一个不错的字符串 hash 函数

unsigned long hash(const char *name,size_t len)
{
unsigned long h=(unsigned long)len;
size_t step = (len>>5)+1;
for (size_t i=len; i>=step; i-=step)
    h = h ^ ((h<<5)+(h>>2)+(unsigned long)name[i-1]);
return h;
}