symtab.c revision 240517 
1/* $Id: symtab.c,v 1.10 2012/05/26 15:16:12 tom Exp $ */
2
3#include "defs.h"
4
5/* TABLE_SIZE is the number of entries in the symbol table. */
6/* TABLE_SIZE must be a power of two.			    */
7
8#define	TABLE_SIZE 1024
9
10static bucket **symbol_table = 0;
11bucket *first_symbol;
12bucket *last_symbol;
13
14static int
15hash(const char *name)
16{
17    const char *s;
18    int c, k;
19
20    assert(name && *name);
21    s = name;
22    k = *s;
23    while ((c = *++s) != 0)
24	k = (31 * k + c) & (TABLE_SIZE - 1);
25
26    return (k);
27}
28
29bucket *
30make_bucket(const char *name)
31{
32    bucket *bp;
33
34    assert(name != 0);
35
36    bp = TMALLOC(bucket, 1);
37    NO_SPACE(bp);
38
39    bp->link = 0;
40    bp->next = 0;
41
42    bp->name = TMALLOC(char, strlen(name) + 1);
43    NO_SPACE(bp->name);
44
45    bp->tag = 0;
46    bp->value = UNDEFINED;
47    bp->index = 0;
48    bp->prec = 0;
49    bp->class = UNKNOWN;
50    bp->assoc = TOKEN;
51    strcpy(bp->name, name);
52
53    return (bp);
54}
55
56bucket *
57lookup(const char *name)
58{
59    bucket *bp, **bpp;
60
61    bpp = symbol_table + hash(name);
62    bp = *bpp;
63
64    while (bp)
65    {
66	if (strcmp(name, bp->name) == 0)
67	    return (bp);
68	bpp = &bp->link;
69	bp = *bpp;
70    }
71
72    *bpp = bp = make_bucket(name);
73    last_symbol->next = bp;
74    last_symbol = bp;
75
76    return (bp);
77}
78
79void
80create_symbol_table(void)
81{
82    int i;
83    bucket *bp;
84
85    symbol_table = TMALLOC(bucket *, TABLE_SIZE);
86    NO_SPACE(symbol_table);
87
88    for (i = 0; i < TABLE_SIZE; i++)
89	symbol_table[i] = 0;
90
91    bp = make_bucket("error");
92    bp->index = 1;
93    bp->class = TERM;
94
95    first_symbol = bp;
96    last_symbol = bp;
97    symbol_table[hash("error")] = bp;
98}
99
100void
101free_symbol_table(void)
102{
103    FREE(symbol_table);
104    symbol_table = 0;
105}
106
107void
108free_symbols(void)
109{
110    bucket *p, *q;
111
112    for (p = first_symbol; p; p = q)
113    {
114	q = p->next;
115	FREE(p);
116    }
117}
118