OPEN_HASH_HELPER(3) OpenBSD Programmer's Manual OPEN_HASH_HELPER(3)NAME
ohash_interval, ohash_create_entry, ohash_qlookup, ohash_qlookupi -
helper functions for open hashing
SYNOPSIS
#include <stdint.h>
#include <stddef.h>
#include <ohash.h>
u_int32_t
ohash_interval(const char *start, const char **pend);
void *
ohash_create_entry(struct ohash_info *info, const char *start, const char
**pend);
unsigned int
ohash_qlookupi(struct ohash *h, const char *start, const char **pend);
unsigned int
ohash_qlookup(struct ohash *h, const char *start);
DESCRIPTION
These functions are commonly used to simplify open hashing usage, and use
similar conventions. They operate indifferently on NUL-terminated
strings (by setting *pend = NULL) or memory ranges (delimited by start
and *pend). For NUL-terminated strings, as a side effect, those
functions set *pend to the terminating NUL byte.
ohash_interval() is a simple hashing function that yields good results on
common data sets.
ohash_create_entry() can be used to create a new record with a given key.
In that case, the alloc field of info should point to a malloc(3)-like
function to allocate the storage.
ohash_qlookupi() is a wrapper function that simply calls ohash_interval()
and ohash_lookup_interval().
ohash_qlookup() is a variation on ohash_qlookupi() designed for NUL-
terminated strings.
SEE ALSOohash_init(3)STANDARDS
Those functions are completely non-standard and should be avoided in
portable programs.
HISTORY
Those functions were designed and written for OpenBSD make(1) by Marc
Espie in 1999.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9