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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997
* Sleepycat Software. All rights reserved.
*
* @(#)db_shash.h 10.2 (Sleepycat) 9/16/97
*/
/* Hash Headers */
typedef SH_TAILQ_HEAD(hash_head) DB_HASHTAB;
/*
* HASHLOOKUP --
*
* Look up something in a shared memory hash table. The "elt" argument
* should be a key, and cmp_func must know how to compare a key to whatever
* structure it is that appears in the hash table. The comparison function
* cmp_func is called as: cmp_func(lookup_elt, table_elt);
* begin: address of the beginning of the hash table.
* type: the structure type of the elements that are linked in each bucket.
* field: the name of the field by which the "type" structures are linked.
* elt: the item for which we are searching in the hash table.
* result: the variable into which we'll store the element if we find it.
* nelems: the number of buckets in the hash table.
* hash_func: the hash function that operates on elements of the type of elt
* cmp_func: compare elements of the type of elt with those in the table (of
* type "type").
*
* If the element is not in the hash table, this macro exits with result
* set to NULL.
*/
#define HASHLOOKUP(begin, type, field, elt, r, n, hash, cmp) do { \
DB_HASHTAB *__bucket; \
u_int32_t __ndx; \
\
__ndx = hash(elt) % (n); \
__bucket = &begin[__ndx]; \
for (r = SH_TAILQ_FIRST(__bucket, type); \
r != NULL; r = SH_TAILQ_NEXT(r, field, type)) \
if (cmp(elt, r)) \
break; \
} while(0)
/*
* HASHINSERT --
*
* Insert a new entry into the hash table. This assumes that lookup has
* failed; don't call it if you haven't already called HASHLOOKUP.
* begin: the beginning address of the hash table.
* type: the structure type of the elements that are linked in each bucket.
* field: the name of the field by which the "type" structures are linked.
* elt: the item to be inserted.
* nelems: the number of buckets in the hash table.
* hash_func: the hash function that operates on elements of the type of elt
*/
#define HASHINSERT(begin, type, field, elt, n, hash) do { \
u_int32_t __ndx; \
DB_HASHTAB *__bucket; \
\
__ndx = hash(elt) % (n); \
__bucket = &begin[__ndx]; \
SH_TAILQ_INSERT_HEAD(__bucket, elt, field, type); \
} while(0)
/*
* HASHREMOVE --
* Remove the entry with a key == elt.
* begin: address of the beginning of the hash table.
* type: the structure type of the elements that are linked in each bucket.
* field: the name of the field by which the "type" structures are linked.
* elt: the item to be deleted.
* nelems: the number of buckets in the hash table.
* hash_func: the hash function that operates on elements of the type of elt
* cmp_func: compare elements of the type of elt with those in the table (of
* type "type").
*/
#define HASHREMOVE(begin, type, field, elt, n, hash, cmp) { \
u_int32_t __ndx; \
DB_HASHTAB *__bucket; \
SH_TAILQ_ENTRY *__entp; \
\
__ndx = hash(elt) % (n); \
__bucket = &begin[__ndx]; \
HASHLOOKUP(begin, type, field, elt, __entp, n, hash, cmp); \
SH_TAILQ_REMOVE(__bucket, __entp, field, type); \
}
/*
* HASHREMOVE_EL --
* Given the object "obj" in the table, remove it.
* begin: address of the beginning of the hash table.
* type: the structure type of the elements that are linked in each bucket.
* field: the name of the field by which the "type" structures are linked.
* obj: the object in the table that we with to delete.
* nelems: the number of buckets in the hash table.
* hash_func: the hash function that operates on elements of the type of elt
*/
#define HASHREMOVE_EL(begin, type, field, obj, n, hash) { \
u_int32_t __ndx; \
DB_HASHTAB *__bucket; \
\
__ndx = hash(obj) % (n); \
__bucket = &begin[__ndx]; \
SH_TAILQ_REMOVE(__bucket, obj, field, type); \
}
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