CSCI3120
Assignment 1
Due: 11:59 AM, Tuesay, May 28, 2019
Introduction
The concepts applicable to operating systems are applicable in many other systems as well.
For example, manufacturing, transportation, and bureaucracies. The air transportation
system (planes and airports) is another prime example of a system that embodies many of
the same concepts found in modern operating systems. If your flight has ever been delayed,
canceled, or rescheduled, it was probably due as a result of the same decisions that are made
by the OS on your computer.
The purpose of this assignment is
1. To refresh your coding abilities in C, and your programming skills in general.
2. To review using and implementing queues and priority queues, which are at the heart
of every operating system
3. To serve as an example of the difficulty, style, and format of assignments that you can
expect in this course.
4. To practice reading and implementing nontrivial specifications. This assignment is as
much about reading and understanding this document, as it is about programming.
In this assignment you will implement a simple air transportation system simulator.
System Requirements

CSCI3120作业代做、代写operating systems作业、代做C++程序语言作业
This assignment is intended to be done and executed in a Unix environment. You can use
the csci3120.cs.dal.ca Unix server, a Mac (in Terminal), or your own Unix-based system,
such as Linux, OpenBSD, FreeBSD, etc. This may also work in the Cygwin environment
under Windows. Note: Your code will be tested on csci3120.cs.dal.ca.
Background
Scheduling flights is a challenging prospect. There are 100,000 flights per day among more
than 17,000 airports. A good schedule minimizes the risk of delayed flights and the amount of
time planes are sitting useless on the ground. A simulation of the air transportation system
with a given schedule can be used to assess the delay and aircraft utilization by simulating
all the scheduled flights.
In its basic form our air transport system comprises airports and planes that fly between
airports, ferrying passengers. A flight consists of a plane that
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CSCI3120 Summer 2019 Assignment 1
1. departs from a gate at a specific airport and a scheduled time;
2. waits for permission to take off;
3. takes off;
4. flies to its destination;
5. waits for permission to land;
6. lands; and
7. taxis to the gate
The amount of time the plane spends flying depends on the distance between the airports and
weather conditions; the amount of time waiting for permission to take-off or land depends
on how busy the airport is; the amount of taxiing between the runways and gates depends
on the size of the airport. A schedule needs to take all these things into account.
A flight is denoted by
Carrier Code: a two letter designator for the airline, e.g., AC for Air Canada
Flight Number: a positive integer denoting the flight number, e.g., 612
Origin: the three letter IATA airport code where the flight commences, e.g.,
YHZ for Halifax International Airport
Departure Time: scheduled time for departing from the gate in the 24-hour
format hh:mm, e.g., 15:35, means a departure time of 3:35pm.
Expected Flight Time: amount of time (in minutes) spent flying from take-off
to landing, e.g., 120
Destination: the three letter IATA airport code where the flight terminates,
e.g., YYZ for Toronto International Airport
A flight schedule consists of 1 or more flights.
A basic simulation of a flight schedule simulates each minute of a single day. In each
minute one of the following events can occur in each of the scheduled flights:
1. A flight may depart from the gate at its origin
2. A flight may take off
3. A flight may arrive at its destination
4. A flight may land
5. A flight may arrive at the gate of its destination
The flight terminates when it arrives at the gate of its destination.
One of the primary causes of delays is when multiple flights compete for the same resource,
specifically. the runway. Only one flight may take off or land on the same runway per minute.
Thus, if multiple flights are ready to take-off from the same runway at the same time, they
will need to wait their turn for the use of the runway. Similarly, if multiple planes arrive at
the same time, they will need to wait in a holding pattern for their turn to land on the same
runway. If planes are waiting to take off and land on the same runway, planes take turns
landing and taking off, i.e. plane A lands, plane B takes off, plane C lands, etc.
Once a flight terminates, the number of minutes that it was delayed can be computed.
Once all flights have terminated, the simulation completes.
Your task will be to implement an air traffic simulator called atsim.
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CSCI3120 Summer 2019 Assignment 1
Simulator Input
Input is read in from the console (stdin). The input consists of one or more lines of text.
Each line of text, except the last one represents a scheduled flight. Each flight has the
following form:
C N P O H:M T D
where
C is the carrier code, e.g., AC
N is the flight number, e.g., 612
P is the plane ID, a positive integer for future assignments, e.g., 42
O is the origin, denoted by the three letter IATA airport code, e.g., YHZ
H : M is the departure time in the 24 hour format, e.g., 15:35
T is the flight time (in minutes), e.g., 120
D is the destination, denoted by a three letter IATA airport code , e.g., YYZ
For example,
AC 621 42 YHZ 15:35 120 YYZ
The last line of the input is a single word “end” that denotes the end of the schedule. There
are many examples in the test suite that is included as part of this assignment.
Processing and Semantics
There will be no more than 1000 flights. All flights are guaranteed to terminate on the
same day, so there is no need to worry about the time wrapping around.
A flight takes 10 minutes to taxi from the gate to the runway and to taxi from the
runway to the gate after it has landed. So, a flight that takes 60 minutes of flight time
and is not delayed will take a total of 80 minutes gate to gate.
Each airport is has its own runway. The runway can handle one flight per minute,
either landing or taking off.
Flights that are waiting to takeoff at the the same airport are processed in first-come-
first-served order. If two or more flights request to take-off at the same time (in the
same minute), the flight with the lowest flight number has priority. I.e., ties are broken
by the flight number.
Flights that are waiting to land at the same airport are also processed in first-come-
first-served order. If two or more flights request to land at the same time, the flight
with the lowest flight number has priority.
