Is a bit field any more efficient (computationally) than masking bits and extracting the data by hand?

Question

I have a numerous small pieces of data that I want to be able to shove into one larger data type. Let\'s say that, hypothetically, this is a date and time. The obvious method is

Answer 1

It is entirely platform and compiler dependent. Some processors, especially microcontrollers, have bit addressing instructions or bit addressable memory, and the compiler can use these directly if you use built-in language constructs. If you use bit-masking to operate on bits on such a processor, the compiler will have to be smarter to spot the potential optimisation.

On most desktop platforms I would suggest that you are sweating the small stuff, but if you need to know, you should test it by profiling or timing the code, or analyse the generated code. Note that you may get very different results depending on compiler optimisation options, and even different compilers.