Retrieve specific bit from a bit mask

Question

I am using the termios library and I am trying to retrieve specific information from a bit mask field. Specifically:

The termios structure has this member: tcflag_t c_iflag.

This member has a constant called IXON which I want to read it to see if it is set or not. How do I do this?

Just for reference: https://man7.org/linux/man-pages/man3/termios.3.html