'{$STAMP BS2}
'{$PBASIC 2.5}
' Author: Jeffrey Sung
' Last Update: January 16, 2004
' Subject: Programming Microcontrollers/Robotics
' Version: 1.41
' Description: An array implementation of a stack


stackData VAR Word
myCount VAR Word

myCount=0


MINIMUM CON 0 'Minimum array index
MAXIMUM CON 1000 '(The absolute maximum is 2047, but EEPROM is also used for program storage)

main:
  LOWER con 0
  HIGHER con 10
  x VAR  Word
  DEBUG "Begin",CR
  FOR x=LOWER TO HIGHER
    DEBUG "x=",DEC x,"  "
    stackData=x+15
    DEBUG "stackData=",DEC stackData,cr
    GOSUB push
  next
  label:
    GOSUB isEmpty
    IF stackData=1 THEN outsideTheLabel
    GOSUB pop
    DEBUG "Popped ",DEC stackData,CR
  GOTO label
  outsideTheLabel:
  DEBUG "Done",CR
END

peekTop:
  READ myCount,stackData
RETURN

pop:
  IF myCount<MINIMUM+1 THEN NullPointerException
  READ myCount,stackData
  myCount=myCount-1
RETURN

push:
  IF myCount=MAXIMUM THEN OutOfMemory
  myCount=myCount+1
  WRITE myCount,stackData
RETURN

isEmpty:
  stackData=0
  IF myCount<MINIMUM+1 THEN:
    stackData=1
  ENDIF
RETURN

NullPointerException:
  DEBUG "Tried to pop empty stack",CR
END

OutOfMemory:
  DEBUG "Stack Overflow: Out of Memory",CR
END