Local Variables (Cont.)

Local variables are created on the runtime stack. They can not be given default values at assembly time, but they can be initialized at runtime. The following examples calculate a geometric series: 
             a×rn-1 + ... + a×r3 + a×r2 + a×r1 + a:
             3×23 + 3×22 + 3×21 + 3 = 45
Using Global Variables
Using Local Variables 
 INCLUDE Irvine32.inc

  a = 3
  r = 2
  n = 4         ; n > 1

 .data
  result  SDWORD  0
  count    DWORD  ?
  r1      SDWORD  ?
  prod    SDWORD  ?
 
 .code
 main PROC
  mov   ecx, n
  dec   ecx

 L1:
  mov   count, ecx
  call  calc

    

     
   
     
     
     
    
    


    
    
    
     		
    

   
  add   result, eax
  loop  L1
  add   result, a
  mov   eax, result
  call  WriteInt
  exit
 main ENDP




  
 ;;
 ;; Calculate a×r**n
 ;;
 calc PROC
  mov   r1, r
  mov   eax, a

  ;; EAX: multiplicand
 L1:
  imul  r1
  loop  L1
  mov   ecx, count
  mov   prod, eax  ; EAX: product

  ret
 calc ENDP
 END main
 
 INCLUDE Irvine32.inc

  a = 3
  r = 2
  n = 4         ; n > 1

 .data
  count    DWORD  ?
  prod    SDWORD  ?


  
 .code
 main PROC
  LOCAL  var:SDWORD
  mov    var, 0
  mov    ecx, n
  dec    ecx

 L1:
  mov    count, ecx
  call   calc

    

     
   
     
     
     
    
    


    
    
    

   
  add    var, eax
  loop   L1
  add    var, a
  mov    eax, var
  call   WriteInt
  exit 
 main ENDP

 ;;
 ;; Calculate a×r**n
 ;; 
 calc PROC
  LOCAL  var:SDWORD
  mov   var, r
  mov   eax, a

  ;; EAX: multiplicand
 L1:
  imul  var
  loop  L1
  mov   ecx, count
  mov   prod, eax  ; EAX: product

  ret
 calc ENDP
 END main
An Execution Example
An Execution Example

    45
    45

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