Description

Bitwise Operations
Matthew Musselman, Mudit Gupta, Ammar Ratnani, David Burns
Contents
1 Objective 2
1.1 Purpose 2
1.2 Tasks 2
1.3 Criteria 2
2 Instructions 2
3 How to run the auto-grader & verifier 3
3.1 Commands 3
4 Rubric 4
5 Deliverables 4
6 Hints 4
6.1 Printing numbers in different bases 4
6.1.1 Example 4
6.2 Multiplication and division 5
7 Rules and Regulations 5
7.1 General Rules 5
7.2 Submission Conventions 5
7.3 Submission Guidelines 5
7.4 Syllabus Excerpt on Academic Misconduct 6
7.5 Is collaboration allowed? 6

1 Objective
1.1 Purpose
The goal of this assignment is for you to understand bitwise operators, and how to use them to manipulate data (including integers and ASCII codes for characters) programmatically. For this assignment you will be programming in Java, because you already know this language. The concepts of bitwise operations that you learn here will be used throughout the remainder of this course, including in machine language, assembly language, and C programs.
1.2 Tasks
You will complete the Java methods in the provided files: Bases.java, Operations.java, and BitVector.java. The comments in the provided starter code describe what each method should accomplish. Please note the restrictions on which operators you are allowed to use, and which ones are prohibited for this assignment.
Please read the rest of this document for more detailed instructions and hints.
1.3 Criteria
Your grade is based on: 1) the correct output from your methods; 2) not using any banned operators; and 3) not hardcoding a literal result from a method, or any other such workaround. The grade you see on gradescope will generally be the grade you receive.
2 Instructions
1. Make sure all 4 files are in the same folder:
(a) Bases.java
(b) Operations.java
(c) BitVector.java
(d) hw1checker.jar
3. Alternatively, you can use the Docker container to test your code. To do this, either run ./cs2110docker.sh and open the terminal inside the graphical client, or run ./cs2110docker.sh -it to open a shell directly in your terminal. Don’t forget to put your homework files/folders in the same directory as cs2110docker.sh.
4. Run the following command to see your grade for BitVector.java:
java -jar hw1checker.jar -g BitVector.java
5. It should show all the test cases you are failing and give a 0/40 score.
6. Implement one of the functions in BitVector.java and re-run step 3 until you get full credit for that part of BitVector.java.
Now complete all the other methods in each of the 3 Java files (the details on how to implement each method is described in the comment above the corresponding method). Run the verifier and autograder frequently to avoid errors and to make sure you are using only the allowed operations.
3 How to run the auto-grader & verifier
1. Make sure that the hw1checker.jar file is in the same folder as your Bases.java, BitVector.java, and Operations.java files.
2. Navigate to this folder in your command line.
3. Run the desired command (see below).
3.1 Commands
Test all methods and verify that no banned operations are being used (all 3 files):
java -jar hw1checker.jar
Note: Your grade will be dependent on the output of the above command, as it will both test the output of your methods, and verify that you are not using banned operations. If you get stuck though, you can use some of the below commands to help you debug.
On Windows and Mac, you can also double click the hw1checker.jar in your file explorer to test and verify all 3 files. The results will be placed in a new file called gradeLog.txt. Any errors with compilation, infinite loops, or other runtime errors will be placed in a new file called errorLog.txt.
Test & verify all methods in a single file (using Bases.java). Useful for when you just want to look at one file at a time. For example:
java -jar hw1checker.jar -g Bases.java
Test all methods in a single file without running verifier (using Bases.java). This means that this will only run the unit tests, and will not check for the use of banned operations. Useful for when you just want to try and get something that works. For example:
java -jar hw1checker.jar -t Bases.java
Verify all methods in a single file without running tests (using Bases.java for example):
java -jar hw1checker.jar -v Bases.java
Any combination of files can also be graded, tested, or verified at the same time. For instance, Bases and Operations can be graded simultaneously as follows:
java -jar hw1checker.jar -g Bases.java Operations.java
4 Rubric
The grade the autograder gives you should be the same as the grade you get (unless you intentionally hardcode just the solutions or try to hack the autograder).
5 Deliverables
