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/*

 * Copyright © 2009-2012 Intel Corporation

 * Copyright © 1988-2004 Keith Packard and Bart Massey.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 *

 * Except as contained in this notice, the names of the authors

 * or their institutions shall not be used in advertising or

 * otherwise to promote the sale, use or other dealings in this

 * Software without prior written authorization from the

 * authors.

 *

 * Authors:

 *    Eric Anholt 

 *    Keith Packard 

 */

#include 

#include 

#include "macros.h"

#include "ralloc.h"

#include "set.h"

/*

 * From Knuth -- a good choice for hash/rehash values is p, p-2 where

 * p and p-2 are both prime.  These tables are sized to have an extra 10%

 * free to avoid exponential performance degradation as the hash table fills

 */

uint32_t deleted_key_value;

const void *deleted_key = &deleted_key_value;

static const struct {

   uint32_t max_entries, size, rehash;

} hash_sizes[] = {

   { 2,            5,            3            },

   { 4,            7,            5            },

   { 8,            13,           11           },

   { 16,           19,           17           },

   { 32,           43,           41           },

   { 64,           73,           71           },

   { 128,          151,          149          },

   { 256,          283,          281          },

   { 512,          571,          569          },

   { 1024,         1153,         1151         },

   { 2048,         2269,         2267         },

   { 4096,         4519,         4517         },

   { 8192,         9013,         9011         },

   { 16384,        18043,        18041        },

   { 32768,        36109,        36107        },

   { 65536,        72091,        72089        },

   { 131072,       144409,       144407       },

   { 262144,       288361,       288359       },

   { 524288,       576883,       576881       },

   { 1048576,      1153459,      1153457      },

   { 2097152,      2307163,      2307161      },

   { 4194304,      4613893,      4613891      },

   { 8388608,      9227641,      9227639      },

   { 16777216,     18455029,     18455027     },

   { 33554432,     36911011,     36911009     },

   { 67108864,     73819861,     73819859     },

   { 134217728,    147639589,    147639587    },

   { 268435456,    295279081,    295279079    },

   { 536870912,    590559793,    590559791    },

   { 1073741824,   1181116273,   1181116271   },

   { 2147483648ul, 2362232233ul, 2362232231ul }

};

static int

entry_is_free(struct set_entry *entry)

{

   return entry->key == NULL;

}

static int

entry_is_deleted(struct set_entry *entry)

{

   return entry->key == deleted_key;

}

static int

entry_is_present(struct set_entry *entry)

{

   return entry->key != NULL && entry->key != deleted_key;

}

struct set *

_mesa_set_create(void *mem_ctx,

                 uint32_t (*key_hash_function)(const void *key),

                 bool (*key_equals_function)(const void *a,

                                             const void *b))

{

   struct set *ht;

   ht = ralloc(mem_ctx, struct set);

   if (ht == NULL)

      return NULL;

   ht->size_index = 0;

   ht->size = hash_sizes[ht->size_index].size;

   ht->rehash = hash_sizes[ht->size_index].rehash;

   ht->max_entries = hash_sizes[ht->size_index].max_entries;

   ht->key_hash_function = key_hash_function;

   ht->key_equals_function = key_equals_function;

   ht->table = rzalloc_array(ht, struct set_entry, ht->size);

   ht->entries = 0;

   ht->deleted_entries = 0;

   if (ht->table == NULL) {

      ralloc_free(ht);

      return NULL;

   }

   return ht;

}

/**

 * Frees the given set.

 *

 * If delete_function is passed, it gets called on each entry present before

 * freeing.

 */

void

_mesa_set_destroy(struct set *ht, void (*delete_function)(struct set_entry *entry))

{

   if (!ht)

      return;

   if (delete_function) {

      struct set_entry *entry;

      set_foreach (ht, entry) {

         delete_function(entry);

      }

   }

   ralloc_free(ht->table);

   ralloc_free(ht);

}

/**

 * Finds a set entry with the given key and hash of that key.

 *

 * Returns NULL if no entry is found.

 */

static struct set_entry *

set_search(const struct set *ht, uint32_t hash, const void *key)

{

   uint32_t hash_address;

   hash_address = hash % ht->size;

   do {

      uint32_t double_hash;

      struct set_entry *entry = ht->table + hash_address;

      if (entry_is_free(entry)) {

         return NULL;

      } else if (entry_is_present(entry) && entry->hash == hash) {

         if (ht->key_equals_function(key, entry->key)) {

            return entry;

         }

      }

      double_hash = 1 + hash % ht->rehash;

      hash_address = (hash_address + double_hash) % ht->size;

   } while (hash_address != hash % ht->size);

   return NULL;

}

struct set_entry *

_mesa_set_search(const struct set *set, const void *key)

{

   assert(set->key_hash_function);

   return set_search(set, set->key_hash_function(key), key);

}

struct set_entry *

_mesa_set_search_pre_hashed(const struct set *set, uint32_t hash,

                            const void *key)

