python string hash 函数

static long
string_hash(PyStringObject *a)
{
register Py_ssize_t len;
register unsigned char *p;
register long x;

if (a->ob_shash != -1)
return a->ob_shash;
len = Py_SIZE(a);
p = (unsigned char *) a->ob_sval;
x = *p << 7;
while (--len >= 0)
x = (1000003*x) ^ *p++;
x ^= Py_SIZE(a);
if (x == -1)
x = -2;
a->ob_shash = x;
return x;
}

#include "stdio.h"
#include "string.h"

unsigned int RS_Hash(char *str)
{
unsigned int a = 63689;
unsigned int b = 378551;
unsigned int v = 0;
while(*str)
{
v = v * a + (*str++);
a *= b;
}
return v;
}

unsigned int JS_Hash(char *str, unsigned int len)
{
unsigned int hash = 1315423911;
unsigned int i = 0;
for(i = 0;i < len;str++, i++)
{
hash ^= ((hash << 5) + (*str) + (hash >> 2));
}
return hash;
}

unsigned int ELF_Hash(char *str, unsigned int len)
{
unsigned int hash = 0;
unsigned int x = 0;
unsigned int i = 0;
for(i=0; i<len; str++,i++)
{
hash = (hash << 4) + (*str);
if((x = hash & 0xF0000000L) != 0)
{
hash ^= (x>>24);
}
hash &= ~x;
}
return hash;
}

unsigned int BP_Hash(char *str, unsigned int len)
{
unsigned int hash = 0;
unsigned int i = 0;
for(i = 0; i < len; str++, i++)
{
hash = hash << 7 ^ (*str);
}
return hash;
}

long PY_Hash(unsigned char *str, int len)
{
long x;
int old_len = len;
x = *str << 7;
while(--len >= 0)
{
x = (1000003*x) ^ (*str++);
}
x ^= old_len;
if( x == -1)
x == -2;
return x;
}

int main(void)
{
char* str = "abc";
int len = strlen(str);
printf("%s RS Hash value is %u\n", str, RS_Hash(str));
printf("%s JS Hash value is %u\n", str, JS_Hash(str, len));
printf("%s ELF Hash value is %u\n", str, ELF_Hash(str, len));
printf("%s BP Hash value is %u\n", str, BP_Hash(str, len));
printf("%s PY Hash value is %ld\n", str, PY_Hash(str, len));
}