Please upload the following 3 files to the “Homework 1” assignment on Gradescope:
1. Bases.java
2. Operations.java
3. BitVector.java
6 Hints
6.1 Printing numbers in different bases
Remember that all numbers are stored in your computer as binary. When you perform operations such as System.out.println(), the computer does the translation into another base for you. All you need to do is tell the computer how you are representing your numbers, and how to interpret them.
For example, you can specify 16 in decimal, octal, or hexadecimal like so:
System.out.println(16); // decimal (base 10), the default
System.out.println(020); // octal (base 8), precede the number with a zero
System.out.println(0x10); // hexadecimal (base 16), precede the number with a “0x” (zero x)
You can also tell Java to print out your number in different bases using a method called printf. printf is the GRANDDADDY of all printing functions! When we get to C programming, you will be using it a lot. It is useful if you would like to write your own tester as well.
printf takes a variable number of arguments, the first of which is a format string. After the format string come the parameters. The formatting for the numbers is controlled by the format string.
6.1.1 Example
System.out.printf(“In decimal: %d”, 16); System.out.printf(“In octal: %o”, 16);
System.out.printf(“In hexadecimal: %x”, 16);
The %d, %o, or %x get replaced by the parameter passed in. printf does not support printing the number out in binary.
For more information about printf read http://en.wikipedia.org/wiki/Printf.
6.2 Multiplication and division
7 Rules and Regulations
7.1 General Rules
3. Please read the assignment in its entirety before asking questions.
5. If you find any problems with the assignment it would be greatly appreciated if you reported them to the author (which can be found at the top of the assignment). Announcements will be posted if the assignment changes.
7.2 Submission Conventions
1. All files you submit for assignments in this course should have your name at the top of the file as a comment for any source code file, and somewhere in the file, near the top, for other files unless otherwise noted.
2. When preparing your submission you should submit all three files you edited to Gradescope (either individually or in a zip archive). You can create an archive by right clicking on files and selecting the appropriate compress option on your system. Both ways (uploading raw files or an archive) are exactly equivalent, so choose whichever is most convenient for you.
3. Do not submit compiled files, that is .class files for Java code and .o files for C code. Only submit the files we ask for in the assignment.
4. Do not submit links to files. The autograder does not understand it, and we will not manually grade assignments submitted this way as it is easy to change the files after the submission period ends.
7.3 Submission Guidelines
2. You are also responsible for ensuring that what you turned in is what you meant to turn in. After submitting you should be sure to download your submission into a brand new folder and test if it works. No excuses if you submit the wrong files, what you turn in is what we grade. In addition, your assignment must be turned in via Canvas/Gradescope. Under no circumstances whatsoever we will accept any email submission of an assignment. Note: if you were granted an extension you will still turn in the assignment over Canvas/Gradescope.
7.4 Syllabus Excerpt on Academic Misconduct
Academic misconduct is taken very seriously in this class. Quizzes, timed labs and the final examination are individual work.
Homework assignments are partially collaborative, but collaboration is limited to high-level discussion (see next section). In addition many if not all homework assignments will be evaluated via demo or code review. During this evaluation, you will be expected to be able to explain every aspect of your submission. Homework assignments will also be examined using computer programs to find evidence of unauthorized collaboration.
You are expressly forbidden to supply a copy of your homework to another student via electronic means. This includes simply e-mailing it to them so they can look at it. If you supply an electronic copy of your homework to another student and they are charged with copying, you will also be charged. This includes storing your code on any site which would allow other parties to obtain your code such as but not limited to public repositories (Github), pastebin, etc. If you would like to use version control, use a private repository on github.gatech.edu
7.5 Is collaboration allowed?

Figure 1: Collaboration rules, explained colorfully