Week 06 Weekly Test Questions

Test Conditions

These questions must be completed under self-administered exam-like conditions. You must time the test yourself and ensure you comply with the conditions below.

You may complete this test in CSE labs or elsewhere using your own machine.
You may complete this test at any time before Wednesday 01 January 00:00.
The maximum time allowed for this test is 1 hour + 5 minutes reading time.
You may first use 5 minutes to read the questions (no typing).
You must then complete the test within 1 hour and submit your answers with give.
You must complete the questions alone: you can not get help in any way from any person.
You can not access your previous answers to lab or tut questions.
You can not access web pages or use the internet in any way.
You can not access books, notes or other written or online materials.
You can not access your own files, programs, code ...
You can not access COMP1521 course materials, except for language documentation linked below.

You may access this language documentation while attempting this test:

C quick reference

You may also access manual entries (the man command).

Any violation of the test conditions will results in a mark of zero for the entire weekly test component.

Set up for the test by creating a new directory called test06, changing to this directory, and fetching the provided code by running these commands:

mkdir test06
cd test06
1521 fetch test06

Or, if you're not working on CSE, you can download the provided code as a zip file or a tar file.

weekly test question:
MIPS Are Not Negative

You have been given not_negative.s, a MIPS assembler program that reads a numbers and then prints it.

1521 spim -f not_negative.s
Loaded: /home/cs1521/share/spim/exceptions.s
Enter a number: 42
You entered: 42

Add code to not_negative.s to make it equivalent to this C program:

// read numbers until a non-negative number entered
#include <stdio.h>

int main(void) {
    int x;

    while (1) {
        printf("Enter a number: ");

        scanf("%d", &x);

        if (x < 0) {
            printf("Enter a positive number\n");
        } else {
            printf("You entered: %d\n", x);
            break;
        }
    }

    return 0;
}

In other words it should read numbers until a non-negative number is entered,

For example:

1521 spim -f not_negative.s
Enter a number: -5
Enter a positive number
Enter a number: -1
Enter a positive number
Enter a number: 24
You entered: 24
1521 spim -f not_negative.s
Loaded: /home/cs1521/share/spim/exceptions.s
Enter a number: -1
Enter a positive number
Enter a number: -2
Enter a positive number
Enter a number: -3
Enter a positive number
Enter a number: -4
Enter a positive number
Enter a number: -5
Enter a positive number
Enter a number: 0
You entered: 0
1521 spim -f not_negative.s
Loaded: /home/cs1521/share/spim/exceptions.s
Enter a number: 100
You entered: 100

When you think your program is working you can autotest to run some simple automated tests:

1521 autotest not_negative

When you are finished working on this exercise you must submit your work by running give:

give cs1521 test06_not_negative not_negative.s

weekly test question:
Reversed MIPS

You have been given reverse_negative.s, a MIPS assembler program that reads numbers into an array.

Add code to reverse_negative.s to make it equivalent to this C program:

// Read numbers into an array until a negative number is entered
// then print the numbers in reverse order

#include <stdio.h>

int numbers[1000];

int main(void) {
    int i = 0;
    while (i < 1000) {
        int x;
        scanf("%d", &x);
        if (x < 0) {
            break;
        } else {
            numbers[i] = x;
        }
        i++;
    }

    while (i > 0) {
        i--;
        printf("%d\n", numbers[i]);
    }
}

In other words make it stop when a negative number is read and then print the numbers readin reverse order.

For example:

1521 spim -f reverse_negative.s
Loaded: /home/cs1521/share/spim/exceptions.s
1
2
3
4
-1
4
3
2
1
1521 spim -f reverse_negative.s
Loaded: /home/cs1521/share/spim/exceptions.s
15
4
1
42
-3
42
1
4
15

When you think your program is working you can autotest to run some simple automated tests:

1521 autotest reverse_negative

When you are finished working on this exercise you must submit your work by running give:

give cs1521 test06_reverse_negative reverse_negative.s

weekly test question:
Different MIPS

You have been given different10.s, a MIPS assembler program that reads 10 numbers into an array. Add code to different10.s to make it equivalent to this C program:

#include <stdio.h>

int numbers[10];

int main(void) {
    int x, i, n_seen;

    n_seen = 0;
    while (n_seen < 10) {
        printf("Enter number: ");
        scanf("%d", &x);

        i = 0;
        while (i < n_seen) {
            if (x == numbers[i]) {
                break;
            }
            i++;
        }

        if (i == n_seen) {
            numbers[n_seen] = x;
            n_seen++;
        }
    }
    printf("10th different number was %d\n", x);

    return 0;
}

In other words make it stop when 10 different numbers have been read and print a message including

For example:

1521 spim -f different10.s
Loaded: /home/cs1521/share/spim/exceptions.s
Enter a number: 11
Enter a number: 12
Enter a number: 13
Enter a number: 14
Enter a number: 15
Enter a number: 16
Enter a number: 17
Enter a number: 18
Enter a number: 19
Enter a number: 20
10th different number was: 20
1521 spim -f different10.s
Loaded: /home/cs1521/share/spim/exceptions.s
Enter a number: 11
Enter a number: 11
Enter a number: 12
Enter a number: 11
Enter a number: 13
Enter a number: 14
Enter a number: 13
Enter a number: 14
Enter a number: 15
Enter a number: 16
Enter a number: 29
Enter a number: 19
Enter a number: 18
Enter a number: 55
10th different number was: 55

When you think your program is working you can autotest to run some simple automated tests:

1521 autotest different10

When you are finished working on this exercise you must submit your work by running give:

give cs1521 test06_different10 different10.s

Submission

When you are finished each exercise make sure you submit your work by running give.

You can run give multiple times. Only your last submission will be marked.

Don't submit any exercises you haven't attempted.

If you are working at home, you may find it more convenient to upload your work via give's web interface.

Remember you have until Wednesday 01 January 00:00 to complete this test.

Automarking will be run by the lecturer several days after the submission deadline for the test, using test cases that you haven't seen: different to the test cases autotest runs for you.

(Hint: do your own testing as well as running autotest)

Test Marks

After automarking is run by the lecturer you can view it here the resulting mark will also be available via via give's web interface or by running this command on a CSE machine:

1521 classrun -sturec

The test exercises for each week are worth in total 1 marks.

The best 6 of your 8 test marks for weeks 3-10 will be summed to give you a mark out of 9.