L8:Flowcharting a program

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L8Flowcharting a program
ECE 2560

• Department of Electrical and
• Computer Engineering
• The Ohio State University

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Flowcharting

• Where does flowcharting come in?
• Flowcharting symbols and examples
• Flowcharting a program

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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

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Flowcharting symbols

• Straight action (or code sequence)
• Enclosed in a box sequence of code goes in the
  box.
• Example exchange 2 items
• A - -gt Temp
• B - -gt A
• Temp - -gt B

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Flowcharting symbols

• Decision structure
• Example
• dec I
• jge yes
• Code for false branch
• jmp after
• yes Code for true branch
• after code that follows structure

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Flowcharting loops

• A for loop
• For I 1 to 10 Loop
• code in loop
• End loop

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Flowchart for a problem

• We considered multiply routine (note different
  register numbers used here)
• Note symbol for subroutine and enter/return

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Other flowchart symbols

• Have seem actions, decision, subprocess,
  enter/return
• A couple of others that are often used

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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.