| 1 |
#ifndef lint |
| 2 |
static const char RCSid[] = "$Id: lookup.c,v 1.8 2003/02/28 20:11:29 greg Exp $"; |
| 3 |
#endif |
| 4 |
/* |
| 5 |
* Table lookup routines |
| 6 |
*/ |
| 7 |
|
| 8 |
#include <stdio.h> |
| 9 |
#include <stdlib.h> |
| 10 |
#include "lookup.h" |
| 11 |
|
| 12 |
#ifndef MEM_PTR |
| 13 |
#define MEM_PTR void * |
| 14 |
#endif |
| 15 |
|
| 16 |
|
| 17 |
int |
| 18 |
lu_init(tbl, nel) /* initialize tbl for at least nel elements */ |
| 19 |
register LUTAB *tbl; |
| 20 |
int nel; |
| 21 |
{ |
| 22 |
static int hsiztab[] = { |
| 23 |
31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, |
| 24 |
32749, 65521, 131071, 262139, 524287, 1048573, 2097143, |
| 25 |
4194301, 8388593, 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 |
unsigned long |
| 44 |
lu_shash(s) /* hash a nul-terminated string */ |
| 45 |
char *s; |
| 46 |
{ |
| 47 |
static unsigned char shuffle[256] = { |
| 48 |
0, 157, 58, 215, 116, 17, 174, 75, 232, 133, 34, |
| 49 |
191, 92, 249, 150, 51, 208, 109, 10, 167, 68, 225, |
| 50 |
126, 27, 184, 85, 242, 143, 44, 201, 102, 3, 160, |
| 51 |
61, 218, 119, 20, 177, 78, 235, 136, 37, 194, 95, |
| 52 |
252, 153, 54, 211, 112, 13, 170, 71, 228, 129, 30, |
| 53 |
187, 88, 245, 146, 47, 204, 105, 6, 163, 64, 221, |
| 54 |
122, 23, 180, 81, 238, 139, 40, 197, 98, 255, 156, |
| 55 |
57, 214, 115, 16, 173, 74, 231, 132, 33, 190, 91, |
| 56 |
248, 149, 50, 207, 108, 9, 166, 67, 224, 125, 26, |
| 57 |
183, 84, 241, 142, 43, 200, 101, 2, 159, 60, 217, |
| 58 |
118, 19, 176, 77, 234, 135, 36, 193, 94, 251, 152, |
| 59 |
53, 210, 111, 12, 169, 70, 227, 128, 29, 186, 87, |
| 60 |
244, 145, 46, 203, 104, 5, 162, 63, 220, 121, 22, |
| 61 |
179, 80, 237, 138, 39, 196, 97, 254, 155, 56, 213, |
| 62 |
114, 15, 172, 73, 230, 131, 32, 189, 90, 247, 148, |
| 63 |
49, 206, 107, 8, 165, 66, 223, 124, 25, 182, 83, |
| 64 |
240, 141, 42, 199, 100, 1, 158, 59, 216, 117, 18, |
| 65 |
175, 76, 233, 134, 35, 192, 93, 250, 151, 52, 209, |
| 66 |
110, 11, 168, 69, 226, 127, 28, 185, 86, 243, 144, |
| 67 |
45, 202, 103, 4, 161, 62, 219, 120, 21, 178, 79, |
| 68 |
236, 137, 38, 195, 96, 253, 154, 55, 212, 113, 14, |
| 69 |
171, 72, 229, 130, 31, 188, 89, 246, 147, 48, 205, |
| 70 |
106, 7, 164, 65, 222, 123, 24, 181, 82, 239, 140, |
| 71 |
41, 198, 99 |
| 72 |
}; |
| 73 |
register int i = 0; |
| 74 |
register unsigned long h = 0; |
| 75 |
register unsigned char *t = (unsigned char *)s; |
| 76 |
|
| 77 |
while (*t) |
| 78 |
h ^= (long)shuffle[*t++] << ((i+=11) & 0xf); |
| 79 |
|
| 80 |
return(h); |
| 81 |
} |
| 82 |
|
| 83 |
|
| 84 |
LUENT * |
| 85 |
lu_find(tbl, key) /* find a table entry */ |
| 86 |
register LUTAB *tbl; |
