The code is partially based on my work when at Microsoft: R Tools for VS Code, which, in turn, was forked off Microsoft RTVS. Mostly tokenizer and parser, translated from C# to TypeScript, simplified and adapted for assembly language syntax.
Some original C# code was already translated to TypeScript in Pyright, hence small amount was taken from there (fragments primarily related to the tokenization and supporting classes).
Documentation on instruction was extracted from ARM doc archives downloaded from here. All documentation belongs to Arm Limited.
Documentation on directives in hover tooltips is fetched online directly from the GAS Web site.
Bugs and feedback
Feel free to file bugs and suggestions at vscode-arm repo.