/*
 * category: [algorithm]
 * apply status: hashset, shm_table, timerqueue, sp_tbs and mod_sipphone
 * edit status: not
 * build status:
 * description:
 */

#ifndef __HASH_H__
#define __HASH_H__

#pragma once

#include "config.h"

#ifdef __cplusplus
extern "C" {
#endif

#define	HASH32_BUF_INIT	5381

/*
 * uint32_t
 * hash32_buf(const void *bf, size_t len, uint32_t hash)
 *	return a 32 bit hash of the binary buffer buf (size len),
 *	seeded with an initial hash value of hash (usually HASH32_BUF_INIT).
 */
static __inline unsigned int hash32_buf(const void *bf, size_t len, unsigned int hash)
{
	const unsigned char *s = (const unsigned char*)bf;

	while (len-- != 0)			/* "nemesi": k=257, r=r*257 */
		hash = hash * 257 + *s++;
	return (hash * 257);
}


#define	HASH32_STR_INIT	5381
/*
 * uint32_t
 * hash32_str(const void *bf, uint32_t hash)
 *	return a 32 bit hash of NUL terminated ASCII string buf,
 *	seeded with an initial hash value of hash (usually HASH32_STR_INIT).
 */
static __inline unsigned int hash32_str(const void *bf, unsigned int hash)
{
	const unsigned char *s = (const unsigned char*)bf;
	unsigned char	c;

	while ((c = *s++) != 0)
		hash = hash * 33 + c;		/* "perl": k=33, r=r+r/32 */
	return (hash + (hash >> 5));
}

/*
 * unsigned int
 * hash32_strn(const void *bf, size_t len, unsigned int hash)
 *	return a 32 bit hash of NUL terminated ASCII string buf up to
 *	a maximum of len bytes,
 *	seeded with an initial hash value of hash (usually HASH32_STR_INIT).
 */
static __inline unsigned int hash32_strn(const void *bf, size_t len, unsigned int hash)
{
	const unsigned char	*s = (const unsigned char *)bf;
	unsigned char c;

	//while ((c = *s++) != 0 && len-- != 0)		// xkm@20160824: sonar fix
	while ((c = *s) != 0 && len != 0)
	{
		s++;
		len--;
		hash = hash * 33 + c;		/* "perl": k=33, r=r+r/32 */
	}

	return (hash + (hash >> 5));
}

/* used for double hash */
static __inline unsigned int hash_incr(unsigned int h1, unsigned int htable_size)
{
	return 1 + ((h1>>5)+1)%(htable_size-1);
}

#ifdef __cplusplus
} // extern "C" {
#endif

#endif //__HASH_H__