src/common/lookup.c

/* Copyright (c) 1998 Silicon Graphics, Inc. */

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

/*
 * Table lookup routines
 */

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

#ifdef  NOSTRUCTASS
#define  copystruct(d,s)        bcopy((char *)(s),(char *)(d),sizeof(*(d)))
#else
#define  copystruct(d,s)        (*(d) = *(s))
#endif

#define MEM_PTR         char *

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 ^= (unsigned 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)
                                copystruct(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++;
}


int
lu_doall(tbl, f)                /* loop through all valid table entries */
register LUTAB  *tbl;
int     (*f)();
{
        int     rval = 0;
        register LUENT  *tp;

        for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; )
                if (tp->data != NULL)
                        if (f != NULL)
                                rval += (*f)(tp);
                        else
                                rval++;
        return(rval);
}


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:	2.5
Committed:	Thu Sep 3 14:22:23 1998 UTC (25 years, 8 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 2.4:	+16 -15 lines
Log Message:	changed lookup routines to use unsigned long hash values
#	User	Rev	Content
1	gwlarson	2.5	/* Copyright (c) 1998 Silicon Graphics, Inc. */
2	greg	2.1
3			#ifndef lint
4	gregl	2.3	static char SCCSid[] = "$SunId$ SGI";
5	greg	2.1	#endif
6
7			/*
8			* Table lookup routines
9			*/
10
11			#include <stdio.h>
12			#include "lookup.h"
13
14	gwlarson	2.5	#ifdef NOSTRUCTASS
15			#define copystruct(d,s) bcopy((char )(s),(char )(d),sizeof(*(d)))
16			#else
17			#define copystruct(d,s) ((d) = (s))
18			#endif
19
20	greg	2.1	#define MEM_PTR char *
21
22			extern MEM_PTR calloc();
23
24
25			int
26			lu_init(tbl, nel) /* initialize tbl for at least nel elements */
27			register LUTAB *tbl;
28			int nel;
29			{
30			static int hsiztab[] = {
31	gregl	2.3	31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381,
32			32749, 65521, 131071, 262139, 524287, 1048573, 2097143,
33			4194301, 8388593, 0
34	greg	2.1	};
35			register int *hsp;
36
37			nel += nel>>1; /* 66% occupancy */
38			for (hsp = hsiztab; *hsp; hsp++)
39			if (*hsp > nel)
40			break;
41			if (!(tbl->tsiz = *hsp))
42			tbl->tsiz = nel2 + 1; / not always prime */
43			tbl->tabl = (LUENT *)calloc(tbl->tsiz, sizeof(LUENT));
44			if (tbl->tabl == NULL)
45			tbl->tsiz = 0;
46			tbl->ndel = 0;
47			return(tbl->tsiz);
48			}
49
50
51	gwlarson	2.5	unsigned long
52	greg	2.1	lu_shash(s) /* hash a nul-terminated string */
53	gregl	2.3	char *s;
54	greg	2.1	{
55	gregl	2.3	static unsigned char shuffle[256] = {
56			0, 157, 58, 215, 116, 17, 174, 75, 232, 133, 34,
57			191, 92, 249, 150, 51, 208, 109, 10, 167, 68, 225,
58			126, 27, 184, 85, 242, 143, 44, 201, 102, 3, 160,
59			61, 218, 119, 20, 177, 78, 235, 136, 37, 194, 95,
60			252, 153, 54, 211, 112, 13, 170, 71, 228, 129, 30,
61			187, 88, 245, 146, 47, 204, 105, 6, 163, 64, 221,
62			122, 23, 180, 81, 238, 139, 40, 197, 98, 255, 156,
63			57, 214, 115, 16, 173, 74, 231, 132, 33, 190, 91,
64			248, 149, 50, 207, 108, 9, 166, 67, 224, 125, 26,
65			183, 84, 241, 142, 43, 200, 101, 2, 159, 60, 217,
66			118, 19, 176, 77, 234, 135, 36, 193, 94, 251, 152,
67			53, 210, 111, 12, 169, 70, 227, 128, 29, 186, 87,
68			244, 145, 46, 203, 104, 5, 162, 63, 220, 121, 22,
69			179, 80, 237, 138, 39, 196, 97, 254, 155, 56, 213,
70			114, 15, 172, 73, 230, 131, 32, 189, 90, 247, 148,
71			49, 206, 107, 8, 165, 66, 223, 124, 25, 182, 83,
