cv/mgflib/lookup.c

/* Copyright (c) 1994 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 * Table lookup routines
 */

#include <stdio.h>
#include "lookup.h"

#ifndef MEM_PTR
#define MEM_PTR         void *
#endif

extern MEM_PTR  calloc();


int
lu_init(tbl, nel)               /* initialize tbl for at least nel elements */
register LUTAB  *tbl;
int     nel;
{
        static int  hsiztab[] = {
                31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, 
                32749, 65521, 131071, 262139, 524287, 1048573, 2097143, 
                4194301, 8388593, 0
        };
        register int  *hsp;

        nel += nel>>1;                  /* 66% occupancy */
        for (hsp = hsiztab; *hsp; hsp++)
                if (*hsp > nel)
                        break;
        if (!(tbl->tsiz = *hsp))
                tbl->tsiz = nel*2 + 1;          /* not always prime */
        tbl->tabl = (LUENT *)calloc(tbl->tsiz, sizeof(LUENT));
        if (tbl->tabl == NULL)
                tbl->tsiz = 0;
        tbl->ndel = 0;
        return(tbl->tsiz);
}


unsigned long
lu_shash(s)                     /* hash a nul-terminated string */
char    *s;
{
        static unsigned char shuffle[256] = {
                0, 157, 58, 215, 116, 17, 174, 75, 232, 133, 34,
                191, 92, 249, 150, 51, 208, 109, 10, 167, 68, 225,
                126, 27, 184, 85, 242, 143, 44, 201, 102, 3, 160,
                61, 218, 119, 20, 177, 78, 235, 136, 37, 194, 95,
                252, 153, 54, 211, 112, 13, 170, 71, 228, 129, 30,
                187, 88, 245, 146, 47, 204, 105, 6, 163, 64, 221,
                122, 23, 180, 81, 238, 139, 40, 197, 98, 255, 156,
                57, 214, 115, 16, 173, 74, 231, 132, 33, 190, 91,
                248, 149, 50, 207, 108, 9, 166, 67, 224, 125, 26,
                183, 84, 241, 142, 43, 200, 101, 2, 159, 60, 217,
                118, 19, 176, 77, 234, 135, 36, 193, 94, 251, 152,
                53, 210, 111, 12, 169, 70, 227, 128, 29, 186, 87,
                244, 145, 46, 203, 104, 5, 162, 63, 220, 121, 22,
                179, 80, 237, 138, 39, 196, 97, 254, 155, 56, 213,
                114, 15, 172, 73, 230, 131, 32, 189, 90, 247, 148,
                49, 206, 107, 8, 165, 66, 223, 124, 25, 182, 83,
                240, 141, 42, 199, 100, 1, 158, 59, 216, 117, 18,
                175, 76, 233, 134, 35, 192, 93, 250, 151, 52, 209,
                110, 11, 168, 69, 226, 127, 28, 185, 86, 243, 144,
                45, 202, 103, 4, 161, 62, 219, 120, 21, 178, 79,
                236, 137, 38, 195, 96, 253, 154, 55, 212, 113, 14,
                171, 72, 229, 130, 31, 188, 89, 246, 147, 48, 205,
                106, 7, 164, 65, 222, 123, 24, 181, 82, 239, 140,
                41, 198, 99
        };
        register int    i = 0;
        register unsigned long  h = 0;
        register unsigned char *t = (unsigned char *)s;

        while (*t)
                h ^= (long)shuffle[*t++] << ((i+=11) & 0xf);

        return(h);
}


LUENT *
lu_find(tbl, key)               /* find a table entry */
register LUTAB  *tbl;
char    *key;
{
        unsigned long   hval;
        int     i, n;
        register int    ndx;
        register LUENT  *le;
                                        /* look up object */
        if (tbl->tsiz == 0 && !lu_init(tbl, 1))
                return(NULL);
        hval = (*tbl->hashf)(key);
tryagain:
        ndx = hval % tbl->tsiz;
        for (i = 0, n = 1; i < tbl->tsiz; i++, n += 2) {
                le = &tbl->tabl[ndx];
                if (le->key == NULL) {
                        le->hval = hval;
                        return(le);
                }
                if (le->hval == hval && 
                      (tbl->keycmp == NULL || !(*tbl->keycmp)(le->key, key))) {
                        return(le);
                }
                if ((ndx += n) >= tbl->tsiz)    /* this happens rarely */
                        ndx = ndx % tbl->tsiz;
        }
                                        /* table is full, reallocate */
        le = tbl->tabl;
        ndx = tbl->tsiz;
        i = tbl->ndel;
        if (!lu_init(tbl, ndx-i+1)) {   /* no more memory! */
                tbl->tabl = le;
                tbl->tsiz = ndx;
                tbl->ndel = i;
                return(NULL);
        }
        /*
         * The following code may fail if the user has reclaimed many
         * deleted entries and the system runs out of memory in a
         * recursive call to lu_find().
         */
        while (ndx--)
                if (le[ndx].key != NULL)
                        if (le[ndx].data != NULL)
                                *lu_find(tbl, le[ndx].key) = le[ndx];
                        else if (tbl->freek != NULL)
                                (*tbl->freek)(le[ndx].key);
        free((MEM_PTR)le);
        goto tryagain;                  /* should happen only once! */
}


