Add nix flake

flake.nix

@@ -0,0 +1,42 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
+  };
+
+  outputs = { self, rust-overlay, nixpkgs }:
+    let
+      system = "x86_64-linux";
+      overlays = [ (import rust-overlay) ];
+      pkgs = import nixpkgs {
+        inherit overlays system;
+      };
+    in
+    {
+      devShells.${system}.default = pkgs.mkShell {
+        buildInputs = [
+          # (pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override {
+          #   targets = [ "thumbv6m-none-eabi" ];
+          #   extensions = [ "rust-src" ];
+          # }))
+          (pkgs.rust-bin.stable.latest.default.override {
+            extensions = [ "rust-src" "llvm-tools-preview" ];
+            targets = [ "thumbv6m-none-eabi" ];
+          })
+          pkgs.rust-analyzer
+          pkgs.flip-link
+          pkgs.probe-run
+          pkgs.probe-rs
+          pkgs.elf2uf2-rs
+          pkgs.rustfmt
+          pkgs.cargo-binutils
+          pkgs.gcc-arm-embedded
+          # For compile_commands.json, run `bear cargo build -r` at least once
+          pkgs.bear
+          # For language server for the C files
+          pkgs.ccls
+        ];
+      };
+    };
+}