A pluggable virtual machine for constrained environments.

Fuste

Fuste is a programmability adapter and virtual machine stack designed for integration with Robles, Ramate's implementation of BFA protocols.

Note

Currently, Fuste implements only the RV32I ISA. Since Fuste is intended as a programmability stack and does not ultimately have general opinions about the ISA, we may choose to implement other ISAs as Fuste virtual machines in the future.

Getting started

Tip

You can shortcut these steps by cloning this repository, cd into fuste/tests/toolchain, and nix develop.

NOTE: Depending on your system you may still need to build fubox beforehand.

1. Review the programs in the tests/toolchain workspace before you begin writing your own.
2. Ensure you have built fubox and that is available on your PATH.
3. Configure a workspace with the desired env/fuste crates.
4. Configure the toolchain similar to tests/toolchain. You can change the memory layout in the linker script if you like.
5. Write your program:

#![no_std]
#![no_main]
use fuste::println;

pub fn add(a: u32, b: u32) -> u32 {
	a + b
}

fuste::entry! {
	fn main() -> Result<(), ()> {
		let mut j = 0;
		for i in 0..10 {
			assert_eq!(i, i);
			j += i;
			j = add(j, i);
			println!("Hello, world!");
			println!("i: {}, j: {}", i, j);
		}

		Ok(())
	}
}

6. Run!

cargo run --target riscv32i-ramate-fuste-elf.json -p my-fuste-program

Environment

env/fuste provides the following:

• fuste-ecall for defining basic ecall interrupt APIs with an implementing machine.
• fuste-exit for defining program termination interrupts.
• fuste-write for making one-way writes to a system. println! is implemented using fuste-write.
• fuste-channel for opening a kernel channel with a stack-allocated buffer. Network requests are implemented using fuste-channel.
• fuste includes all of the above for those who want a complete stack-based set of symbols.
• fuste-galloc defines a global heap allocator for those interested in writing heap programs. It is not in fuste because--owing to the highly constrained targets for the virtual machine--purely stack-based programs are preferred.

fubox currently implements a debugging form of the fuste environment.

Example programs

• my-program: a program for the fuste target without any of the fuste prelude
• my-fuste-program: a simple program using the fuste prelude.
• my-fuste-heap-program: a program using the fuste galloc dynamic memory allocator.
• my-fuste-dlt-program: a program using the fuste DLT primitives.

Contributing

Task	Description
Upcoming Events	High-priority event issues with planned completion dates.
Release Candidates	Feature-complete versions linked to events.
Features & Bugs	High-priority feature and bug issues.