Procedures

A procedure is a sequence of instructions for performing a particular task. This allows the procedure code to be called from multiple places, even from within itself (in which case it is called recursive). The assembly language implementation takes care of returning control to (just after) the calling location. There are two methods to implement a procedure:
  1. Define and use procedures in a program by using directive, and and instructions.
  2. Call procedures from a library, which is a file containing procedures that have been assembled into machine code. The linker would look for the procedure in the link library, and copy the appropriate machine instructions from the library into your program’s executable file. For example, the following command links to and : 
    C:\> link myAsm.obj irvine32.lib kernel32.lib
Removing Spaces from a String 
 INCLUDE Irvine32.inc
 .data
   buffer  BYTE  128 DUP(?)
 
 .code
 main PROC
   mov    edx, OFFSET buffer
   mov    ecx, (SIZEOF buffer) - 1
   call   ReadString                 ; Read an input string.
   mov    ecx, OFFSET buffer
   add    ecx, eax                   ; EAX = the string length
   mov    esi, OFFSET buffer         ; ESI = the original string position
   mov    edi, OFFSET buffer         ; EDI = the final    string position
 
 L1:
   call   SkipSpaces
   cmp    ecx, esi
 
   je     L2

    
  


    
  		
  
  
    
    
    
    

  


   inc    edi
   inc    esi
   cmp    ecx, esi
   jg     L1
 
 L2:
   mov    BYTE PTR [edi], 0          ; 0 is the end-of-string symbol
   mov    edx, OFFSET buffer
   call   WriteString
   call   Crlf
   call   Crlf
   exit
 main ENDP
 
 SkipSpaces PROC
 L1:
   mov    dl, [esi]
   cmp    dl, ' '
   jne    L2
   inc    esi
   jmp    L1
 
 L2:
   ret
 SkipSpaces ENDP
 END main
An Execution Example

   This is only a test . 
  Thisisonlyatest.

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