Sleeping for milliseconds on Windows, Linux, Solaris, HP-UX, IBM AIX, Vxworks, Wind River Linux?

Question

I have to write a C program which has to sleep for milliseconds, which has to run on various platforms like Windows, Linux, Solaris, HP-UX, IBM AIX, Vxworks, and Windriver Linux

• On Windows, the Sleep system call will work on milliseconds only.
• On Linux, sleep will work on seconds; usleep will perform on microseconds and it's available on Solaris also.
• In Vxworks, I hope I can implement using taskDelay and sysClkRateSet.

How can I achieve this millisecond sleep on HP-UX, IBM AIX and Wind River Linux?

Answer 1

Propably a wrapper using platform specific #defines will do:

#if defined(WIN32)
  #include <windows.h>
#elif defined(__UNIX__)
  #include <unistd.h>
#else
#endif

...

int millisleep(unsigned ms)
{
#if defined(WIN32)
  SetLastError(0);
  Sleep(ms);
  return GetLastError() ?-1 :0;
#elif defined(LINUX)
  return usleep(1000 * ms);
#else
#error ("no milli sleep available for platform")
  return -1;
#endif
}

---

Update

Referring to Jonathan's comment below, please find a more modern, more portable (and as well corrected :}) version here:

#if defined(WIN32)
  #include <windows.h>
#elif defined(__unix__)
  #include <time.h>
  #include <unistd.h>
#else
#endif

...

int millisleep(unsigned ms)
{
#if defined(WIN32)

  SetLastError(0);
  Sleep(ms);
  return GetLastError() ?-1 :0;

#elif _POSIX_C_SOURCE >= 199309L

  /* prefer to use nanosleep() */

  const struct timespec ts = {
    ms / 1000, /* seconds */
    (ms % 1000) * 1000 * 1000 /* nano seconds */
  };

  return nanosleep(&ts, NULL);

#elif _BSD_SOURCE || \
  (_XOPEN_SOURCE >= 500 || \
     _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) && \
  !(_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)

  /* else fallback to obsolte usleep() */

  return usleep(1000 * ms);

#else

# error ("No millisecond sleep available for this platform!")
  return -1;

#endif
}

Answer 2

Consider select with empty FD sets and the timeout you want. From man select:

Some code calls select() with all three sets empty, nfds zero, and a non-NULL timeout as a fairly portable way to sleep with subsecond precision.

Actually it might be the best solution for any non-Windows system.