Programmer Humor

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It's called attaining divinity (sh.itjust.works)

submitted 5 months ago by [email protected] to c/[email protected]

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[–] [email protected] 5 points 5 months ago (2 children)

This is pedantic, but assembly languages get "assembled" to machine code. This is somewhat similar to higher level languages being "compiled," which eventually becomes assembly which gets assembled. The major reason why these are different is because a compiler changes the structure of the code. Assembly is a direct mapping to instructions. It just converts the text into machine code directly, which is why it's easy to go from machine code to assembly but decompiling doesn't give you identical results to the original source code.

Also, binary and hexadecimal are just different ways to view the same binary data and aren't different things. There is only "machine code" which is a type of binary data but you can view binary with any arbitrary base, though obviously powers of 2 work better.

[–] [email protected] 4 points 5 months ago

Assembly is a direct mapping to instructions. It just converts the text into machine code directly,

Kinda... yes and no? At least with x86 there's still things like encoding selection going on, there's not a 1:1 mapping between assembly syntax and opcodes.

Also assemblers, at least those meant for human consumption (mostly nasm nowadays) tend to have powerful macro systems. That's not assembly as such, of course.

But I think your "a compiler changes the structure of the code" thing is spot-on, an assembler will not reorder instructions, it won't do dead code elimination, but I think it's not really out of scope of an assembler to be able to do those things -- compilers weren't doing them for the longest time, either.

I think a clearer division would be that compilers deal with two sets of semantics: That of the source language, and that of the CPU. The CPU semantics don't say things like "result after overflow is undefined", that's C speaking, and compilers can use those differences to do all kind of shennanigans. With assemblers there's no such translation between different language semantics, it's always the CPU semantics.