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

 *

 * Copyright 2008 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.

 *

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

/**

 * @file

 * Generic handle table implementation.

 *

 * @author José Fonseca 

 */

#include "pipe/p_compiler.h"

#include "util/u_debug.h"

#include "util/u_memory.h"

#include "util/u_handle_table.h"

#define HANDLE_TABLE_INITIAL_SIZE 16

struct handle_table

{

   /** Object array. Empty handles have a null object */

   void **objects;

   /** Number of objects the handle can currently hold */

   unsigned size;

   /** Number of consecutive objects allocated at the start of the table */

   unsigned filled;

   /** Optional object destructor */

   void (*destroy)(void *object);

};

struct handle_table *

handle_table_create(void)

{

   struct handle_table *ht;

   ht = MALLOC_STRUCT(handle_table);

   if(!ht)

      return NULL;

   ht->objects = (void **)CALLOC(HANDLE_TABLE_INITIAL_SIZE, sizeof(void *));

   if(!ht->objects) {

      FREE(ht);

      return NULL;

   }

   ht->size = HANDLE_TABLE_INITIAL_SIZE;

   ht->filled = 0;

   ht->destroy = NULL;

   return ht;

}

void

handle_table_set_destroy(struct handle_table *ht,

                         void (*destroy)(void *object))

{

   assert(ht);

   if (!ht)

      return;

   ht->destroy = destroy;

}

/**

 * Resize the table if necessary

 */

static INLINE int

handle_table_resize(struct handle_table *ht,

                    unsigned minimum_size)

{

   unsigned new_size;

   void **new_objects;

   if(ht->size > minimum_size)

      return ht->size;

   new_size = ht->size;

   while(!(new_size > minimum_size))

      new_size *= 2;

   assert(new_size);

   new_objects = (void **)REALLOC((void *)ht->objects,

				  ht->size*sizeof(void *),

				  new_size*sizeof(void *));

   if(!new_objects)

      return 0;

   memset(new_objects + ht->size, 0, (new_size - ht->size)*sizeof(void *));

   ht->size = new_size;

   ht->objects = new_objects;

   return ht->size;

}

static INLINE void

handle_table_clear(struct handle_table *ht,

                   unsigned index)

{

   void *object;

   /* The order here is important so that the object being destroyed is not

    * present in the table when seen by the destroy callback, because the

    * destroy callback may directly or indirectly call the other functions in

    * this module.

    */

   object = ht->objects[index];

   if(object) {

      ht->objects[index] = NULL;

      if(ht->destroy)

         ht->destroy(object);

   }

}

unsigned

handle_table_add(struct handle_table *ht,

                 void *object)

{

   unsigned index;

   unsigned handle;

   assert(ht);

   assert(object);

   if(!object || !ht)

      return 0;

   /* linear search for an empty handle */

   while(ht->filled < ht->size) {

      if(!ht->objects[ht->filled])

	 break;

      ++ht->filled;

   }

   index = ht->filled;

   handle = index + 1;

   /* check integer overflow */

   if(!handle)

      return 0;

   /* grow the table if necessary */

   if(!handle_table_resize(ht, index))

      return 0;

   assert(!ht->objects[index]);

   ht->objects[index] = object;

   ++ht->filled;

   return handle;

}

unsigned

handle_table_set(struct handle_table *ht,

                 unsigned handle,

                 void *object)

{

   unsigned index;

   assert(ht);

   assert(handle);

   if(!handle || !ht)

      return 0;

   assert(object);

   if(!object)

      return 0;

   index = handle - 1;

   /* grow the table if necessary */

   if(!handle_table_resize(ht, index))

      return 0;

   handle_table_clear(ht, index);

   ht->objects[index] = object;

   return handle;

}

void *

handle_table_get(struct handle_table *ht,

                 unsigned handle)

{

   void *object;

   assert(ht);

   assert(handle);

   if(!handle || !ht || handle > ht->size)

      return NULL;

   object = ht->objects[handle - 1];

   return object;

}

void

handle_table_remove(struct handle_table *ht,

                    unsigned handle)

{

   void *object;

   unsigned index;

   assert(ht);

   assert(handle);

   if(!handle || !ht || handle > ht->size)

      return;

   index = handle - 1;

   object = ht->objects[index];

   if(!object)

      return;

   handle_table_clear(ht, index);

   if(index < ht->filled)

      ht->filled = index;

}

unsigned

handle_table_get_next_handle(struct handle_table *ht,

                             unsigned handle)

{

   unsigned index;

   for(index = handle; index < ht->size; ++index) {

      if(ht->objects[index])

	 return index + 1;

   }

   return 0;

}

unsigned

handle_table_get_first_handle(struct handle_table *ht)

{

   return handle_table_get_next_handle(ht, 0);

}

void

handle_table_destroy(struct handle_table *ht)

{

   unsigned index;

   assert(ht);

   if (!ht)

      return;

   if(ht->destroy)

      for(index = 0; index < ht->size; ++index)

         handle_table_clear(ht, index);

   FREE(ht->objects);

   FREE(ht);

}