xtask: a first pass at a cargo runner

see #6

.cargo/config

@@ -1,10 +1,10 @@
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
-runner = "gdb -q -x .gdbconfig"
+runner = "cargo run -q --bin xtask --"
 
 rustflags = [
   "-C", "link-arg=-Tlink.x",
 #  "-C", "linker=flip-link", # TODO
-  "-C", "force-frame-pointers=yes",
+#  "-C", "force-frame-pointers=yes",
 ]
 
 
@@ -15,13 +15,16 @@ rustflags = [
 #
 # But, it doesn't look like the feature above is headed towards stabilization
 # anytime soon and we don't want to tie ourselves to nightly so we stick with
-# this and stomach needing to be in the repo root to `cargo run`/`cargo flash`.
+# this and use aliases where possible to specify the target triple.
+#
+# See: https://github.com/ut-utp/tm4c/issues/6 for more details.
 [build]
-target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
+# target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
 
 [alias]
-b = "build --release"
-r = "run --release"
+r = "run --release --target thumbv7em-none-eabihf"
+b = "build --release --target thumbv7em-none-eabihf"
+ben = "bench --target thumbv7em-none-eabihf"
 
 # Notes:
 # call stack: cargo +nightly call-stack  --bin utp-tm4c | dot -Tpng > out.png

Cargo.toml

@@ -1,7 +1,7 @@
 [workspace]
 members = [
     ".",
-#     "xtask",
+    "xtask",
 ]
 
 [package]

xtask/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "xtask"
+version = "0.0.0"
+edition = "2021"
+publish = false
+build = "build.rs"
+
+[[bin]]
+name = "xtask"
+path = "xtask.rs"
+
+[build-dependencies]
+which = "4.2"
+
+[dependencies]
+crossbeam-utils = "0.8"
+downloader = { version = "0.2", features = ["tui"] }
+owo-colors = "3.4"
+serialport = "4.2"
+xshell = "0.2"
+which = "4.2"

xtask/build.rs

@@ -0,0 +1,59 @@
+use std::{env, fs, ffi, path::{Path, PathBuf}};
+
+fn var(name: impl AsRef<ffi::OsStr>) -> Result<String, env::VarError> {
+    println!("cargo:rerun-if-env-changed=RUSTC");
+    env::var(name)
+}
+
+fn which(query: impl AsRef<ffi::OsStr>) -> which::Result<PathBuf> {
+    println!("cargo:rerun-if-env-changed=PATH");
+    which::which(query)
+}
+
+fn main() {
+    // Tell `xtask` where rustc is so it can find the sysroot:
+    let rustc = var("RUSTC").expect("cargo sets $RUSTC for build scripts");
+    let rustc = Path::new(&rustc);
+
+    let rustc = if rustc.exists() && rustc.is_absolute() {
+        rustc.to_path_buf()
+    } else {
+        // Assume it's a command that we need to get the path of with `which`:
+        //
+        // (this will work with relative paths too; we'll declare false
+        // dependence on `$PATH` in these cases but that's fine)
+        which(rustc).unwrap()
+    };
+    println!("cargo:rerun-if-changed={}", rustc.display());
+    println!("cargo:rustc-env=RUSTC_PATH={}", rustc.display());
+
+
+    // Tell `xtask` where it can stick its artifacts:
+    let out_dir = var("OUT_DIR").expect("cargo sets $OUT_DIR for build scripts");
+    let out_dir = Path::new(&out_dir);
+
+    // We seem to get paths like `target/debug/build/xtask-55dae522e1d36b80/out`
+    let potential_target_dir = {
+        let mut path = Some(out_dir);
+
+        // Try to go 4 directories up!
+        for _ in 0..4 {
+            if let Some(p) = path {
+                path = p.parent();
+            }
+        }
+
+        path
+    };
+    let target_dir = if let Some(p) = potential_target_dir.filter(|p| p.file_name().unwrap() == "target") {
+        p
+    } else {
+        out_dir
+    };
+    let artifact_dir = target_dir.join("xtask");
+    fs::create_dir_all(&artifact_dir).unwrap();
+    println!("cargo:rustc-env=XTASK_ARTIFACT_DIR={}", artifact_dir.display());
+
+    // Forward the host target triple:
+    println!("cargo:rustc-env=HOST_TRIPLE={}", var("HOST").unwrap());
+}