Basic Hash Functions

// SDBM Hashunsigned int SDBMHash(char *str){    unsigned int hash = 0;     while (*str)    {        // equivalent to: hash = 65599*hash + (*str++);        hash = (*str++) + (hash << 6) + (hash << 16) - hash;    }     return (hash & 0x7FFFFFFF);} // RS Hash unsigned int RSHash(char *str){    unsigned int b = 378551;    unsigned int a = 63689;    unsigned int hash = 0;     while (*str)    {        hash = hash * a + (*str++);        a *= b;    }     return (hash & 0x7FFFFFFF);} // JS Hash unsigned int JSHash(char *str){    unsigned int hash = 1315423911;     while (*str)    {         hash ^= ((hash << 5) + (*str++) + (hash >> 2));    }     return (hash & 0x7FFFFFFF);} // P. J. Weinberger Hash unsigned int PJWHash(char *str){    unsigned int BitsInUnignedInt = (unsigned int)(sizeof(unsigned int) * 8);    unsigned int ThreeQuarters = (unsigned int)((BitsInUnignedInt  * 3) / 4);    unsigned int OneEighth = (unsigned int)(BitsInUnignedInt / 8);    unsigned int HighBits = (unsigned int)(0xFFFFFFFF) << (BitsInUnignedInt unsigned int SDBMHash(char *str) - OneEighth);    unsigned int hash = 0;    unsigned int test = 0;     while (*str)    {        hash = (hash << OneEighth) + (*str++);        if ((test = hash & HighBits) != 0)        {            hash = ((hash ^ (test >> ThreeQuarters)) & (~HighBits));        }    }     return (hash & 0x7FFFFFFF);} // ELF Hash unsigned int ELFHash(char *str){    unsigned int hash = 0;    unsigned int x = 0;     while (*str)    {        hash = (hash << 4) + (*str++);        if ((x = hash & 0xF0000000L) != 0)        {             hash ^= (x >> 24);             hash &= ~x;        }     }      return (hash & 0x7FFFFFFF);} // BKDR Hash unsigned int BKDRHash(char *str){    unsigned int seed = 131; // 31 131 1313 13131 131313 etc..    unsigned int hash = 0;     while (*str)    {         hash = hash * seed + (*str++);    }     return (hash & 0x7FFFFFFF);} // DJB Hash unsigned int DJBHash(char *str){    unsigned int hash = 5381;     while (*str)    {        hash += (hash << 5) + (*str++);    }     return (hash & 0x7FFFFFFF);} // AP Hash unsigned int APHash(char *str){    unsigned int hash = 0;    int i;     for (i=0; *str; i++)    {         if ((i & 1) == 0)         {              hash ^= ((hash << 7) ^ (*str++) ^ (hash >> 3));         }         else         {              hash ^= (~((hash << 11) ^ (*str++) ^ (hash >> 5)));         }     }      return (hash & 0x7FFFFFFF);}