HOMEWORK 8 Due on 04/07/2015
INTRODUCTION: In Reverse Polish(postfix) notation the operators follow their operands; for instance, to add three and four one would write “3 4 +” rather than “3 + 4”. If there are multiple operations, the operator is given immediately after its second operand; so the expression written “3 − 4 + 5” in conventional infix notation would be written “3 4 − 5 +” in RPN: first subtract 4 from 3, then add 5 to that. An advantage of RPN is that it obviates the need for parentheses that are required by infix. While “3 − 4 + 5” can also be written “(3 − 4) + 5”, that means something quite different from “3 − (4 + 5)”, and only the parentheses disambiguate the two meanings. In postfix, the latter would be written “3 4 5 + −”, which unambiguously means “3 (4 5 +) −”.
Interpreters of Reverse Polish notation are stack-‐based; that is, operands are pushed onto a stack, and when an operation is performed, its operands are popped from a stack and its result pushed back on. Stacks, and therefore RPN, have the advantage of being easy to implement and very fast.
Please complete the implementation of the two functions given in the questions section below. Test your functions using the main program given. After you complete the homework rename the file “HW8_AssemblyFunctions.S” to “HW8_yourredID.S” and submit only this file on blackboard. Do not include main.c or add contents of main.c to this file. QUESTION 1: Write a function to convert a given function from infix to postfix in assembly. The basic structure of the function is given in the attached assembly language file. QUESTION 2: Write a function to convert a given function from postfix to infix in assembly language. The basic structure of the function is given in the attached assembly language file.