Implement time-out mechanism in lower layers

Fixes issue #45.

source/BrickIO.m

@@ -12,6 +12,11 @@
 % - The write function should be given a uint8 datatype as a parameter
 
 classdef BrickIO < handle
+    properties (Abstract)
+        % time-out period (if 0, no time-out)
+        timeOut 
+    end
+    
     properties (Abstract, Access = 'protected')
         % connection handle
         handle

source/btBrickIO.m

@@ -30,6 +30,8 @@ classdef btBrickIO < BrickIO
         debug = 0;
         % bluetooth serial port
         serialPort = '/dev/rfcomm0'
+        % time-out period in seconds (if 0, no time-out)
+        timeOut = 10;
     end
     
     properties (Access = 'protected')
@@ -221,5 +223,17 @@ classdef btBrickIO < BrickIO
                 end
             end
         end
+        
+        function set.timeOut(brickIO, timeOut)
+            if ~isnumeric(timeOut) || timeOut < 0
+                error(ID(), 'timeOut-period of Bluetooth-handle can only be set to positive numerical values.'); 
+            end
+            
+            brickIO.timeOut = timeOut;
+            
+            if timeOut == 0
+               brickIO.handle.Timeout = 9999999; % MATLAB.serial seems to have no option to disable timeout
+            end
+        end 
     end 
 end

source/hidapi.m

@@ -253,8 +253,63 @@ classdef hidapi < handle
             hid.handle = [];
         end
         
+        % @ MMI
+        function rmsg = read_timeout(hid, timeOut)
+            %hidapi.read_timeout Read from hid object with a time-out
+            %
+            % rmsg = hid.read_timeout() reads from a hid device and returns the
+            % read bytes. Will print an error if no data was read during the time-out period.
+            %
+            % Arguments::
+            %  timeOut          time-out period in milliseconds
+            %
+            % Throws::
+            %  CommError        Error during communication with device
+            %  InvalidHandle    Handle to USB-device not valid
+            %
+            
+            if hid.debug > 0
+                fprintf('hidapi read_timeout\n');
+            end
+            
+            % Read buffer of nReadBuffer length
+            buffer = zeros(1,hid.nReadBuffer);
+            % Create a uint8 pointer
+            pbuffer = libpointer('uint8Ptr', uint8(buffer));
+            
+            % Check if pointer is (unexpectedly) already invalidated
+            assert(isLibPointerValid(hid.handle)==1, ...
+                [hid.slib, ':', 'InvalidHandle'], ...
+                'Failed to read USB-data because pointer to USB-device is invalidated.');
+            
+            % Read data from HID device
+            [res,h] = calllib(hid.slib,'hid_read_timeout',hid.handle,pbuffer,uint64(length(buffer)),timeOut);
+            
+            % Check the response (No assert as there are multiple cases)
+            if res < 1
+                % Error occurred
+                id = [hid.slib, ':', 'CommError'];
+                % Narrow error down
+                if res == -1
+                    msg = 'Connection error (probably lost connection to device)';
+                elseif res == 0
+                    msg = ['Could not read data from device (device is still connected, ',...
+                           'but does not react)'];
+                else
+                    msg = 'Unexpected connection error';
+                end
+                causeException = MException(id, msg);
+                ME = MException(id, 'Failed to read data via USB.');
+                addCause(ME, causeException);
+                throw(ME);
+            end
+            
+            % Return the string value
+            rmsg = pbuffer.Value;
+        end
+        
         function rmsg = read(hid)
-            %hidapi.rmsg Read from hid object
+            %hidapi.read Read from hid object
             %
             % rmsg = hid.read() reads from a hid device and returns the
             % read bytes. Will print an error if no data was read.

source/usbBrickIO.m

@@ -28,6 +28,8 @@ classdef usbBrickIO < BrickIO
         nReadBuffer = 1024;
         % write buffer size
         nWriteBuffer = 1024;
+        % time-out period in milliseconds (if 0, no time-out)
+        timeOut = 10000;
     end
     
     properties (Access = 'protected')
@@ -173,7 +175,11 @@ classdef usbBrickIO < BrickIO
             
             % Read from the usb handle
             try
-                rmsg = brickIO.handle.read;
+                if brickIO.timeOut ~= 0
+                    rmsg = brickIO.handle.read_timeout(brickIO.timeOut);
+                else
+                    rmsg = brickIO.handle.read();
+                end
             catch ME
                 if ~isempty(strfind(ME.identifier, 'CommError'))
                     % Throw a clean CommError to avoid confusion in upper layers
@@ -241,5 +247,13 @@ classdef usbBrickIO < BrickIO
                 end
             end
         end
+        
+        function set.timeOut(brickIO, timeOut)
+            if ~isnumeric(timeOut) || timeOut < 0
+                error(ID(), 'timeOut-period of USB-handle can only be set to positive numerical values.'); 
+            end
+            
+            brickIO.timeOut = timeOut*1000;
+        end 
     end 
 end