lookup3.h

/*
 * lookup3.h - header file for hashing functions. 
 * 
 * 
 * This is adapted from the lru_slabhash code in unbound 1.2.1. Originally adapted
 * by Jake Montgomery for DynDNS 6-2-09. See below for original licence.
 * 
 * This implementation may have been modified to be more optimized for our
 * specific purposes.
 * 
 * ===========================================
 * ORIGINAL License from unbound 1.2.1:
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * 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.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 REGENTS OR CONTRIBUTORS 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.
 */

/**
 * \file
 *
 * This file contains header definitions for the hash functions we use.
 * The hash functions are public domain (see lookup3.c).
 */

#pragma once


#define	DNSP_HASHINIT	0xabcdef98  // Arbitrary.

/**
 * Hash key made of 4byte chunks.
 * @param k: the key, an array of uint32_t values
 * @param length: the length of the key, in uint32_ts
 * @param initval: the previous hash, or an arbitrary value
 * @return: hash value.
 */
uint32_t hashword(const uint32_t *k, size_t length, uint32_t initval = DNSP_HASHINIT);

/**
 * Hash key data.
 * @param k: the key, array of uint8_t
 * @param length: the length of the key, in uint8_ts
 * @param initval: the previous hash, or an arbitrary value
 * @return: hash value.
 */
uint32_t hashlittle(const void *k, size_t length, uint32_t initval = DNSP_HASHINIT);