t)0x0f0f0f0f0f0f0f0fULL) *
(uint64_t)0x0101010101010101ULL;
c = (unsigned int)(v >> 56);
