Using bit fields Since device registers usually contain fields of one or more bits, each of which corresponds to specific functionality (as shown in the example above), it would seem logical to use ...

Programming C without variables is like, well, programming C without variables. They are so essential to the language that it doesn’t even require an analogy here. We can declare and use them… ...

In the video after the break he begins by explaining what a bit field is and how it is defined. Basically you’re using a C structure to track a flag using just one bit of storage.