1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/cx/hash_key.h Wed Jun 08 21:33:31 2022 +0200
1.3 @@ -0,0 +1,125 @@
1.4 +/*
1.5 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
1.6 + *
1.7 + * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
1.8 + *
1.9 + * Redistribution and use in source and binary forms, with or without
1.10 + * modification, are permitted provided that the following conditions are met:
1.11 + *
1.12 + * 1. Redistributions of source code must retain the above copyright
1.13 + * notice, this list of conditions and the following disclaimer.
1.14 + *
1.15 + * 2. Redistributions in binary form must reproduce the above copyright
1.16 + * notice, this list of conditions and the following disclaimer in the
1.17 + * documentation and/or other materials provided with the distribution.
1.18 + *
1.19 + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.20 + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.21 + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.22 + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
1.23 + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.24 + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.25 + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.26 + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.27 + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.28 + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.29 + * POSSIBILITY OF SUCH DAMAGE.
1.30 + */
1.31 +/**
1.32 + * \file hash_key.h
1.33 + * \brief Interface for map implementations.
1.34 + * \author Mike Becker
1.35 + * \author Olaf Wintermann
1.36 + * \version 3.0
1.37 + * \copyright 2-Clause BSD License
1.38 + */
1.39 +
1.40 +
1.41 +#ifndef UCX_HASH_KEY_H
1.42 +#define UCX_HASH_KEY_H
1.43 +
1.44 +#include "stddef.h"
1.45 +
1.46 +#ifdef __cplusplus
1.47 +extern "C" {
1.48 +#endif
1.49 +
1.50 +/** Internal structure for a key within a hash map. */
1.51 +struct cx_hash_key_s {
1.52 + /** The key data. */
1.53 + union {
1.54 + unsigned char *bytes;
1.55 + unsigned char const *cbytes;
1.56 + char const *cstr;
1.57 + char *str;
1.58 + void *obj;
1.59 + } data;
1.60 + /**
1.61 + * The key data length.
1.62 + */
1.63 + size_t len;
1.64 + /** The hash value of the key data. */
1.65 + unsigned hash;
1.66 +};
1.67 +
1.68 +/**
1.69 + * Type for a hash key.
1.70 + */
1.71 +typedef struct cx_hash_key_s CxHashKey;
1.72 +
1.73 +/**
1.74 + * Computes a murmur hash-2.
1.75 + *
1.76 + * You need to initialize data and len in the key struct.
1.77 + * The hash is then directly written to that struct.
1.78 + *
1.79 + * @param key the key, the hash shall be computed for
1.80 + */
1.81 +void cx_hash_murmur(CxHashKey *key);
1.82 +
1.83 +/**
1.84 + * Computes a hash key from a string.
1.85 + *
1.86 + * The string needs to be zero-terminated.
1.87 + *
1.88 + * @param str the string
1.89 + * @return the hash key
1.90 + */
1.91 +__attribute__((__warn_unused_result__))
1.92 +CxHashKey cx_hash_key_str(char const *str);
1.93 +
1.94 +/**
1.95 + * Computes a hash key from a byte array.
1.96 + *
1.97 + * @param bytes the array
1.98 + * @param len the length
1.99 + * @return the hash key
1.100 + */
1.101 +__attribute__((__warn_unused_result__))
1.102 +CxHashKey cx_hash_key_bytes(
1.103 + unsigned char const *bytes,
1.104 + size_t len
1.105 +);
1.106 +
1.107 +/**
1.108 + * Computes a hash key for an arbitrary object.
1.109 + *
1.110 + * The computation uses the in-memory representation that might not be
1.111 + * the same on different platforms. Therefore, this hash should not be
1.112 + * used for data exchange with different machines.
1.113 + *
1.114 + * @param obj a pointer to an arbitrary object
1.115 + * @param len the length of object in memory
1.116 + * @return the hash key
1.117 + */
1.118 +__attribute__((__warn_unused_result__))
1.119 +CxHashKey cx_hash_key(
1.120 + void *obj,
1.121 + size_t len
1.122 +);
1.123 +
1.124 +#ifdef __cplusplus
1.125 +} // extern "C"
1.126 +#endif
1.127 +
1.128 +#endif /* UCX_HASH_KEY_H */