void
lu_delete(tbl, key)             /* delete a table entry */
register LUTAB  *tbl;
char    *key;
{
        register LUENT  *le;

        if ((le = lu_find(tbl, key)) == NULL)
                return;
        if (le->key == NULL || le->data == NULL)
                return;
        if (tbl->freed != NULL)
                (*tbl->freed)(le->data);
        le->data = NULL;
        tbl->ndel++;
}


void
lu_done(tbl)                    /* free table and contents */
register LUTAB  *tbl;
{
        register LUENT  *tp;

        if (!tbl->tsiz)
                return;
        for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; )
                if (tp->key != NULL) {
                        if (tbl->freek != NULL)
                                (*tbl->freek)(tp->key);
                        if (tp->data != NULL && tbl->freed != NULL)
                                (*tbl->freed)(tp->data);
                }
        free((MEM_PTR)tbl->tabl);
        tbl->tabl = NULL;
        tbl->tsiz = 0;
        tbl->ndel = 0;
}
Revision:	1.7
Committed:	Fri Sep 4 09:05:09 1998 UTC (25 years, 8 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 1.6:	+7 -12 lines
Log Message:	changed lookup routines to use unsigned long hash values
#	User	Rev	Content
1	greg	1.1	/* 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			#ifndef MEM_PTR
15			#define MEM_PTR void *
16			#endif
17
18			extern MEM_PTR calloc();
19
20
21			int
22			lu_init(tbl, nel) /* initialize tbl for at least nel elements */
23			register LUTAB *tbl;
24			int nel;
25			{
26			static int hsiztab[] = {
27	gregl	1.6	31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381,
28			32749, 65521, 131071, 262139, 524287, 1048573, 2097143,
29			4194301, 8388593, 0
30	greg	1.1	};
31			register int *hsp;
32
33	greg	1.2	nel += nel>>1; /* 66% occupancy */
34	greg	1.1	for (hsp = hsiztab; *hsp; hsp++)
35			if (*hsp > nel)
36			break;
37			if (!(tbl->tsiz = *hsp))
38			tbl->tsiz = nel2 + 1; / not always prime */
39			tbl->tabl = (LUENT *)calloc(tbl->tsiz, sizeof(LUENT));
40			if (tbl->tabl == NULL)
41			tbl->tsiz = 0;
42	greg	1.2	tbl->ndel = 0;
43	greg	1.1	return(tbl->tsiz);
44			}
45
46
47	gwlarson	1.7	unsigned long
48	greg	1.4	lu_shash(s) /* hash a nul-terminated string */
49	gregl	1.6	char *s;
50	greg	1.1	{
51	gregl	1.6	static unsigned char shuffle[256] = {
52			0, 157, 58, 215, 116, 17, 174, 75, 232, 133, 34,
53			191, 92, 249, 150, 51, 208, 109, 10, 167, 68, 225,
54			126, 27, 184, 85, 242, 143, 44, 201, 102, 3, 160,
55			61, 218, 119, 20, 177, 78, 235, 136, 37, 194, 95,
56			252, 153, 54, 211, 112, 13, 170, 71, 228, 129, 30,
57			187, 88, 245, 146, 47, 204, 105, 6, 163, 64, 221,
58			122, 23, 180, 81, 238, 139, 40, 197, 98, 255, 156,
59			57, 214, 115, 16, 173, 74, 231, 132, 33, 190, 91,
60			248, 149, 50, 207, 108, 9, 166, 67, 224, 125, 26,
61			183, 84, 241, 142, 43, 200, 101, 2, 159, 60, 217,
62			118, 19, 176, 77, 234, 135, 36, 193, 94, 251, 152,
63			53, 210, 111, 12, 169, 70, 227, 128, 29, 186, 87,
64			244, 145, 46, 203, 104, 5, 162, 63, 220, 121, 22,
65			179, 80, 237, 138, 39, 196, 97, 254, 155, 56, 213,
66			114, 15, 172, 73, 230, 131, 32, 189, 90, 247, 148,
67			49, 206, 107, 8, 165, 66, 223, 124, 25, 182, 83,
68			240, 141, 42, 199, 100, 1, 158, 59, 216, 117, 18,
