USES Operator

The USES operator, coupled with the PROC directive, lets you list the names of all registers modified within a procedure. It performs two tasks:
  1. Generate PUSH instructions that save the registers on the stack at the beginning of the procedure.
  2. Generate POP instructions that restore the register values at the end of the procedure.
The USES operator immediately follows PROC, and is itself followed by a list of registers on the same line separated by spaces or tabs (not commas).

 Converting Lowercase Letters into Uppercase Letters by Using 
 PUSHAD Instruction   USES Operator  
 

 INCLUDE Irvine32.inc
 

 .data
 

 buffer  BYTE  64 DUP (0)
 

 .code
 

 main PROC
 

     mov   edx, OFFSET buffer
 

     mov   ecx, (SIZEOF buffer) - 1
 

     call  ReadString
 

     mov   esi, OFFSET buffer
 

     mov   ecx, LENGTHOF buffer - 1

 

 L1: cmp   BYTE PTR [esi], 'a'
 

     jl    L2
 

     cmp   BYTE PTR [esi], 'z'
 

     jg    L2
 

     call  convert
 

 L2: inc   esi
 

     loop  L1

 

     mov   edx, OFFSET buffer
 

     call  WriteString
 

     exit
 

 main ENDP

 

 convert PROC


     

      
 


     

      
      
 


    
    
    

      

     

    
 

     mov   cl, [esi]
 

     sub   cl, 'a'
 

     add   cl, 'A'
 

     mov   [esi], cl
 

     popad
 

     ret
 

 convert ENDP

 

 END main
 
 

 INCLUDE Irvine32.inc
 

 .data
 

 buffer  BYTE  64 DUP (0)
 

 .code
 

 main PROC
 

     mov   edx, OFFSET buffer
 

     mov   ecx, (SIZEOF buffer) - 1
 

     call  ReadString
 

     mov   esi, OFFSET buffer
 

     mov   ecx, LENGTHOF buffer - 1

 

 L1: cmp   BYTE PTR [esi], 'a'
 

     jl    L2
 

     cmp   BYTE PTR [esi], 'z'
 

     jg    L2
 

     call  convert
 

 L2: inc   esi
 

     loop  L1

 

     mov   edx, OFFSET buffer
 

     call  WriteString
 

     exit
 

 main ENDP




     

      
 


 

      
      
 


    
    
    

      

     

    
 

     mov   cl, [esi]
 

     sub   cl, 'a'
 

     add   cl, 'A'
 

     mov   [esi], cl
 

     ret
 

 convert ENDP

 

 END main


      “I’m not arguing, I’m just explaining why I’m right.”    
      ― Unknown