<'
struct instruction { 
  %opcode     : uint (bits : 3); 
  %operand    : uint (bits : 5); 
  %address    : uint (bits : 8); 
};

extend sys { 
  post_generate() is also { 
    var inst : instruction; 
    var packed_data: list of bit; 
    packed_data = {1;1;1;1;0;0;0;0;1;0;0;1;1;0;0;1}; 
    unpack(packing.high, packed_data, inst); 
    print packed_data using bin;
    out("Unpacking high");
    print inst using bin;
    unpack(packing.low, packed_data, inst); 
    out("Unpacking low");
    print inst using bin;
  }; 
};
'>