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/* Copyright (c) 1994 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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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 "lookup.h" |
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|
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#ifndef MEM_PTR |
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#define MEM_PTR void * |
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#endif |
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|
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extern MEM_PTR calloc(); |
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|
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|
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int |
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lu_init(tbl, nel) /* initialize tbl for at least nel elements */ |
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register LUTAB *tbl; |
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int nel; |
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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, 0 |
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}; |
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register 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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int |
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lu_hash(s) /* hash a nul-terminated string */ |
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register char *s; |
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{ |
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register int h = 0; |
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|
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while (*s) |
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h = (h<<1 & 0x7fff) ^ (*s++ & 0xff); |
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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(tbl, key) /* find a table entry */ |
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register LUTAB *tbl; |
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char *key; |
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{ |
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int hval, i; |
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register int ndx; |
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register LUENT *oldtabl; |
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/* look up object */ |
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hval = lu_hash(key); |
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tryagain: |
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for (i = 0; i < tbl->tsiz; i++) { |
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ndx = (hval + i*i) % tbl->tsiz; |
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if (tbl->tabl[ndx].key == NULL || |
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!strcmp(tbl->tabl[ndx].key, key)) |
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return(&tbl->tabl[ndx]); |
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} |
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/* table is full, reallocate */ |
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oldtabl = 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)) { /* no more memory! */ |
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tbl->tabl = oldtabl; |
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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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if (!ndx) |
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goto tryagain; |
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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 (oldtabl[ndx].key != NULL) |
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if (oldtabl[ndx].data != NULL) |
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*lu_find(tbl, oldtabl[ndx].key) = oldtabl[ndx]; |
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else if (tbl->freek != NULL) |
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(*tbl->freek)(oldtabl[ndx].key); |
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free((MEM_PTR)oldtabl); |
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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(tbl, key) /* delete a table entry */ |
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register LUTAB *tbl; |
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char *key; |
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{ |
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register 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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void |
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lu_done(tbl) /* free table and contents */ |
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register LUTAB *tbl; |
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{ |
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register 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((MEM_PTR)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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} |
