时间处理函数备忘

linux 

#include <time.h>
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
//时间戳转化为时间 毫秒级
std::string Stamp2Time(long long timestamp)
{
    int ms = timestamp % 1000;//取毫秒
    time_t tick = (time_t)(timestamp/1000000);//转换时间
    struct tm tm;
    char s[40];
    tm = *localtime(&tick);

    strftime(s, sizeof(s), "%Y-%m-%d %H:%M:%S", &tm);
    std::string str(s);
    str = str+ " " + std::to_string(ms);
    return str;
}

int main()
{
    for( int i = 0 ; i < 10 ; i++){
        struct timespec ts;
        clock_gettime (CLOCK_REALTIME , &ts);
        unsigned long long  nano_tms =  (ts.tv_sec*(unsigned long long)(1000000)) + (ts.tv_nsec/(1000));
        std::cout<<"time is "<< nano_tms  <<std::endl;
        std::cout<<Stamp2Time(nano_tms)<<std::endl;
        usleep(1000000);
    }

}
~

LARGE_INTEGER
getFILETIMEoffset()
{
    SYSTEMTIME s;
    FILETIME f;
    LARGE_INTEGER t;

    s.wYear = 1970;
    s.wMonth = 1;
    s.wDay = 1;
    s.wHour = 0;
    s.wMinute = 0;
    s.wSecond = 0;
    s.wMilliseconds = 0;
    SystemTimeToFileTime(&s, &f);
    t.QuadPart = f.dwHighDateTime;
    t.QuadPart <<= 32;
    t.QuadPart |= f.dwLowDateTime;
    return (t);
}

int
clock_gettime(int X, struct timeval *tv)
{
    LARGE_INTEGER           t;
    FILETIME            f;
    double                  microseconds;
    static LARGE_INTEGER    offset;
    static double           frequencyToMicroseconds;
    static int              initialized = 0;
    static BOOL             usePerformanceCounter = 0;

    if (!initialized) {
        LARGE_INTEGER performanceFrequency;
        initialized = 1;
        usePerformanceCounter = QueryPerformanceFrequency(&performanceFrequency);
        if (usePerformanceCounter) {
            QueryPerformanceCounter(&offset);
            frequencyToMicroseconds = (double)performanceFrequency.QuadPart / 1000000.;
        } else {
            offset = getFILETIMEoffset();
            frequencyToMicroseconds = 10.;
        }
    }
    if (usePerformanceCounter) QueryPerformanceCounter(&t);
    else {
        GetSystemTimeAsFileTime(&f);
        t.QuadPart = f.dwHighDateTime;
        t.QuadPart <<= 32;
        t.QuadPart |= f.dwLowDateTime;
    }

    t.QuadPart -= offset.QuadPart;
    microseconds = (double)t.QuadPart / frequencyToMicroseconds;
    t.QuadPart = microseconds;
    tv->tv_sec = t.QuadPart / 1000000;
    tv->tv_usec = t.QuadPart % 1000000;
    return (0);
}