/*
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* hashkey.h -- definition of hash key type and helper functions
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*
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* Copyright (C) 2010-2011 Olaf Bergmann <bergmann@tzi.org>
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*
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* This file is part of the CoAP library libcoap. Please see README for terms
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* of use.
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*/
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/**
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* @file hashkey.h
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* @brief definition of hash key type and helper functions
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*/
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#ifndef _COAP_HASHKEY_H_
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#define _COAP_HASHKEY_H_
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#include "str.h"
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typedef unsigned char coap_key_t[4];
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#ifndef coap_hash
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/**
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* Calculates a fast hash over the given string @p s of length @p len and stores
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* the result into @p h. Depending on the exact implementation, this function
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* cannot be used as one-way function to check message integrity or simlar.
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*
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* @param s The string used for hash calculation.
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* @param len The length of @p s.
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* @param h The result buffer to store the calculated hash key.
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*/
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void coap_hash_impl(const unsigned char *s, unsigned int len, coap_key_t h);
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#define coap_hash(String,Length,Result) \
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coap_hash_impl((String),(Length),(Result))
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/* This is used to control the pre-set hash-keys for resources. */
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#define __COAP_DEFAULT_HASH
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#else
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#undef __COAP_DEFAULT_HASH
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#endif /* coap_hash */
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/**
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* Calls coap_hash() with given @c str object as parameter.
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*
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* @param Str Must contain a pointer to a coap string object.
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* @param H A coap_key_t object to store the result.
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*
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* @hideinitializer
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*/
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#define coap_str_hash(Str,H) { \
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assert(Str); \
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memset((H), 0, sizeof(coap_key_t)); \
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coap_hash((Str)->s, (Str)->length, (H)); \
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}
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#endif /* _COAP_HASHKEY_H_ */
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