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-rw-r--r--src/mesa/main/hash.c363
1 files changed, 363 insertions, 0 deletions
diff --git a/src/mesa/main/hash.c b/src/mesa/main/hash.c
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+/**
+ * \file hash.c
+ * Generic hash table.
+ *
+ * Used for display lists and texture objects. The hash functions are
+ * thread-safe.
+ *
+ * \note key=0 is illegal.
+ *
+ * \author Brian Paul
+ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version: 6.2.2
+ *
+ * Copyright (C) 1999-2005 Brian Paul 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, 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 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
+ * BRIAN PAUL 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.
+ */
+
+
+#include "glheader.h"
+#include "imports.h"
+#include "glthread.h"
+#include "hash.h"
+#include "context.h"
+
+
+#define TABLE_SIZE 1023 /**< Size of lookup table/array */
+
+#define HASH_FUNC(K) ((K) % TABLE_SIZE)
+
+/**
+ * An entry in the hash table.
+ *
+ * This struct is private to this file.
+ */
+struct HashEntry {
+ GLuint Key; /**< the entry's key */
+ void *Data; /**< the entry's data */
+ struct HashEntry *Next; /**< pointer to next entry */
+};
+
+/**
+ * The hash table data structure.
+ *
+ * This is an opaque types (it's not defined in hash.h file).
+ */
+struct _mesa_HashTable {
+ struct HashEntry *Table[TABLE_SIZE]; /**< the lookup table */
+ GLuint MaxKey; /**< highest key inserted so far */
+ _glthread_Mutex Mutex; /**< mutual exclusion lock */
+};
+
+
+
+/**
+ * Create a new hash table.
+ *
+ * \return pointer to a new, empty hash table.
+ */
+struct _mesa_HashTable *_mesa_NewHashTable(void)
+{
+ struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable);
+ if (table) {
+ _glthread_INIT_MUTEX(table->Mutex);
+ }
+ return table;
+}
+
+
+
+/**
+ * Delete a hash table.
+ *
+ * \param table the hash table to delete.
+ *
+ * Frees each entry on the hash table and then the hash table structure itself.
+ */
+void _mesa_DeleteHashTable(struct _mesa_HashTable *table)
+{
+ GLuint i;
+ assert(table);
+ for (i=0;i<TABLE_SIZE;i++) {
+ struct HashEntry *entry = table->Table[i];
+ while (entry) {
+ struct HashEntry *next = entry->Next;
+ FREE(entry);
+ entry = next;
+ }
+ }
+ _glthread_DESTROY_MUTEX(table->Mutex);
+ FREE(table);
+}
+
+
+
+/**
+ * Lookup an entry in the hash table.
+ *
+ * \param table the hash table.
+ * \param key the key.
+ *
+ * \return pointer to user's data or NULL if key not in table
+ *
+ * Walks through the hash entry until finding the matching key.
+ */
+void *_mesa_HashLookup(const struct _mesa_HashTable *table, GLuint key)
+{
+ GLuint pos;
+ const struct HashEntry *entry;
+
+ assert(table);
+ assert(key);
+
+ pos = HASH_FUNC(key);
+ entry = table->Table[pos];
+ while (entry) {
+ if (entry->Key == key) {
+ return entry->Data;
+ }
+ entry = entry->Next;
+ }
+ return NULL;
+}
+
+
+
+/**
+ * Insert into the hash table.
+ *
+ * If an entry with this key already exists we'll replace the existing entry.
+ *
+ * \param table the hash table.
+ * \param key the key (not zero).
+ * \param data pointer to user data.
+ *
+ * While holding the hash table's lock, walk through the hash entry list replacing the data if a
+ * matching key is found, or inserts a new table entry otherwise.
+ */
+void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data)
+{
+ /* search for existing entry with this key */
+ GLuint pos;
+ struct HashEntry *entry;
+
+ assert(table);
+ assert(key);
+
+ _glthread_LOCK_MUTEX(table->Mutex);
+
+ if (key > table->MaxKey)
+ table->MaxKey = key;
+
+ pos = HASH_FUNC(key);
+ entry = table->Table[pos];
+ while (entry) {
+ if (entry->Key == key) {
+ /* replace entry's data */
+ entry->Data = data;
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return;
+ }
+ entry = entry->Next;
+ }
+
+ /* alloc and insert new table entry */
+ entry = MALLOC_STRUCT(HashEntry);
+ entry->Key = key;
+ entry->Data = data;
+ entry->Next = table->Table[pos];
+ table->Table[pos] = entry;
+
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+}
+
+
+
+/**
+ * Remove an entry from the hash table.
