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562 lines
14 KiB
C
562 lines
14 KiB
C
/**
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* \file hash.c
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* Generic hash table.
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*
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* Used for display lists, texture objects, vertex/fragment programs,
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* buffer objects, etc. The hash functions are thread-safe.
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*
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* \note key=0 is illegal.
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*
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* \author Brian Paul
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*/
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/*
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* Mesa 3-D graphics library
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* Version: 6.5.1
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*
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* Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <precomp.h>
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#define TABLE_SIZE 1023 /**< Size of lookup table/array */
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#define HASH_FUNC(K) ((K) % TABLE_SIZE)
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/**
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* An entry in the hash table.
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*/
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struct HashEntry {
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GLuint Key; /**< the entry's key */
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void *Data; /**< the entry's data */
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struct HashEntry *Next; /**< pointer to next entry */
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};
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/**
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* The hash table data structure.
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*/
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struct _mesa_HashTable {
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struct HashEntry *Table[TABLE_SIZE]; /**< the lookup table */
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GLuint MaxKey; /**< highest key inserted so far */
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_glthread_Mutex Mutex; /**< mutual exclusion lock */
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_glthread_Mutex WalkMutex; /**< for _mesa_HashWalk() */
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GLboolean InDeleteAll; /**< Debug check */
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};
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/**
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* Create a new hash table.
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*
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* \return pointer to a new, empty hash table.
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*/
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struct _mesa_HashTable *
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_mesa_NewHashTable(void)
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{
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struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable);
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if (table) {
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_glthread_INIT_MUTEX(table->Mutex);
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_glthread_INIT_MUTEX(table->WalkMutex);
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}
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return table;
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}
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/**
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* Delete a hash table.
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* Frees each entry on the hash table and then the hash table structure itself.
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* Note that the caller should have already traversed the table and deleted
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* the objects in the table (i.e. We don't free the entries' data pointer).
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*
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* \param table the hash table to delete.
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*/
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void
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_mesa_DeleteHashTable(struct _mesa_HashTable *table)
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{
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GLuint pos;
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assert(table);
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for (pos = 0; pos < TABLE_SIZE; pos++) {
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struct HashEntry *entry = table->Table[pos];
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while (entry) {
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struct HashEntry *next = entry->Next;
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if (entry->Data) {
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_mesa_problem(NULL,
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"In _mesa_DeleteHashTable, found non-freed data");
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}
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free(entry);
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entry = next;
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}
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}
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_glthread_DESTROY_MUTEX(table->Mutex);
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_glthread_DESTROY_MUTEX(table->WalkMutex);
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free(table);
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}
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/**
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* Lookup an entry in the hash table, without locking.
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* \sa _mesa_HashLookup
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*/
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static inline void *
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_mesa_HashLookup_unlocked(struct _mesa_HashTable *table, GLuint key)
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{
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GLuint pos;
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const struct HashEntry *entry;
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assert(table);
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assert(key);
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pos = HASH_FUNC(key);
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entry = table->Table[pos];
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while (entry) {
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if (entry->Key == key) {
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return entry->Data;
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}
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entry = entry->Next;
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}
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return NULL;
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}
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/**
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* Lookup an entry in the hash table.
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*
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* \param table the hash table.
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* \param key the key.
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*
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* \return pointer to user's data or NULL if key not in table
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*/
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void *
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_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key)
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{
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void *res;
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assert(table);
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_glthread_LOCK_MUTEX(table->Mutex);
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res = _mesa_HashLookup_unlocked(table, key);
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return res;
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}
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/**
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* Insert a key/pointer pair into the hash table.
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* If an entry with this key already exists we'll replace the existing entry.
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*
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* \param table the hash table.
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* \param key the key (not zero).
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* \param data pointer to user data.
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*/
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void
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_mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data)
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{
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/* search for existing entry with this key */
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GLuint pos;
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struct HashEntry *entry;
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assert(table);
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assert(key);
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_glthread_LOCK_MUTEX(table->Mutex);
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if (key > table->MaxKey)
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table->MaxKey = key;
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pos = HASH_FUNC(key);
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/* check if replacing an existing entry with same key */
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for (entry = table->Table[pos]; entry; entry = entry->Next) {
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if (entry->Key == key) {
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/* replace entry's data */
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#if 0 /* not sure this check is always valid */
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if (entry->Data) {
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_mesa_problem(NULL, "Memory leak detected in _mesa_HashInsert");
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}
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#endif
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entry->Data = data;
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return;
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}
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}
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/* alloc and insert new table entry */
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entry = MALLOC_STRUCT(HashEntry);
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if (entry) {
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entry->Key = key;
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entry->Data = data;
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entry->Next = table->Table[pos];
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table->Table[pos] = entry;
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}
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_glthread_UNLOCK_MUTEX(table->Mutex);
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}
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/**
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* Remove an entry from the hash table.