72			240, 141, 42, 199, 100, 1, 158, 59, 216, 117, 18,
73			175, 76, 233, 134, 35, 192, 93, 250, 151, 52, 209,
74			110, 11, 168, 69, 226, 127, 28, 185, 86, 243, 144,
75			45, 202, 103, 4, 161, 62, 219, 120, 21, 178, 79,
76			236, 137, 38, 195, 96, 253, 154, 55, 212, 113, 14,
77			171, 72, 229, 130, 31, 188, 89, 246, 147, 48, 205,
78			106, 7, 164, 65, 222, 123, 24, 181, 82, 239, 140,
79			41, 198, 99
80			};
81	greg	2.1	register int i = 0;
82	gwlarson	2.5	register unsigned long h = 0;
83	gregl	2.3	register unsigned char t = (unsigned char )s;
84	greg	2.1
85	gregl	2.3	while (*t)
86	gwlarson	2.5	h ^= (unsigned long)shuffle[*t++] << ((i+=11) & 0xf);
87	gregl	2.3
88	greg	2.1	return(h);
89			}
90
91
92			LUENT *
93			lu_find(tbl, key) /* find a table entry */
94			register LUTAB *tbl;
95			char *key;
96			{
97	gwlarson	2.5	unsigned long hval;
98	gregl	2.3	int i, n;
99	greg	2.1	register int ndx;
100	gregl	2.3	register LUENT *le;
101	greg	2.1	/* look up object */
102	gwlarson	2.5	if (tbl->tsiz == 0 && !lu_init(tbl, 1))
103			return(NULL);
104	greg	2.1	hval = (*tbl->hashf)(key);
105			tryagain:
106	gregl	2.3	ndx = hval % tbl->tsiz;
107			for (i = 0, n = 1; i < tbl->tsiz; i++, n += 2) {
108	gwlarson	2.5	le = &tbl->tabl[ndx];
109	gregl	2.3	if (le->key == NULL) {
110			le->hval = hval;
111			return(le);
112	greg	2.1	}
113	gregl	2.3	if (le->hval == hval &&
114			(tbl->keycmp == NULL \|\| !(*tbl->keycmp)(le->key, key))) {
115			return(le);
116			}
117	gwlarson	2.5	if ((ndx += n) >= tbl->tsiz) /* this happens rarely */
118	gregl	2.3	ndx = ndx % tbl->tsiz;
119	greg	2.1	}
120			/* table is full, reallocate */
121	gregl	2.3	le = tbl->tabl;
122	greg	2.1	ndx = tbl->tsiz;
123			i = tbl->ndel;
124	greg	2.2	if (!lu_init(tbl, ndx-i+1)) { /* no more memory! */
125	gregl	2.3	tbl->tabl = le;
126	greg	2.1	tbl->tsiz = ndx;
127			tbl->ndel = i;
128			return(NULL);
129			}
130			/*
131			* The following code may fail if the user has reclaimed many
132			* deleted entries and the system runs out of memory in a
133			* recursive call to lu_find().
134			*/
135			while (ndx--)
136	gregl	2.3	if (le[ndx].key != NULL)
137			if (le[ndx].data != NULL)
138	gwlarson	2.5	copystruct(lu_find(tbl,le[ndx].key), &le[ndx]);
139	greg	2.1	else if (tbl->freek != NULL)
140	gregl	2.3	(*tbl->freek)(le[ndx].key);
141			free((MEM_PTR)le);
142	greg	2.1	goto tryagain; /* should happen only once! */
143			}
144
145
146			void
147			lu_delete(tbl, key) /* delete a table entry */
148			register LUTAB *tbl;
149			char *key;
150			{
151			register LUENT *le;
152
153			if ((le = lu_find(tbl, key)) == NULL)
154			return;
155			if (le->key == NULL \|\| le->data == NULL)
156			return;
157			if (tbl->freed != NULL)
158			(*tbl->freed)(le->data);
159			le->data = NULL;
160			tbl->ndel++;
161			}
162
163
164	gwlarson	2.4	int
165			lu_doall(tbl, f) /* loop through all valid table entries */
166			register LUTAB *tbl;
167			int (*f)();
168			{
169			int rval = 0;
170			register LUENT *tp;
171
172			for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; )
173			if (tp->data != NULL)
174			if (f != NULL)
175			rval += (*f)(tp);
176			else
177			rval++;
178			return(rval);
179			}
180
181
182	greg	2.1	void
183			lu_done(tbl) /* free table and contents */
184			register LUTAB *tbl;
185			{
186			register LUENT *tp;
187
188			if (!tbl->tsiz)
189			return;
190			for (tp = tbl->tabl + tbl->tsiz; tp-- > tbl->tabl; )
191			if (tp->key != NULL) {
192			if (tbl->freek != NULL)
193			(*tbl->freek)(tp->key);
194			if (tp->data != NULL && tbl->freed != NULL)
195			(*tbl->freed)(tp->data);
196			}
197			free((MEM_PTR)tbl->tabl);
198			tbl->tabl = NULL;
199			tbl->tsiz = 0;
200			tbl->ndel = 0;
201			}