+ *
+ * \param table the hash table.
+ * \param key key of entry to remove.
+ *
+ * While holding the hash table's lock, searches the entry with the matching
+ * key and unlinks it.
+ */
+void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key)
+{
+ GLuint pos;
+ struct HashEntry *entry, *prev;
+
+ assert(table);
+ assert(key);
+
+ _glthread_LOCK_MUTEX(table->Mutex);
+
+ pos = HASH_FUNC(key);
+ prev = NULL;
+ entry = table->Table[pos];
+ while (entry) {
+ if (entry->Key == key) {
+ /* found it! */
+ if (prev) {
+ prev->Next = entry->Next;
+ }
+ else {
+ table->Table[pos] = entry->Next;
+ }
+ FREE(entry);
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return;
+ }
+ prev = entry;
+ entry = entry->Next;
+ }
+
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+}
+
+
+
+/**
+ * Get the key of the "first" entry in the hash table.
+ *
+ * This is used in the course of deleting all display lists when
+ * a context is destroyed.
+ *
+ * \param table the hash table
+ *
+ * \return key for the "first" entry in the hash table.
+ *
+ * While holding the lock, walks through all table positions until finding
+ * the first entry of the first non-empty one.
+ */
+GLuint _mesa_HashFirstEntry(struct _mesa_HashTable *table)
+{
+ GLuint pos;
+ assert(table);
+ _glthread_LOCK_MUTEX(table->Mutex);
+ for (pos=0; pos < TABLE_SIZE; pos++) {
+ if (table->Table[pos]) {
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return table->Table[pos]->Key;
+ }
+ }
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return 0;
+}
+
+
+#ifdef HASH_TEST_HARNESS
+/**
+ * Dump contents of hash table for debugging.
+ *
+ * \param table the hash table.
+ */
+void _mesa_HashPrint(const struct _mesa_HashTable *table)
+{
+ GLuint i;
+ assert(table);
+ for (i=0;i<TABLE_SIZE;i++) {
+ const struct HashEntry *entry = table->Table[i];
+ while (entry) {
+ _mesa_debug(NULL, "%u %p\n", entry->Key, entry->Data);
+ entry = entry->Next;
+ }
+ }
+}
+#endif
+
+
+
+/**
+ * Find a block of adjacent unused hash keys.
+ *
+ * \param table the hash table.
+ * \param numKeys number of keys needed.
+ *
+ * \return Starting key of free block or 0 if failure.
+ *
+ * If there are enough free keys between the maximum key existing in the table
+ * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
+ * the adjacent key. Otherwise do a full search for a free key block in the
+ * allowable key range.
+ */
+GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys)
+{
+ GLuint maxKey = ~((GLuint) 0);
+ _glthread_LOCK_MUTEX(table->Mutex);
+ if (maxKey - numKeys > table->MaxKey) {
+ /* the quick solution */
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return table->MaxKey + 1;
+ }
+ else {
+ /* the slow solution */
+ GLuint freeCount = 0;
+ GLuint freeStart = 1;
+ GLuint key;
+ for (key=1; key!=maxKey; key++) {
+ if (_mesa_HashLookup(table, key)) {
+ /* darn, this key is already in use */
+ freeCount = 0;
+ freeStart = key+1;
+ }
+ else {
+ /* this key not in use, check if we've found enough */
+ freeCount++;
+ if (freeCount == numKeys) {
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return freeStart;
+ }
+ }
+ }
+ /* cannot allocate a block of numKeys consecutive keys */
+ _glthread_UNLOCK_MUTEX(table->Mutex);
+ return 0;
+ }
+}
+
+
+
+#ifdef HASH_TEST_HARNESS
+int main(int argc, char *argv[])
+{
+ int a, b, c;
+ struct HashTable *t;
+
+ _mesa_printf("&a = %p\n", &a);
+ _mesa_printf("&b = %p\n", &b);
+
+ t = _mesa_NewHashTable();
+ _mesa_HashInsert(t, 501, &a);
+ _mesa_HashInsert(t, 10, &c);
+ _mesa_HashInsert(t, 0xfffffff8, &b);
+ _mesa_HashPrint(t);
+
+ _mesa_printf("Find 501: %p\n", _mesa_HashLookup(t,501));
+ _mesa_printf("Find 1313: %p\n", _mesa_HashLookup(t,1313));
+ _mesa_printf("Find block of 100: %d\n", _mesa_HashFindFreeKeyBlock(t, 100));
+
+ _mesa_DeleteHashTable(t);
+
+ return 0;
+}
+#endif
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