{
  description = "Firmware for MQTT-controlled 4-channel DDS signal generator using Urukul, Humpback and STM32 NUCLEO.";

  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-21.11;
  inputs.rust-overlay.url = github:oxalica/rust-overlay;
  inputs.rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
  inputs.src-migen = { url = github:m-labs/migen; flake = false; };

  outputs = { self, nixpkgs, rust-overlay, src-migen }:
    let
      pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ (import rust-overlay) ]; };

      rustToolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;

      migen = pkgs.python3Packages.buildPythonPackage rec {
        name = "migen";
        src = src-migen;
        propagatedBuildInputs = [ pkgs.python3Packages.colorama ];
      };

      rustPlatform = pkgs.makeRustPlatform {
        rustc = rustToolchain;
        cargo = rustToolchain;
      };

      itm = rustPlatform.buildRustPackage rec {
        version = "0.3.1";
        pname = "itm";

        src = pkgs.fetchFromGitHub {
          owner = "rust-embedded";
          repo = "itm";
          rev = "v${version}";
          sha256 = "sha256-UmWI3NOE8Lf8ICHOR8nNpbCP9+g3R8XHRX+nUJsH6pY=";
        };

        cargoPatches = [ ./itm-cargo-lock.patch ];
        cargoSha256 = "sha256-3odQabrzjFm5rTkeqZWDFLnculwGeB3gG71jNuCtqIo=";
        nativeBuildInputs = [ pkgs.pkgconfig ];

        doCheck = false;
      };

      runOpenOcdBlock = pkgs.writeShellScriptBin "run-openocd-block" ''
          openocd -f openocd/openocd.cfg
      '';

      openocdFlash = pkgs.writeShellScriptBin "openocd-flash" ''
          openocd -f openocd/openocd.cfg -f openocd/main.cfg
      '';

      publishMqtt = pkgs.writeShellScriptBin "publish-mqtt" ''
          mosquitto_pub -h localhost -t $1 -m "$2" -d
      '';

      openOCDFlashCustomised = pkgs.writeShellScriptBin "openocd-flash-customised" ''
        python3 flash.py $@
        openocd -f openocd/openocd.cfg \
                -c "init 
                    reset init 
                    halt 
                    stm32h7x mass_erase 1 
                    flash write_image erase target/thumbv7em-none-eabihf/release/humpback-dds 
                    flash write_image flash_config.bin 0x081e0000 bin 
                    reset run 
                    shutdown"
      '';

      humpback-dds = rustPlatform.buildRustPackage rec {
        name = "humpback-dds";
        version = "0.0.0";

        src = self;
        cargoLock = { 
          lockFile = ./Cargo.lock;
          outputHashes = {
            "SaiTLS-0.1.0" = "sha256-T3hyASQGZAXGLKfOB3mh33VrvRlYSMc1CJdX4XvDFrQ=";
            "rsa-0.3.0" = "sha256-9X2kDAOu0HG94HhwYoUtX/ezq99w7u95XMzn3h/JUwk=";
            "minimq-0.1.0" = "sha256-yPqMAwyusZZW7571Jn3QVYK2jqmuSMNU6LiZXRYAGGM=";
            "smoltcp-0.6.0" = "sha256-BCqcphWF3AotQfuIFYhDiWIMhh2eUCuqD4MPz4dASQ4=";
          };
        };

        nativeBuildInputs = [
          pkgs.llvm
          pkgs.yosys
          pkgs.nextpnr
          pkgs.icestorm
          (pkgs.python3.withPackages(ps: [ migen ]))
        ];

        buildPhase = ''
          cargo build --release --bin humpback-dds
        '';

        installPhase = ''
          mkdir -p $out $out/nix-support
          cp target/thumbv7em-none-eabihf/release/humpback-dds $out/humpback-dds.elf
          echo file binary-dist $out/humpback-dds.elf >> $out/nix-support/hydra-build-products
          llvm-objcopy -O binary target/thumbv7em-none-eabihf/release/humpback-dds $out/humpback-dds.bin
          echo file binary-dist $out/humpback-dds.bin >> $out/nix-support/hydra-build-products
        '';

        doCheck = false;
        dontFixup = true;
      };
    in {
      packages.x86_64-linux = {
        inherit humpback-dds;
      };

      hydraJobs = {
        inherit humpback-dds;
      };

      devShell.x86_64-linux = pkgs.mkShell {
        name = "humpback-dds-dev-shell";
        buildInputs = with pkgs; [
          rustPlatform.rust.rustc
          rustPlatform.rust.cargo
          openocd dfu-util
          yosys nextpnr icestorm
          gdb mosquitto
          itm runOpenOcdBlock
          openocdFlash publishMqtt
          openOCDFlashCustomised
          ] ++ (with python3Packages; [
            numpy matplotlib migen
          ]);
      };
      defaultPackage.x86_64-linux = humpback-dds;
    };
}