6. Rust

Writing Rust:

#![no_std]
#![no_main]

extern "C" {
    fn printf(fmt: *const u8, ...) -> i32;
}

fn square(num: i32) -> i32 {
    num * num
}

#[no_mangle]
pub extern "C" fn main() -> i32 {
    let fmt: *const u8 = b"The square of %d is: %d\0".as_ptr(); /* convert to a pointer for the null terminated string, thats how it expects in C */
    let n: i32 = 10;

    unsafe {
        printf(fmt, n, square(n));
    }

    return 0;
}

For this example we will not be using the standard libraries with #![no_std].

extern "C" is used to access printf. The string has to be converted into a pointer for a null terminated string, but you could always write a custom function in Luau to avoid this.

Compiling:

I compiled the code in Compiler Explorer with options of: --target=riscv32imfd-unknown-none-elf, you can also pick to use -C opt-level=3 for optimizations.

From the ASM file, you can generate Luau like usual:

reasm main.s -o main.luau

Important

The compiler will be assuming the entry point to be main, if you would like another entry point symbol you can use the -e symbol parameter.

Results: