一些字符串哈希算法

作者: 客昂康 | 来源:发表于2019-02-23 15:22 被阅读23375次

感知哈希算法
一些字符串哈希算法
哈希算法
mysql---索引优化
MySQL索引优化
区块基础知识
struct
iOS-RSA2加签、验签
算法系列：5分钟了解哈希算法
加密算法 MD5 AES

见代码：

unsigned int hash_BPHash(unsigned char *str){
    unsigned int hash = 0;
    while(*str){
        hash = (hash << 7) ^ (*str++);
    }
    return hash;
}

unsigned int hash_FNVHash(unsigned char *str){
    unsigned int hash = 0;
    while(*str){
        hash = (hash * 0x811C9DC5) ^ (*str++);
    }
    return hash;
}

unsigned int hash_BKDRHash(unsigned char *str){
    unsigned int hash = 0;
    while(*str){
        hash = (hash * 131) + (*str++); // 31 131 1313 13131 131313 etc...
    }
    return hash;
}

unsigned int hash_DJBHash(unsigned char *str){
    unsigned int hash = 5381;
    while(*str){
        hash += ((hash << 5) + (*str++));
    }
    return hash;
}

unsigned int hash_JSHash(unsigned char *str){
    unsigned int hash = 1315423911;
    while(*str){
        hash ^= ((hash << 5) + (hash >> 2) + (*str++));
    }
    return hash;
}

unsigned int hash_DEKHash(unsigned char *str){
    unsigned int hash = strlen(str);
    while(*str){
        hash = ((hash << 5) ^ (hash >> 27)) ^ (*str++);
    }
    return hash;
}

unsigned int hash_SDBMHash(unsigned char *str){
    unsigned int hash = 0;
    while(*str){
        hash = (hash << 6) + (hash << 16) + (*str++) - hash;
    }
    return hash;
}

unsigned int hash_RSHash(unsigned char *str){
    unsigned int a = 63689;
    unsigned int hash = 0;
    while(*str){
        hash = hash * a + (*str++);
        a *= 378551;
    }
    return hash;
}

unsigned int hash_APHash(unsigned char *str){
    unsigned int hash = 0;   //0x00000000, 0xAAAAAAAA
    unsigned int flag = 0;
    while(*str){
        if(flag&1){
            hash ^= (~((hash << 11) ^ (*str++) ^ (hash >> 5)));
        }
        else{
            hash ^= ((hash << 7) ^ (*str++) ^ (hash >> 3));
        }
        flag++;
    }
    return hash;
}

unsigned int hash_PJWHash(unsigned char *str){
    unsigned int hash = 0;
    unsigned int test = 0;
    while(*str){
        hash = (hash << 4) + (*str++);
        if((test = hash & 0xF0000000) != 0){
            hash = ((hash ^ (test >> 24)) & 0x0FFFFFFF);
        }
    }
    return hash;
}

unsigned int hash_ELFHash(unsigned char *str){
    unsigned int hash = 0;
    unsigned int test = 0;
    while(*str){
        hash = (hash << 4) + (*str++);
        if((test = hash & 0xF0000000) != 0){
            hash = ((hash ^ (test >> 24)) & (~test));
        }
    }
    return hash;
}

另外收集了一个查表法的CRC32校验算法，也可用于字符串哈希，见《一种查表法实现的CRC32校验算法》这篇笔记。
记于 2019-02-23