Week 05 Laboratory Exercises
Objectives
- understanding how array indices are calculated
- practicing using MIPS control instructions (branch)
- learning how MIPS memory access works (lw/sw)
- practicing running MIPS programs with mipsy, mipsy-web
Preparation
Before the lab you should re-read the relevant lecture slides and their accompanying examples.
Getting Started
lab05 and changing to this directory.
mkdir lab05 cd lab05
There are some provided files for this lab which you can fetch with this command:
1092 fetch lab05
If you're not working at CSE, you can download the provided files as a zip file or a tar file.
Exercise — individual:
Bigger MIPS
In the files for this lab,
you have been given print_bigger.s,
a MIPS assembler program that
reads 10 numbers and then prints them:
cat numbers1.txt 12086 24363 47363 64268 34001 6800 60742 48867 26002 54999 1092 mipsy print_bigger.s <numbers1.txt 12086 24363 47363 64268 34001 6800 60742 48867 26002 54999
Add code to print_bigger.s
to make it equivalent to this C program:
// Read 10 numbers into an array then print the numbers which are
// larger than the final number read.
#include <stdio.h>
#define ARRAY_LEN 10
int main(void) {
int i, final_number;
int numbers[ARRAY_LEN] = { 0 };
i = 0;
while (i < ARRAY_LEN) {
scanf("%d", &numbers[i]);
final_number = numbers[i];
i++;
}
i = 0;
while (i < ARRAY_LEN) {
if (numbers[i] >= final_number) {
printf("%d\n", numbers[i]);
}
i++;
}
}
For example:
1092 mipsy print_bigger.s <numbers1.txt 64268 60742 54999 cat numbers2.txt 53906 9064 40906 4504 4774 7892 15334 45515 55387 5681 1092 mipsy print_bigger.s <numbers2.txt 53906 9064 40906 7892 15334 45515 55387 5681
When you think your program is working,
you can use autotest
to run some simple automated tests:
1092 autotest print_bigger
When you are finished working on this exercise,
you must
submit your work by running give:
give dp1092 lab05_print_bigger print_bigger.s
You must run give
before Monday 15 June 09:00 (2026-06-15 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.
Exercise — individual:
MIPS Order Checking
In the files for this lab,
you have been given unordered.s,
a MIPS assembler program that
reads 10 numbers and then prints 42:
Add code to unordered.s
to make it equivalent to this C program:
// Read 10 numbers into an array
// print 0 if they are in non-decreasing order
// print 1 otherwise
#include <stdio.h>
#define ARRAY_LEN 10
int main(void) {
int i;
int numbers[ARRAY_LEN] = { 0 };
i = 0;
while (i < ARRAY_LEN) {
scanf("%d", &numbers[i]);
i++;
}
int swapped = 0;
i = 1;
while (i < ARRAY_LEN) {
int x = numbers[i];
int y = numbers[i - 1];
if (x < y) {
swapped = 1;
}
i++;
}
printf("%d\n", swapped);
}
For example:
cat numbers1.txt 12086 24363 47363 64268 34001 6800 60742 48867 26002 54999 1092 mipsy unordered.s <numbers1.txt 1 cat sorted.txt 1 2 3 4 5 6 7 8 9 10 1092 mipsy unordered.s <sorted.txt 0
When you think your program is working,
you can use autotest
to run some simple automated tests:
1092 autotest unordered
When you are finished working on this exercise,
you must
submit your work by running give:
give dp1092 lab05_unordered unordered.s
You must run give
before Monday 15 June 09:00 (2026-06-15 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.
