Add preprocessing step

flake.nix

@@ -0,0 +1,31 @@
+{
+  description = "c compile experiments";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+  };
+
+  outputs = { nixpkgs, ... }:
+    let
+      systems = [ "x86_64-linux" ];
+    in
+      {
+        config = {
+          nixpkgs.config.allowUnfree = true;
+        };
+
+        devShells = nixpkgs.lib.genAttrs systems (system:
+          let
+            pkgs = nixpkgs.legacyPackages.${system};
+          in
+            {
+              default = pkgs.mkShell {
+                packages = [
+                  pkgs.gnumake
+                  pkgs.gcc-arm-embedded
+                ];
+              };
+            }
+        );
+      };
+}