src/cx/hash_key.h@69a83fad8a35
src/cx/hash_key.h
Wed, 08 Jun 2022 21:33:31 +0200
- author
- Mike Becker <universe@uap-core.de>
- date
- Wed, 08 Jun 2022 21:33:31 +0200
- changeset 563
- 69a83fad8a35
- child 603
- c49104015a6b
- permissions
- -rw-r--r--
improve hash key handling
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28 /**
29 * \file hash_key.h
30 * \brief Interface for map implementations.
31 * \author Mike Becker
32 * \author Olaf Wintermann
33 * \version 3.0
34 * \copyright 2-Clause BSD License
35 */
38 #ifndef UCX_HASH_KEY_H
39 #define UCX_HASH_KEY_H
41 #include "stddef.h"
43 #ifdef __cplusplus
44 extern "C" {
45 #endif
47 /** Internal structure for a key within a hash map. */
48 struct cx_hash_key_s {
49 /** The key data. */
50 union {
51 unsigned char *bytes;
52 unsigned char const *cbytes;
53 char const *cstr;
54 char *str;
55 void *obj;
56 } data;
57 /**
58 * The key data length.
59 */
60 size_t len;
61 /** The hash value of the key data. */
62 unsigned hash;
63 };
65 /**
66 * Type for a hash key.
67 */
68 typedef struct cx_hash_key_s CxHashKey;
70 /**
71 * Computes a murmur hash-2.
72 *
73 * You need to initialize data and len in the key struct.
74 * The hash is then directly written to that struct.
75 *
76 * @param key the key, the hash shall be computed for
77 */
78 void cx_hash_murmur(CxHashKey *key);
80 /**
81 * Computes a hash key from a string.
82 *
83 * The string needs to be zero-terminated.
84 *
85 * @param str the string
86 * @return the hash key
87 */
88 __attribute__((__warn_unused_result__))
89 CxHashKey cx_hash_key_str(char const *str);
91 /**
92 * Computes a hash key from a byte array.
93 *
94 * @param bytes the array
95 * @param len the length
96 * @return the hash key
97 */
98 __attribute__((__warn_unused_result__))
99 CxHashKey cx_hash_key_bytes(
100 unsigned char const *bytes,
101 size_t len
102 );
104 /**
105 * Computes a hash key for an arbitrary object.
106 *
107 * The computation uses the in-memory representation that might not be
108 * the same on different platforms. Therefore, this hash should not be
109 * used for data exchange with different machines.
110 *
111 * @param obj a pointer to an arbitrary object
112 * @param len the length of object in memory
113 * @return the hash key
114 */
115 __attribute__((__warn_unused_result__))
116 CxHashKey cx_hash_key(
117 void *obj,
118 size_t len
119 );
121 #ifdef __cplusplus
122 } // extern "C"
123 #endif
125 #endif /* UCX_HASH_KEY_H */
