45 #define timerclear(a)   \  argument
46         ((a)->tv_sec = (a)->tv_usec = 0)
48 #define timerisset(a)    \  argument
49         ((a)->tv_sec != 0 || (a)->tv_usec != 0)
51 #define timercmp(a, b, op)               \  argument
52         ((a)->tv_sec == (b)->tv_sec      \
53         ? (a)->tv_usec op (b)->tv_usec   \
54         : (a)->tv_sec op (b)->tv_sec)
56 #define timeradd(a, b, res)                           \  argument
58         (res)->tv_sec  = (a)->tv_sec  + (b)->tv_sec;  \
59         (res)->tv_usec = (a)->tv_usec + (b)->tv_usec; \
66 #define timersub(a, b, res)                           \  argument
68         (res)->tv_sec  = (a)->tv_sec  - (b)->tv_sec;  \
69         (res)->tv_usec = (a)->tv_usec - (b)->tv_usec; \