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#ifndef lint |
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static const char RCSid[] = "$Id: lookup.c,v 2.18 2011/02/18 00:40:25 greg Exp $"; |
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#endif |
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/* |
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* Table lookup routines |
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*/ |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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|
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#include "lookup.h" |
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|
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|
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int |
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lu_init( /* initialize tbl for at least nel elements */ |
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LUTAB *tbl, |
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int nel |
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) |
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{ |
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static int hsiztab[] = { |
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31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, |
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32749, 65521, 131071, 262139, 524287, 1048573, 2097143, |
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4194301, 8388593, 0 |
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}; |
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int *hsp; |
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|
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nel += nel>>1; /* 66% occupancy */ |
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for (hsp = hsiztab; *hsp; hsp++) |
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if (*hsp > nel) |
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break; |
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if (!(tbl->tsiz = *hsp)) |
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tbl->tsiz = nel*2 + 1; /* not always prime */ |
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tbl->tabl = (LUENT *)calloc(tbl->tsiz, sizeof(LUENT)); |
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if (tbl->tabl == NULL) |
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tbl->tsiz = 0; |
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tbl->ndel = 0; |
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return(tbl->tsiz); |
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} |
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|
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|
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unsigned long |
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lu_shash( /* hash a nul-terminated string */ |
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const char *s |
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) |
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{ |
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static unsigned char shuffle[256] = { |
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0, 157, 58, 215, 116, 17, 174, 75, 232, 133, 34, |
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191, 92, 249, 150, 51, 208, 109, 10, 167, 68, 225, |
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126, 27, 184, 85, 242, 143, 44, 201, 102, 3, 160, |
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61, 218, 119, 20, 177, 78, 235, 136, 37, 194, 95, |
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252, 153, 54, 211, 112, 13, 170, 71, 228, 129, 30, |
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187, 88, 245, 146, 47, 204, 105, 6, 163, 64, 221, |
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122, 23, 180, 81, 238, 139, 40, 197, 98, 255, 156, |
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57, 214, 115, 16, 173, 74, 231, 132, 33, 190, 91, |
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248, 149, 50, 207, 108, 9, 166, 67, 224, 125, 26, |
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183, 84, 241, 142, 43, 200, 101, 2, 159, 60, 217, |
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118, 19, 176, 77, 234, 135, 36, 193, 94, 251, 152, |
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53, 210, 111, 12, 169, 70, 227, 128, 29, 186, 87, |
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244, 145, 46, 203, 104, 5, 162, 63, 220, 121, 22, |
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179, 80, 237, 138, 39, 196, 97, 254, 155, 56, 213, |
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114, 15, 172, 73, 230, 131, 32, 189, 90, 247, 148, |
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49, 206, 107, 8, 165, 66, 223, 124, 25, 182, 83, |
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240, 141, 42, 199, 100, 1, 158, 59, 216, 117, 18, |
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175, 76, 233, 134, 35, 192, 93, 250, 151, 52, 209, |
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110, 11, 168, 69, 226, 127, 28, 185, 86, 243, 144, |
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45, 202, 103, 4, 161, 62, 219, 120, 21, 178, 79, |
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236, 137, 38, 195, 96, 253, 154, 55, 212, 113, 14, |
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171, 72, 229, 130, 31, 188, 89, 246, 147, 48, 205, |
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106, 7, 164, 65, 222, 123, 24, 181, 82, 239, 140, |
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41, 198, 99 |
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}; |
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int i = 0; |
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unsigned long h = 0; |
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unsigned const char *t = (unsigned const char *)s; |
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|
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while (*t) |
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h ^= (unsigned long)shuffle[*t++] << ((i+=11) & 0xf); |
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|
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return(h); |
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} |
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|
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|
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LUENT * |
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lu_find( /* find a table entry */ |
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LUTAB *tbl, |
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const char *key |
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) |
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{ |
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unsigned long hval; |
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int i, n; |
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int ndx; |
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LUENT *le; |
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/* look up object */ |
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if (tbl->tsiz == 0 && !lu_init(tbl, 1)) |
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return(NULL); |
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hval = (*tbl->hashf)(key); |
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tryagain: |
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ndx = hval % tbl->tsiz; |
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for (i = 0, n = 1; i < tbl->tsiz; i++, n += 2) { |
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le = &tbl->tabl[ndx]; |
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if (le->key == NULL) { |
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le->hval = hval; |
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return(le); |
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} |
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if (le->hval == hval && |
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(tbl->keycmp == NULL || !(*tbl->keycmp)(le->key, key))) { |
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return(le); |
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} |
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if ((ndx += n) >= tbl->tsiz) /* this happens rarely */ |
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ndx = ndx % tbl->tsiz; |
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} |
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/* table is full, reallocate */ |
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le = tbl->tabl; |
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ndx = tbl->tsiz; |
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i = tbl->ndel; |
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if (!lu_init(tbl, ndx-i+1)) { /* no more memory! */ |
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tbl->tabl = le; |
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tbl->tsiz = ndx; |
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tbl->ndel = i; |
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return(NULL); |
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} |
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/* |
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* The following code may fail if the user has reclaimed many |
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* deleted entries and the system runs out of memory in a |
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* recursive call to lu_find(). |
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*/ |
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while (ndx--) |
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if (le[ndx].key != NULL) { |
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if (le[ndx].data != NULL) |
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*lu_find(tbl,le[ndx].key) = le[ndx]; |
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else if (tbl->freek != NULL) |
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(*tbl->freek)(le[ndx].key); |
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} |
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free((void *)le); |
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goto tryagain; /* should happen only once! */ |
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} |
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|
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|
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void |
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lu_delete( /* delete a table entry */ |
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LUTAB *tbl, |
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const char *key |
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) |
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{ |
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LUENT *le; |
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|
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if ((le = lu_find(tbl, key)) == NULL) |
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return; |
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if (le->key == NULL || le->data == NULL) |
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return; |
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if (tbl->freed != NULL) |
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(*tbl->freed)(le->data); |
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le->data = NULL; |
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tbl->ndel++; |
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} |
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|
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|
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int |
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lu_doall( /* loop through all valid table entries */ |
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const LUTAB *tbl, |
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/* int (*f)(const LUENT *, void *) */ |
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lut_doallf_t *f, |
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void *p |
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) |
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{ |
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int rval = 0; |
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const LUENT *tp; |
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|
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for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; ) |
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if (tp->data != NULL) { |
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if (f != NULL) { |
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int r = (*f)(tp, p); |
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if (r < 0) |
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return(-1); |
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rval += r; |
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} else |
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rval++; |
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} |
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return(rval); |
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} |
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|
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|
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void |
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lu_done( /* free table and contents */ |
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LUTAB *tbl |
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) |
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{ |
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LUENT *tp; |
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|
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if (!tbl->tsiz) |
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return; |
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for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; ) |
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if (tp->key != NULL) { |
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if (tbl->freek != NULL) |
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(*tbl->freek)(tp->key); |
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if (tp->data != NULL && tbl->freed != NULL) |
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(*tbl->freed)(tp->data); |
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} |
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free((void *)tbl->tabl); |
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tbl->tabl = NULL; |
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tbl->tsiz = 0; |
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tbl->ndel = 0; |
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} |