Exercise — individual:
MIPS Swapping
In the files for this lab,
you have been given swap_numbers.s,
a MIPS assembler program that
reads 10 numbers and then prints them:
Add code to swap_numbers.s
to make it equivalent to this C program:
// Read 10 numbers into an array
// swap any pair of numbers which are out of order
// then print the array
#include <stdio.h>
#define ARRAY_LEN 10
int main(void) {
int i;
int numbers[ARRAY_LEN] = { 0 };
i = 0;
while (i < ARRAY_LEN) {
scanf("%d", &numbers[i]);
i++;
}
i = 1;
while (i < ARRAY_LEN) {
int x = numbers[i];
int y = numbers[i - 1];
if (x < y) {
numbers[i] = y;
numbers[i - 1] = x;
}
i++;
}
i = 0;
while (i < ARRAY_LEN) {
printf("%d\n", numbers[i]);
i++;
}
}
For example:
1092 mipsy swap_numbers.s <numbers1.txt 12086 24363 47363 34001 6800 60742 48867 26002 54999 64268 1092 mipsy swap_numbers.s <numbers2.txt 9064 40906 4504 4774 7892 15334 45515 53906 5681 55387
When you think your program is working,
you can use autotest
to run some simple automated tests:
1092 autotest swap_numbers
When you are finished working on this exercise,
you must
submit your work by running give:
give dp1092 lab05_swap_numbers swap_numbers.s
You must run give
before Monday 15 June 09:00 (2026-06-15 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.
Challenge Exercise — individual:
MIPS Bubbles
In the files for this lab,
you have been given bubblesort.s,
a MIPS assembler program that
reads 10 numbers and then prints them:
Add code to bubblesort.s
to make it equivalent to this C program:
// Reads 10 numbers into an array, bubblesorts them
// and then prints the 10 numbers
// then print them
#include <stdio.h>
#define ARRAY_LEN 10
int main(void) {
int i;
int numbers[ARRAY_LEN] = { 0 };
i = 0;
while (i < ARRAY_LEN) {
scanf("%d", &numbers[i]);
i++;
}
int swapped = 1;
while (swapped) {
swapped = 0;
i = 1;
while (i < ARRAY_LEN) {
int x = numbers[i];
int y = numbers[i - 1];
if (x < y) {
numbers[i] = y;
numbers[i - 1] = x;
swapped = 1;
}
i++;
}
}
i = 0;
while (i < ARRAY_LEN) {
printf("%d\n", numbers[i]);
i++;
}
}
For example:
1092 mipsy bubblesort.s <numbers1.txt 6800 12086 24363 26002 34001 47363 48867 54999 60742 64268 1092 mipsy bubblesort.s <numbers2.txt 4504 4774 5681 7892 9064 15334 40906 45515 53906 55387
When you think your program is working,
you can use autotest
to run some simple automated tests:
1092 autotest bubblesort
When you are finished working on this exercise,
you must
submit your work by running give:
give dp1092 lab05_bubblesort bubblesort.s
You must run give
before Monday 15 June 09:00 (2026-06-15 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.
Challenge Exercise — individual:
MIPS NUXI
We have two 32 bit values which the bytes have placed in an unknown order.
Fortunately we know the 4 bytes of the first value
originally contained the ASCII values "UNIX",
and the two values were shuffled in an identical manner.
e.g. if the first value was "IXUN",
and the second value was "PSMI",
then the second value correctly ordered would be "MIPS".
Write a MIPS program nuxi.s which read the two values and prints
the second value with its bytes correctly ordered.
For example:
1092 mipsy nuxi.s 1481199189 -2023406815 -2023406815 1092 mipsy nuxi.s 1431193944 -2023406815 558065031 1092 mipsy nuxi.s 1230525774 -559038737 -1377898562 1092 mipsy nuxi.s 1229871189 305419896 1444033656
When you think your program is working,
you can use autotest
to run some simple automated tests:
1092 autotest nuxi
When you are finished working on this exercise,
you must
submit your work by running give:
give dp1092 lab05_nuxi nuxi.s
You must run give
before Monday 15 June 09:00 (2026-06-15 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.
Submission
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 Week 6 Monday 09:00:00 to submit your work.
You cannot obtain marks by e-mailing your code to tutors or lecturers.
You check the files you have submitted here.
Automarking will be run by the lecturer several days after the submission deadline,
using test cases different to those autotest runs for you.
(Hint: do your own testing as well as running autotest.)
After automarking is run by the lecturer you can view your results here. The resulting mark will also be available via give's web interface.
Lab Marks
When all components of a lab are automarked you should be able to view the the marks via give's web interface or by running this command on a CSE machine:
1092 classrun -sturec