Lab 4: Roman Numeral Conversion
Part A: Due Sunday, 19 May 2019, 11:59 PM Part B: Due Friday, 24 May 2019, 11:59 PM
Minimum Submission Requirements
● Ensure that your Lab4 folder contains the following files (note the capitalization convention):
○ Diagram.pdf ○ Lab4.asm
○ README.txt
● Commit and push your repository Lab Objective
In this lab, you will develop a more detailed understanding of how data is
represented, stored, and manipulated at the processor level. In addition to
strengthening your understanding of MIPS coding, you will use program arguments to
read a string input and learn how to convert Roman numerals into binary and how to
print digits as ASCII characters.
Lab Preparation
1. Read sections 9.2 – 9.3 from Introduction To MIPS Assembly Language Programming.
2. Learn how to interpret Roman numerals here Specification
You will write a program in the MIPS32 language using the MARS integrated development
environment to convert a Roman numeral input into an integer. You will then print the
integer as a binary ASCII string.
Input
You will be using program arguments instead of a syscall to take user inputs. See this document on how to use program arguments.
Sample Outputs
You entered the Roman numerals: XXVI
The binary representation is: 0b11010
— program is finished running —
Lab 4 Page 1 of 8 Spring 2019 © 2019, Computer Engineering Department, University of California – Santa Cruz
You entered the Roman numerals: CXCIX
The binary representation is: 0b11000111
— program is finished running —
You entered the Roman numerals: CIC
Error: Invalid program argument. — program is finished running —
You entered the Roman numerals: IIIV
Error: Invalid program argument. — program is finished running —
You entered the Roman numerals: DCII
The binary representation is: 0b1001011010
— program is finished running —
For full credit, the output should match this format exactly. Take note of the:
1. Exact wording of the statements.
2. Program argument printed on a new line. 3. Blank line under the program argument. 4. Binary value printed on a new line.
5. Blank line under the final result.
Functionality
The functionality of your program will be as follows:
1. Read a Roman numeral input from the program arguments. ● Valid ASCII characters are I, V, X, L, and C.
2. Print the user’s input.
3. Convert the Roman numeral input to an integer and store in $s0.
Lab 4 Page 2 of 8 Spring 2019 © 2019, Computer Engineering Department, University of California – Santa Cruz
● Your program should parse through the ASCII string and compare adjacent characters to decide if you must add or subtract or if the input is invalid.
● Basic conversion algorithm:
i. Iterate over each character of the string
1. Compare value of the current character to the value of the next character
a. If current value is greater or equal, add value to running sum
b. Else, subtract value from running total 4. Print an ERROR message if:
● The user entered invalid ASCII characters
● An invalid Roman numeral string has been entered 5. Exit the program cleanly using syscall 10.
6. (Extra Credit) Include D as a valid input from the user.
Part A: Block Diagram, Pseudocode, and Program Arguments
In part A, you must create a block diagram and pseudocode to aid in the development
of your MIPS assembly program. In addition, you must generate code to print the
program argument to the console.
Block Diagram
Before coding, create a top level block diagram or flowchart to show how the
different portions of your program will work together. Start by creating a flow chart
of the steps that were previously described. Next, break each step into its own block
diagram.
Use https://www.draw.io or a similar drafting program to create this document. This diagram will be contained in the file Diagram.pdf. This diagram must be computer generated to receive full credit.
Pseudocode
Next, you will create pseudocode that outlines your program. Your pseudocode will appear underneath the header comment in Lab4.asm. Guidelines on developing pseudocode can be found here: https://www.geeksforgeeks.org/how-to-write-a-pseudo-code/
You may modify your pseudocode as you develop your program. Your pseudocode must also be present in your final submission (part B).
Program Arguments
Your code must read and print the program argument to the screen. For example:
Input
Output
Lab 4 Page 3 of 8 Spring 2019 © 2019, Computer Engineering Department, University of California – Santa Cruz
You entered the Roman numerals: XXVI
— program is finished running —
Part B: Assembly Code
Implement the functionality of the program previously listed.