If flights are waiting to both take-off and land at the same airport, then priority
alternates between take-off and landing. For example, if the most recent runway event
was a take-off, then a landing flight is given priority.
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CSCI3120 Summer 2019 Assignment 1
A plane’s flight time begins at take-off and ends at landing.
The delay of a flight is
delay = arrival time ? departure time ? flight time ? 20
where the 20 minutes is the time it takes to taxi to and from the runway.
Expected Output
All output must be performed to the console (stdout). The output consists of flight records,
one per flight per line. The flight record has the format:
[h:m] C N from O to D, departed H:M, delay d.
where C, N, O, D, H, and M are as defined in the Input section; and where h : m is the
arrival time in the 24 hour format, e.g., 17:55; and d is the delay (in minutes), e.g., 0.
The flight records should be sorted in chronological order of arrival time, with tie breakers
broken by the lexical order of the carrier code and then the flight number. e.g.,
[02:31] AC 308 from YUL to YYZ, departed 01:03, delay 0.
[02:32] AT 179 from YVR to YXE, departed 00:22, delay 0.
[02:32] CP 601 from YYC to YVR, departed 00:49, delay 0.
[02:33] AT 875 from YOW to YYZ, departed 01:15, delay 2.
Nonfunctional Requirements
Please download the starting code found in the tarball assn1.tar.gz, which can be
found on Brightspace.
You must use the provided makefile to build your simulator simply by running make.
You may extend the makefile as needed. Note: The marker will use this makefile
to build your assignment.
Included in the tarball is the runme.sh shell script. If you implement this assignment
in Java, you will need to modify this shell script to run your Java program instead of
the executable.
Test Your Code!
To test your code the tarball includes a test suite, which will run on the csci3120.cs.dal.ca
Unix server (it will also run on other Linux and Mac systems as well). Please see the
README.txt file in the tarball for details. The test suite works by comparing the output
of your simulator to what is expected. The included test.sh script uses the runme.sh
script to invoke your implementation and compare it against the expected results. Ideally,
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CSCI3120 Summer 2019 Assignment 1
there should be no differences. If there are differences, then either your implementation,
or the solution has a bug. For example, if your program fails a test 13, the input is found
in test.13.in, the expected output is found in test.13.gold, and the output from your
program is found in test.13.out. Thus, you can effectively test your implementation.
Note: We will be using similar tests to evaluate your assignment.
Hints and Suggestions
1. Your program will rely on queues and/or priority queues. You should implement a
general purpose queue and/or a general purpose priority queue that you will use in
your program. Note: the solution just uses a priority queue implementation, which
when used with a fixed priority behaves as a queue.
2. Use an airport struct to represent an airport. Your airport struct will need to contain a
few different queues/priority queues to keep track of planes that are waiting to depart,
waiting to take-off, are en route, and waiting to land. You will need to create new a
airport each time you read in a flight that originates or terminates at a new airport.
3. Your main program should consists of two loops. The first loop reads in all the flights.
The second loop simulates each minute of the air traffic system.
4. A starting point for your main program atsim.c is provided.
5. Start early, the solution totals less than 350 lines of code (100 for the priority queue
and 250 for the rest). If you are not comfortable with C, it may take you a bit longer.
The Java Option
You may choose to implement this assignment in Java rather than C. However, there are
two penalties for using Java. First, there is a 10 point penalty. I.e., Your grade on the
assignment is reduced by 10 points. Second, the solution for Assignment 1, which is also the
starting point for Assignment 2, is only provided in C. So, you will need to rely on your Java
solution to Assignment 1 as a starting point for Assignment 2 if you decide to implement
Assignment 2 in Java. The amount of code needed for the Java version is under 250 lines of
code because the JDK already has a priority queue implementation, ready to go.
To use Java instead of C, you need to
1. Create a class called ATSim.java where the main program starts running.
2. Modify the runme.sh script to invoke your Java program instead of the C executable.
What to Hand In
You need only submit an electronic of your assignment. Submission must be done by 11:59
AM of the due date. Submission is done via Brightspace.
The assignment submission should be a single zip file (.zip) comprising the source code
files that implement the simulator as well as the makefile and the runme.sh file.
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CSCI3120 Summer 2019 Assignment 1
Programming Guidelines
1. The program must read the input from the console (stdin) and must print out the
results to the console (stdout) unless otherwise specified. Do not print out any output
or request any input other than what is specified by the assignment.
2. Use the file and function names specified in the assignment.
3. Your programs will be compiled and tested on the csci3120.cs.dal.ca Unix server.
In order to receive credit, your programs must compile and run on this server.
4. Your program must compile. Programs that do not compile will receive a 0.
5. The programs must be well commented, properly indented, and clearly written. Please
see the style guidelines under Assignments or Resources on the course website.
Grading Scheme
The assignment will be graded based on three criteria:
Functionality “Does it work according to specifications?”. This is determined in an automated
fashion by running your program on a number of inputs and ensuring that the
outputs match the expected outputs. The score is determined based on the number
of tests that your program passes. So, if your program passes t
T
tests, you will receive
that proportion of the marks.
Quality of Solution “Is it a good solution?” This considers whether the solution is correct,
efficient, covers boundary conditions, does not have any obvious bugs, etc. This is
determined by visual inspection of the code. Initially full marks are given to each
solution and marks are deducted based on faults found in the solution.
Code Clarity “Is it well written?” This considers whether the solution is properly formatted,
well documented, and follows coding style guidelines.
If your program does not compile, it is considered non-functional and of extremely poor
quality, meaning you will receive 0 for the solution.
Mark
Code Quality (Priority Queue) /10
Code Quality (Simulator) /10
Functionality (automated tests) /20
Code Clarity /10
Total /100

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