anchor.diff:      crcmod
     ];
   
  -  postPatch = ''
  -    substituteInPlace software/setup.py \
  -      --replace 'versioneer.get_version()' '"${realVersion}"'
  -  '';
  -
     preBuild = ''
       make -C firmware LIBFX2=${fx2}/share/libfx2
       cp firmware/glasgow.ihex software/glasgow
       cd software
  +    export SETUPTOOLS_SCM_PRETEND_VERSION="${realVersion}"
     '';
   
     # a couple failing tests and also installCheck tries to build_ext again
  
positive.code: 
  buildPythonPackage rec {
    pname = "glasgow";
    version = "unstable-2019-08-31";
    realVersion = lib.substring 0 7 src.rev;
  
    src = fetchFromGitHub {
      owner = "GlasgowEmbedded";
      repo = "Glasgow";
      rev = "21641a13c6a0daaf8618aff3c5bfffcb26ef6cca";
      sha256 = "1dpm1jmm4fg8xf17s6h9g5sc09gq8b6xq955sv2x11nrbqf98l4v";
    };
  
    nativeBuildInputs = [ sdcc ];
  
    propagatedBuildInputs = [
      nmigen
      fx2
      libusb1
  
negative.code: { lib
  , buildPythonPackage
  , fetchFromGitHub
  , setuptools
  , setuptools_scm
  , sdcc
  , nmigen
  , fx2
  