Copyright (c) 2001 Marc Espie <espie@openbsd.org>
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$FreeBSD: releng/11.0/lib/libopenbsd/ohash_interval.3 269250 2014-07-29 19:46:13Z joel $
.Dd June 5, 2013 .Dt OHASH_INTERVAL 3 .Os .Sh NAME .Nm ohash_interval , .Nm ohash_create_entry , .Nm ohash_qlookup , .Nm ohash_qlookupi .Nd helper functions for open hashing .Sh SYNOPSIS n stdint.h n stddef.h n ohash.h .Ft uint32_t .Fn ohash_interval "const char *start" "const char **pend" .Ft "void *" .Fn ohash_create_entry "struct ohash_info *info" "const char *start" "const char **pend" .Ft "unsigned int" .Fn ohash_qlookupi "struct ohash *h" "const char *start" "const char **pend" .Ft "unsigned int" .Fn ohash_qlookup "struct ohash *h" "const char *start" .Sh DESCRIPTION These functions are commonly used to simplify open hashing usage, and use similar conventions. They operate indifferently on NUL-terminated strings
o by setting .Fa *pend = .Dv NULL
c or memory ranges
o delimited by .Fa start and .Fa *pend
c . For NUL-terminated strings, as a side effect, those functions set .Fa *pend to the terminating NUL byte.
p .Fn ohash_interval is a simple hashing function that yields good results on common data sets.
p .Fn ohash_create_entry can be used to create a new record with a given key. In that case, the alloc field of .Fa info should point to a .Xr malloc 3 Ns -like function to allocate the storage: d -literal -offset indent p = (*info->alloc)(sz, info->data); .Ed
p .Fn ohash_qlookupi is a wrapper function that simply calls .Fn ohash_interval and .Fn ohash_lookup_interval .
p .Fn ohash_qlookup is a variation on .Fn ohash_qlookupi designed for NUL-terminated strings. .Sh SEE ALSO .Xr ohash_init 3 .Sh STANDARDS Those functions are completely non-standard and should be avoided in portable programs. .Sh HISTORY Those functions were designed and written for .Ox .Xr make 1 by Marc Espie in 1999.