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Diffstat (limited to 'Documentation/technical/api-hash.txt')
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diff --git a/Documentation/technical/api-hash.txt b/Documentation/technical/api-hash.txt new file mode 100644 index 0000000..e5061e0 --- /dev/null +++ b/Documentation/technical/api-hash.txt @@ -0,0 +1,52 @@ +hash API +======== + +The hash API is a collection of simple hash table functions. Users are expected +to implement their own hashing. + +Data Structures +--------------- + +`struct hash_table`:: + + The hash table structure. The `array` member points to the hash table + entries. The `size` member counts the total number of valid and invalid + entries in the table. The `nr` member keeps track of the number of + valid entries. + +`struct hash_table_entry`:: + + An opaque structure representing an entry in the hash table. The `hash` + member is the entry's hash key and the `ptr` member is the entry's + value. + +Functions +--------- + +`init_hash`:: + + Initialize the hash table. + +`free_hash`:: + + Release memory associated with the hash table. + +`insert_hash`:: + + Insert a pointer into the hash table. If an entry with that hash + already exists, a pointer to the existing entry's value is returned. + Otherwise NULL is returned. This allows callers to implement + chaining, etc. + +`lookup_hash`:: + + Lookup an entry in the hash table. If an entry with that hash exists + the entry's value is returned. Otherwise NULL is returned. + +`for_each_hash`:: + + Call a function for each entry in the hash table. The function is + expected to take the entry's value as its only argument and return an + int. If the function returns a negative int the loop is aborted + immediately. Otherwise, the return value is accumulated and the sum + returned upon completion of the loop. |