let FESA = {};

function MakeItemRequest(h, item, fullpath, option) {
   return { req: "dabc.bin", kind: "bin" }; // use binary request to receive data
}

function AfterItemRequest(h, item, data, option) {
   if (!data) return null;

   var hist = JSROOT.createHistogram("TH2I", 16, 16);
   hist.fName  = "BeamProfile";
   hist.fTitle = "Beam profile from FESA";
   hist.fOption = "col";

   if ((data==null) || (data.length != 16*16*4)) {
      alert("no proper data for beam profile");
      return false;
   }

   var o = 0;

   function ntou4() {
      // convert (read) 4 bytes into uint32_t
      var n  = (data.charCodeAt(o)  & 0xff);
      n += (data.charCodeAt(o+1) & 0xff) << 8;
      n += (data.charCodeAt(o+2) & 0xff) << 16;
      n += (data.charCodeAt(o+3) & 0xff) << 24;
      return n;
   }

   for (var iy=0;iy<16;iy++)
      for (var ix=0;ix<16;ix++) {
         var value = ntou4(); o+=4;
         var bin = hist.getBin(ix+1, iy+1);
         hist.setBinContent(bin, value);
      }

   return hist;
}

JSROOT.addDrawFunc({
   name: "kind:FESA.2D",
   make_request: MakeItemRequest,
   after_request: AfterItemRequest,
   icon: "img_histo2d",
   opt: "col;colz"
});

globalThis.FESA = FESA;