Code segmentation guide

You've been working hard on your Homebrew title, slowly adding in more content, when suddenly you realize that the game's having weird hanging issues related to assets you've just added to your ROM. What gives?

Why does the Code segment size matter?

When the console boots, the Initial Program Load which is contained in every ROM copies the first megabyte (1,048,576 bytes) of code to RAM and executes it. This means that if you've been linking your assets directly into your code segment, you can very quickly go past this 1MB limit.

Code by itself usually has very small memory footprint (But not negligible footprint, as we'll see later!), therefore, depending on how your engine is set up, you might only be required to split your assets from the main code and not have to worry about anything else.

Where to go from here?

These pages are aimed at providing users who are new to embedded systems programming to work around this limitation. It is expected that you have a strong understanding of C. They should hopefully provide you with useful techniques and sample code to aid in your homebrew development, and it is recommended that they be read in the provided order:

• Splitting assets from code
• Data compression and filesystems

Once you have read through those two pages, it is also recommended you look into techniques to split your code. It is preferable that you write your game to support at least one of these methods before you start adding too much to it, as it might become more challenging to modify such an intricate part of your engine after the fact:

• Overlays
• Relocatable Modules
• Relocatable Overlays
• TLB Mapping