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ab05f33a | 1 | /* $Header$ |
2 | * | |
3 | * Generic hash table routines. Uses integer keys to store integer values. | |
4 | * | |
5 | * (c) Copyright 1996 by the Massachusetts Institute of Technology. | |
6 | * For copying and distribution information, please see the file | |
7 | * <mit-copyright.h>. | |
8 | */ | |
9 | ||
10 | #include <mit-copyright.h> | |
11 | #include <ctype.h> | |
12 | /* #include <moira.h> */ | |
13 | ||
14 | struct int_bucket { | |
15 | struct int_bucket *next; | |
16 | int key; | |
17 | int data; | |
18 | }; | |
19 | struct int_hash { | |
20 | int size; | |
21 | struct int_bucket **data; | |
22 | }; | |
23 | ||
24 | extern char *malloc(); | |
25 | ||
26 | #define NULL 0 | |
27 | #define int_hash_func(h, key) (key >= 0 ? (key % h->size) : (-key % h->size)) | |
28 | ||
29 | /* Create an int_hash table. The size is just a hint, not a maximum. */ | |
30 | ||
31 | struct int_hash *create_int_hash(size) | |
32 | int size; | |
33 | { | |
34 | struct int_hash *h; | |
35 | ||
36 | h = (struct int_hash *) malloc(sizeof(struct int_hash)); | |
37 | if (h == (struct int_hash *) NULL) | |
38 | return((struct int_hash *) NULL); | |
39 | h->size = size; | |
40 | h->data = (struct int_bucket **) malloc(size * sizeof(char *)); | |
41 | if (h->data == (struct int_bucket **) NULL) { | |
42 | free(h); | |
43 | return((struct int_hash *) NULL); | |
44 | } | |
45 | bzero(h->data, size * sizeof(char *)); | |
46 | return(h); | |
47 | } | |
48 | ||
49 | /* Lookup an object in the int_hash table. Returns the value associated with | |
50 | * the key, or NULL (thus NULL is not a very good value to store...) | |
51 | */ | |
52 | ||
53 | int int_hash_lookup(h, key) | |
54 | struct int_hash *h; | |
55 | register int key; | |
56 | { | |
57 | register struct int_bucket *b; | |
58 | ||
59 | b = h->data[int_hash_func(h, key)]; | |
60 | while (b && b->key != key) | |
61 | b = b->next; | |
62 | if (b && b->key == key) | |
63 | return(b->data); | |
64 | else | |
65 | return(0); | |
66 | } | |
67 | ||
68 | ||
69 | /* Update an existing object in the int_hash table. Returns 1 if the object | |
70 | * existed, or 0 if not. | |
71 | */ | |
72 | ||
73 | int int_hash_update(h, key, value) | |
74 | struct int_hash *h; | |
75 | register int key; | |
76 | int value; | |
77 | { | |
78 | register struct int_bucket *b; | |
79 | ||
80 | b = h->data[int_hash_func(h, key)]; | |
81 | while (b && b->key != key) | |
82 | b = b->next; | |
83 | if (b && b->key == key) { | |
84 | b->data = value; | |
85 | return(1); | |
86 | } else | |
87 | return(0); | |
88 | } | |
89 | ||
90 | ||
91 | /* Store an item in the int_hash table. Returns 0 if the key was not previously | |
92 | * there, 1 if it was, or -1 if we ran out of memory. | |
93 | */ | |
94 | ||
95 | int int_hash_store(h, key, value) | |
96 | struct int_hash *h; | |
97 | register int key; | |
98 | int value; | |
99 | { | |
100 | register struct int_bucket *b, **p; | |
101 | ||
102 | p = &(h->data[int_hash_func(h, key)]); | |
103 | if (*p == NULL) { | |
104 | b = *p = (struct int_bucket *) malloc(sizeof(struct int_bucket)); | |
105 | if (b == (struct int_bucket *) NULL) | |
106 | return(-1); | |
107 | b->next = NULL; | |
108 | b->key = key; | |
109 | b->data = value; | |
110 | return(0); | |
111 | } | |
112 | ||
113 | for (b = *p; b && b->key != key; b = *p) | |
114 | p = (struct int_bucket **) *p; | |
115 | if (b && b->key == key) { | |
116 | b->data = value; | |
117 | return(1); | |
118 | } | |
119 | b = *p = (struct int_bucket *) malloc(sizeof(struct int_bucket)); | |
120 | if (b == (struct int_bucket *) NULL) | |
121 | return(-1); | |
122 | b->next = NULL; | |
123 | b->key = key; | |
124 | b->data = value; | |
125 | return(0); | |
126 | } | |
127 | ||
128 | ||
129 | /* Search through the int_hash table for a given value. For each piece of | |
130 | * data with that value, call the callback proc with the corresponding key. | |
131 | */ | |
132 | ||
133 | int_hash_search(h, value, callback) | |
134 | struct int_hash *h; | |
135 | register int value; | |
136 | void (*callback)(); | |
137 | { | |
138 | register struct int_bucket *b, **p; | |
139 | ||
140 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
141 | for (b = *p; b; b = b->next) { | |
142 | if (b->data == value) | |
143 | (*callback)(b->key); | |
144 | } | |
145 | } | |
146 | } | |
147 | ||
148 | ||
149 | /* Step through the int_hash table, calling the callback proc with each key. | |
150 | */ | |
151 | ||
152 | int_hash_step(h, callback, hint) | |
153 | struct int_hash *h; | |
154 | void (*callback)(); | |
155 | char *hint; | |
156 | { | |
157 | register struct int_bucket *b, **p; | |
158 | ||
159 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
160 | for (b = *p; b; b = b->next) { | |
161 | (*callback)(b->key, b->data, hint); | |
162 | } | |
163 | } | |
164 | } | |
165 | ||
166 | ||
167 | /* Deallocate all of the memory associated with a table */ | |
168 | ||
169 | int_hash_destroy(h) | |
170 | struct int_hash *h; | |
171 | { | |
172 | register struct int_bucket *b, **p, *b1; | |
173 | ||
174 | for (p = &(h->data[h->size - 1]); p >= h->data; p--) { | |
175 | for (b = *p; b; b = b1) { | |
176 | b1 = b->next; | |
177 | free(b); | |
178 | } | |
179 | } | |
180 | } |