Machine Code Isn't Scary

Summary

Machine Code Isn't Scary The first programming language I ever learned was ActionScript. Writing code for Macromedia's Flash might be the furthest away from "bare metal" as you can possibly get. As I continued learning new languages, this starting heritage stuck with me. I was mostly interested in high-level, "web languages". Low-level languages felt impenetrable. Over time, I learned a bit more about them here and there, but for some reason, this notion stuck with me. Low-level things are scary, and machine code epitomized that most directly. When I Googled things asking about writing in "straight machine code", I was met with discouraging messages rather than learning. Eventually, I decided I needed to overcome this barrier if I was going to achieve my goals. In doing so, I learned something I didn't expect. Machine code isn't scary. If you can make sure your JSON conforms to a JSON schema, you can write machine code. Which Machine Code? One problem with machine code is that there isn't simply one standard. There are many different "instruction sets" depending on the processor. Most modern PCs use x86-64 machine code, but newer Macs, Raspberry Pis, and most mobile devices use ARM. There are other architectures out there, especially as you go back in time. The goal of this article won't be to give you a deep understanding of any particular instruction set, but instead, to give you enough information about how machine code typically works so you cannot be afraid of machine code. So we will start by having our examples be in ARM 64-bit (also written as aarch64). Once we have a decent understanding of that, we will talk a bit about x86-64. Machine Code Basics To understand the basics of machine code, you need three concepts: Instructions Registers Memory Instructions are exactly what they sound like; they are the code that will run. Machine code instructions are just numbers. In fact, in AArch64, every instruction is a 32-bit number. Instructions encode what operation...