Automation
Note that part of our grading script is automated, so it is imperative that your program’s output matches the specification exactly. Output
that deviates from the spec will cause point deduction.
Your code should end cleanly without error. Make sure to use the exit
syscall (syscall 10). Files
Diagram.pdf
This file will contain a block diagram or flowchart of how the different components
of your code work together.
Lab4.asm
This file contains your pseudocode and assembly code. Follow the code documentation guidelines here.
README.txt
This file must be a plain text (.txt) file. It should contain your first and last
name (as it appears on Canvas) and your CruzID. Your answers to the questions should
total at least 150 words. Your README should adhere to the following template:
Lab 4 Page 4 of 8 Spring 2019 © 2019, Computer Engineering Department, University of California – Santa Cruz
————————
Lab 4: Roman Numeral Conversion CMPE 012 Spring 2019
Last Name, First Name CruzID ————————-
Can you validly represent the decimal value 1098 with Roman numerals using only I, V, X, and C?
Write the answer here.
What was your approach for recognizing an invalid program argument? Write the answer here.
What did you learn in this lab? Write the answer here.
Did you encounter any issues? Were there parts of this lab you found enjoyable?
Write the answer here.
How would you redesign Write the answer here.
What resources did you Write the answer here.
this lab to make it better?
use to complete this lab?
Did you work with anyone on the labs? Describe the level of collaboration. Write the answer here.
Syscalls
When printing the integer values, you may use syscall system services 4 (print string) and 11 (print character). You may not use the following syscalls:
1(print integer)
5(read integer)
12 (read character)
34 (print integer as hexadecimal)
35 (print integer as binary)
36 (print integer as unsigned)
You will lose a significant number of points if you use any of these syscalls. See
the rubric for more details.
Make sure to exit your program cleanly using syscall 10.
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Note
It is important that you do not hard-code the values for any of the addresses in your program.
Other Requirements
Turn Off Delayed Branching
From the settings menu, make sure Delayed branching is unchecked
Checking this option will insert a “delay slot” which makes the next instruction
after a branch execute, no matter the outcome of the branch. To avoid having your
program behave in unpredictable ways, make sure Delayed branching is turned off. In
addition, add a nop instruction after each branch instruction. For example:
MIPS Memory Configuration
To find the program arguments more easily in memory, you may choose to develop your
program using a compact memory configuration (Settings -> Memory Configuration).
However, your program MUST function properly using the Default memory configuration. You should not run into issues as long as you do not hard-code any memory addresses in your program. Make sure to test your program thoroughly using the Default memory configuration.
Lab 4 Page 6 of 8 Spring 2019 © 2019, Computer Engineering Department, University of California – Santa Cruz
LI $t12
LOOP: NOP
ADDI $t0 $t0 1
BLT $t0 $t1 LOOP
NOP # nop added after the branch instruction ADD $t3 $t5 $t6
Submission Instructions
This assignment will be submitted in two parts. Late hours will not be used for Part
A of the assignment. If you do not submit a diagram or pseudocode by the Part A
deadline, you can submit it with your Part B submission for less points.
Lab 4 Page 7 of 8 Spring 2019 © 2019, Computer Engineering Department, University of California – Santa Cruz
Grading Rubric
point values to be determined
Part A
pseudocode
block diagram
program arguments
Part B
pseudocode quality
block diagram quality
assembles without errors
correct value in $s0
statements match specification
invalid input detection
test cases
extra credit
-50% if program only runs in a specific memory configuration or memory addresses are
hard coded
No credit if you use a forbidden syscall (1, 5, 12, 34, 35, 36)
6 pt style and documentation
1 ptcomment on register usage
1 ptuseful and sufficient comments
1 ptlabels, instructions, operands, comments lined up in columns
2 ptreadme file complete (should total at least 150 words)
1 ptcomplete headers for code and README
Note: program header must include name, CruzID, date, lab name, course name, quarter, school, program description, note on program argument usage
README must include name, CruzID, lab name, course name
Lab 4
© 2019, Computer Engineering Department, University of California – Santa Cruz
Page 8 of 8 Spring 2019
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