Computing Machinery I Assignment 3

Computing Machinery I
Assignment 3

Objective
The objective of this assignment is to practice binary multiplication, division, and shifting in ARMv8
assembly.
Skills Needed for this Assignment:
• Ability to work with basic arithmetic, loops, and if-else constructs in assembly
• Ability to print to standard output using the printf() and scanf() functions
• Ability to use shifting instructions to implement multiplication
• Ability to assemble programs using gcc and use m4 to process macros
• Ability to use gdb to debug and display assembly language programs
Overview
Your programs will convert decimal numbers to binary and vice-versa.
Details
1. The first program converts a binary number to decimal. It prompts the user for N,a number entered in
binary. For reading N, you will need to call the C library scanf() function. Read it as a long integer.
Let M be any number; we will refer to the least significant bit in M as M[0]. Implement the following
algorithms to convert N to a decimal value:
Binary to decimal:
If N is negative, pos_N = 2s complement of N
Else, pos_N = N
decimal_N = 0
For (i = 0; i < 64; i++) {
If pos_N(0) is 1 {
Decimal_N = decimal_N + 2i
}
pos_N 1
}
If N is negative, decimal_N = –decimal_N
Calculating 2i
:
Pow_2 = 1
For (i = 0; i < n; i++) {
Pow_2 << 1
}
2. The second program converts a decimal number or binary. The user enters a decimal value N. Use the
following algorithm:
Decimal to binary:
If N is negative, decimal_N = –decimal_N 
binary_N = 0
quotient = N
i = 0
while quotient != 0 {
quotient, remainder = quotient / 2
// Divide quotient by 2 producing a new quotient and a remainder
remainder = remainder << i
binary_N = binary_N | remainder
i++
}
If N is negative, binary_N = 2s complement of binary_N
You do not need to check for a valid input (especially for program 1 where the entered number must be
binary). Make sure your code is properly formatted into columns, is readable and fully documented, and
includes identifying information at the top of each file. You must comment each line of assembly code.
Your code should also be well designed: make sure it is well organized, clear, and concise.
Submission
• Note: The TA may provide further submission instructions
• Name your programs assign3a.asm (binary to decimal) and assign3b.asm (decimal to binary)
• Create a script file for each program. Call them assign3a.script and assign3b.script. Both script
files must contain a GDB session.
• Submit a README file providing extra instructions or information for your TA (optional)
• Submit your work to the appropriate dropbox on D2L.
Late Submission Policy
Late submissions will be penalized as follows:
-12.5% for each late day or portion of a day for the first two days
-25% for each additional day or portion of a day after the first two days
Hence, no submissions will be accepted after 5 days (including weekend days) of the announced deadline.
Academic Misconduct
This assignment is to be done by individual students: your final submission must be your own original
work. Teamwork is not allowed. Any similarities between submissions will be further investigated for
academic misconduct. While you are encouraged to discuss the assignment with your colleagues, this must
be limited to conceptual and design decisions. Code sharing by any means is prohibited, including looking
at someone else’s paper or screen. The submission of compiler generated assembly code is absolutely
prohibited. Any re-used code of excess of 5 lines in C and 10 lines in assembly (10 assembly language
instructions) must be cited and have its source acknowledged. Failure to credit the source will also result in
a misconduct investigation.
D2L Marks
Marks posted on D2L are subject to change (up or down).
Computing Machinery I
Assignment 3 Rubric
Student:__________________________________________
Item Max Points Points
Code compiles 5
Code runs 5
Calculating 2i 5
Binary to decimal 30
Decimal to binary 30
Handling negative numbers (both programs) 10
Code readability (formatting and documentation) 15
Total Points 100