Documentation / technical / api-hash.txton commit Better advice on using topic branches for kernel development (352953a)
   1hash API
   2========
   3
   4The hash API is a collection of simple hash table functions. Users are expected
   5to implement their own hashing.
   6
   7Data Structures
   8---------------
   9
  10`struct hash_table`::
  11
  12        The hash table structure. The `array` member points to the hash table
  13        entries. The `size` member counts the total number of valid and invalid
  14        entries in the table. The `nr` member keeps track of the number of
  15        valid entries.
  16
  17`struct hash_table_entry`::
  18
  19        An opaque structure representing an entry in the hash table. The `hash`
  20        member is the entry's hash key and the `ptr` member is the entry's
  21        value.
  22
  23Functions
  24---------
  25
  26`init_hash`::
  27
  28        Initialize the hash table.
  29
  30`free_hash`::
  31
  32        Release memory associated with the hash table.
  33
  34`insert_hash`::
  35
  36        Insert a pointer into the hash table. If an entry with that hash
  37        already exists, a pointer to the existing entry's value is returned.
  38        Otherwise NULL is returned.  This allows callers to implement
  39        chaining, etc.
  40
  41`lookup_hash`::
  42
  43        Lookup an entry in the hash table. If an entry with that hash exists
  44        the entry's value is returned. Otherwise NULL is returned.
  45
  46`for_each_hash`::
  47
  48        Call a function for each entry in the hash table. The function is
  49        expected to take the entry's value as its only argument and return an
  50        int. If the function returns a negative int the loop is aborted
  51        immediately.  Otherwise, the return value is accumulated and the sum
  52        returned upon completion of the loop.