phash.c

来自「一些经典的HASH函数及测试数据」· C语言 代码 · 共 28 行

/* table for the mapping for the perfect hash */
#ifndef STANDARD
#include "standard.h"
#endif /* STANDARD */
#ifndef PHASH
#include "phash.h"
#endif /* PHASH */
#ifndef LOOKUPA
#include "lookupa.h"
#endif /* LOOKUPA */

/* small adjustments to _a_ to make values distinct */
ub1 tab[] = {
19,49,28,0,28,10,51,51,0,22,0,33,12,51,51,26,
7,60,36,51,33,50,60,60,0,10,19,16,0,46,58,38,
};

/* The hash function */
ub4 phash(key, len)
char *key;
int   len;
{
  ub4 rsl, val = lookup(key, len, 0x9e3779b9);
  rsl = ((val>>27)^tab[val&0x1f]);
  return rsl;
}