3 * $Id: sym.c,v 1.9 1999/10/22 22:36:37 mdw Exp $
5 * Symbol table management
7 * (c) 1998 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.9 1999/10/22 22:36:37 mdw
34 * New test structure for symbol tables.
36 * Revision 1.8 1999/08/02 14:45:48 mdw
37 * Break low-level hashtable code out from sym.
39 * Revision 1.7 1999/06/01 09:49:08 mdw
40 * Allow things to be looked up by just their caller-supplied hashes. This
41 * actually needs to be thought through better.
43 * Revision 1.6 1999/05/26 21:08:31 mdw
44 * Rename symbols in line with newer conventions.
46 * Revision 1.5 1999/05/13 22:48:37 mdw
47 * Twiddle the extension threshold. Change `-ise' to `-ize' throughout.
49 * Revision 1.4 1999/05/06 19:51:35 mdw
50 * Reformatted the LGPL notice a little bit.
52 * Revision 1.3 1999/05/05 18:50:31 mdw
53 * Change licensing conditions to LGPL.
55 * Revision 1.2 1998/11/26 19:27:33 mdw
56 * Move SYM_NAME into the header file. Fix bugs.
58 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
59 * Initial version of mLib
63 /*----- Header files ------------------------------------------------------*/
65 /* --- ANSI headers --- */
71 /* --- Local headers --- */
82 /*----- Tuning parameters -------------------------------------------------*/
84 /* --- Initial hash table size --- *
86 * This is the initial @mask@ value. It must be of the form %$2^n - 1$%,
87 * so that it can be used to mask of the bottom bits of a hash value.
90 #define SYM_INITSZ 64 /* Size of a new hash table */
92 /* --- Maximum load factor --- *
94 * This parameter controls how much the table has to be loaded before the
95 * table is extended. The number of elements %$n$%, the number of bins %$b$%
96 * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is
97 * added to the table and this relation is found to be false, the table is
101 #define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */
103 /*----- Main code ---------------------------------------------------------*/
105 /* --- @sym_create@ --- *
107 * Arguments: @sym_table *t@ = symbol table to initialize
111 * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if
112 * there isn't enough memory.
115 void sym_create(sym_table *t)
117 TRACK_CTX("symbol table creation");
119 hash_create(&t->t, SYM_INITSZ);
120 t->load = SYM_LIMIT(SYM_INITSZ);
124 /* --- @sym_destroy@ --- *
126 * Arguments: @sym_table *t@ = pointer to symbol table in question
130 * Use: Destroys a symbol table, freeing all the memory it used to
134 void sym_destroy(sym_table *t)
138 TRACK_CTX("symbol table destruction");
147 if (p->len > SYM_BUFSZ)
148 sub_free(p->name.p, p->len);
156 /* --- @sym_find@ --- *
158 * Arguments: @sym_table *t@ = pointer to symbol table in question
159 * @const char *n@ = pointer to symbol table to look up
160 * @long l@ = length of the name string or negative to measure
161 * @size_t sz@ = size of desired symbol object, or zero
162 * @unsigned *f@ = pointer to a flag, or null.
164 * Returns: The address of a @sym_base@ structure, or null if not found
167 * Use: Looks up a symbol in a given symbol table. The name is
168 * passed by the address of its first character. The length
169 * may be given, in which case the name may contain arbitrary
170 * binary data, or it may be given as a negative number, in
171 * which case the length of the name is calculated as
174 * The return value is the address of a pointer to a @sym_base@
175 * block (which may have other things on the end, as above). If
176 * the symbol could be found, the return value points to the
177 * symbol block. If the symbol wasn't there, then if @sz@ is
178 * nonzero, a new symbol is created and its address is returned;
179 * otherwise a null pointer is returned. The exception
180 * @EXC_NOMEM@ is raised if the block can't be allocated.
182 * The value of @*f@ indicates whether a new symbol entry was
183 * created: a nonzero value indicates that an old value was
187 void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
191 hash_base **bin, **p;
194 /* --- Find the correct bin --- */
196 len = l < 0 ? strlen(n) + 1 : l;
197 CRC32(hash, 0, n, len);
198 bin = HASH_BIN(&t->t, hash);
200 /* --- Search the bin list --- */
202 for (p = bin; *p; p = &(*p)->next) {
204 if (hash == q->b.hash && len == q->len && !memcmp(n, SYM_NAME(q), len)) {
206 /* --- Found a match --- *
208 * As a minor, and probably pointless, tweak, move the item to the
209 * front of its bin list.
216 /* --- Return the block --- */
223 /* --- Couldn't find the item there --- */
228 /* --- Create a new symbol block and initialize it --- */
231 TRACK_CTX("new symbol creation");
239 if (len <= SYM_BUFSZ)
240 memcpy(q->name.b, n, len);
243 q->name.p = sub_alloc(len);
244 memcpy(q->name.p, n, len);
258 /* --- Consider growing the array --- */
262 if (!t->load && hash_extend(&t->t))
263 t->load = SYM_LIMIT(t->t.mask / 2 + 1);
265 /* --- Finished that, so return the new symbol block --- */
270 /* --- @sym_remove@ --- *
272 * Arguments: @sym_table *i@ = pointer to a symbol table object
273 * @void *p@ = pointer to symbol table entry
277 * Use: Removes the object from the symbol table. The space occupied
278 * by the object and its name is freed; anything else attached
279 * to the entry should already be gone by this point.
282 void sym_remove(sym_table *t, void *p)
285 hash_remove(&t->t, &q->b);
286 if (q->len > SYM_BUFSZ)
287 sub_free(q->name.p, q->len);
292 /* --- @sym_mkiter@ --- *
294 * Arguments: @sym_iter *i@ = pointer to an iterator object
295 * @sym_table *t@ = pointer to a symbol table object
299 * Use: Creates a new symbol table iterator which may be used to
300 * iterate through a symbol table.
303 void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); }
305 /* --- @sym_next@ --- *
307 * Arguments: @sym_iter *i@ = pointer to iterator object
309 * Returns: Pointer to the next symbol found, or null when finished.
311 * Use: Returns the next symbol from the table. Symbols are not
312 * returned in any particular order.
315 void *sym_next(sym_iter *i)
322 /*----- That's all, folks -------------------------------------------------*/