83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
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/* $NetBSD: popcount64.c,v 1.5 2009/08/05 15:04:15 joerg Exp $ */
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/*-
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* Copyright (c) 2009 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Joerg Sonnenberger.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: popcount64.c,v 1.5 2009/08/05 15:04:15 joerg Exp $");
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#if !defined(_KERNEL) && !defined(_STANDALONE)
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#include <limits.h>
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#include <strings.h>
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#else
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#include <lib/libkern/libkern.h>
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#include <machine/limits.h>
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#endif
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/*
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* If uint64_t is larger than size_t, the follow assumes that
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* splitting into 32bit halfes is faster.
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*
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* The native pocount64 version is based on the same ideas as popcount32(3),
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* see popcount32.c for comments.
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*/
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#if SIZE_MAX < 0xffffffffffffffffULL
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unsigned int
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popcount64(uint64_t v)
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{
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return popcount32((uint32_t)(v >> 32)) +
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popcount32((uint32_t)(v & 0xffffffffULL));
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}
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#else
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unsigned int
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popcount64(uint64_t v)
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{
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unsigned int c;
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v = v - ((v >> 1) & 0x5555555555555555ULL);
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v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL);
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v = ((v + (v >> 4)) & 0x0f0f0f0f0f0f0f0fULL) * 0x0101010101010101ULL;
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c = v >> 56;
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return c;
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}
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#endif
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#if ULONG_MAX == 0xffffffffffffffffULL
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__strong_alias(popcountl, popcount64)
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#endif
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#if ULLONG_MAX == 0xffffffffffffffffULL
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__strong_alias(popcountll, popcount64)
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#endif
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