Add nix flake

Author: Emin017

flake.nix

@@ -0,0 +1,37 @@
+{
+  description = "MEMU";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }@inputs:
+    flake-utils.lib.eachDefaultSystem
+      (system:
+      let
+        pkgs = import nixpkgs { inherit system;};
+        deps = with pkgs; [
+          git
+          gnumake autoconf automake
+          cmake ninja
+          pkgsCross.riscv64-embedded.buildPackages.gcc
+        ];
+      in
+        {
+          legacyPackages = pkgs;
+          devShell = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
+            buildInputs = deps;
+            RV64_TOOLCHAIN_ROOT = "${pkgs.pkgsCross.riscv64-embedded.buildPackages.gcc}";
+            shellHook = ''
+							export EMU_CC=$RV64_TOOLCHAIN_ROOT/bin/riscv64-none-elf-gcc
+							export EMU_OBJCOPY=$RV64_TOOLCHAIN_ROOT/bin/riscv64-none-elf-objcopy
+							make test-img
+							unset EMU_CC
+							unset EMU_OBJCOPY
+            '';
+          };
+        }
+      )
+    // { inherit inputs;};
+}