src/common/lookup.h

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

/* SCCSid "$SunId$ SGI" */

/*
 * Header file for general associative table lookup routines
 */

typedef struct {
        char    *key;                   /* key name */
        unsigned long   hval;           /* key hash value (for efficiency) */
        char    *data;                  /* pointer to client data */
} LUENT;

typedef struct {
        unsigned long   (*hashf)();     /* key hash function */
        int     (*keycmp)();            /* key comparison function */
        void    (*freek)();             /* free a key */
        void    (*freed)();             /* free the data */
        int     tsiz;                   /* current table size */
        LUENT   *tabl;                  /* table, if allocated */
        int     ndel;                   /* number of deleted entries */
} LUTAB;

#undef strcmp
#define LU_SINIT(fk,fd)         {lu_shash,strcmp,(void (*)())(fk),\
                                (void (*)())(fd),0,NULL,0}

/*
 * The lu_init routine is called to initialize a table.  The number of
 * elements passed is not a limiting factor, as a table can grow to
 * any size permitted by memory.  However, access will be more efficient
 * if this number strikes a reasonable balance between default memory use
 * and the expected (minimum) table size.  The value returned is the
 * actual allocated table size (or zero if there was insufficient memory).
 *
 * The hashf, keycmp, freek and freed member functions must be assigned
 * separately.  If the hash value is sufficient to guarantee equality
 * between keys, then the keycmp pointer may be NULL.  Otherwise, it
 * should return 0 if the two passed keys match.  If it is not necessary
 * (or possible) to free the key and/or data values, then the freek and/or
 * freed member functions may be NULL.
 *
 * It isn't fully necessary to call lu_init to initialize the LUTAB structure.
 * If tsiz is 0, then the first call to lu_find will allocate a minimal table.
 * The LU_SINIT macro provides a convenient static declaration for character
 * string keys.
 *
 * The lu_find routine returns the entry corresponding to the given
 * key.  If the entry does not exist, the corresponding key field will
 * be NULL.  If the entry has been previously deleted but not yet freed,
 * then only the data field will be NULL.  It is the caller's
 * responsibility to (allocate and) assign the key and data fields when
 * creating a new entry.  The only case where lu_find returns NULL is when
 * the system has run out of memory.
 *
 * The lu_delete routine frees an entry's data (if any) by calling
 * the freed member function, but does not free the key field.  This
 * will be freed later during (or instead of) table reallocation.
 * It is therefore an error to reuse or do anything with the key
 * field after calling lu_delete.
 *
 * The lu_doall routine loops through every filled table entry, calling
 * the given function once on each entry.  If a NULL pointer is passed
 * for this function, then lu_doall simply returns the total number of
 * active entries.  Otherwise, it returns the sum of all the function
 * evaluations.
 *
 * The lu_done routine calls the given free function once for each
 * assigned table entry (i.e. each entry with an assigned key value).
 * The user must define these routines to free the key and the data
 * in the LU_TAB structure.  The final action of lu_done is to free the
 * allocated table itself.
 */

extern int      lu_init();
extern LUENT    *lu_find();
extern void     lu_delete();
extern int      lu_doall();
extern void     lu_done();
extern unsigned long    lu_shash();

extern int      strcmp();
Revision:	2.5
Committed:	Wed Sep 2 18:42:11 1998 UTC (25 years, 8 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 2.4:	+13 -13 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	gwlarson	2.5	/* SCCSid "$SunId$ SGI" */
4	greg	2.1
5			/*
6			* Header file for general associative table lookup routines
7			*/
8
9			typedef struct {
10	gwlarson	2.5	char key; / key name */
11			unsigned long hval; /* key hash value (for efficiency) */
12			char data; / pointer to client data */
13	greg	2.1	} LUENT;
14
15			typedef struct {
16	gwlarson	2.5	unsigned long (hashf)(); / key hash function */
17			int (keycmp)(); / key comparison function */
18			void (freek)(); / free a key */
19			void (freed)(); / free the data */
20			int tsiz; /* current table size */
21			LUENT tabl; / table, if allocated */
22			int ndel; /* number of deleted entries */
23	greg	2.1	} LUTAB;
24
25	gregl	2.3	#undef strcmp
26	greg	2.1	#define LU_SINIT(fk,fd) {lu_shash,strcmp,(void (*)())(fk),\
27			(void (*)())(fd),0,NULL,0}
28
29			/*
30			* The lu_init routine is called to initialize a table. The number of
31			* elements passed is not a limiting factor, as a table can grow to
32			* any size permitted by memory. However, access will be more efficient
33			* if this number strikes a reasonable balance between default memory use
34			* and the expected (minimum) table size. The value returned is the
35			* actual allocated table size (or zero if there was insufficient memory).
36			*
37			* The hashf, keycmp, freek and freed member functions must be assigned
38			* separately. If the hash value is sufficient to guarantee equality
39			* between keys, then the keycmp pointer may be NULL. Otherwise, it
40			* should return 0 if the two passed keys match. If it is not necessary
41			* (or possible) to free the key and/or data values, then the freek and/or
42			* freed member functions may be NULL.
43			*
44			* It isn't fully necessary to call lu_init to initialize the LUTAB structure.
45			* If tsiz is 0, then the first call to lu_find will allocate a minimal table.
46			* The LU_SINIT macro provides a convenient static declaration for character
47			* string keys.
48			*
49			* The lu_find routine returns the entry corresponding to the given
50			* key. If the entry does not exist, the corresponding key field will
51			* be NULL. If the entry has been previously deleted but not yet freed,
52			* then only the data field will be NULL. It is the caller's
53			* responsibility to (allocate and) assign the key and data fields when
54			* creating a new entry. The only case where lu_find returns NULL is when
55			* the system has run out of memory.
56			*
57			* The lu_delete routine frees an entry's data (if any) by calling
58			* the freed member function, but does not free the key field. This
59			* will be freed later during (or instead of) table reallocation.
60	greg	2.2	* It is therefore an error to reuse or do anything with the key
61			* field after calling lu_delete.
62	greg	2.1	*
63	gwlarson	2.4	* The lu_doall routine loops through every filled table entry, calling
64			* the given function once on each entry. If a NULL pointer is passed
65			* for this function, then lu_doall simply returns the total number of
66			* active entries. Otherwise, it returns the sum of all the function
67			* evaluations.
68			*
69	greg	2.1	* The lu_done routine calls the given free function once for each
70			* assigned table entry (i.e. each entry with an assigned key value).
71			* The user must define these routines to free the key and the data
72			* in the LU_TAB structure. The final action of lu_done is to free the
73			* allocated table itself.
74			*/
75
76			extern int lu_init();
77			extern LUENT *lu_find();
78			extern void lu_delete();
79	gwlarson	2.4	extern int lu_doall();
80	greg	2.1	extern void lu_done();
81	gwlarson	2.5	extern unsigned long lu_shash();
82	greg	2.1
83			extern int strcmp();