1 |
/* Copyright (c) 1994 Regents of the University of California */ |
2 |
|
3 |
#ifndef lint |
4 |
static char SCCSid[] = "$SunId$ LBL"; |
5 |
#endif |
6 |
|
7 |
/* |
8 |
* Table lookup routines |
9 |
*/ |
10 |
|
11 |
#include <stdio.h> |
12 |
#include "lookup.h" |
13 |
|
14 |
#define MEM_PTR char * |
15 |
|
16 |
extern MEM_PTR calloc(); |
17 |
|
18 |
|
19 |
int |
20 |
lu_init(tbl, nel) /* initialize tbl for at least nel elements */ |
21 |
register LUTAB *tbl; |
22 |
int nel; |
23 |
{ |
24 |
static int hsiztab[] = { |
25 |
31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, 0 |
26 |
}; |
27 |
register int *hsp; |
28 |
|
29 |
nel += nel>>1; /* 66% occupancy */ |
30 |
for (hsp = hsiztab; *hsp; hsp++) |
31 |
if (*hsp > nel) |
32 |
break; |
33 |
if (!(tbl->tsiz = *hsp)) |
34 |
tbl->tsiz = nel*2 + 1; /* not always prime */ |
35 |
tbl->tabl = (LUENT *)calloc(tbl->tsiz, sizeof(LUENT)); |
36 |
if (tbl->tabl == NULL) |
37 |
tbl->tsiz = 0; |
38 |
tbl->ndel = 0; |
39 |
return(tbl->tsiz); |
40 |
} |
41 |
|
42 |
|
43 |
long |
44 |
lu_shash(s) /* hash a nul-terminated string */ |
45 |
register char *s; |
46 |
{ |
47 |
register int i = 0; |
48 |
register long h = 0; |
49 |
|
50 |
while (*s) |
51 |
h ^= (long)(*s++ & 0xff) << (i++ & 0xf); |
52 |
return(h); |
53 |
} |
54 |
|
55 |
|
56 |
LUENT * |
57 |
lu_find(tbl, key) /* find a table entry */ |
58 |
register LUTAB *tbl; |
59 |
char *key; |
60 |
{ |
61 |
long hval; |
62 |
int i; |
63 |
register int ndx; |
64 |
register LUENT *oldtabl; |
65 |
/* look up object */ |
66 |
hval = (*tbl->hashf)(key); |
67 |
tryagain: |
68 |
for (i = 0; i < tbl->tsiz; i++) { |
69 |
ndx = (hval + i*i) % tbl->tsiz; |
70 |
if (tbl->tabl[ndx].key == NULL) { |
71 |
tbl->tabl[ndx].hval = hval; |
72 |
return(&tbl->tabl[ndx]); |
73 |
} |
74 |
if ( tbl->tabl[ndx].hval == hval && (tbl->keycmp == NULL || |
75 |
!(*tbl->keycmp)(tbl->tabl[ndx].key, key)) ) |
76 |
return(&tbl->tabl[ndx]); |
77 |
} |
78 |
/* table is full, reallocate */ |
79 |
oldtabl = tbl->tabl; |
80 |
ndx = tbl->tsiz; |
81 |
i = tbl->ndel; |
82 |
if (!lu_init(tbl, ndx-i+1)) { /* no more memory! */ |
83 |
tbl->tabl = oldtabl; |
84 |
tbl->tsiz = ndx; |
85 |
tbl->ndel = i; |
86 |
return(NULL); |
87 |
} |
88 |
if (!ndx) |
89 |
goto tryagain; |
90 |
/* |
91 |
* The following code may fail if the user has reclaimed many |
92 |
* deleted entries and the system runs out of memory in a |
93 |
* recursive call to lu_find(). |
94 |
*/ |
95 |
while (ndx--) |
96 |
if (oldtabl[ndx].key != NULL) |
97 |
if (oldtabl[ndx].data != NULL) |
98 |
*lu_find(tbl, oldtabl[ndx].key) = oldtabl[ndx]; |
99 |
else if (tbl->freek != NULL) |
100 |
(*tbl->freek)(oldtabl[ndx].key); |
101 |
free((MEM_PTR)oldtabl); |
102 |
goto tryagain; /* should happen only once! */ |
103 |
} |
104 |
|
105 |
|
106 |
void |
107 |
lu_delete(tbl, key) /* delete a table entry */ |
108 |
register LUTAB *tbl; |
109 |
char *key; |
110 |
{ |
111 |
register LUENT *le; |
112 |
|
113 |
if ((le = lu_find(tbl, key)) == NULL) |
114 |
return; |
115 |
if (le->key == NULL || le->data == NULL) |
116 |
return; |
117 |
if (tbl->freed != NULL) |
118 |
(*tbl->freed)(le->data); |
119 |
le->data = NULL; |
120 |
tbl->ndel++; |
121 |
} |
122 |
|
123 |
|
124 |
void |
125 |
lu_done(tbl) /* free table and contents */ |
126 |
register LUTAB *tbl; |
127 |
{ |
128 |
register LUENT *tp; |
129 |
|
130 |
if (!tbl->tsiz) |
131 |
return; |
132 |
for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; ) |
133 |
if (tp->key != NULL) { |
134 |
if (tbl->freek != NULL) |
135 |
(*tbl->freek)(tp->key); |
136 |
if (tp->data != NULL && tbl->freed != NULL) |
137 |
(*tbl->freed)(tp->data); |
138 |
} |
139 |
free((MEM_PTR)tbl->tabl); |
140 |
tbl->tabl = NULL; |
141 |
tbl->tsiz = 0; |
142 |
tbl->ndel = 0; |
143 |
} |