fwi: split into input and solver

All branches compile with several hacks.

garlic/apps/fwi/input.nix

@@ -0,0 +1,40 @@
+{
+  stdenv
+}:
+
+with stdenv.lib;
+
+stdenv.mkDerivation rec {
+  name = "fwi-header";
+
+  src = builtins.fetchGit {
+    url = "https://gitlab.com/srodrb/BSC-FWI.git";
+    ref = "garlic/seq";
+  };
+
+  enableParallelBuilding = false;
+
+  # FIXME: This is an ugly hack.
+  # When using _GNU_SOURCE or any other definition used in features.h, we need
+  # to define them before mcc includes nanos6.h from the command line. So the
+  # only chance is by setting it at the command line with -D. Using the DEFINES
+  # below, reaches the command line of the preprocessing stage with gcc.
+  preConfigure = ''
+    export DEFINES=-D_GNU_SOURCE
+  '';
+  
+  # We compile the ModelGenerator using gcc *only*, as otherwise it will
+  # be compiled with nanos6, which requires access to /sys to determine
+  # hardware capabilities. So it will fail in the nix-build environment,
+  # as there is no /sys mounted.
+  # Also, we need to compile it with the builder platform as target, as is going
+  # to be executed during the build to generate the src/generated_model_params.h
+  # header.
+  makeFlags = [ "COMPILER=GNU" "params" "input" ];
+
+  installPhase = ''
+    mkdir -p $out/
+    cp src/generated_model_params.h $out/
+    cp -r InputModels $out/
+  '';
+}