Subversion Repositories Kolibri OS

/**************************************************************************

 *

 * Copyright 2007 VMware, Inc.

 * All Rights Reserved.

 *

 * 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, sub license, 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 NON-INFRINGEMENT.

 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS 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.

 *

 **************************************************************************/

 /*

  * Authors:

  *   Zack Rusin 

  */

#include "util/u_debug.h"

#include "util/u_memory.h"

#include "cso_hash.h"

#ifndef MAX

#define MAX(a, b) ((a > b) ? (a) : (b))

#endif

static const int MinNumBits = 4;

static const unsigned char prime_deltas[] = {

   0,  0,  1,  3,  1,  5,  3,  3,  1,  9,  7,  5,  3,  9, 25,  3,

   1, 21,  3, 21,  7, 15,  9,  5,  3, 29, 15,  0,  0,  0,  0,  0

};

static int primeForNumBits(int numBits)

{

   return (1 << numBits) + prime_deltas[numBits];

}

/*

    Returns the smallest integer n such that

    primeForNumBits(n) >= hint.

*/

static int countBits(int hint)

{

   int numBits = 0;

   int bits = hint;

   while (bits > 1) {

      bits >>= 1;

      numBits++;

   }

   if (numBits >= (int)sizeof(prime_deltas)) {

      numBits = sizeof(prime_deltas) - 1;

   } else if (primeForNumBits(numBits) < hint) {

      ++numBits;

   }

   return numBits;

}

struct cso_node {

   struct cso_node *next;

   unsigned key;

   void *value;

};

struct cso_hash_data {

   struct cso_node *fakeNext;

   struct cso_node **buckets;

   int size;

   int nodeSize;

   short userNumBits;

   short numBits;

   int numBuckets;

};

struct cso_hash {

   union {

      struct cso_hash_data *d;

      struct cso_node      *e;

   } data;

};

static void *cso_data_allocate_node(struct cso_hash_data *hash)

{

   return MALLOC(hash->nodeSize);

}

static void cso_free_node(struct cso_node *node)

{

   FREE(node);

}

static struct cso_node *

cso_hash_create_node(struct cso_hash *hash,

                      unsigned akey, void *avalue,

                      struct cso_node **anextNode)

{

   struct cso_node *node = cso_data_allocate_node(hash->data.d);

   if (!node)

      return NULL;

   node->key = akey;

   node->value = avalue;

   node->next = (struct cso_node*)(*anextNode);

   *anextNode = node;

   ++hash->data.d->size;

   return node;

}

static void cso_data_rehash(struct cso_hash_data *hash, int hint)

{

   if (hint < 0) {

      hint = countBits(-hint);

      if (hint < MinNumBits)

         hint = MinNumBits;

      hash->userNumBits = (short)hint;

      while (primeForNumBits(hint) < (hash->size >> 1))

         ++hint;

   } else if (hint < MinNumBits) {

      hint = MinNumBits;

   }

   if (hash->numBits != hint) {

      struct cso_node *e = (struct cso_node *)(hash);

      struct cso_node **oldBuckets = hash->buckets;

      int oldNumBuckets = hash->numBuckets;

      int  i = 0;

      hash->numBits = (short)hint;

      hash->numBuckets = primeForNumBits(hint);

      hash->buckets = MALLOC(sizeof(struct cso_node*) * hash->numBuckets);

      for (i = 0; i < hash->numBuckets; ++i)

         hash->buckets[i] = e;

      for (i = 0; i < oldNumBuckets; ++i) {

         struct cso_node *firstNode = oldBuckets[i];

         while (firstNode != e) {

            unsigned h = firstNode->key;

            struct cso_node *lastNode = firstNode;

            struct cso_node *afterLastNode;

            struct cso_node **beforeFirstNode;

            while (lastNode->next != e && lastNode->next->key == h)

               lastNode = lastNode->next;

            afterLastNode = lastNode->next;

            beforeFirstNode = &hash->buckets[h % hash->numBuckets];

            while (*beforeFirstNode != e)

               beforeFirstNode = &(*beforeFirstNode)->next;

            lastNode->next = *beforeFirstNode;

