minix/usr.bin/m4/lib/ohash_interval.c

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/* $OpenBSD: ohash_interval.c,v 1.3 2006/01/16 15:52:25 espie Exp $ */
/* ex:ts=8 sw=4:
*/
/* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "ohash_int.h"
uint32_t
ohash_interval(const char *s, const char **e)
{
uint32_t k;
if (!*e)
*e = s + strlen(s);
if (s == *e)
k = 0;
else
k = *s++;
while (s != *e)
k = ((k << 2) | (k >> 30)) ^ *s++;
return k;
}