# LCPU Idea/Working Model Sheet

This is basically the working ideas for the LCPU project.

## Core features

- CPU SENTs
	- RISC-V rv32ima core
		- Would supporting more than one CPU core type be worthwhile? If so, the project is relatively setup for such workflow...
	- Controllable paramaters (RAM size, ...)

## Code upload

- Upload a raw binary to execute, generated from any user tooling (goes into server `data/lcpu/users/[steamid]/`)
	- Yes, this means you can run Linux in GMod. No, I'm not sorry.

## Integrated simple project workflow (WIP, not in the addon yet)

- Uses official RISC-V GCC toolchain
	- In a podman container for jailing reasons?

- Write assembly/C/C++ code using a tiny project system (source for them would go in server `data/lcpu/users/[steamid]/projects/[project]`)
	- At the root of a project, a `project.json` file is expected to exist, with contents like:
	```json
	{
		"Project": {
			"Name": "test",

			// Define all build configurations here
			"Configurations": {
				"Debug": {
					"CCompileFlags": "-O0 ${BaseCCompileFlags}",
					"CppCompileFlags": "-O0 ${BaseCppCompileFlags}"
				},
				"Release": {
					"CCompileFlags": "-O2 ${BaseCCompileFlags}",
					"CppCompileFlags": "-O2 ${BaseCppCompileFlags}",
					// If a variable is unset it will usually default to
					// ${Base${VariableName}}
					"LinkerFlags": "-Wl,--gc-sections ${BaseLinkerFlags}"
				}
			},

			"Sources": [
				"binary.ld",
				"start.S",
				"main.c"
			]
		}
	}
	```

	- `BaseCCompileFlags` and `BaseCppCompileFlags` are defaulted to sane values for each language.

	- This will be transpiled into a `Makefile` by the addon.
		- A standalone tool will be provided and used for transpiling `project.json` to a `Makefile` (and maybe even built into the container and transpiled there, to reduce the actions on the host to just the podman run?)
		- which, when a Build is done in GMod; is then run with `make` in a temporary podman container which only has access to the source code folder for the project (and nothing else, besides riscv tools which are in the image).
			- Command line is probably something like `make CONFIG=${config}`
		- the output binary will be stored alongside the source code on the server side, with a name like `${name}-${config}.bin`
			- This file can then be selected for loading (without needing to be uploaded from the client).


- There is no conditional compilation in the `project.json` system
	- All files in a project are always built by that project.

- No notion of subprojects/build dependencies
	- This is meant to be simple for easy development in GMod. If you want complex build features you can export the project onto your own computer and use `lcpu_projgen` to generate Makefiles (which you can then maintain)

- Text editor used to edit project source files
	- Use the Wire editor? (we need wiremod anyways, and the text editor is.. OK I suppose.)
		- Or: https://github.com/Metastruct/gmod-monaco
			- https://github.com/JustMrPhoenix/Noir/tree/master

- Some example projects?
	- A simple bare metal "Hello World"
	- I joke about it, but an RTOS would be really nice and a good stress test of the project system (for usage in "real" projects.)

## Moderation/administration tools
- Admin controlled per-user max RAM size (default 64mb)

- Admin controlled per-user max LCPU entity count (default 8)

- Admin controled global (affects all placed LCPUs) scheduler cycle rate/instruction count.
		- default is 0.1/1024 instructions

## Addon interopability

- Wiremod interopability
	- Wiremod GPIO peripheral (to interface with wire world)
	- special Console Screen peripheral (interfacing specifically with it)
	- frambuffer peripheral which uses the Digital Screen