DUE DATE: Friday, October 11, 2002, 5:00 pm

(no late submissions accepted)

Summary

This project introduces students to ASCII / binary conversion, hexadecimal number manipulation, logical operations, and user input / output. Your task is to write an assembly language program that would serve as a hexadecimal calculator. The program would allow the user to input a hexadecimal arithmetic or logical expression, perform the requested operation and then display the hexadecimal result. The operations your calculator should support are:

• Arithmetic: addition (+), subtraction (-), multiplication (*), division (/)
• Logical: binary AND (&), binary OR ( $\mid$ ), binary XOR ( $\hat{}$ )

Assume all numbers entered by the user are hexademical. Continue taking input until the user presses ENTER without entering anything. For example:

                $ ./hexcalc
                Enter an expression: 10 - B
                                     = 5
                Enter an expression: A * A
                                     = 64
                Enter an expression: B1 | 5
                                     = B5
                Enter an expression: 
                $

Notes

• It is up to you to put restrictions on the syntax. For example, you may require to user to put a space between the operands and operator (5 + 3) or accept input without spaces (5+3). It is up to you which you choose, but make sure you print instructions telling the user what to do. If you do not print any instructions, I will assume you program will take both syntaxes. Another example would be the case of letters used for some hex digits. (Do you allow upper case or lower case or both?)
• Make sure you check the validity of the user input. If the user inputs hello or me + you at the prompt, your calculator should generate an error. Also perform error checking - do not assume every operation completed successfully.
• Allow numbers to be up to 32 bits in size (up to 8 hex digits).
• Split your code into several files; create and use a Makefile for your project.

Extra Credit

• (10 pts) Implement a binary negation operation ( $\tilde{}$ ). Note that this operation only requires one operand, whereas all the other operators require two.
• (20 pts) Allow the user to input expressions with arbitrary number of operators and operands. For example, 15 + FC + 108 - D7 and so on. Make sure you follow operator precedence, i.e. perform multiplication before addition. If you are feeling particularly adventurous, you can even allow parentheses.

What to turn in

Please submit your source code, Makefile, object file, and executable to your submit directory for this class. (located under /home/submit/cs210.) In addition please submit a printout of your source code to the instructor.