COMP 2718 Lab 8

Student Name -- Student Number

This lab should be completed by editing and submitting this HTML file and by submitting scripts and output files.

Submit via all materials by D2L by the end of the lab session.

Exercise 1: COMP1710 Assignment Setup

The following shell script creates a directory and initial files for a COMP 1710 assignment.

    #!/bin/bash

    if [[ $# != 2 ]]; then
        echo "usage: setup-1710.sh dir java_file"
        exit 1
    fi
    dir=$1
    java_file=$2

    if [[ ! -e $dir ]] ; then
        mkdir -p $dir
    fi

    java_pathname=$dir/$java_file
    if [[ ! -e $java_pathname ]] ; then
        echo -e "public class $java_file {n}" > $java_pathname
    fi
    if [[ ! -e $dir/README ]] ; then
        echo "$java_file is the java file" > $dir/README
    fi

This script could be called as follows:

    $ ./setup-1710.make assign1 Main.java

1. Create a makefile, called fixed_args.make, that has four targets, one for creating the directory, one for creating the README, and one for creating the main class, and an all target to create everything. Your makefile should perform the same as the above bash script. Define two variables at the beginning, the first called DIR to store assign1 as the directory, the second called JAVA_FILE to store Main.java as the Java file to create.

Submit fixed_args.make.

2. Copy the makefile fixed_args.make to cmdline_args.make. Now remove the lines where DIR and JAVA_FILE are defined. You can now call this makefile from the command line with DIR and JAVA_FILE specified as follows:

    make -f cmdline_args.make DIR=assign1 JAVA_FILE=Main.java

Test that this works (there is nothing to submit for this step).

3. Create a very small script that invokes cmdline_args.make 8 times to generate directories and files for assignments 1 - 8. Main.java can be used for all of the Java files. The directories should be assign1, assign2, ... up to assign8.
   Call this script setup-1710-all.sh.

Exercise 2: Compiling C Programs

The directory arith contains four files: arith.h, gcd.s, lcm.c, and main.c. These files can be used to created an executable program, called arith_pgm. that prints out the Least Common Multiple and Greatest Common Divisors for several pairs of numbers.

1. Give below the individual commands, which can be used to transform the C files into object .o files?

   Change this with your answer

2. The source code for the gcd module is not provided. Instead you have gcd.s which is the assembly code produced from compiling the missing gcd module. You can create an object file from this code by executing as -o gcd.o gcd.s. Execute this command. There is no other action to take here but you should take a look at gcd.s.

3. What command is used to combine all of the .o files into the arith_pgm executable?

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4. What is the output of the arith_pgm program?

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Exercise 3: Makefile for arith

Create a Makefile that creates the arith_pgm executable from the files in the arith directory. Your Makefile should contain rules, that create lcm.o, main.o, gcd.o, and arith_pgm. Provide a clean target to remove all the object files and the executable. Place your makefile in the arith directory, and call it Makefile.

1. Submit your Makefile.

2. What is the output from executing make?

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3. What is the output from executing make clean?

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4. Execute make again to rebuild the executable. Then remove the file lcm.o and execute make.

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5. Explain what happened in the previous step. Why does the output from part 4 differ from the output of part 2?

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