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*
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* \param table the hash table.
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* \param key key of entry to remove.
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*
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* While holding the hash table's lock, searches the entry with the matching
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* key and unlinks it.
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*/
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void
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_mesa_HashRemove(struct _mesa_HashTable *table, GLuint key)
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{
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GLuint pos;
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struct HashEntry *entry, *prev;
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assert(table);
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assert(key);
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/* have to check this outside of mutex lock */
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if (table->InDeleteAll) {
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_mesa_problem(NULL, "_mesa_HashRemove illegally called from "
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"_mesa_HashDeleteAll callback function");
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return;
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}
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_glthread_LOCK_MUTEX(table->Mutex);
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pos = HASH_FUNC(key);
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prev = NULL;
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entry = table->Table[pos];
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while (entry) {
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if (entry->Key == key) {
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/* found it! */
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if (prev) {
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prev->Next = entry->Next;
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}
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else {
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table->Table[pos] = entry->Next;
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}
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free(entry);
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return;
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}
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prev = entry;
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entry = entry->Next;
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}
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_glthread_UNLOCK_MUTEX(table->Mutex);
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}
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/**
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* Delete all entries in a hash table, but don't delete the table itself.
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* Invoke the given callback function for each table entry.
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*
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* \param table the hash table to delete
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* \param callback the callback function
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* \param userData arbitrary pointer to pass along to the callback
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* (this is typically a struct gl_context pointer)
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*/
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void
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_mesa_HashDeleteAll(struct _mesa_HashTable *table,
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void (*callback)(GLuint key, void *data, void *userData),
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void *userData)
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{
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GLuint pos;
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ASSERT(table);
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ASSERT(callback);
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_glthread_LOCK_MUTEX(table->Mutex);
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table->InDeleteAll = GL_TRUE;
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for (pos = 0; pos < TABLE_SIZE; pos++) {
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struct HashEntry *entry, *next;
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for (entry = table->Table[pos]; entry; entry = next) {
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callback(entry->Key, entry->Data, userData);
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next = entry->Next;
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free(entry);
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}
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table->Table[pos] = NULL;
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}
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table->InDeleteAll = GL_FALSE;
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_glthread_UNLOCK_MUTEX(table->Mutex);
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}
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/**
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* Walk over all entries in a hash table, calling callback function for each.
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* Note: we use a separate mutex in this function to avoid a recursive
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* locking deadlock (in case the callback calls _mesa_HashRemove()) and to
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* prevent multiple threads/contexts from getting tangled up.
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* A lock-less version of this function could be used when the table will
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* not be modified.
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* \param table the hash table to walk
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* \param callback the callback function
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* \param userData arbitrary pointer to pass along to the callback
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* (this is typically a struct gl_context pointer)
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*/
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void
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_mesa_HashWalk(const struct _mesa_HashTable *table,
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void (*callback)(GLuint key, void *data, void *userData),
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void *userData)
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{
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/* cast-away const */
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struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table;
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GLuint pos;
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ASSERT(table);
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ASSERT(callback);
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_glthread_LOCK_MUTEX(table2->WalkMutex);
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for (pos = 0; pos < TABLE_SIZE; pos++) {
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struct HashEntry *entry, *next;
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for (entry = table->Table[pos]; entry; entry = next) {
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/* save 'next' pointer now in case the callback deletes the entry */
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next = entry->Next;
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callback(entry->Key, entry->Data, userData);
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}
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}
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_glthread_UNLOCK_MUTEX(table2->WalkMutex);
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}
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/**
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* Return the key of the "first" entry in the hash table.
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* While holding the lock, walks through all table positions until finding
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* the first entry of the first non-empty one.
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*
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* \param table the hash table
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* \return key for the "first" entry in the hash table.
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*/
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GLuint
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_mesa_HashFirstEntry(struct _mesa_HashTable *table)
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{
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GLuint pos;
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assert(table);
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_glthread_LOCK_MUTEX(table->Mutex);
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for (pos = 0; pos < TABLE_SIZE; pos++) {
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if (table->Table[pos]) {
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return table->Table[pos]->Key;
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}
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}
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return 0;
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}
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/**
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* Given a hash table key, return the next key. This is used to walk
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* over all entries in the table. Note that the keys returned during
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* walking won't be in any particular order.
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* \return next hash key or 0 if end of table.
