1 files changed, 86 insertions, 0 deletions
diff --git a/hash.h b/hash.h
new file mode 100644
index 0000000..8e26174
--- /dev/null
+++ b/hash.h
@@ -0,0 +1,86 @@
+/*
+ * netsniff-ng - the packet sniffing beast
+ * Copyright 2009, 2010 Daniel Borkmann.
+ * Subject to the GPL, version 2.
+ */
+
+#ifndef HASH_H
+#define HASH_H
+
+/* Hash table implementation from the GIT project. */
+/* Copyright 2008 (C) Linus Torvalds, GPL version 2 */
+/*
+ * These are some simple generic hash table helper functions.
+ * Not necessarily suitable for all users, but good for things
+ * where you want to just keep track of a list of things, and
+ * have a good hash to use on them.
+ *
+ * It keeps the hash table at roughly 50-75% free, so the memory
+ * cost of the hash table itself is roughly
+ *
+ *	3 * 2*sizeof(void *) * nr_of_objects
+ *
+ * bytes.
+ *
+ * FIXME: on 64-bit architectures, we waste memory. It would be
+ * good to have just 32-bit pointers, requiring a special allocator
+ * for hashed entries or something.
+ */
+
+#include <stdio.h>
+
+#define alloc_nr(x) (((x) + 16) * 3 / 2)
+#define INSERT_HASH_PROTOS(ops, table)					\
+	do {								\
+		void **pos = insert_hash((ops).key, &(ops), &(table));	\
+		/* We already had an entry there? */			\
+		if (pos) {						\
+			(ops).next = *pos;				\
+			*pos = &(ops);					\
+		}							\
+	} while (0)
+
+struct hash_table_entry {
+	unsigned int hash;
+	void *ptr;
+};
+
+struct hash_table {
+	unsigned int size, nr;
+	struct hash_table_entry *array;
+};
+
+extern void *lookup_hash(unsigned int hash, const struct hash_table *table);
+extern void **insert_hash(unsigned int hash, void *ptr,
+			  struct hash_table *table);
+extern void *remove_hash(unsigned int hash, void *ptr, void *ptr_next,
+			 struct hash_table *table);
+extern int for_each_hash(const struct hash_table *table, int (*fn)(void *));
+extern int for_each_hash_int(const struct hash_table *table,
+			     int (*fn)(void *, int), int arg);
+extern void free_hash(struct hash_table *table);
+
+static inline void init_hash(struct hash_table *table)
+{
+	table->size = 0;
+	table->nr = 0;
+	table->array = NULL;
+}
+
+static inline unsigned char icase_hash(unsigned char c)
+{
+	return c & ~((c & 0x40) >> 1);
+}
+
+static inline unsigned int hash_name(const char *name, int namelen)
+{
+	unsigned int hash = 0x123;
+	do {
+		unsigned char c = *name++;
+		c = icase_hash(c);
+		hash = hash * 101 + c;
+	} while (--namelen);
+	return hash;
+}
+
+#endif