{

   assert(set->key_hash_function == NULL ||

          hash == set->key_hash_function(key));

   return set_search(set, hash, key);

}

static struct set_entry *

set_add(struct set *ht, uint32_t hash, const void *key);

static void

set_rehash(struct set *ht, unsigned new_size_index)

{

   struct set old_ht;

   struct set_entry *table, *entry;

   if (new_size_index >= ARRAY_SIZE(hash_sizes))

      return;

   table = rzalloc_array(ht, struct set_entry,

                         hash_sizes[new_size_index].size);

   if (table == NULL)

      return;

   old_ht = *ht;

   ht->table = table;

   ht->size_index = new_size_index;

   ht->size = hash_sizes[ht->size_index].size;

   ht->rehash = hash_sizes[ht->size_index].rehash;

   ht->max_entries = hash_sizes[ht->size_index].max_entries;

   ht->entries = 0;

   ht->deleted_entries = 0;

   for (entry = old_ht.table;

        entry != old_ht.table + old_ht.size;

        entry++) {

      if (entry_is_present(entry)) {

         set_add(ht, entry->hash, entry->key);

      }

   }

   ralloc_free(old_ht.table);

}

/**

 * Inserts the key with the given hash into the table.

 *

 * Note that insertion may rearrange the table on a resize or rehash,

 * so previously found hash_entries are no longer valid after this function.

 */

static struct set_entry *

set_add(struct set *ht, uint32_t hash, const void *key)

{

   uint32_t hash_address;

   struct set_entry *available_entry = NULL;

   if (ht->entries >= ht->max_entries) {

      set_rehash(ht, ht->size_index + 1);

   } else if (ht->deleted_entries + ht->entries >= ht->max_entries) {

      set_rehash(ht, ht->size_index);

   }

   hash_address = hash % ht->size;

   do {

      struct set_entry *entry = ht->table + hash_address;

      uint32_t double_hash;

      if (!entry_is_present(entry)) {

         /* Stash the first available entry we find */

         if (available_entry == NULL)

            available_entry = entry;

         if (entry_is_free(entry))

            break;

      }

      /* Implement replacement when another insert happens

       * with a matching key.  This is a relatively common

       * feature of hash tables, with the alternative

       * generally being "insert the new value as well, and

       * return it first when the key is searched for".

       *

       * Note that the hash table doesn't have a delete callback.

       * If freeing of old keys is required to avoid memory leaks,

       * perform a search before inserting.

       */

      if (entry->hash == hash &&

          ht->key_equals_function(key, entry->key)) {

         entry->key = key;

         return entry;

      }

      double_hash = 1 + hash % ht->rehash;

      hash_address = (hash_address + double_hash) % ht->size;

   } while (hash_address != hash % ht->size);

   if (available_entry) {

      if (entry_is_deleted(available_entry))

         ht->deleted_entries--;

      available_entry->hash = hash;

      available_entry->key = key;

      ht->entries++;

      return available_entry;

   }

   /* We could hit here if a required resize failed. An unchecked-malloc

    * application could ignore this result.

    */

   return NULL;

}

struct set_entry *

_mesa_set_add(struct set *set, const void *key)

{

   assert(set->key_hash_function);

   return set_add(set, set->key_hash_function(key), key);

}

struct set_entry *

_mesa_set_add_pre_hashed(struct set *set, uint32_t hash, const void *key)

{

   assert(set->key_hash_function == NULL ||

          hash == set->key_hash_function(key));

   return set_add(set, hash, key);

}

/**

 * This function deletes the given hash table entry.

 *

 * Note that deletion doesn't otherwise modify the table, so an iteration over

 * the table deleting entries is safe.

 */

void

_mesa_set_remove(struct set *ht, struct set_entry *entry)

{

   if (!entry)

      return;

   entry->key = deleted_key;

   ht->entries--;

   ht->deleted_entries++;

}

/**

 * This function is an iterator over the hash table.

 *

 * Pass in NULL for the first entry, as in the start of a for loop.  Note that

 * an iteration over the table is O(table_size) not O(entries).

 */

struct set_entry *

_mesa_set_next_entry(const struct set *ht, struct set_entry *entry)

{

   if (entry == NULL)

      entry = ht->table;

   else

      entry = entry + 1;

   for (; entry != ht->table + ht->size; entry++) {

      if (entry_is_present(entry)) {

         return entry;

      }

   }

   return NULL;

}

struct set_entry *

_mesa_set_random_entry(struct set *ht,

                       int (*predicate)(struct set_entry *entry))

{

   struct set_entry *entry;

   uint32_t i = rand() % ht->size;

   if (ht->entries == 0)

      return NULL;

   for (entry = ht->table + i; entry != ht->table + ht->size; entry++) {

      if (entry_is_present(entry) &&

          (!predicate || predicate(entry))) {

         return entry;

      }

   }

   for (entry = ht->table; entry != ht->table + i; entry++) {

      if (entry_is_present(entry) &&

          (!predicate || predicate(entry))) {

         return entry;

      }

   }

   return NULL;

}