/*
RESCUE ROBOTICS WORKSHOP
ReadFromFile

                           Introduction to File IO
                                 Ron Kessler
                              Created 8/17/2018

Updated: 8/17/2018
				Did final compile/test. Reads one byte of data from the NXT File (test.txt).


PURPOSE: While the datalogger is good for real time sensor testing, you may need to
				save data in your own format. This project shows how to read a file
				on the robot and save a short integer (16 bits) to that file.

				Use the companion project called Save2File to store one piece of data.


SETUP: 	Be sure to run the Save2File.c program before running this one. Your NXT screen
				will show you if the actions were sucessful or not and display your saved values.

				We will start by defining the file to read and the usual variables.
*/


task main()
{
	//STEP 1: Define the stuff we need to access this file
	TFileHandle   fileNumber;								//internal number used to locate the file.
  TFileIOResult IOException;							//tells us if there is an error during the IO
  string        myFileName = "test.txt";	//my file name.
  int           fileSize = 100;						//same as when we saved 2 file

	//STEP 2: Tell the robot to open our file so we can read from it. Send it the 4 arguments in ().
  OpenRead(fileNumber, IOException, myFileName, fileSize);

  //---STEP 3: Create a variable to grab our data. It is a short integer (16bits or 2 bytes)
  short lineFromFile = 0;

  //---STEP 4: Now actually read the line of data and store it in the 'lineFromFile' variable.
  ReadShort(fileNumber, IOException, lineFromFile);


  //---STEP 5: ALWAYS CLOSE THE FILE
  Close(fileNumber, IOException);


  //---STEP 6: Display the data value on the NXT display. the %d or %i formats it as a number.
  nxtDisplayCenteredTextLine(1, "Rescue Robotics");
  nxtDisplayCenteredTextLine(2, "Reading data");
  nxtDisplayTextLine(5, "Your data = %d", lineFromFile);

  //---keep it on screen for 5 seconds so we can view it
	wait1Msec(5000);
}