struct timeval的处理（timeval比较及相减）

timeval的大小比较

/**
 ******************************************************************************
 * @brief   时间比较 t1 == t2 返回0, t1 > t2 返回 1, t1 < t2 返回 -1 
******************************************************************************
 */
int timevalcmp(struct timeval * t1, struct timeval * t2)
{
    if (t1->tv_sec == t2->tv_sec)
        return (t1->tv_usec == t2->tv_usec) ? 0 :
                (t1->tv_usec > t2->tv_usec) ? 1 : -1;
    return (t1->tv_sec > t2->tv_sec) ? 1 : -1;
}

timeval转为double类型的秒

double timeval_to_double(struct timeval * tv)
{
    double d;
    d = tv->tv_sec + tv->tv_usec / 1000000;
    return d;
}

两个timeval类型之间的时间差

/**
 ******************************************************************************
 * @brief   tv0 与 tv1 相减, 返回double类型时间差
******************************************************************************
 */
double timeval_diff(struct timeval * tv0, struct timeval * tv1)
{
    double time1, time2;
    
    time1 = tv0->tv_sec + (tv0->tv_usec / 1000000.0);
    time2 = tv1->tv_sec + (tv1->tv_usec / 1000000.0);

    time1 = time1 - time2;
    if (time1 < 0)
        time1 = -time1;
    return time1;
}

函数耗时测试

#define GET_TIME(t, code) { t = GetMicrosecondCount();\
                            code; \
                            t = GetMicrosecondCount() - t;}

/**
 * 获取当前时间的微妙数
*/
long int GetMicrosecondCount()
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return tv.tv_sec*1000000 + tv.tv_usec;
}