69			175, 76, 233, 134, 35, 192, 93, 250, 151, 52, 209,
70			110, 11, 168, 69, 226, 127, 28, 185, 86, 243, 144,
71			45, 202, 103, 4, 161, 62, 219, 120, 21, 178, 79,
72			236, 137, 38, 195, 96, 253, 154, 55, 212, 113, 14,
73			171, 72, 229, 130, 31, 188, 89, 246, 147, 48, 205,
74			106, 7, 164, 65, 222, 123, 24, 181, 82, 239, 140,
75			41, 198, 99
76			};
77	greg	1.4	register int i = 0;
78	gwlarson	1.7	register unsigned long h = 0;
79	gregl	1.6	register unsigned char t = (unsigned char )s;
80	greg	1.1
81	gregl	1.6	while (*t)
82			h ^= (long)shuffle[*t++] << ((i+=11) & 0xf);
83
84	greg	1.1	return(h);
85			}
86
87
88			LUENT *
89			lu_find(tbl, key) /* find a table entry */
90			register LUTAB *tbl;
91			char *key;
92			{
93	gwlarson	1.7	unsigned long hval;
94	gregl	1.6	int i, n;
95	greg	1.4	register int ndx;
96	gregl	1.6	register LUENT *le;
97	greg	1.1	/* look up object */
98	gwlarson	1.7	if (tbl->tsiz == 0 && !lu_init(tbl, 1))
99			return(NULL);
100	greg	1.4	hval = (*tbl->hashf)(key);
101	greg	1.1	tryagain:
102	gregl	1.6	ndx = hval % tbl->tsiz;
103			for (i = 0, n = 1; i < tbl->tsiz; i++, n += 2) {
104	gwlarson	1.7	le = &tbl->tabl[ndx];
105	gregl	1.6	if (le->key == NULL) {
106			le->hval = hval;
107			return(le);
108	greg	1.4	}
109	gregl	1.6	if (le->hval == hval &&
110			(tbl->keycmp == NULL \|\| !(*tbl->keycmp)(le->key, key))) {
111			return(le);
112			}
113	gwlarson	1.7	if ((ndx += n) >= tbl->tsiz) /* this happens rarely */
114	gregl	1.6	ndx = ndx % tbl->tsiz;
115	greg	1.1	}
116			/* table is full, reallocate */
117	gregl	1.6	le = tbl->tabl;
118	greg	1.1	ndx = tbl->tsiz;
119	greg	1.2	i = tbl->ndel;
120	greg	1.5	if (!lu_init(tbl, ndx-i+1)) { /* no more memory! */
121	gregl	1.6	tbl->tabl = le;
122	greg	1.1	tbl->tsiz = ndx;
123	greg	1.2	tbl->ndel = i;
124	greg	1.1	return(NULL);
125			}
126	greg	1.3	/*
127			* The following code may fail if the user has reclaimed many
128			* deleted entries and the system runs out of memory in a
129			* recursive call to lu_find().
130			*/
131	greg	1.1	while (ndx--)
132	gregl	1.6	if (le[ndx].key != NULL)
133			if (le[ndx].data != NULL)
134			*lu_find(tbl, le[ndx].key) = le[ndx];
135	greg	1.2	else if (tbl->freek != NULL)
136	gregl	1.6	(*tbl->freek)(le[ndx].key);
137			free((MEM_PTR)le);
138	greg	1.1	goto tryagain; /* should happen only once! */
139			}
140
141
142			void
143	greg	1.2	lu_delete(tbl, key) /* delete a table entry */
144			register LUTAB *tbl;
145			char *key;
146	greg	1.1	{
147	greg	1.2	register LUENT *le;
148
149			if ((le = lu_find(tbl, key)) == NULL)
150			return;
151			if (le->key == NULL \|\| le->data == NULL)
152			return;
153			if (tbl->freed != NULL)
154			(*tbl->freed)(le->data);
155			le->data = NULL;
156			tbl->ndel++;
157			}
158
159
160			void
161			lu_done(tbl) /* free table and contents */
162			register LUTAB *tbl;
163			{
164	greg	1.1	register LUENT *tp;
165
166			if (!tbl->tsiz)
167			return;
168	greg	1.2	for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; )
169			if (tp->key != NULL) {
170			if (tbl->freek != NULL)
171			(*tbl->freek)(tp->key);
172			if (tp->data != NULL && tbl->freed != NULL)
173			(*tbl->freed)(tp->data);
174			}
175	greg	1.1	free((MEM_PTR)tbl->tabl);
176			tbl->tabl = NULL;
177			tbl->tsiz = 0;
178	greg	1.2	tbl->ndel = 0;
179	greg	1.1	}