            *beforeFirstNode = firstNode;

            firstNode = afterLastNode;

         }

      }

      FREE(oldBuckets);

   }

}

static void cso_data_might_grow(struct cso_hash_data *hash)

{

   if (hash->size >= hash->numBuckets)

      cso_data_rehash(hash, hash->numBits + 1);

}

static void cso_data_has_shrunk(struct cso_hash_data *hash)

{

   if (hash->size <= (hash->numBuckets >> 3) &&

       hash->numBits > hash->userNumBits) {

      int max = MAX(hash->numBits-2, hash->userNumBits);

      cso_data_rehash(hash,  max);

   }

}

static struct cso_node *cso_data_first_node(struct cso_hash_data *hash)

{

   struct cso_node *e = (struct cso_node *)(hash);

   struct cso_node **bucket = hash->buckets;

   int n = hash->numBuckets;

   while (n--) {

      if (*bucket != e)

         return *bucket;

      ++bucket;

   }

   return e;

}

static struct cso_node **cso_hash_find_node(struct cso_hash *hash, unsigned akey)

{

   struct cso_node **node;

   if (hash->data.d->numBuckets) {

      node = (struct cso_node **)(&hash->data.d->buckets[akey % hash->data.d->numBuckets]);

      assert(*node == hash->data.e || (*node)->next);

      while (*node != hash->data.e && (*node)->key != akey)

         node = &(*node)->next;

   } else {

      node = (struct cso_node **)((const struct cso_node * const *)(&hash->data.e));

   }

   return node;

}

struct cso_hash_iter cso_hash_insert(struct cso_hash *hash,

                                       unsigned key, void *data)

{

   cso_data_might_grow(hash->data.d);

   {

      struct cso_node **nextNode = cso_hash_find_node(hash, key);

      struct cso_node *node = cso_hash_create_node(hash, key, data, nextNode);

      if (!node) {

         struct cso_hash_iter null_iter = {hash, 0};

         return null_iter;

      }

      {

         struct cso_hash_iter iter = {hash, node};

         return iter;

      }

   }

}

struct cso_hash * cso_hash_create(void)

{

   struct cso_hash *hash = MALLOC_STRUCT(cso_hash);

   if (!hash)

      return NULL;

   hash->data.d = MALLOC_STRUCT(cso_hash_data);

   if (!hash->data.d) {

      FREE(hash);

      return NULL;

   }

   hash->data.d->fakeNext = 0;

   hash->data.d->buckets = 0;

   hash->data.d->size = 0;

   hash->data.d->nodeSize = sizeof(struct cso_node);

   hash->data.d->userNumBits = (short)MinNumBits;

   hash->data.d->numBits = 0;

   hash->data.d->numBuckets = 0;

   return hash;

}

void cso_hash_delete(struct cso_hash *hash)

{

   struct cso_node *e_for_x = (struct cso_node *)(hash->data.d);

   struct cso_node **bucket = (struct cso_node **)(hash->data.d->buckets);

   int n = hash->data.d->numBuckets;

   while (n--) {

      struct cso_node *cur = *bucket++;

      while (cur != e_for_x) {

         struct cso_node *next = cur->next;

         cso_free_node(cur);

         cur = next;

      }

   }

   FREE(hash->data.d->buckets);

   FREE(hash->data.d);

   FREE(hash);

}

struct cso_hash_iter cso_hash_find(struct cso_hash *hash,

                                     unsigned key)

{

   struct cso_node **nextNode = cso_hash_find_node(hash, key);

   struct cso_hash_iter iter = {hash, *nextNode};

   return iter;

}

unsigned cso_hash_iter_key(struct cso_hash_iter iter)

