Project: Assembly Language II

Project: Assembly Language II
COSC 216.001

1 Overview
Each student is asked to write an assembly language program that accesses and makes use of C-subroutines.
1.1 Objectives
ˆ Understanding Assembly language code
ˆ Interfacing C and Assembly code.
2 Detailed Description
2.1 Introduction
In this project you are asked to integrate pre-existing C-functions into your assembly language program.
Your code, while written in assembly language, will have to pass parameters, call C functions, and utilize
the return values. You will need to understand the C-function interface and call structure.
2.2 What to do
You are to implement a simple postx to inx expression converter. You assembly language program should
assume a string address is passed in via R0 as a packed C-style string. You should then run the simplied
postx to inx algorithm specied below, and return a new string in inx notation via R0. Your code should
call the following C-style functions, as necessary (these functions are provided in VisUAL compatible ARM
format in util.s):
// returns the length of string s 1
int _STRLEN(char *s);
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// allocates and returns a string that is the concatenation of strings s1 and s2.
char *_CONCAT(char *s1, char *s2); 5
// If possible, allocates bytes from the heap. This is an all-or-nothing attempt. 7
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void *_ALLOC(unsigned long bytes);
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// returns the number of items stored in stack
int _STACK_SIZE(); 11
// adds s to the top of the stack. 13
void _PUSH(char *s);
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// removes and returns the string at the top of the stack.
char *_POP(); 17
// returns the string at the top of the stack, without modifying the stack. 19
char *_PEEK();
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2.2.1 Postx to Inx Algorithm
Process each character of the input as follows:
1. if the character is a blank, skip it.
2. if the character is a digit, put it onto the stack.
3. otherwise, it is an operator
(a) pop the term2 o the stack
(b) pop the term1 o the stack
(c) concatenate: '(' + term1 + operator + term2 + ')'
(d) push the concatenated string onto the stack
4. At the end of the input string, if there is only one thing on the stack, it is the converted inx formulation
of the expression.
2.3 Running your code
Please use the VisUAL ARM emulator to test your code. You can download VisUAL at: https://
salmanarif.bitbucket.io/visual/downloads.html
3 Submission
Each of your source code les must have a comment near the top that contains your name, StudentID, and
M-number.
The project should be submitted via Blackboard by November 3, 2021, 11:59pm. Follow these instructions to turn in your project.
You should submit the following les:
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ˆ post2inx.s
ˆ any other source les your project needs
The following submission directions use the instructions that we will use for all projects this semester.
1. create a directory for your project:
mkdir asm2
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2. create (or copy) all of your source les in this directory. Example: To copy a le called example.s into
your c2asm directory:
cp example.s asm2 1
3. change parent directory of your project directory:
cd asm2/.. 1
4. Create a tar le named <user_name>.tar.gz, where <user_name> is your studentID and <proj_dir>
is the directory containing the code for your project, by typing:
tar -czf <user_name>.tar asm2
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5. Finally, submit the compressed tar le to Blackboard in accordance with the class policies.
Late assignments will not be given credit.
4 Grading
While this rubric is subject to change based on class performance, the current grading rubric for this assignment is as follows:
component value
Correctness 40
Completeness 40
Code Quality 20
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