When is it worthwhile to use bit fields?

Question

Is it worthwhile using C\'s bit-field implementation? If so, when is it ever used?

I was looking through some emulator code and it looks like the registers for the c

Answer 1

One use for bitfields which hasn't yet been mentioned is that unsigned bitfields provide arithmetic modulo a power-of-two "for free". For example, given:

struct { unsigned x:10; } foo;

arithmetic on foo.x will be performed modulo 2¹⁰ = 1024.

(The same can be achieved directly by using bitwise & operations, of course - but sometimes it might lead to clearer code to have the compiler do it for you).