Computing Machinery I Assignment 1 Solution



Basic Assembly Language Programming

Create an ARMv8 A64 assembly language program that finds the minimum of y = 2x4 145x2 44x  in the range  x 10, by stepping through the range one by one in a loop and testing. Use only long integers for x, and do not factor the expression. Use the printf() function to display to the screen the values of x, y and the current minimum on each iteration of your loop.

You are to create 2 versions of your program:

  1. Write the program without macros (i.e. don’t use m4), and use only the mul, add, and mov instructions to do your calculations. Use a pre-test loop, where the test is at the top of the loop.

  2. Optimize the above program by putting the loop test at the bottom of the loop (make sure it is still a pre-test loop), and by making use of the madd instruction. Also, add macros to the above program to make it more readable (use m4). In particular, provide macros for heavily used registers.

Running Your Program

To verify that your assembly language program works, run both versions under gdb, capturing output from each session using the script UNIX command. For version 1, single step through the program (use ni) for at least one iteration of your loop, displaying the instruction being executed (use display/i $pc). Also print out the contents of particular registers (use p) at key points in your program to show that it is working as expected. For version 2, set a breakpoint just after the place where the final result is calculated, and then print out the minimum. Do not single step through this version.

Other Requirements

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.

New 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() function

  • Ability to optimize assembly code by rearranging loops and using alternate instructions

  • Ability to use macros in assembly code

  • Ability to assemble programs using gcc and use m4 to process macros

  • Ability to use gdb to debug and display assembly language programs

Submit the following:

  1. Your assembly source code files for both programs and 2 scripts via electronic submission. Use the Assignment 1 Dropbox Folder in D2L to submit electronically. Your TA will assemble and run your programs to test them. Name your programs assign1a.s and assign1b.asm, and your scripts script1.txt and script2.txt.

Computing Machinery I

Assignment 1 Grading


Functionality (Version 1)

Equation calculation 4 ______

Test for minimum 4 ______

Display to screen using printf() 2 ______

Loop 4 ______

Optimization (Version 2) 3 ______

Use of Macros (Version 2) 3 ______

2 Scripts showing use of gdb 4 ______

Complete documentation and commenting 4 ______

Formatting (use of columns and white space) 4 ______

Design quality 2 ______

Total 34 ______ _____%