49 #define timerclear(a)   \  argument
50         ((a)->tv_sec = (a)->tv_usec = 0)
52 #define timerisset(a)    \  argument
53         ((a)->tv_sec != 0 || (a)->tv_usec != 0)
55 #define timercmp(a, b, op)               \  argument
56         ((a)->tv_sec == (b)->tv_sec      \
57         ? (a)->tv_usec op (b)->tv_usec   \
58         : (a)->tv_sec op (b)->tv_sec)
60 #define timeradd(a, b, res)                           \  argument
62         (res)->tv_sec  = (a)->tv_sec  + (b)->tv_sec;  \
63         (res)->tv_usec = (a)->tv_usec + (b)->tv_usec; \
70 #define timersub(a, b, res)                           \  argument
72         (res)->tv_sec  = (a)->tv_sec  - (b)->tv_sec;  \
73         (res)->tv_usec = (a)->tv_usec - (b)->tv_usec; \