Updated comedi.c with comments.

src/Computer/comedi/comedi.c

@@ -11,47 +11,64 @@ comedi_t *device;
 comedi_range * range_info;
 lsampl_t maxdata;
 
+// Send physical value from computer to process:
 int comedi_write(int comediNbr, int subdev, int chan, double physical_value) {
 	static int comedi_value;
 	static int retval;
+	// Convert physical value to comedi value:
 	range_info = comedi_get_range(device, subdev, chan, range);
 	maxdata = comedi_get_maxdata(device, subdev, chan);
 	comedi_value = comedi_from_phys(physical_value, range_info, maxdata);
+	// Send the converted value to device:
 	retval = comedi_data_write(device, subdev, chan, range, aref, comedi_value);
     return retval;
 }
 
+// Get physical value from process to computer:
 double comedi_read(int comediNbr, int subdev, int chan) {
 	static double physical_value;
 	lsampl_t comedi_value;
+	// Get comedi value:
 	comedi_data_read(device, subdev, chan, range, aref, &comedi_value);
+	// Convert comedi value to physical value:
 	range_info = comedi_get_range(device, subdev, chan, range);
 	maxdata = comedi_get_maxdata(device, subdev, chan);
 	physical_value = comedi_to_phys(comedi_value, range_info, maxdata);
+	// Return the converted value:
 	return physical_value;
 }
 
 // comedi_path example: "/dev/comedi0"
 int comedi_start(char* comedi_name) {
+    // Check for connection:
 	device = comedi_open(comedi_name);
 		if(device == NULL)
 	{
 		comedi_perror("comedi_open_error");
 		return -1;
 	}
+	// Set out-of-range behavior. This affects the behavior of comedi_to_phys 
+	// when converting endpoint sample values, that is, sample values equal to 
+	// 0 or maxdata. With COMEDI_OOR_NUMBER, the endpoint values
+	// are converted similarly to other values.
 	comedi_set_global_oor_behavior(COMEDI_OOR_NUMBER);
 	return 0;
 }
 
+// Send physical value zero from computer to process. This might, for instance,
+// be useful prior to closing the connection with the process.
 void comedi_write_zero(int comediNbr, int subdev, int chan) {
-	static double physical_value_zero = 0.0;
+	static double physical_value_zero = 0.0; // Physical value zero to send.
 	static lsampl_t comedi_value;
+	// Convert physical value zero to comedi value:
 	range_info = comedi_get_range(device, subdev, chan, range);
 	maxdata = comedi_get_maxdata(device, subdev, chan);
 	comedi_value = comedi_from_phys(physical_value_zero, range_info, maxdata);
+	// Send converted value to process.
 	comedi_data_write(device, subdev, chan, range, aref, comedi_value);
 }
 
+// Shut down communication between computer and process.
 void comedi_stop(int comediNbr) {
 	comedi_close(device);
 }