| 87 |
char *key; |
| 88 |
{ |
| 89 |
unsigned long hval; |
| 90 |
int i, n; |
| 91 |
register int ndx; |
| 92 |
register LUENT *le; |
| 93 |
/* look up object */ |
| 94 |
if (tbl->tsiz == 0 && !lu_init(tbl, 1)) |
| 95 |
return(NULL); |
| 96 |
hval = (*tbl->hashf)(key); |
| 97 |
tryagain: |
| 98 |
ndx = hval % tbl->tsiz; |
| 99 |
for (i = 0, n = 1; i < tbl->tsiz; i++, n += 2) { |
| 100 |
le = &tbl->tabl[ndx]; |
| 101 |
if (le->key == NULL) { |
| 102 |
le->hval = hval; |
| 103 |
return(le); |
| 104 |
} |
| 105 |
if (le->hval == hval && |
| 106 |
(tbl->keycmp == NULL || !(*tbl->keycmp)(le->key, key))) { |
| 107 |
return(le); |
| 108 |
} |
| 109 |
if ((ndx += n) >= tbl->tsiz) /* this happens rarely */ |
| 110 |
ndx = ndx % tbl->tsiz; |
| 111 |
} |
| 112 |
/* table is full, reallocate */ |
| 113 |
le = tbl->tabl; |
| 114 |
ndx = tbl->tsiz; |
| 115 |
i = tbl->ndel; |
| 116 |
if (!lu_init(tbl, ndx-i+1)) { /* no more memory! */ |
| 117 |
tbl->tabl = le; |
| 118 |
tbl->tsiz = ndx; |
| 119 |
tbl->ndel = i; |
| 120 |
return(NULL); |
| 121 |
} |
| 122 |
/* |
| 123 |
* The following code may fail if the user has reclaimed many |
| 124 |
* deleted entries and the system runs out of memory in a |
| 125 |
* recursive call to lu_find(). |
| 126 |
*/ |
| 127 |
while (ndx--) |
| 128 |
if (le[ndx].key != NULL) { |
| 129 |
if (le[ndx].data != NULL) |
| 130 |
*lu_find(tbl, le[ndx].key) = le[ndx]; |
| 131 |
else if (tbl->freek != NULL) |
| 132 |
(*tbl->freek)(le[ndx].key); |
| 133 |
} |
| 134 |
free((MEM_PTR)le); |
| 135 |
goto tryagain; /* should happen only once! */ |
| 136 |
} |
| 137 |
|
| 138 |
|
| 139 |
void |
| 140 |
lu_delete(tbl, key) /* delete a table entry */ |
| 141 |
register LUTAB *tbl; |
| 142 |
char *key; |
| 143 |
{ |
| 144 |
register LUENT *le; |
| 145 |
|
| 146 |
if ((le = lu_find(tbl, key)) == NULL) |
| 147 |
return; |
| 148 |
if (le->key == NULL || le->data == NULL) |
| 149 |
return; |
| 150 |
if (tbl->freed != NULL) |
| 151 |
(*tbl->freed)(le->data); |
| 152 |
le->data = NULL; |
| 153 |
tbl->ndel++; |
| 154 |
} |
| 155 |
|
| 156 |
|
| 157 |
void |
| 158 |
lu_done(tbl) /* free table and contents */ |
| 159 |
register LUTAB *tbl; |
| 160 |
{ |
| 161 |
register LUENT *tp; |
| 162 |
|
| 163 |
if (!tbl->tsiz) |
| 164 |
return; |
| 165 |
for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; ) |
| 166 |
if (tp->key != NULL) { |
| 167 |
if (tbl->freek != NULL) |
| 168 |
(*tbl->freek)(tp->key); |
| 169 |
if (tp->data != NULL && tbl->freed != NULL) |
| 170 |
(*tbl->freed)(tp->data); |
| 171 |
} |
| 172 |
free((MEM_PTR)tbl->tabl); |
| 173 |
tbl->tabl = NULL; |
| 174 |
tbl->tsiz = 0; |
| 175 |
tbl->ndel = 0; |
| 176 |
} |
