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Commit | Line | Data |
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b93ad422 | 1 | /* $Header$ |
2 | * | |
3 | * Generic hash table routines. Uses integer keys to store char * values. | |
babbc197 | 4 | * |
5 | * (c) Copyright 1988 by the Massachusetts Institute of Technology. | |
6 | * For copying and distribution information, please see the file | |
7 | * <mit-copyright.h>. | |
b93ad422 | 8 | */ |
9 | ||
babbc197 | 10 | #include <mit-copyright.h> |
b93ad422 | 11 | #include <ctype.h> |
12 | #include "sms_app.h" | |
13 | #define NULL 0 | |
14 | ||
15 | ||
16 | /* Create a hash table. The size is just a hint, not a maximum. */ | |
17 | ||
18 | struct hash *create_hash(size) | |
19 | int size; | |
20 | { | |
21 | struct hash *h; | |
22 | ||
23 | h = (struct hash *) malloc(sizeof(struct hash)); | |
24 | h->size = size; | |
25 | h->data = (struct bucket **) malloc(size * sizeof(char *)); | |
26 | bzero(h->data, size * sizeof(char *)); | |
27 | return(h); | |
28 | } | |
29 | ||
30 | /* Lookup an object in the hash table. Returns the value associated with | |
31 | * the key, or NULL (thus NULL is not a very good value to store...) | |
32 | */ | |
33 | ||
34 | char *hash_lookup(h, key) | |
35 | struct hash *h; | |
36 | register int key; | |
37 | { | |
38 | register struct bucket *b; | |
39 | ||
40 | b = h->data[key % h->size]; | |
41 | while (b && b->key != key) | |
42 | b = b->next; | |
43 | if (b && b->key == key) | |
44 | return(b->data); | |
45 | else | |
46 | return(NULL); | |
47 | } | |
48 | ||
49 | ||
50 | /* Update an existing object in the hash table. Returns 1 if the object | |
51 | * existed, or 0 if not. | |
52 | */ | |
53 | ||
54 | int hash_update(h, key, value) | |
55 | struct hash *h; | |
56 | register int key; | |
57 | char *value; | |
58 | { | |
59 | register struct bucket *b; | |
60 | ||
61 | b = h->data[key % h->size]; | |
62 | while (b && b->key != key) | |
63 | b = b->next; | |
64 | if (b && b->key == key) { | |
65 | b->data = value; | |
66 | return(1); | |
67 | } else | |
68 | return(0); | |
69 | } | |
70 | ||
71 | ||
72 | /* Store an item in the hash table. Returns 0 if the key was not previously | |
73 | * there, or 1 if it was. | |
74 | */ | |
75 | ||
76 | int hash_store(h, key, value) | |
77 | struct hash *h; | |
78 | register int key; | |
79 | char *value; | |
80 | { | |
81 | register struct bucket *b, **p; | |
82 | ||
83 | p = &(h->data[key % h->size]); | |
84 | if (*p == NULL) { | |
85 | b = *p = (struct bucket *) malloc(sizeof(struct bucket)); | |
86 | b->next = NULL; | |
87 | b->key = key; | |
88 | b->data = value; | |
89 | return(0); | |
90 | } | |
91 | ||
92 | for (b = *p; b && b->key != key; b = *p) | |
93 | p = (struct bucket **) *p; | |
94 | if (b && b->key == key) { | |
95 | b->data = value; | |
96 | return(1); | |
97 | } | |
98 | b = *p = (struct bucket *) malloc(sizeof(struct bucket)); | |
99 | b->next = NULL; | |
100 | b->key = key; | |
101 | b->data = value; | |
102 | return(0); | |
103 | } | |
104 | ||
105 | ||
106 | /* Search through the hash table for a given value. For each piece of | |
107 | * data with that value, call the callback proc with the corresponding key. | |
108 | */ | |
109 | ||
110 | hash_search(h, value, callback) | |
111 | struct hash *h; | |
112 | register char *value; | |
113 | void (*callback)(); | |
114 | { | |
115 | register struct bucket *b, **p; | |
116 | ||
117 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
118 | for (b = *p; b; b = b->next) { | |
119 | if (b->data == value) | |
120 | (*callback)(b->key); | |
121 | } | |
122 | } | |
123 | } | |
124 | ||
125 | ||
0efcee1f | 126 | /* Step through the hash table, calling the callback proc with each key. |
127 | */ | |
128 | ||
07d9123c | 129 | hash_step(h, callback, hint) |
0efcee1f | 130 | struct hash *h; |
131 | void (*callback)(); | |
07d9123c | 132 | char *hint; |
0efcee1f | 133 | { |
134 | register struct bucket *b, **p; | |
135 | ||
136 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
137 | for (b = *p; b; b = b->next) { | |
07d9123c | 138 | (*callback)(b->key, b->data, hint); |
0efcee1f | 139 | } |
140 | } | |
141 | } | |
142 | ||
143 | ||
b93ad422 | 144 | /* Deallocate all of the memory associated with a table */ |
145 | ||
146 | hash_destroy(h) | |
147 | struct hash *h; | |
148 | { | |
149 | register struct bucket *b, **p, *b1; | |
150 | ||
151 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
152 | for (b = *p; b; b = b1) { | |
153 | b1 = b->next; | |
154 | free(b); | |
155 | } | |
156 | } | |
157 | } |