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.\" $OpenBSD: hashinit.9,v 1.9 2016/09/24 18:59:04 tedu Exp $
.\"
.\" Copyright (c) 2001 Tobias Weingartner
.\" All rights reserved.
.\"
.\" 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.
.\" 3. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
.\"
.Dd $Mdocdate: September 24 2016 $
.Dt HASHINIT 9
.Os
.Sh NAME
.Nm hashinit ,
.Nm hashfree
.Nd kernel hashtable functions
.Sh SYNOPSIS
.In sys/systm.h
.Ft void *
.Fn hashinit "int num" "int type" "int flags" "u_long *mask"
.Ft void
.Fn hashfree "void *hash" "int num" "int type"
.Sh DESCRIPTION
The
.Fn hashinit
function is used to allocate a hashtable of a desired size given by the
.Fa num
argument.
The
.Fn hashinit
function will round this number to the next power of two, and
allocate and initialize the requested hashtable.
The
.Fa type
and
.Fa flags
arguments are passed to the
.Xr malloc 9
function unchanged.
The
.Fa mask
argument is used to pass back the mask for use with the allocated
hashing table.
.Pp
The
.Fn hashfree
function causes memory allocated by the
.Fn hashinit
function to be released.
The
.Fa num
and
.Fa type
arguments of related calls must match.
.Sh RETURN VALUES
The
.Fn hashinit
function returns a pointer to the allocated and initialized hash table.
.Sh SEE ALSO
.Xr free 9 ,
.Xr malloc 9
.Sh LIMITATIONS
The
.Fn hashinit
function currently only allocates hash tables with LIST bucket pointers
at this time.
Future enhancements to allocate QUEUE bucket pointers may be warranted.
This may necessitate an API change to accommodate.
.Sh HISTORY
The
.Nm
function first appeared in
.Bx 4.4 .
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