debug message macro in C

dmsg.h

#include <time.h>
#include <sys/time.h>
#include <stdarg.h>
#include <stdio.h>

#define dmsg(X, ...)		\
  do {					\
  struct tm td;			\
  struct timeval tv;			\
  struct timezone tz;			\
  FILE * out = stdout;			\
  if (X) {				\
  gettimeofday (&tv, &tz);						\
  localtime_r (&tv.tv_sec, &td);					\
  fprintf (out, "(DEBUG %02d:%02d:%02d.%03d %s:%d %s) ", td.tm_hour, td.tm_min, td.tm_sec, (int) (tv.tv_usec / 1000), __FILE__, __LINE__, __FUNCTION__); \
  fprintf (out, __VA_ARGS__);						\
  fprintf (out, "\n");							\
  fflush (out);							\
  }								\
  } while (0);