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fls.c
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/*-------------------------------------------------------------------------
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*
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* fls.c
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* finds the last (most significant) bit that is set
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*
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* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
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*
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*
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* IDENTIFICATION
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* src/port/fls.c
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*
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* This file was taken from FreeBSD to provide an implementation of fls()
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* for platforms that lack it. Note that the operating system's version may
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* be substantially more efficient than ours, since some platforms have an
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* assembly instruction that does exactly this.
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*
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* The FreeBSD copyright terms follow.
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*/
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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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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* 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 the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT 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 "
c.h
"
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/*
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* Find Last Set bit
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*/
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int
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fls
(
int
mask)
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{
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int
bit
;
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if
(mask == 0)
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return
(0);
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for
(
bit
= 1; mask != 1;
bit
++)
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mask = (
unsigned
int
) mask >> 1;
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return
(
bit
);
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}
c.h
fls
int fls(int mask)
Definition:
fls.c:55
bit
Datum bit(PG_FUNCTION_ARGS)
Definition:
varbit.c:391
src
port
fls.c
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