gistfile1.c

#include <stdio.h>
#include <string.h>
#define mix(a,b,c)                              \
    {                                           \
        a -= b; a -= c; a ^= (c >> 13);         \
        b -= c; b -= a; b ^= (a << 8);          \
        c -= a; c -= b; c ^= (b >> 13);         \
        a -= b; a -= c; a ^= (c >> 12);         \
        b -= c; b -= a; b ^= (a << 16);         \
        c -= a; c -= b; c ^= (b >> 5);          \
        a -= b; a -= c; a ^= (c >> 3);          \
        b -= c; b -= a; b ^= (a << 10);         \
        c -= a; c -= b; c ^= (b >> 15);         \
    }

unsigned int bob_hash(void *val, unsigned int length)
{
    char *k = (char *)val;
    unsigned long a,b,c,len;

    /* Set up the internal state */
    len = length;
    a = b = c = 0x9e3779b9;  /* the golden ratio; an arbitrary value */

    /* Handle most of the key */
    while (len >= 12)
    {
        a += (k[0] +((unsigned long)k[1] << 8) +((unsigned long)k[2] << 16) +((unsigned long)k[3] << 24));
        b += (k[4] +((unsigned long)k[5] << 8) +((unsigned long)k[6] << 16) +((unsigned long)k[7] << 24));
        c += (k[8] +((unsigned long)k[9] << 8) +((unsigned long)k[10]<< 16)+((unsigned long)k[11] << 24));
        mix(a,b,c);
        k += 12; len -= 12;
    }

    /* Handle the last 11 bytes */
    c += length;
    switch(len)              /* all the case statements fall through */
    {
    case 11: c+=((unsigned long)k[10] << 24);
    case 10: c+=((unsigned long)k[9]  << 16);
    case 9 : c+=((unsigned long)k[8]  << 8);
        /* the first byte of c is reserved for the length */
    case 8 : b+=((unsigned long)k[7] << 24);
    case 7 : b+=((unsigned long)k[6] << 16);
    case 6 : b+=((unsigned long)k[5] << 8);
    case 5 : b+=k[4];
    case 4 : a+=((unsigned long)k[3] << 24);
    case 3 : a+=((unsigned long)k[2] << 16);
    case 2 : a+=((unsigned long)k[1] << 8);
    case 1 : a+=k[0];
    }
    mix(a,b,c);

    return c;
}

int hash_string(void *tmpstr)
{
    int hash = (int)bob_hash(tmpstr, strlen(tmpstr));
    if(hash < 0)
    {
        hash = -hash;
    }
    return (int)(hash % 200);
}

int main()
{
    printf("%d", hash_string("15882917276"));
}