GeneralHashFunctions.c

#include "GeneralHashFunctions.h"

unsigned int RSHash(char* str, unsigned int len) {
    unsigned int b    = 378551;
    unsigned int a    = 63689;
    unsigned int hash = 0;
    unsigned int i    = 0;

    for (i = 0; i < len; str++, i++) {
        hash = hash * a + (*str);
        a    = a * b;
    }

    return hash;
}
/* End Of RS Hash Function */


unsigned int JSHash(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;
}
/* End Of JS Hash Function */


unsigned int PJWHash(char* str, unsigned int len) {
    const unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8);
    const unsigned int ThreeQuarters     = (unsigned int)((BitsInUnsignedInt  * 3) / 4);
    const unsigned int OneEighth         = (unsigned int)(BitsInUnsignedInt / 8);
    const unsigned int HighBits          = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);
    unsigned int hash              = 0;
    unsigned int test              = 0;
    unsigned int i                 = 0;

    for (i = 0; i < len; str++, i++) {
        hash = (hash << OneEighth) + (*str);

        if ((test = hash & HighBits)  != 0) {
            hash = ((hash ^(test >> ThreeQuarters)) & (~HighBits));
        }
    }

    return hash;
}
/* End Of  P. J. Weinberger Hash Function */


unsigned int ELFHash(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;
}
/* End Of ELF Hash Function */


unsigned int BKDRHash(char* str, unsigned int len) {
    unsigned int seed = 131; /* 31 131 1313 13131 131313 etc.. */
    unsigned int hash = 0;
    unsigned int i    = 0;

    for (i = 0; i < len; str++, i++) {
        hash = (hash * seed) + (*str);
    }

    return hash;
}
/* End Of BKDR Hash Function */


unsigned int SDBMHash(char* str, unsigned int len) {
    unsigned int hash = 0;
    unsigned int i    = 0;

    for (i = 0; i < len; str++, i++) {
        hash = (*str) + (hash << 6) + (hash << 16) - hash;
    }

    return hash;
}
/* End Of SDBM Hash Function */


unsigned int DJBHash(char* str, unsigned int len) {
    unsigned int hash = 5381;
    unsigned int i    = 0;

    for (i = 0; i < len; str++, i++) {
        hash = ((hash << 5) + hash) + (*str);
    }

    return hash;
}
/* End Of DJB Hash Function */


unsigned int DEKHash(char* str, unsigned int len) {
    unsigned int hash = len;
    unsigned int i    = 0;

    for (i = 0; i < len; str++, i++) {
        hash = ((hash << 5) ^(hash >> 27)) ^(*str);
    }
    return hash;
}
/* End Of DEK Hash Function */


unsigned int BPHash(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;
}
/* End Of BP Hash Function */


unsigned int FNVHash(char* str, unsigned int len) {
    const unsigned int fnv_prime = 0x811C9DC5;
    unsigned int hash      = 0;
    unsigned int i         = 0;

    for (i = 0; i < len; str++, i++) {
        hash *= fnv_prime;
        hash ^= (*str);
    }

    return hash;
}
/* End Of FNV Hash Function */


unsigned int APHash(char* str, unsigned int len) {
    unsigned int hash = 0xAAAAAAAA;
    unsigned int i    = 0;

    for (i = 0; i < len; str++, i++) {
        hash ^= ((i & 1) == 0) ? ((hash <<  7) ^(*str) * (hash >> 3)) :
                (~((hash << 11) + ((*str) ^(hash >> 5))));
    }

    return hash;
}
/* End Of AP Hash Function */