static int r_read (RSFD rfd, void *buf);
static int r_write (RSFD rfd, const void *buf);
static void r_pos (RSFD rfd, double *current, double *total);
static int r_read (RSFD rfd, void *buf);
static int r_write (RSFD rfd, const void *buf);
static void r_pos (RSFD rfd, double *current, double *total);