uuid.h

Go to the documentation of this file.

#ifndef __UUID_H
#define __UUID_H

#include <chrono>
#include <iomanip>
#include <random>
#include <sstream>
#include <string>

#include <cstdint>


#define     UUID_SIZE       16
#define     UUID_VERSION    4


static inline std::string uuid4() {
    int uuid[UUID_SIZE];
    std::stringstream uuid_sstr;

    /* generate random bytes */
    auto seed = std::chrono::system_clock::now().time_since_epoch().count();
    std::default_random_engine rand((unsigned int)seed);
    std::uniform_int_distribution<int> dist(0, 255);

    for (int i=0; i<UUID_SIZE; ++i) {
        uuid[i] = dist(rand);
    }

    /* set variant */
    uuid[8] = (uuid[8] & 0x3F) | 0x80;
    /* set version */
    uuid[6] = (uuid[6] & 0x0F) | ((UUID_VERSION << 4) & 0xF0);

    uuid_sstr << std::internal << std::setfill('0') << std::hex
        << std::setw(2) << uuid[0]
        << std::setw(2) << uuid[1]
        << std::setw(2) << uuid[2]
        << std::setw(2) << uuid[3] << "-"
        << std::setw(2) << uuid[4]
        << std::setw(2) << uuid[5] << "-"
        << std::setw(2) << uuid[6]
        << std::setw(2) << uuid[7] << "-"
        << std::setw(2) << uuid[8]
        << std::setw(2) << uuid[9] << "-"
        << std::setw(2) << uuid[10]
        << std::setw(2) << uuid[11]
        << std::setw(2) << uuid[12]
        << std::setw(2) << uuid[13]
        << std::setw(2) << uuid[14]
        << std::setw(2) << uuid[15];

    return uuid_sstr.str();
}

#endif /* __UUID_H */