I don’t understand why bit masking and manipulation is so popular when it makes the code impossible to read. I like using Ruby, string, and pack and unpack.
Well one reason is that bit operations are significantly faster than other methods, it’s one reason for example, why compilers will turn a divide by a constant into bit manipulation.
Using a scripting language’s string packing is hundreds of times slower than doing a couple of bit operations, and if there’s a memory allocation involved, it can be thousands of times slower. If you’re curious about this, I recommend doing some profiling to find out how fast your favorite algorithms are when using C bitwise operators compared to Ruby string packing.
FWIW, having the code be readable is mostly a familiarity problem that you can resolve by practicing more bitwise operations, if you want. If you spend your days in Ruby, then there might not be strong reasons to, but if you’re curious and want to improve, you might have fun playing in C or C++. I spend my days mostly in CUDA, and using bit manipulation is par for the course, failure to use the best tricks can result in much lower compute throughput and much higher power consumption.
C23 finally introduces binary literals, e.g. you can write now "0b11110000" instead of "0xf0" for situations where binaries are more readable (but with a bit of 'training', hexadecimal works just as well).
Also, bitwise operations are essentially "SIMD for bits" and important down on the machine code level, it makes a lot of sense to have that same functionality also in higher level languages (unfortunately not all common bitwise instructions - like rotations - made it into high level languages).
It takes some getting used to but the operations by themselves are readable, it is just that what you do with them can be complex. It is like arithmetic. People usually don't have a problem with addition, subtraction, multiplication and division, but it doesn't mean they won't have a hard time dealing with complex equations.
Packing and unpacking are just some of the things you can do with bitwise operations. They are a common problem, and they are often tricky, so having an API for that makes a lot of sense. But if what you need to do is not packing and unpacking, I find it harder to understand the unpack -> string manipulation -> pack workflow than bitwise operations, it also tends to be more verbose and slower.
Do Ruby's pack and unpack routines let you access a field smaller than a byte? What about a field that is split across a byte boundary?
I agree that bit masking and manipulation is hard to read and can be misused by ego-driven programmers. But the "popularity" because because bit masking and manipulation are both fundamental to computer science and an absolute necessity in certain situations.
