timeradd.h

用于传感器网络的节点操作系统 TinyOS 结构设计非常有意思

/* I'm not sure how portable is to use these macros (they are available
   on my system, but not mentioned in the glibc manual I have).
   Similar macros are provided here for systems that don't have them.  -MM */

#include <sys/time.h>

#ifndef timeradd
#define	timeradd(a, b, result)						      \
  do {									      \
    (result)->tv_sec = (a)->tv_sec + (b)->tv_sec;			      \
    (result)->tv_usec = (a)->tv_usec + (b)->tv_usec;			      \
    if ((result)->tv_usec >= 1000000)					      \
      {									      \
	++(result)->tv_sec;						      \
	(result)->tv_usec -= 1000000;					      \
      }									      \
  } while (0)

#endif

#ifndef timersub
#define	timersub(a, b, result)						      \
  do {									      \
    (result)->tv_sec = (a)->tv_sec - (b)->tv_sec;			      \
    (result)->tv_usec = (a)->tv_usec - (b)->tv_usec;			      \
    if ((result)->tv_usec < 0) {					      \
      --(result)->tv_sec;						      \
      (result)->tv_usec += 1000000;					      \
    }									      \
  } while (0)
#endif

#ifndef timercmp
#define	timercmp(a, b, CMP) 						      \
  (((a)->tv_sec == (b)->tv_sec) ? 					      \
   ((a)->tv_usec CMP (b)->tv_usec) : 					      \
   ((a)->tv_sec CMP (b)->tv_sec))

#endif