Week 12 Laboratory Exercises

In the files for this lab, you have been given factorial.s. Add code to the factorial function to make it equivalent to this C program:

// Recursive factorial function
// n < 1 yields n! = 1

#include <stdio.h>

int factorial(int);

int main(void) {
    int n = 0;
    printf("Enter n: ");
    scanf("%d", &n);
    int f = factorial(n);
    printf("%d! = %d\n", n, f);
    return 0;
}

int factorial(int n) {
    int result;
    if (n > 1) {
        result = n * factorial(n - 1);
    } else {
        result = 1;
    }
    return result;
}

For example:

1092 mipsy factorial.s
Enter n: 5
5! = 120
1092 mipsy factorial.s
Enter n: 7
7! = 5040
1092 mipsy factorial.s
Enter n: 1
1! = 1

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

1092 autotest factorial 

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

give dp1092 lab12_factorial factorial.s

You must run give before Tuesday 19 November 09:00 (2024-11-19 09:00:00) to obtain the marks for this lab exercise. Note that this is an individual exercise, the work you submit with give must be entirely your own.

Your task is to add code to this function in add.c:

// return the MIPS opcode for add $d, $s, $t
uint32_t make_add(uint32_t d, uint32_t s, uint32_t t) {

    return 42; // REPLACE WITH YOUR CODE

}

The function make_add is given the operands for a MIPS add instruction . Add code so that it returns the opcode for that instruction. Reminder the bit pattern for MIPS add instruction is:

This is how your code should behave

./add 17 19 3
make_add(17, 19, 3) returned  0x02638820
./add 9 27 12
make_add(9, 27, 12) returned 0x036c4820

Use make(1) to build your code:

make    # or 'make add'

Assumptions/Limitations/Clarifications

• You may define and call your own functions if you wish.

• You are not permitted to change the main function you have been given, or to change add' prototype (its return type and argument types).

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

1092 autotest add 

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

give dp1092 lab12_add add.c

You must run give before Tuesday 19 November 09:00 (2024-11-19 09:00:00) to obtain the marks for this lab exercise. Note that this is an individual exercise, the work you submit with give must be entirely your own.

Write a C program, are_bytes_equal.c, which takes four (4) command-line argument: a pair of filenamess and positions:

1. filename 1
2. position 1
3. filename 2
4. position 2

Your program should compare the byte at first position in the first file with the byte at second position in the second file.

Your program should then print a message saying if the two bytes are or are not equal.

If either position is past the end of the corresponding file then the bytes are not equal

dcc are_bytes_equal.c -o are_bytes_equal
./are_bytes_equal data1.txt 0 data2.txt 0
byte 0 in data1.txt and byte 0 in data2.txt are the same
./are_bytes_equal data1.txt 0 data2.txt 33
byte 0 in data1.txt and byte 33 in data2.txt are not the same
./are_bytes_equal data1.txt 454 data2.txt 454
byte 454 in data1.txt and byte 454 in data2.txt are not the same
./are_bytes_equal data1.txt 454 data3.txt 454
byte 454 in data1.txt and byte 454 in data3.txt are the same

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

1092 autotest are_bytes_equal 

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

give dp1092 lab12_are_bytes_equal are_bytes_equal.c

You must run give before Tuesday 19 November 09:00 (2024-11-19 09:00:00) to obtain the marks for this lab exercise. Note that this is an individual exercise, the work you submit with give must be entirely your own.

Write a C program, is_directory.c, which takes one argument a pathname.

If the pathname exists and is a directory, it should print 1, otherwise it should print 0.

dcc is_directory.c -o is_directory
mkdir test_directory
echo >test_file
./is_directory test_directory
1
./is_directory test_file
0
./is_directory non_existant_path
0
./is_directory /home/cs1521/public_html
1
./is_directory /etc/resolv.conf
0

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

1092 autotest is_directory 

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

give dp1092 lab12_is_directory is_directory.c

You must run give before Tuesday 19 November 09:00 (2024-11-19 09:00:00) to obtain the marks for this lab exercise. Note that this is an individual exercise, the work you submit with give must be entirely your own.

This is a past exam question

You have been given final_q4.s, which contains a MIPS function final_q4, that takes two arguments: an array and its length, and returns the value 42.

Add code to final_q4 so that it is equivalent to this C function:

int final_q4(int array[], int length) {
    int total = 0;
    int i = 1;

    while (i < length - 1) {
        if (array[i] > array[i - 1] && array[i] > array[i + 1]) {
            total++;
        }
        i++;
    }

    return total;
}

The function final_q4 returns the number of peaks in an array of integers

A peak is (in this case) a value that is both preceded and succeeded by a value smaller than itself

In other words, the value before and the value after the current value are smaller than the current value

For example:

1521 mipsy test_final_q4.s final_q4.s
1
3
2
5
4
4
9
0
1
-9
4
1521 mipsy test_final_q4.s final_q4.s
1
2
3
4
5
6
7
8
9
0
1
1521 mipsy test_final_q4.s final_q4.s
9
8
7
6
5
4
3
2
1
0
0

You can use make(1) to build the provided C code:

make final_q4

You can use 1521 mipsy to run your MIPS code:

1521 mipsy test_final_q4.s final_q4.s

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

1092 autotest 22t1final_q4 

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

give dp1092 lab12_22t1final_q4 final_q4.s

You must run give before Tuesday 19 November 09:00 (2024-11-19 09:00:00) to obtain the marks for this lab exercise. Note that this is an individual exercise, the work you submit with give must be entirely your own.