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drm_hashtab.c

/**************************************************************************
 *
 * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND. USA.
 * 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
 * THE COPYRIGHT HOLDERS, AUTHORS 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.
 *
 *
 **************************************************************************/
/*
 * Simple open hash tab implementation.
 *
 * Authors:
 * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
 */

#include "drmP.h"
#include "drm_hashtab.h"
#include <linux/hash.h>

int drm_ht_create(struct drm_open_hash *ht, unsigned int order)
{
      unsigned int i;

      ht->size = 1 << order;
      ht->order = order;
      ht->fill = 0;
      ht->table = NULL;
      ht->use_vmalloc = ((ht->size * sizeof(*ht->table)) > PAGE_SIZE);
      if (!ht->use_vmalloc) {
            ht->table = drm_calloc(ht->size, sizeof(*ht->table),
                               DRM_MEM_HASHTAB);
      }
      if (!ht->table) {
            ht->use_vmalloc = 1;
            ht->table = vmalloc(ht->size*sizeof(*ht->table));
      }
      if (!ht->table) {
            DRM_ERROR("Out of memory for hash table\n");
            return -ENOMEM;
      }
      for (i=0; i< ht->size; ++i) {
            INIT_HLIST_HEAD(&ht->table[i]);
      }
      return 0;
}

void drm_ht_verbose_list(struct drm_open_hash *ht, unsigned long key)
{
      struct drm_hash_item *entry;
      struct hlist_head *h_list;
      struct hlist_node *list;
      unsigned int hashed_key;
      int count = 0;

      hashed_key = hash_long(key, ht->order);
      DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
      h_list = &ht->table[hashed_key];
      hlist_for_each(list, h_list) {
            entry = hlist_entry(list, struct drm_hash_item, head);
            DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
      }
}

static struct hlist_node *drm_ht_find_key(struct drm_open_hash *ht, 
                                unsigned long key)
{
      struct drm_hash_item *entry;
      struct hlist_head *h_list;
      struct hlist_node *list;
      unsigned int hashed_key;

      hashed_key = hash_long(key, ht->order);
      h_list = &ht->table[hashed_key];
      hlist_for_each(list, h_list) {
            entry = hlist_entry(list, struct drm_hash_item, head);
            if (entry->key == key)
                  return list;
            if (entry->key > key)
                  break;
      }
      return NULL;
}


int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
      struct drm_hash_item *entry;
      struct hlist_head *h_list;
      struct hlist_node *list, *parent;
      unsigned int hashed_key;
      unsigned long key = item->key;

      hashed_key = hash_long(key, ht->order);
      h_list = &ht->table[hashed_key];
      parent = NULL;
      hlist_for_each(list, h_list) {
            entry = hlist_entry(list, struct drm_hash_item, head);
            if (entry->key == key)
                  return -EINVAL;
            if (entry->key > key)
                  break;
            parent = list;
      }
      if (parent) {
            hlist_add_after(parent, &item->head);
      } else {
            hlist_add_head(&item->head, h_list);
      }
      return 0;
}

/*
 * Just insert an item and return any "bits" bit key that hasn't been 
 * used before.
 */
int drm_ht_just_insert_please(struct drm_open_hash *ht, struct drm_hash_item *item,
                        unsigned long seed, int bits, int shift,
                        unsigned long add)
{
      int ret;
      unsigned long mask = (1 << bits) - 1;
      unsigned long first, unshifted_key;

      unshifted_key = hash_long(seed, bits);
      first = unshifted_key;
      do {
            item->key = (unshifted_key << shift) + add;
            ret = drm_ht_insert_item(ht, item);
            if (ret)
                  unshifted_key = (unshifted_key + 1) & mask;
      } while(ret && (unshifted_key != first));

      if (ret) {
            DRM_ERROR("Available key bit space exhausted\n");
            return -EINVAL;
      }
      return 0;
}

int drm_ht_find_item(struct drm_open_hash *ht, unsigned long key,
                 struct drm_hash_item **item)
{
      struct hlist_node *list;

      list = drm_ht_find_key(ht, key);
      if (!list)
            return -EINVAL;

      *item = hlist_entry(list, struct drm_hash_item, head);
      return 0;
}

int drm_ht_remove_key(struct drm_open_hash *ht, unsigned long key)
{
      struct hlist_node *list;

      list = drm_ht_find_key(ht, key);
      if (list) {
            hlist_del_init(list);
            ht->fill--;
            return 0;
      }
      return -EINVAL;
}

int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
      hlist_del_init(&item->head);
      ht->fill--;
      return 0;
}

void drm_ht_remove(struct drm_open_hash *ht)
{
      if (ht->table) {
            if (ht->use_vmalloc)
                  vfree(ht->table);
            else
                  drm_free(ht->table, ht->size * sizeof(*ht->table),
                         DRM_MEM_HASHTAB);
            ht->table = NULL;
      }
}


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