feat: add 0x03_button_rust driver with 8 unit tests

drivers/0x03_button_rust/build.rs

@@ -0,0 +1,68 @@
+//! SPDX-License-Identifier: MIT OR Apache-2.0
+//!
+//! Copyright (c) 2021–2024 The rp-rs Developers
+//! Copyright (c) 2021 rp-rs organization
+//! Copyright (c) 2025 Raspberry Pi Ltd.
+//!
+//! Set up linker scripts
+
+use std::fs::{ File, read_to_string };
+use std::io::Write;
+use std::path::PathBuf;
+
+use regex::Regex;
+
+fn main() {
+    println!("cargo::rustc-check-cfg=cfg(rp2040)");
+    println!("cargo::rustc-check-cfg=cfg(rp2350)");
+
+    // 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());
+
+    println!("cargo:rerun-if-changed=.pico-rs");
+    let contents = read_to_string(".pico-rs")
+        .map(|s| s.trim().to_string().to_lowercase())
+        .unwrap_or_else(|e| {
+            eprintln!("Failed to read file: {}", e);
+            String::new()
+        });
+
+    // 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 target;
+    if contents == "rp2040" {
+        target = "thumbv6m-none-eabi";
+        let memory_x = include_bytes!("rp2040.x");
+        let mut f = File::create(out.join("memory.x")).unwrap();
+        f.write_all(memory_x).unwrap();
+        println!("cargo::rustc-cfg=rp2040");
+        println!("cargo:rerun-if-changed=rp2040.x");
+    } else {
+        if contents.contains("riscv") {
+            target = "riscv32imac-unknown-none-elf";
+        } else {
+            target = "thumbv8m.main-none-eabihf";
+        }
+        let memory_x = include_bytes!("rp2350.x");
+        let mut f = File::create(out.join("memory.x")).unwrap();
+        f.write_all(memory_x).unwrap();
+        println!("cargo::rustc-cfg=rp2350");
+        println!("cargo:rerun-if-changed=rp2350.x");
+    }
+
+    let re = Regex::new(r"target = .*").unwrap();
+    let config_toml = include_str!(".cargo/config.toml");
+    let result = re.replace(config_toml, format!("target = \"{}\"", target));
+    let mut f = File::create(".cargo/config.toml").unwrap();
+    f.write_all(result.as_bytes()).unwrap();
+
+    // The file `rp2350_riscv.x` is what we specify in `.cargo/config.toml` for
+    // RISC-V builds
+    let rp2350_riscv_x = include_bytes!("rp2350_riscv.x");
+    let mut f = File::create(out.join("rp2350_riscv.x")).unwrap();
+    f.write_all(rp2350_riscv_x).unwrap();
+    println!("cargo:rerun-if-changed=rp2350_riscv.x");
+
+    println!("cargo:rerun-if-changed=build.rs");
+}