1 /* This file is taken from kazlib 1.20 (see URL
2 http://users.footprints.net/~kaz/kazlib.html)
3 Only this initial comment has been added and a protection for the original
5 The next comment gives the original copyright notice.
10 * Copyright (C) 1997 Kaz Kylheku <kaz@ashi.footprints.net>
12 * Free Software License:
14 * All rights are reserved by the author, with the following exceptions:
15 * Permission is granted to freely reproduce and distribute this software,
16 * possibly in exchange for a fee, provided that this copyright notice appears
17 * intact. Permission is also granted to adapt this software to produce
18 * derivative works, as long as the modified versions carry this copyright
19 * notice and additional notices stating that the work has been modified.
20 * This source code may be translated into executable form and incorporated
21 * into proprietary software; there is no requirement for such software to
22 * contain a copyright notice related to this source.
24 * $kkId: hash.h,v 1.22.2.7 2000/11/13 01:36:45 kaz Exp $
25 * $kkName: kazlib_1_20 $
32 #ifdef KAZLIB_SIDEEFFECT_DEBUG
37 * Blurb for inclusion into C++ translation units
44 typedef unsigned long hashcount_t;
45 #define HASHCOUNT_T_MAX ULONG_MAX
47 typedef unsigned long hash_val_t;
48 #define HASH_VAL_T_MAX ULONG_MAX
50 extern int hash_val_t_bit;
52 #ifndef HASH_VAL_T_BIT
53 #define HASH_VAL_T_BIT ((int) hash_val_t_bit)
57 * Hash chain node structure.
59 * 1. This preprocessing directive is for debugging purposes. The effect is
60 * that if the preprocessor symbol KAZLIB_OPAQUE_DEBUG is defined prior to the
61 * inclusion of this header, then the structure shall be declared as having
62 * the single member int __OPAQUE__. This way, any attempts by the
63 * client code to violate the principles of information hiding (by accessing
64 * the structure directly) can be diagnosed at translation time. However,
65 * note the resulting compiled unit is not suitable for linking.
66 * 2. This is a pointer to the next node in the chain. In the last node of a
67 * chain, this pointer is null.
68 * 3. The key is a pointer to some user supplied data that contains a unique
69 * identifier for each hash node in a given table. The interpretation of
70 * the data is up to the user. When creating or initializing a hash table,
71 * the user must supply a pointer to a function for comparing two keys,
72 * and a pointer to a function for hashing a key into a numeric value.
73 * 4. The value is a user-supplied pointer to void which may refer to
74 * any data object. It is not interpreted in any way by the hashing
76 * 5. The hashed key is stored in each node so that we don't have to rehash
77 * each key when the table must grow or shrink.
80 typedef struct hnode_t {
81 #if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG) /* 1 */
82 struct hnode_t *hash_next; /* 2 */
83 const void *hash_key; /* 3 */
84 void *hash_data; /* 4 */
85 hash_val_t hash_hkey; /* 5 */
92 * The comparison function pointer type. A comparison function takes two keys
93 * and produces a value of -1 if the left key is less than the right key, a
94 * value of 0 if the keys are equal, and a value of 1 if the left key is
95 * greater than the right key.
98 typedef int (*hash_comp_t)(const void *, const void *);
101 * The hashing function performs some computation on a key and produces an
102 * integral value of type hash_val_t based on that key. For best results, the
103 * function should have a good randomness properties in *all* significant bits
104 * over the set of keys that are being inserted into a given hash table. In
105 * particular, the most significant bits of hash_val_t are most significant to
106 * the hash module. Only as the hash table expands are less significant bits
107 * examined. Thus a function that has good distribution in its upper bits but
108 * not lower is preferrable to one that has poor distribution in the upper bits
109 * but not the lower ones.
112 typedef hash_val_t (*hash_fun_t)(const void *);
115 * allocator functions
118 typedef hnode_t *(*hnode_alloc_t)(void *);
119 typedef void (*hnode_free_t)(hnode_t *, void *);
122 * This is the hash table control structure. It keeps track of information
123 * about a hash table, as well as the hash table itself.
125 * 1. Pointer to the hash table proper. The table is an array of pointers to
126 * hash nodes (of type hnode_t). If the table is empty, every element of
127 * this table is a null pointer. A non-null entry points to the first
128 * element of a chain of nodes.
129 * 2. This member keeps track of the size of the hash table---that is, the
130 * number of chain pointers.
131 * 3. The count member maintains the number of elements that are presently
133 * 4. The maximum count is the greatest number of nodes that can populate this
134 * table. If the table contains this many nodes, no more can be inserted,
135 * and the hash_isfull() function returns true.
