Learning a little assembly language is not only good for the soul, but it has value for anyone wanting to deepen their understanding of a processor, t

Code in Assembly for Apple Silicon with the AsmAttic app

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2021-06-07 08:00:18

Learning a little assembly language is not only good for the soul, but it has value for anyone wanting to deepen their understanding of a processor, those who want to read disassembled code such as security researchers, and anyone writing code in a higher-level language such as Objective-C or Swift. Although there are several good books about ARM assembly (see references), using it in Xcode apps is not well documented. Apple’s developer information is most helpful to those who already write assembly and are accustomed to its quirks.

This article is the first of what I hope will be a series to open up access to assembly coding for Apple Silicon Macs. Here I take you through building a simple app which wraps itself around four lines of ARM64 assembly code, and provides a platform for subsequent articles. To work through this, you’ll need an M1 Mac and Xcode 12.5 (free from the App Store), and I assume that you’re sufficiently familiar with that and Swift to be able to build a basic app in AppKit or similar.

Start by creating a new project for a macOS app, which I’ve named AsmAttic. Set its Interface and Life Cycle to support your favourite model. In my case, that’s a conventional Storyboard with an AppKit App Delegate and Swift as its language. You’re welcome to use SwiftUI or anything else which you find straightforward.