;; get time in microsecond resolution
(foreign-declare "#include \"windows.h\"")
(define %gettime/microsecs (foreign-lambda* double ()
                                            "
                                             static double factor = 0.0;
                                             LARGE_INTEGER li;
                                             if (factor == 0.0) {
                                                 if (!QueryPerformanceFrequency(&li)) {
                                                     C_return(-1.0);
                                                 }
                                                 ///* microsecs */
                                                 factor = (double)(li.QuadPart) / 1000000.0;
                                             }
                                             if (!QueryPerformanceCounter(&li)) {
                                                 C_return(-1.0);
                                             }
                                             C_return((double)li.QuadPart / factor);
                                            "))