136 * 5. The high mark is a population threshold, measured as a number of nodes,
137 * which, if exceeded, will trigger a table expansion. Only dynamic hash
138 * tables are subject to this expansion.
139 * 6. The low mark is a minimum population threshold, measured as a number of
140 * nodes. If the table population drops below this value, a table shrinkage
141 * will occur. Only dynamic tables are subject to this reduction. No table
142 * will shrink beneath a certain absolute minimum number of nodes.
143 * 7. This is the a pointer to the hash table's comparison function. The
144 * function is set once at initialization or creation time.
145 * 8. Pointer to the table's hashing function, set once at creation or
146 * initialization time.
147 * 9. The current hash table mask. If the size of the hash table is 2^N,
148 * this value has its low N bits set to 1, and the others clear. It is used
149 * to select bits from the result of the hashing function to compute an
150 * index into the table.
151 * 10. A flag which indicates whether the table is to be dynamically resized. It
152 * is set to 1 in dynamically allocated tables, 0 in tables that are
153 * statically allocated.
156 typedef struct hash_t {
157 #if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG)
158 struct hnode_t **hash_table; /* 1 */
159 hashcount_t hash_nchains; /* 2 */
160 hashcount_t hash_nodecount; /* 3 */
161 hashcount_t hash_maxcount; /* 4 */
162 hashcount_t hash_highmark; /* 5 */
163 hashcount_t hash_lowmark; /* 6 */
164 hash_comp_t hash_compare; /* 7 */
165 hash_fun_t hash_function; /* 8 */
166 hnode_alloc_t hash_allocnode;
167 hnode_free_t hash_freenode;
169 hash_val_t hash_mask; /* 9 */
170 int hash_dynamic; /* 10 */
177 * Hash scanner structure, used for traversals of the data structure.
179 * 1. Pointer to the hash table that is being traversed.
180 * 2. Reference to the current chain in the table being traversed (the chain
181 * that contains the next node that shall be retrieved).
182 * 3. Pointer to the node that will be retrieved by the subsequent call to
186 typedef struct hscan_t {
187 #if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG)
188 hash_t *hash_table; /* 1 */
189 hash_val_t hash_chain; /* 2 */
190 hnode_t *hash_next; /* 3 */
196 extern hash_t *hash_create(hashcount_t, hash_comp_t, hash_fun_t);
197 extern void hash_set_allocator(hash_t *, hnode_alloc_t, hnode_free_t, void *);
198 extern void hash_destroy(hash_t *);
199 extern void hash_free_nodes(hash_t *);
200 extern void hash_free(hash_t *);
201 extern hash_t *hash_init(hash_t *, hashcount_t, hash_comp_t,
202 hash_fun_t, hnode_t **, hashcount_t);
203 extern void hash_insert(hash_t *, hnode_t *, const void *);
204 extern hnode_t *hash_lookup(hash_t *, const void *);
205 extern hnode_t *hash_delete(hash_t *, hnode_t *);
206 extern int hash_alloc_insert(hash_t *, const void *, void *);
207 extern void hash_delete_free(hash_t *, hnode_t *);
209 extern void hnode_put(hnode_t *, void *);
210 extern void *hnode_get(hnode_t *);
211 extern const void *hnode_getkey(hnode_t *);
212 extern hashcount_t hash_count(hash_t *);
213 extern hashcount_t hash_size(hash_t *);
215 extern int hash_isfull(hash_t *);
216 extern int hash_isempty(hash_t *);
218 extern void hash_scan_begin(hscan_t *, hash_t *);
219 extern hnode_t *hash_scan_next(hscan_t *);
220 extern hnode_t *hash_scan_delete(hash_t *, hnode_t *);
221 extern void hash_scan_delfree(hash_t *, hnode_t *);
223 extern int hash_verify(hash_t *);
225 extern hnode_t *hnode_create(void *);
226 extern hnode_t *hnode_init(hnode_t *, void *);
227 extern void hnode_destroy(hnode_t *);
229 #if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG)
230 #ifdef KAZLIB_SIDEEFFECT_DEBUG
231 #define hash_isfull(H) (SFX_CHECK(H)->hash_nodecount == (H)->hash_maxcount)
233 #define hash_isfull(H) ((H)->hash_nodecount == (H)->hash_maxcount)
235 #define hash_isempty(H) ((H)->hash_nodecount == 0)
236 #define hash_count(H) ((H)->hash_nodecount)
237 #define hash_size(H) ((H)->hash_nchains)
238 #define hnode_get(N) ((N)->hash_data)
239 #define hnode_getkey(N) ((N)->hash_key)
240 #define hnode_put(N, V) ((N)->hash_data = (V))