classdef MyNewportUsbComm < MySingletone
    
    properties (GetAccess=public, SetAccess=private)
        isbusy = false  % driver in use 
        QueryData       % query buffer
    end
    
    properties (Access=public)
        Usb % Instance of Newport.USBComm.USB class 
    end
    
    methods(Access=private)
        % The constructor of a singletone class should only be invoked from
        % the getInstance method.
        function this = MyNewportUsbComm()
            this.QueryData=System.Text.StringBuilder(64);
            loadLib(this);
        end
    end
    
    methods(Access=public)
        
        % Load dll
        function loadLib(this)
            dll_path = which('UsbDllWrap.dll');
            if isempty(dll_path)
                error(['UsbDllWrap.dll is not found. This library ',...
                    'is a part of Newport USB driver and needs ',...
                    'to be present on Matlab path.'])
            end
            NetAsm=NET.addAssembly(dll_path);
            % Create an instance of Newport.USBComm.USB class
            Type=GetType(NetAsm.AssemblyHandle,'Newport.USBComm.USB');
            this.Usb=System.Activator.CreateInstance(Type);
        end
        
        function str=query(this, addr, cmd)
            this.isbusy=true;
            % Send query using the QueryData buffer
            stat = Query(this.Usb, addr, cmd, this.QueryData);
            if stat==0
                str = char(ToString(this.QueryData));
            else
                str='';
                warning('Query to Newport usb driver was unsuccessful.');
            end
            this.isbusy=false;
        end
    end
   
    methods(Static)
        % Concrete implementation of the singletone constructor.
        function this = instance()
            persistent UniqueInstance

            if isempty(UniqueInstance)||(~isvalid(UniqueInstance))
                this = MyNewportUsbComm();
                UniqueInstance = this;
                disp('creating new instance of NewportUsbComm')
            else
                this = UniqueInstance;
                disp('returning existing instance of NewportUsbComm')
            end
        end
    end
end