RISCV32IM Stylus Simulator

This code simulates RISCV32IM code, with some supported ecalls for EVM and Stylus-specific operations. It's intended to be used with Arbitrum Stylus, with a forked SDK.

This is still very much in a TODO state!

Installation

To build the simulator, the following is needed:

• OCaml

You can install the OCaml programming language using a OS package manager easily using instructions from the website.

• Dune

You can install the Dune package manager with these instructions.

• binutils-dev

It's best to figure out how to do this based on what you use locally, on Debian:

sudo apt-get install -y binutils-dev

Building

dune build bin

This builds the executable, located at _build/default/bin/main.exe. The command line tool takes a smple path to load. The program can exit by using EBREAK.

Usage

The simplest use is with a test executable, test/risc-hello-world:

cast --abi-decode 'hello()(uint256)' $(\
	./_build/default/bin/main.exe test/risc-hello-world $(\
		cast calldata 'hello(uint256)' 123
	)
)

This contains the contract code:

#[entrypoint]
#[storage]
struct Storage {
    pub message: StorageU256,
}

#[public]
impl Storage {
    pub fn hello(&mut self, x: U256) -> U256 {
        self.message.set(x);
        self.message.get()
    }
}

Supported environment calls

The following environment calls are supported:

• Storage loads/stores
• Calldata loading and return data

The following won't be supported:

• Calling
• Sending

TODOs

• Read actual program headers instead of sections so stripped binaries work

I had some linking issues that prevented me from using a approach I wanted here. So the section haeders is the current approach.

• Tighten up the use of the int to int32 types (this is abit messy)