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*/
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GLuint
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_mesa_HashNextEntry(const struct _mesa_HashTable *table, GLuint key)
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{
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const struct HashEntry *entry;
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GLuint pos;
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assert(table);
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assert(key);
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/* Find the entry with given key */
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pos = HASH_FUNC(key);
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for (entry = table->Table[pos]; entry ; entry = entry->Next) {
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if (entry->Key == key) {
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break;
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}
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}
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if (!entry) {
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/* the given key was not found, so we can't find the next entry */
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return 0;
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}
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if (entry->Next) {
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/* return next in linked list */
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return entry->Next->Key;
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}
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else {
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/* look for next non-empty table slot */
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pos++;
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while (pos < TABLE_SIZE) {
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if (table->Table[pos]) {
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return table->Table[pos]->Key;
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}
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pos++;
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}
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return 0;
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}
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}
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/**
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* Dump contents of hash table for debugging.
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*
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* \param table the hash table.
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*/
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void
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_mesa_HashPrint(const struct _mesa_HashTable *table)
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{
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GLuint pos;
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assert(table);
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for (pos = 0; pos < TABLE_SIZE; pos++) {
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const struct HashEntry *entry = table->Table[pos];
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while (entry) {
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_mesa_debug(NULL, "%u %p\n", entry->Key, entry->Data);
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entry = entry->Next;
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}
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}
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}
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/**
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* Find a block of adjacent unused hash keys.
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*
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* \param table the hash table.
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* \param numKeys number of keys needed.
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*
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* \return Starting key of free block or 0 if failure.
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*
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* If there are enough free keys between the maximum key existing in the table
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* (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
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* the adjacent key. Otherwise do a full search for a free key block in the
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* allowable key range.
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*/
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GLuint
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_mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys)
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{
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const GLuint maxKey = ~((GLuint) 0);
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_glthread_LOCK_MUTEX(table->Mutex);
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if (maxKey - numKeys > table->MaxKey) {
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/* the quick solution */
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return table->MaxKey + 1;
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}
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else {
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/* the slow solution */
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GLuint freeCount = 0;
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GLuint freeStart = 1;
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GLuint key;
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for (key = 1; key != maxKey; key++) {
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if (_mesa_HashLookup_unlocked(table, key)) {
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/* darn, this key is already in use */
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freeCount = 0;
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freeStart = key+1;
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}
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else {
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/* this key not in use, check if we've found enough */
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freeCount++;
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if (freeCount == numKeys) {
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return freeStart;
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}
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}
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}
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/* cannot allocate a block of numKeys consecutive keys */
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_glthread_UNLOCK_MUTEX(table->Mutex);
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return 0;
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}
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}
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/**
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* Return the number of entries in the hash table.
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*/
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GLuint
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_mesa_HashNumEntries(const struct _mesa_HashTable *table)
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{
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GLuint pos, count = 0;
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for (pos = 0; pos < TABLE_SIZE; pos++) {
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const struct HashEntry *entry;
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for (entry = table->Table[pos]; entry; entry = entry->Next) {
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count++;
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}
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}
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return count;
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}
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#if 0 /* debug only */
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/**
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* Test walking over all the entries in a hash table.
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*/
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static void
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test_hash_walking(void)
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{
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struct _mesa_HashTable *t = _mesa_NewHashTable();
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const GLuint limit = 50000;
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GLuint i;
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/* create some entries */
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for (i = 0; i < limit; i++) {
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GLuint dummy;
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GLuint k = (rand() % (limit * 10)) + 1;
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while (_mesa_HashLookup(t, k)) {
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/* id already in use, try another */
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k = (rand() % (limit * 10)) + 1;
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}
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_mesa_HashInsert(t, k, &dummy);
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}
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/* walk over all entries */
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{
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GLuint k = _mesa_HashFirstEntry(t);
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GLuint count = 0;
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while (k) {
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GLuint knext = _mesa_HashNextEntry(t, k);
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assert(knext != k);
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_mesa_HashRemove(t, k);
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count++;
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k = knext;
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}
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assert(count == limit);
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k = _mesa_HashFirstEntry(t);
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assert(k==0);
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}
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_mesa_DeleteHashTable(t);
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}
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void
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_mesa_test_hash_functions(void)
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{
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int a, b, c;
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struct _mesa_HashTable *t;
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t = _mesa_NewHashTable();
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_mesa_HashInsert(t, 501, &a);
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_mesa_HashInsert(t, 10, &c);
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_mesa_HashInsert(t, 0xfffffff8, &b);
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/*_mesa_HashPrint(t);*/
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assert(_mesa_HashLookup(t,501));
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assert(!_mesa_HashLookup(t,1313));
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assert(_mesa_HashFindFreeKeyBlock(t, 100));
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_mesa_DeleteHashTable(t);
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test_hash_walking();
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}
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#endif
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