Factor out a sys crate.

example/Cargo.toml

@@ -2,7 +2,7 @@
 name = "example"
 version = "0.1.0"
 authors = ["Adam Becker <im.adam.becker@gmail.com>"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

libretro-rs-sys/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "libretro-rs-sys"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libc = "0.2"
+
+[build-dependencies]
+bindgen = "0.59"

libretro-rs-sys/README.md

@@ -0,0 +1,3 @@
+# libretro-rs-sys
+
+Raw API bindings for `libretro.h`, minus the forward declarations for functions.

libretro-rs-sys/build.rs

@@ -0,0 +1,25 @@
+extern crate bindgen;
+
+use std::env;
+use std::path::PathBuf;
+
+const LIBRETRO_HEADER_FILE: &'static str = "include/libretro.h";
+
+fn main() {
+  println!("cargo:rerun-if-changed={}", LIBRETRO_HEADER_FILE);
+
+  let bindings = bindgen::Builder::default()
+    .header(LIBRETRO_HEADER_FILE)
+    .allowlist_type("^retro_.+$")
+    .allowlist_var("^RETRO_.+$")
+    .default_enum_style(bindgen::EnumVariation::Rust { non_exhaustive: false })
+    .layout_tests(false)
+    .parse_callbacks(Box::new(bindgen::CargoCallbacks))
+    .generate()
+    .expect("Unable to generate bindings");
+
+  let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+  bindings
+    .write_to_file(out_path.join("libretro.rs"))
+    .expect("Couldn't write bindings!");
+}