Assembly

Intro

Hey everyone! In this tutorial, we’re going to start adding in multithreading to the Iridium VM. Please make sure you are starting from this point in the code: https://gitlab.com/subnetzero/iridium/tags/0.0.16. Going forward, I’m going to make a tag per tutorial so that everyone starts from a common point. === A Note on Assumed Knowledge I write these tutorials target towards more advanced users. I sometimes skip small steps, such as "add in this line to file X".

Home Stretch

This is going to be a longer post. In it, we’ll wrap up our two-pass assembler, add a PRTS opcode for printing, and tie up some other loose ends. At the end, we should have an interpreter with a good amount of functionality and a simple assembly language. We are, of course, far from done with the project. I want to work on a different tutorial series for a bit, then we’ll continue with Iridium. === Quick Change Add the following dependencies in your Cargo.toml. We’ll need them later:

CLI Improvements

Having to start the interpreter, then type .load_file, etc is cumbersome. Let’s change it so that the VM tries to execute the file given to it as an argument. There’s a super handy-dandy crate called clap in Rust that will make this trivial. The behavior we want is:

If the user types iridium and nothing else, they will go directly to a REPL

If the user types iridium /path/to/valid/*.iasm, that is, they want to execute a file of code directly, it should do that then exit

Note

Assembler Struct

Welcome back! When we last left our intrepid readers, we were about to write an assembler struct.

But why? What does it do?

What does it all mean?! Why don’t more people love interrobangs?! Ahem.

Intro

Hello!

What are Strings?

This may shock you, but they are a bit more complicated than they might seem. Since a computer cares about bytes, it has no concept of the letter s, ! or any other letter. These having meaning to us humans. But we want our users to be able to give input and read output without having to do it all in hex. The solution is to use some sort of character encoding. This maps a particular character to a number. You’ll hear two common encodings mentioned these days: ASCII and UTF. I’m not going to go into an exhaustive history of them; for that, check out this article for ASCII and this article for UTF-8. I will cover enough for us to put in support for strings, though.

Intro

Improving the Assembler

Our assembler right now can recognize one opcode, load. We need to teach it to recognize all the rest. There’s a couple ways we can do that:

We can write a parser for each opcode
We can write a parser that recognizes the letters a-z and then check if they are a valid Opcode.

Let’s go with option #2, since it will require much less copy-paste. It also gives us an excuse to implement From<CompleteStr<_>> for our opcodes! == The From<&str> Trait In instruction.rs, below the block where we implemented From<u8>, put this:

Fixy fixy

You know how I’ve written several times we’ll come back and fix/change stuff later?

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Assembly

So You Want to Build a Language VM - Part 17 - Basic Threads

Intro

So You Want to Build a Language VM - Part 16 - String Constants And More

Home Stretch

So You Want to Build a Language VM - Part 15 - Assembler CLI Improvements

CLI Improvements

So You Want to Build a Language VM - Part 14 - Symbol Tables

Assembler Struct

So You Want to Build a Language VM - Part 13 - Labels

Intro

So You Want to Build a Language VM - Interlude 02

Hello!

So You Want to Build a Language VM - Part 12 - Strings

What are Strings?

So You Want to Build a Language VM - Part 11 - Memory

Intro

So You Want to Build a Language VM - Part 10 - Assembler 3: Assemble Harder

Improving the Assembler

So You Want to Build a Language VM - Interlude 01

Fixy fixy