ns-precision monotonic clock in C on Linux and OS X

Question

clock_gettime(CLOCK_MONOTONIC, ...) is available in Linux but not OS X. The Mach timers are available in OS X but not in Linux.

How can I get a ns-preci

Answer 1

I used the answer by Douglas (accepted answer), his references and other examples floating around the internet (such as this question).

This answer is to include my version of the code which emulates the clock_gettime for CLOCK_REALTIME and CLOCK_MONOTONIC. It also emulates the function clock_nanosleep() for absolute monotonic time. The code is hosted on GitHub here.

For it to work, the only additional bit needed in your code is

#ifdef __MACH__
timing_mach_init();
#endif

then use clock_gettime() and clock_nanosleep_abstime() as if you were using a system that is actually POSIX compliant (with realtime extensions).