no-std
Build
The feature no_std
automatically converts the scripting engine into a no-std
build.
Usually, a no-std
build goes hand-in-hand with minimal builds because typical embedded
hardware (the primary target for no-std
) has limited storage.
Currently, [`no_std`] requires the nightly compiler due to the crates that it uses.
Implementation
Rhai allocates, so the first thing that must be included in any no-std
project is
an allocator crate, such as wee_alloc
.
Then there is the need to set up proper error/panic handlers.
The following example uses panic = "abort"
and wee_alloc
as the allocator.
// Set up for no-std.
#![no_std]
// The following no-std features are usually needed.
#![feature(alloc_error_handler, start, core_intrinsics, lang_items, link_cfg)]
// Set up the global allocator.
extern crate alloc;
extern crate wee_alloc;
#[global_allocator]
static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
// Rust needs a CRT runtime on Windows when compiled with MSVC.
#[cfg(all(windows, target_env = "msvc"))]
#[link(name = "msvcrt")]
#[link(name = "libcmt")]
extern "C" {}
// Set up panic and error handlers
#[alloc_error_handler]
fn err_handler(_: core::alloc::Layout) -> ! {
core::intrinsics::abort();
}
#[panic_handler]
#[lang = "panic_impl"]
extern "C" fn rust_begin_panic(_: &core::panic::PanicInfo) -> ! {
core::intrinsics::abort();
}
#[lang = "eh_personality"]
extern "C" fn eh_personality() {}
#[no_mangle]
extern "C" fn rust_eh_register_frames() {}
#[no_mangle]
extern "C" fn rust_eh_unregister_frames() {}
#[no_mangle]
extern "C" fn _Unwind_Resume() {}
#[start]
fn main(_argc: isize, _argv: *const *const u8) -> isize {
// ... main program ...
}
Check out the [`no-std` sample applications]({{rootUrl}}/examples/rust.md#no-std-samples)
for different operating environments.