#include <sys/time.h>/* Subtract the `struct timeval' values X and Y,   storing the result in RESULT.   Return 1 if the difference is negative, otherwise 0.  */int timeval_subtract (struct timeval *result, struct timeval *x, struct timeval *y){        /* Perform the carry for the later subtraction by updating y. */        if (x->tv_usec < y->tv_usec) {                int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1;                y->tv_usec -= 1000000 * nsec;                y->tv_sec += nsec;        }        if (x->tv_usec - y->tv_usec > 1000000) {                int nsec = (y->tv_usec - x->tv_usec) / 1000000;                y->tv_usec += 1000000 * nsec;                y->tv_sec -= nsec;        }        /* Compute the time remaining to wait.           tv_usec  is certainly positive. */        result->tv_sec = x->tv_sec - y->tv_sec;        result->tv_usec = x->tv_usec - y->tv_usec;        /* Return 1 if result is negative. */        return x->tv_sec < y->tv_sec;}