src/gallium/auxiliary/cso_cache/cso_hash.h

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 VMware, Inc.
   4  * All Rights Reserved.
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  11  * permit persons to whom the Software is furnished to do so, subject to
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  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
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  27
  28 /**
  29  * @file
  30  * Hash table implementation.
  31  *
  32  * This file provides a hash implementation that is capable of dealing
  33  * with collisions. It stores colliding entries in linked list. All
  34  * functions operating on the hash return an iterator. The iterator
  35  * itself points to the collision list. If there wasn't any collision
  36  * the list will have just one entry, otherwise client code should
  37  * iterate over the entries to find the exact entry among ones that
  38  * had the same key (e.g. memcmp could be used on the data to check
  39  * that)
  40  *
  41  * @author Zack Rusin <zackr@vmware.com>
  42  */
  43
  44 #ifndef CSO_HASH_H
  45 #define CSO_HASH_H
  46
  47 #include "pipe/p_compiler.h"
  48
  49 #ifdef  __cplusplus
  50 extern "C" {
  51 #endif
  52
  53
  54 struct cso_node {
  55    struct cso_node *next;
  56    unsigned key;
  57    void *value;
  58 };
  59
  60 struct cso_hash_iter {
  61    struct cso_hash *hash;
  62    struct cso_node  *node;
  63 };
  64
  65 struct cso_hash_data {
  66    struct cso_node *fakeNext;
  67    struct cso_node **buckets;
  68    int size;
  69    short userNumBits;
  70    short numBits;
  71    int numBuckets;
  72 };
  73
  74 struct cso_hash {
  75    struct cso_hash_data data;
  76    struct cso_node      *end;
  77 };
  78
  79 void cso_hash_init(struct cso_hash *hash);
  80 void cso_hash_deinit(struct cso_hash *hash);
  81
  82
  83 int cso_hash_size(struct cso_hash *hash);
  84
  85
  86 /**
  87  * Adds a data with the given key to the hash. If entry with the given
  88  * key is already in the hash, this current entry is instered before it
  89  * in the collision list.
  90  * Function returns iterator pointing to the inserted item in the hash.
  91  */
  92 struct cso_hash_iter cso_hash_insert(struct cso_hash *hash, unsigned key,
  93                                      void *data);
  94 /**
  95  * Removes the item pointed to by the current iterator from the hash.
  96  * Note that the data itself is not erased and if it was a malloc'ed pointer
  97  * it will have to be freed after calling this function by the callee.
  98  * Function returns iterator pointing to the item after the removed one in
  99  * the hash.
 100  */
 101 struct cso_hash_iter cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter);
 102
 103 void *cso_hash_take(struct cso_hash *hash, unsigned key);
 104
 105
 106
 107 struct cso_hash_iter cso_hash_first_node(struct cso_hash *hash);
 108
 109 /**
 110  * Returns true if a value with the given key exists in the hash
 111  */
 112 bool cso_hash_contains(struct cso_hash *hash, unsigned key);
 113
 114
 115 unsigned cso_hash_iter_key(struct cso_hash_iter iter);
 116
 117
 118 struct cso_hash_iter cso_hash_iter_prev(struct cso_hash_iter iter);
 119
 120
 121 /**
 122  * Convenience routine to iterate over the collision list while doing a memory
 123  * comparison to see which entry in the list is a direct copy of our template
 124  * and returns that entry.
 125  */
 126 void *cso_hash_find_data_from_template(struct cso_hash *hash,
 127                                        unsigned hash_key,
 128                                        void *templ,
 129                                        int size);
 130
 131 struct cso_node *cso_hash_data_next(struct cso_node *node);
 132
 133 static inline bool
 134 cso_hash_iter_is_null(struct cso_hash_iter iter)
 135 {
 136    return !iter.node || iter.node == iter.hash->end;
 137 }
 138
 139 static inline void *
 140 cso_hash_iter_data(struct cso_hash_iter iter)
 141 {
 142    if (!iter.node || iter.hash->end == iter.node)
 143       return NULL;
 144    return iter.node->value;
 145 }
 146
 147 static inline struct cso_node **
 148 cso_hash_find_node(struct cso_hash *hash, unsigned akey)
 149 {
 150    struct cso_node **node;
 151
 152    if (hash->data.numBuckets) {
 153       node = &hash->data.buckets[akey % hash->data.numBuckets];
 154       assert(*node == hash->end || (*node)->next);
 155       while (*node != hash->end && (*node)->key != akey)
 156          node = &(*node)->next;
 157    } else {
 158       node = &hash->end;
 159    }
 160    return node;
 161 }
 162
 163 /**
 164  * Return an iterator pointing to the first entry in the collision list.
 165  */
 166 static inline struct cso_hash_iter
 167 cso_hash_find(struct cso_hash *hash, unsigned key)
 168 {
 169    struct cso_node **nextNode = cso_hash_find_node(hash, key);
 170    struct cso_hash_iter iter = {hash, *nextNode};
 171    return iter;
 172 }
 173
 174 static inline struct cso_hash_iter
 175 cso_hash_iter_next(struct cso_hash_iter iter)
 176 {
 177    struct cso_hash_iter next = {iter.hash, cso_hash_data_next(iter.node)};
 178    return next;
 179 }
 180
 181 #ifdef  __cplusplus
 182 }
 183 #endif
 184
 185 #endif