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/*
* Copyright (c) 2007, Novell Inc.
*
* This program is licensed under the BSD license, read LICENSE.BSD
* for further information
*/
/*
* hash.h
* generic hash functions
*/
#ifndef LIBSOLV_HASH_H
#define LIBSOLV_HASH_H
#include "pooltypes.h"
/* value of a hash */
typedef unsigned int Hashval;
/* mask for hash, used as modulo operator to ensure 'wrapping' of hash
values -> hash table */
typedef unsigned int Hashmask;
/* inside the hash table, Ids are stored. Hash maps: string -> hash -> Id */
typedef Id *Hashtable;
/* hash chain */
#define HASHCHAIN_START 7
#define HASHCHAIN_NEXT(h, hh, mask) (((h) + (hh)++) & (mask))
/* very simple hash function
* string -> hash
*/
static inline Hashval
strhash(const char *str)
{
Hashval r = 0;
unsigned int c;
while ((c = *(const unsigned char *)str++) != 0)
r += (r << 3) + c;
return r;
}
static inline Hashval
strnhash(const char *str, unsigned len)
{
Hashval r = 0;
unsigned int c;
while (len-- && (c = *(const unsigned char *)str++) != 0)
r += (r << 3) + c;
return r;
}
static inline Hashval
strhash_cont(const char *str, Hashval r)
{
unsigned int c;
while ((c = *(const unsigned char *)str++) != 0)
r += (r << 3) + c;
return r;
}
/* hash for rel
* rel -> hash
*/
static inline Hashval
relhash(Id name, Id evr, int flags)
{
return name + 7 * evr + 13 * flags;
}
/* compute bitmask for value
* returns smallest (2^n-1) > 2 * num
*
* used for Hashtable 'modulo' operation
*/
static inline Hashmask
mkmask(unsigned int num)
{
num *= 2;
while (num & (num - 1))
num &= num - 1;
return num * 2 - 1;
}
#endif /* LIBSOLV_HASH_H */
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