{

   if (!iter.node || iter.hash->data.e == iter.node)

      return 0;

   return iter.node->key;

}

void * cso_hash_iter_data(struct cso_hash_iter iter)

{

   if (!iter.node || iter.hash->data.e == iter.node)

      return 0;

   return iter.node->value;

}

static struct cso_node *cso_hash_data_next(struct cso_node *node)

{

   union {

      struct cso_node *next;

      struct cso_node *e;

      struct cso_hash_data *d;

   } a;

   int start;

   struct cso_node **bucket;

   int n;

   a.next = node->next;

   if (!a.next) {

      debug_printf("iterating beyond the last element\n");

      return 0;

   }

   if (a.next->next)

      return a.next;

   start = (node->key % a.d->numBuckets) + 1;

   bucket = a.d->buckets + start;

   n = a.d->numBuckets - start;

   while (n--) {

      if (*bucket != a.e)

         return *bucket;

      ++bucket;

   }

   return a.e;

}

static struct cso_node *cso_hash_data_prev(struct cso_node *node)

{

   union {

      struct cso_node *e;

      struct cso_hash_data *d;

   } a;

   int start;

   struct cso_node *sentinel;

   struct cso_node **bucket;

   a.e = node;

   while (a.e->next)

      a.e = a.e->next;

   if (node == a.e)

      start = a.d->numBuckets - 1;

   else

      start = node->key % a.d->numBuckets;

   sentinel = node;

   bucket = a.d->buckets + start;

   while (start >= 0) {

      if (*bucket != sentinel) {

         struct cso_node *prev = *bucket;

         while (prev->next != sentinel)

            prev = prev->next;

         return prev;

      }

      sentinel = a.e;

      --bucket;

      --start;

   }

   debug_printf("iterating backward beyond first element\n");

   return a.e;

}

struct cso_hash_iter cso_hash_iter_next(struct cso_hash_iter iter)

{

   struct cso_hash_iter next = {iter.hash, cso_hash_data_next(iter.node)};

   return next;

}

int cso_hash_iter_is_null(struct cso_hash_iter iter)

{

   if (!iter.node || iter.node == iter.hash->data.e)

      return 1;

   return 0;

}

void * cso_hash_take(struct cso_hash *hash,

                      unsigned akey)

{

   struct cso_node **node = cso_hash_find_node(hash, akey);

   if (*node != hash->data.e) {

      void *t = (*node)->value;

      struct cso_node *next = (*node)->next;

      cso_free_node(*node);

      *node = next;

      --hash->data.d->size;

      cso_data_has_shrunk(hash->data.d);

      return t;

   }

   return 0;

}

struct cso_hash_iter cso_hash_iter_prev(struct cso_hash_iter iter)

{

   struct cso_hash_iter prev = {iter.hash,

                                 cso_hash_data_prev(iter.node)};

   return prev;

}

struct cso_hash_iter cso_hash_first_node(struct cso_hash *hash)

{

   struct cso_hash_iter iter = {hash, cso_data_first_node(hash->data.d)};

   return iter;

}

int cso_hash_size(struct cso_hash *hash)

{

   return hash->data.d->size;

}

struct cso_hash_iter cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter)

{

   struct cso_hash_iter ret = iter;

   struct cso_node *node = iter.node;

   struct cso_node **node_ptr;

   if (node == hash->data.e)

      return iter;

   ret = cso_hash_iter_next(ret);

   node_ptr = (struct cso_node**)(&hash->data.d->buckets[node->key % hash->data.d->numBuckets]);

   while (*node_ptr != node)

      node_ptr = &(*node_ptr)->next;

   *node_ptr = node->next;

   cso_free_node(node);

   --hash->data.d->size;

   return ret;

}

boolean cso_hash_contains(struct cso_hash *hash, unsigned key)

{

   struct cso_node **node = cso_hash_find_node(hash, key);

   return (*node != hash->data.e);

}