/*
 * $Id$
 *
 * Copyright (C) 2006 iptelorg GmbH 
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
/*
 * History:
 * --------
 *  2006-02-02  created by andrei
 *  2006-11-24  added numeric string optimized hash function (andrei)
 */


#ifndef _hashes_h
#define _hashes_h

#include "str.h"
#include "mem/mem.h"
#include "clist.h"



/* internal use: hash update
 * params: char* s   - string start,
 *         char* end - end
 *         char* p,  and unsigned v temporary vars (used)
 *         unsigned h - result
 * h should be initialized (e.g. set it to 0), the result in h */
#define hash_update_str(s, end, p, v, h) \
	do{ \
		for ((p)=(s); (p)<=((end)-4); (p)+=4){ \
			(v)=(*(p)<<24)+((p)[1]<<16)+((p)[2]<<8)+(p)[3]; \
			(h)+=(v)^((v)>>3); \
		} \
		(v)=0; \
		for (;(p)<(end); (p)++){ (v)<<=8; (v)+=*(p);} \
		(h)+=(v)^((v)>>3); \
	}while(0)


/* internal use: call it to adjust the h from hash_update_str */
#define hash_finish(h) (((h)+((h)>>11))+(((h)>>13)+((h)>>23)))



/* "raw" 2 strings hash
 * returns an unsigned int (which you can use modulo table_size as hash value)
 */
inline static unsigned int get_hash2_raw(str* key1, str* key2)
{
	char* p;
	register unsigned v;
	register unsigned h;
	
	h=0;
	
	hash_update_str(key1->s, key1->s+key1->len, p, v, h);
	hash_update_str(key2->s, key2->s+key2->len, p, v, h);
	return hash_finish(h);
}



/* "raw" 1 string hash
 * returns an unsigned int (which you can use modulo table_size as hash value)
 */
inline static unsigned int get_hash1_raw(char* s, int len)
{
	char* p;
	register unsigned v;
	register unsigned h;
	
	h=0;
	
	hash_update_str(s, s+len, p, v, h);
	return hash_finish(h);
}



/* a little slower than hash_* , but better distribution for 
 * numbers and about the same for strings */
#define hash_update_str2(s, end, p, v, h) \
	do{ \
		for ((p)=(s); (p)<=((end)-4); (p)+=4){ \
			(v)=(*(p)*16777213)+((p)[1]*65537)+((p)[2]*257)+(p)[3]; \
			(h)=16777259*(h)+((v)^((v)<<17)); \
		} \
		(v)=0; \
		for (;(p)<(end); (p)++){ (v)*=251; (v)+=*(p);} \
		(h)=16777259*(h)+((v)^((v)<<17)); \
	}while(0)

/* internal use: call it to adjust the h from hash_update_str */
#define hash_finish2(h) (((h)+((h)>>7))+(((h)>>13)+((h)>>23)))



/* a little slower than get_hash1_raw() , but better distribution for 
 * numbers and about the same for strings */
inline static unsigned int get_hash1_raw2(char* s, int len)
{
	char* p;
	register unsigned v;
	register unsigned h;
	
	h=0;
	
	hash_update_str2(s, s+len, p, v, h);
	return hash_finish2(h);
}



/* "raw" 2 strings hash optimized for numeric strings (see above)
 * returns an unsigned int (which you can use modulo table_size as hash value)
 */
inline static unsigned int get_hash2_raw2(str* key1, str* key2)
{
	char* p;
	register unsigned v;
	register unsigned h;
	
	h=0;
	
	hash_update_str2(key1->s, key1->s+key1->len, p, v, h);
	hash_update_str2(key2->s, key2->s+key2->len, p, v, h);
	return hash_finish(h);
}



/* generic, simple str keyed hash */

struct str_hash_entry{
	struct str_hash_entry* next;
	struct str_hash_entry* prev;
	str key;
	unsigned int flags;
	union{
		void* p;
		char* s;
		int   n;
		char  data[sizeof(void*)];
	}u;
};


struct str_hash_head{
	struct str_hash_entry* next;
	struct str_hash_entry* prev;
};


struct str_hash_table{
	struct str_hash_head* table;
	int size;
};



/* returns 0 on success, <0 on failure */
inline static int str_hash_alloc(struct str_hash_table* ht, int size)
{
	ht->table=pkg_malloc(sizeof(struct str_hash_head)*size);
	if (ht->table==0)
		return -1;
	ht->size=size;
	return 0;
}



inline static void str_hash_init(struct str_hash_table* ht)
{
	int r;
	
	for (r=0; r<ht->size; r++) clist_init(&(ht->table[r]), next, prev);
}



inline static void str_hash_add(struct str_hash_table* ht, 
								struct str_hash_entry* e)
{
	int h;
	
	h=get_hash1_raw(e->key.s, e->key.len) % ht->size;
	clist_insert(&ht->table[h], e, next, prev);
}



inline static struct str_hash_entry* str_hash_get(struct str_hash_table* ht,
									char* key, int len)
{
	int h;
	struct str_hash_entry* e;
	
	h=get_hash1_raw(key, len) % ht->size;
	clist_foreach(&ht->table[h], e, next){
		if ((e->key.len==len) && (memcmp(e->key.s, key, len)==0))
			return e;
	}
	return 0;
}


#define str_hash_del(e) clist_rm(e, next, prev)



#endif