build.rs

//! This build script copies the `memory.x` file from the crate root into
//! a directory where the linker can always find it at build time.
//! For many projects this is optional, as the linker always searches the
//! project root directory -- wherever `Cargo.toml` is. However, if you
//! are using a workspace or have a more complicated build setup, this
//! build script becomes required. Additionally, by requesting that
//! Cargo re-run the build script whenever `memory.x` is changed,
//! updating `memory.x` ensures a rebuild of the application with the
//! new memory settings.

use std::fs::File;
use std::io::Write as _;
use std::path::PathBuf;

fn main() {
    // Put the linker script somewhere the linker can find it
    let out = PathBuf::from(std::env::var_os("OUT_DIR").unwrap());
    println!("cargo:rustc-link-search={}", out.display());

    // The file `memory.x` is loaded by cortex-m-rt's `link.x` script, which
    // is what we specify in `.cargo/config.toml` for Arm builds
    let memory_x = include_bytes!("memory.x");
    let mut f = File::create(out.join("memory.x")).unwrap();
    f.write_all(memory_x).unwrap();
    println!("cargo:rerun-if-changed=memory.x");

    println!("cargo:rerun-if-changed=build.rs");
}