Programs don't have to be particularly large complex to become relatively unweildy and difficult to understand in assembly. I find it takes me much more time to

Programs don't have to be particularly large complex to become relatively unweildy and difficult to understand in assembly. I find it takes me much more time to comprehend large portions of written assembly than higher-level languages. Your mileage may vary. Other engineers might be more talented than I am in this regard, however I think this is more or less everyone's experience. Abstractions like functions are still present, just not in the way that you might think of them in a higher-level language. You use 'branching' instructions to jump from one part of the code to another. Either by referencing labeled sections of the code to perform 'absolute' jumps, or by jumping 'relative' to the current instruction. This forms the building blocks that can be used to implement more abstract constructs such as loops, functions and conditionals. This is a gross simplification, I hope it helps answer your question though.