ECE Lecture 1 1 L8:Flowcharting a program Department of Electrical and Computer Engineering The Ohio State University ECE 2560

Flowcharting Where does flowcharting come in? Flowcharting symbols and examples Flowcharting a program ECE Lecture 1 2

What is flowcharting Flowcharting is a method of documenting an algorithm or method for performing a sequence of actions. Could be something that is not intended for a computer program. Provides a graphical view of the process or method. For assembler language can even indicate register and memory usage ECE Lecture 1 3

Flowcharting symbols Straight action (or code sequence) Enclosed in a box – sequence of code goes in the box. Example – exchange 2 items A - -> Temp B - -> A Temp - -> B ECE Lecture 1 4

Flowcharting symbols Decision structure Example dec I jge yes Code for false branch jmp after yes Code for true branch aftercode that follows structure ECE Lecture 1 5

Flowcharting loops A for loop For I = 1 to 10 Loop code in loop End loop; ECE Lecture 1 6

Flowchart for a problem We considered multiply routine (note: different register numbers used here) Note symbol for subroutine and enter/return ECE Lecture 1 7

Other flowchart symbols Have seem actions, decision, subprocess, enter/return A couple of others that are often used ECE Lecture 1 8

Flowchart hierarcy Flowchart can be written such that what is in the action (process) box is a high level statement. The high level statement can be a program in and of itself OR A flowchart can be done indicating assembler instructions and which registers are used. ECE Lecture 1 9