src/mesa/shader/hash_table.h

   1 /*
   2  * Copyright © 2008 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file hash_table.h
  26  * \brief Implementation of a generic, opaque hash table data type.
  27  *
  28  * \author Ian Romanick <ian.d.romanick@intel.com>
  29  */
  30
  31 #ifndef HASH_TABLE_H
  32 #define HASH_TABLE_H
  33
  34 #include <string.h>
  35
  36 struct hash_table;
  37
  38 typedef unsigned (*hash_func_t)(const void *key);
  39 typedef int (*hash_compare_func_t)(const void *key1, const void *key2);
  40
  41 /**
  42  * Hash table constructor
  43  *
  44  * Creates a hash table with the specified number of buckets.  The supplied
  45  * \c hash and \c compare routines are used when adding elements to the table
  46  * and when searching for elements in the table.
  47  *
  48  * \param num_buckets  Number of buckets (bins) in the hash table.
  49  * \param hash         Function used to compute hash value of input keys.
  50  * \param compare      Function used to compare keys.
  51  */
  52 extern struct hash_table *hash_table_ctor(unsigned num_buckets,
  53     hash_func_t hash, hash_compare_func_t compare);
  54
  55
  56 /**
  57  * Release all memory associated with a hash table
  58  *
  59  * \warning
  60  * This function cannot release memory occupied either by keys or data.
  61  */
  62 extern void hash_table_dtor(struct hash_table *ht);
  63
  64
  65 /**
  66  * Flush all entries from a hash table
  67  *
  68  * \param ht  Table to be cleared of its entries.
  69  */
  70 extern void hash_table_clear(struct hash_table *ht);
  71
  72
  73 /**
  74  * Search a hash table for a specific element
  75  *
  76  * \param ht   Table to be searched
  77  * \param key  Key of the desired element
  78  *
  79  * \return
  80  * The \c data value supplied to \c hash_table_insert when the element with
  81  * the matching key was added.  If no matching key exists in the table,
  82  * \c NULL is returned.
  83  */
  84 extern void *hash_table_find(struct hash_table *ht, const void *key);
  85
  86
  87 /**
  88  * Add an element to a hash table
  89  */
  90 extern void hash_table_insert(struct hash_table *ht, void *data,
  91     const void *key);
  92
  93
  94 /**
  95  * Compute hash value of a string
  96  *
  97  * Computes the hash value of a string using the DJB2 algorithm developed by
  98  * Professor Daniel J. Bernstein.  It was published on comp.lang.c once upon
  99  * a time.  I was unable to find the original posting in the archives.
 100  *
 101  * \param key  Pointer to a NUL terminated string to be hashed.
 102  *
 103  * \sa hash_table_string_compare
 104  */
 105 extern unsigned hash_table_string_hash(const void *key);
 106
 107
 108 /**
 109  * Compare two strings used as keys
 110  *
 111  * This is just a macro wrapper around \c strcmp.
 112  *
 113  * \sa hash_table_string_hash
 114  */
 115 #define hash_table_string_compare ((hash_compare_func_t) strcmp)
 116
 117 #endif /* HASH_TABLE_H */