clock.h

// A current_time function for use in the tests.  Returns time in
// milliseconds.

#ifdef _WIN32
#include <Windows.h>
double current_time() {
    LARGE_INTEGER freq, t;
    QueryPerformanceCounter(&t);
    QueryPerformanceFrequency(&freq);
    return (t.QuadPart * 1000.0) / freq.QuadPart;
}
// Gross, these come from Windows.h
#undef max
#undef min
#else
#include <sys/time.h>
double current_time() {
    static bool first_call = true;
    static timeval reference_time;
    if (first_call) {
        first_call = false;
        gettimeofday(&reference_time, NULL);
        return 0.0;
    } else {
        timeval t;
        gettimeofday(&t, NULL);
        return ((t.tv_sec - reference_time.tv_sec)*1000.0 +
                (t.tv_usec - reference_time.tv_usec)/1000.0);
    }
}
#endif