src/gallium/auxiliary/cso_cache/cso_hash.h

   1 /**************************************************************************
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   3  * Copyright 2007 VMware, Inc.
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  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    void *value;
  57    unsigned key;
  58 };
  59
  60 struct cso_hash_iter {
  61    struct cso_hash *hash;
  62    struct cso_node  *node;
  63 };
  64
  65 struct cso_hash {
  66    struct cso_node *fakeNext;
  67    struct cso_node **buckets;
  68    struct cso_node *end;
  69    int size;
  70    short userNumBits;
  71    short numBits;
  72    int numBuckets;
  73 };
  74
  75 void cso_hash_init(struct cso_hash *hash);
  76 void cso_hash_deinit(struct cso_hash *hash);
  77
  78
  79 int cso_hash_size(struct cso_hash *hash);
  80
  81
  82 /**
  83  * Adds a data with the given key to the hash. If entry with the given
  84  * key is already in the hash, this current entry is instered before it
  85  * in the collision list.
  86  * Function returns iterator pointing to the inserted item in the hash.
  87  */
  88 struct cso_hash_iter cso_hash_insert(struct cso_hash *hash, unsigned key,
  89                                      void *data);
  90 /**
  91  * Removes the item pointed to by the current iterator from the hash.
  92  * Note that the data itself is not erased and if it was a malloc'ed pointer
  93  * it will have to be freed after calling this function by the callee.
  94  * Function returns iterator pointing to the item after the removed one in
  95  * the hash.
  96  */
  97 struct cso_hash_iter cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter);
  98
  99 void *cso_hash_take(struct cso_hash *hash, unsigned key);
 100
 101
 102
 103 struct cso_hash_iter cso_hash_first_node(struct cso_hash *hash);
 104
 105 /**
 106  * Returns true if a value with the given key exists in the hash
 107  */
 108 bool cso_hash_contains(struct cso_hash *hash, unsigned key);
 109
 110
 111 unsigned cso_hash_iter_key(struct cso_hash_iter iter);
 112
 113
 114 struct cso_hash_iter cso_hash_iter_prev(struct cso_hash_iter iter);
 115
 116
 117 /**
 118  * Convenience routine to iterate over the collision list while doing a memory
 119  * comparison to see which entry in the list is a direct copy of our template
 120  * and returns that entry.
 121  */
 122 void *cso_hash_find_data_from_template(struct cso_hash *hash,
 123                                        unsigned hash_key,
 124                                        void *templ,
 125                                        int size);
 126
 127 struct cso_node *cso_hash_data_next(struct cso_node *node);
 128
 129 static inline bool
 130 cso_hash_iter_is_null(struct cso_hash_iter iter)
 131 {
 132    return !iter.node || iter.node == iter.hash->end;
 133 }
 134
 135 static inline void *
 136 cso_hash_iter_data(struct cso_hash_iter iter)
 137 {
 138    if (!iter.node || iter.hash->end == iter.node)
 139       return NULL;
 140    return iter.node->value;
 141 }
 142
 143 static inline struct cso_node **
 144 cso_hash_find_node(struct cso_hash *hash, unsigned akey)
 145 {
 146    struct cso_node **node;
 147
 148    if (hash->numBuckets) {
 149       node = &hash->buckets[akey % hash->numBuckets];
 150       assert(*node == hash->end || (*node)->next);
 151       while (*node != hash->end && (*node)->key != akey)
 152          node = &(*node)->next;
 153    } else {
 154       node = &hash->end;
 155    }
 156    return node;
 157 }
 158
 159 /**
 160  * Return an iterator pointing to the first entry in the collision list.
 161  */
 162 static inline struct cso_hash_iter
 163 cso_hash_find(struct cso_hash *hash, unsigned key)
 164 {
 165    struct cso_node **nextNode = cso_hash_find_node(hash, key);
 166    struct cso_hash_iter iter = {hash, *nextNode};
 167    return iter;
 168 }
 169
 170 static inline struct cso_hash_iter
 171 cso_hash_iter_next(struct cso_hash_iter iter)
 172 {
 173    struct cso_hash_iter next = {iter.hash, cso_hash_data_next(iter.node)};
 174    return next;
 175 }
 176
 177 #ifdef  __cplusplus
 178 }
 179 #endif
 180
 181 #endif