Move the 'core_generator' from a build script to an in-repository tool

The core generator will be run manually before release.

Cargo.toml

@@ -1,3 +1,9 @@
+[workspace]
+members = [
+  ".",
+  "./core_generator",
+]
+
 [package]
 name = "ruduino"
 version = "0.2.7"
@@ -15,8 +21,6 @@ description = """
 Reusable components for AVR microcontrollers
 """
 
-build = "core_generator/build.rs"
-
 keywords = ["avr", "arduino", "uno"]
 
 [features]
@@ -25,8 +29,3 @@ default = ["avr-std-stub"]
 [dependencies]
 avr-std-stub = { version = "1.0", optional = true }
 target-cpu-macro = "0.1"
-
-[build-dependencies]
-avr-mcu = "0.3"
-target-cpu-fetch = "0.1"
-

core_generator/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "ruduino-core-generator"
+version = "0.0.0" # not versioned
+publish = false
+edition = "2018"
+authors = [
+  "The AVR-Rust Project Developers",
+  "Jake Goulding <jake.goulding@gmail.com>",
+  "Dylan McKay <me@dylanmckay.io>",
+]
+
+license = "MIT/Apache-2.0"
+readme = "README.md"
+repository = "https://github.com/avr-rust/ruduino"
+
+[[bin]]
+name = "ruduino-core-generator"
+path = "src/main.rs"
+
+[dependencies]
+avr-mcu = "0.3"
+target-cpu-fetch = "0.1"

core_generator/src/main.rs

@@ -14,12 +14,15 @@ const DEFAULT_MCU_FOR_NON_AVR_DOCS: &'static str = "atmega328";
 
 const DEFAULT_FREQUENCY_HZ_FOR_NON_AVR_DOCS: u64 = 16_000_000;
 
-fn src_path() -> PathBuf {
-    Path::new(env!("CARGO_MANIFEST_DIR")).join("src")
+fn base_output_path() -> PathBuf {
+    match std::env::args().skip(1).next() {
+        Some(path) => Path::new(&path).to_owned(),
+        None => panic!("please pass a destination path for the generated cores on the command line"),
+    }
 }
 
 fn cores_path() -> PathBuf {
-    src_path().join("cores")
+    base_output_path().join("cores")
 }
 
 fn core_module_name(mcu: &Mcu) -> String {
@@ -57,7 +60,7 @@ fn generate_cores(mcus: &[Mcu]) -> Result<(), io::Error> {
 }
 
 fn generate_config_module() -> Result<(), io::Error> {
-    let path = src_path().join("config.rs");
+    let path = base_output_path().join("config.rs");
     let mut f = File::create(&path)?;
 
     let clock: u64 = if cfg!(arch = "avr") {

regenerate-cores.sh

@@ -0,0 +1,10 @@
+#! /bin/sh -ea
+
+set -o pipefail
+
+SCRIPT_DIR=$(dirname $0)
+
+cd "${SCRIPT_DIR}/core_generator"
+
+cargo run "../src"
+