a36eca08bb
libopenbsd is an internal library which to bring in compatibility stuff from OpenBSD. This will allow us to bring in more OpenBSD utilities into the FreeBSD base system. We similarly use libnetbsd for bringing in stuff from NetBSD. Reviewed by: bapt Differential Revision: https://reviews.freebsd.org/D4078
96 lines
2.6 KiB
Groff
96 lines
2.6 KiB
Groff
.\" $OpenBSD: ohash_interval.3,v 1.1 2014/05/12 19:09:00 espie Exp $
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.\" Copyright (c) 2001 Marc Espie <espie@openbsd.org>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 5, 2013
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.Dt OHASH_INTERVAL 3
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.Os
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.Sh NAME
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.Nm ohash_interval ,
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.Nm ohash_create_entry ,
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.Nm ohash_qlookup ,
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.Nm ohash_qlookupi
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.Nd helper functions for open hashing
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.Sh SYNOPSIS
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.In stdint.h
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.In stddef.h
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.In ohash.h
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.Ft uint32_t
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.Fn ohash_interval "const char *start" "const char **pend"
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.Ft "void *"
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.Fn ohash_create_entry "struct ohash_info *info" "const char *start" "const char **pend"
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.Ft "unsigned int"
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.Fn ohash_qlookupi "struct ohash *h" "const char *start" "const char **pend"
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.Ft "unsigned int"
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.Fn ohash_qlookup "struct ohash *h" "const char *start"
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.Sh DESCRIPTION
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These functions are commonly used to simplify open hashing usage, and use
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similar conventions.
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They operate indifferently on NUL-terminated strings
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.Po
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by setting
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.Fa *pend
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=
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.Dv NULL
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.Pc
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or memory ranges
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.Po
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delimited by
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.Fa start
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and
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.Fa *pend
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.Pc .
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For NUL-terminated strings, as a side effect, those functions
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set
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.Fa *pend
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to the terminating NUL byte.
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.Pp
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.Fn ohash_interval
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is a simple hashing function that yields good results on common data sets.
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.Pp
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.Fn ohash_create_entry
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can be used to create a new record with a given key.
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In that case,
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the alloc field of
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.Fa info
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should point to a
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.Xr malloc 3 Ns -like
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function to allocate the storage:
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.Bd -literal -offset indent
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p = (*info->alloc)(sz, info->data);
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.Ed
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.Pp
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.Fn ohash_qlookupi
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is a wrapper function that simply calls
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.Fn ohash_interval
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and
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.Fn ohash_lookup_interval .
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.Pp
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.Fn ohash_qlookup
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is a variation on
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.Fn ohash_qlookupi
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designed for NUL-terminated strings.
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.Sh SEE ALSO
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.Xr ohash_init 3
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.Sh STANDARDS
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Those functions are completely non-standard and should be avoided in
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portable programs.
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.Sh HISTORY
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Those functions were designed and written for
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.Ox
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.Xr make 1
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by Marc Espie in 1999.
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