--- /dev/null
+/* $Id: hash.c,v 1.4 1998/02/07 14:25:12 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version: 2.5
+ * Copyright (C) 1995-1997 Brian Paul
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+/*
+ * $Log: hash.c,v $
+ * Revision 1.4 1998/02/07 14:25:12 brianp
+ * fixed small Sun compiler warning (John Stone)
+ *
+ * Revision 1.3 1997/09/22 02:33:07 brianp
+ * added HashRemove() and HashFirstEntry()
+ *
+ * Revision 1.2 1997/09/03 13:13:45 brianp
+ * added a few pointer casts
+ *
+ * Revision 1.1 1997/08/22 01:15:10 brianp
+ * Initial revision
+ *
+ */
+
+
+#ifdef PC_HEADER
+#include "all.h"
+#else
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "hash.h"
+#endif
+
+
+/*
+ * Generic hash table. Only dependency is the GLuint datatype.
+ *
+ * This is used to implement display list and texture object lookup.
+ * NOTE: key=0 is illegal.
+ */
+
+
+#define TABLE_SIZE 1001
+
+struct HashEntry {
+ GLuint Key;
+ void *Data;
+ struct HashEntry *Next;
+};
+
+struct HashTable {
+ struct HashEntry *Table[TABLE_SIZE];
+ GLuint MaxKey;
+};
+
+
+
+/*
+ * Return pointer to a new, empty hash table.
+ */
+struct HashTable *NewHashTable(void)
+{
+ return (struct HashTable *) calloc(sizeof (struct HashTable), 1);
+}
+
+
+
+/*
+ * Delete a hash table.
+ */
+void DeleteHashTable(struct 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;
+ }
+ }
+ free(table);
+}
+
+
+
+/*
+ * Lookup an entry in the hash table.
+ * Input: table - the hash table
+ * key - the key
+ * Return: user data pointer or NULL if key not in table
+ */
+void *HashLookup(const struct HashTable *table, GLuint key)
+{
+ GLuint pos;
+ struct HashEntry *entry;
+
+ assert(table);
+ assert(key);
+
+ pos = key % TABLE_SIZE;
+ 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.
+ * Input: table - the hash table
+ * key - the key (not zero)
+ * data - pointer to user data
+ */
+void HashInsert(struct HashTable *table, GLuint key, void *data)
+{
+ /* search for existing entry with this key */
+ GLuint pos;
+ struct HashEntry *entry;
+
+ assert(table);
+ assert(key);
+
+ if (key > table->MaxKey)
+ table->MaxKey = key;
+
+ pos = key % TABLE_SIZE;
+ entry = table->Table[pos];
+ while (entry) {
+ if (entry->Key == key) {
+ /* replace entry's data */
+ entry->Data = data;
+ return;
+ }
+ entry = entry->Next;
+ }
+
+ /* alloc and insert new table entry */
+ entry = (struct HashEntry *) calloc(sizeof(struct HashEntry), 1);
+ entry->Key = key;
+ entry->Data = data;
+ entry->Next = table->Table[pos];
+ table->Table[pos] = entry;
+}
+
+
+
+/*
+ * Remove an entry from the hash table.
+ * Input: table - the hash table
+ * key - key of entry to remove
+ */
+void HashRemove(struct HashTable *table, GLuint key)
+{
+ GLuint pos;
+ struct HashEntry *entry, *prev;
+
+ assert(table);
+ assert(key);
+
+ pos = key % TABLE_SIZE;
+ 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);
+ return;
+ }
+ prev = entry;
+ entry = entry->Next;
+ }
+}
+
+
+
+/*
+ * Return the key of the "first" entry in the hash table.
+ * By calling this function until zero is returned we can get
+ * the keys of all entries in the table.
+ */
+GLuint HashFirstEntry(const struct HashTable *table)
+{
+ GLuint pos;
+ assert(table);
+ for (pos=0; pos < TABLE_SIZE; pos++) {
+ if (table->Table[pos])
+ return table->Table[pos]->Key;
+ }
+ return 0;
+}
+
+
+
+/*
+ * Dump contents of hash table for debugging.
+ */
+void HashPrint(const struct HashTable *table)
+{
+ GLuint i;
+ assert(table);
+ for (i=0;i<TABLE_SIZE;i++) {
+ struct HashEntry *entry = table->Table[i];
+ while (entry) {
+ printf("%u %p\n", entry->Key, entry->Data);
+ entry = entry->Next;
+ }
+ }
+}
+
+
+
+/*
+ * Find a block of 'numKeys' adjacent unused hash keys.
+ * Input: table - the hash table
+ * numKeys - number of keys needed
+ * Return: startint key of free block or 0 if failure
+ */
+GLuint HashFindFreeKeyBlock(const struct HashTable *table, GLuint numKeys)
+{
+ GLuint maxKey = ~((GLuint) 0);
+ if (maxKey - numKeys > table->MaxKey) {
+ /* the quick solution */
+ return table->MaxKey + 1;
+ }
+ else {
+ /* the slow solution */
+ GLuint freeCount = 0;
+ GLuint freeStart = 0;
+ GLuint key;
+ for (key=0; key!=maxKey; key++) {
+ if (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) {
+ return freeStart;
+ }
+ }
+ }
+ /* cannot allocate a block of numKeys consecutive keys */
+ return 0;
+ }
+}
+
+
+
+#ifdef HASH_TEST_HARNESS
+int main(int argc, char *argv[])
+{
+ int a, b, c;
+ struct HashTable *t;
+
+ printf("&a = %p\n", &a);
+ printf("&b = %p\n", &b);
+
+ t = NewHashTable();
+ HashInsert(t, 501, &a);
+ HashInsert(t, 10, &c);
+ HashInsert(t, 0xfffffff8, &b);
+ HashPrint(t);
+ printf("Find 501: %p\n", HashLookup(t,501));
+ printf("Find 1313: %p\n", HashLookup(t,1313));
+ printf("Find block of 100: %d\n", HashFindFreeKeyBlock(t, 100));
+ DeleteHashTable(t);
+
+ return 0;
+}
+#endif
projects / reactos.git / blobdiff