Variable DD 6372h
...
MOV EAX, Variable                ; Load the contents of Variable
MOV EAX, OFFSET Variable     ; Load the adress of Variable
    

MOV EAX, Variable                ; Load the adress of Variable
MOV EAX, [Variable]            ; Load the contents of Variable
    

format PE GUI 4.0
entry start

include 'win32a.inc'

section '.text' code readable executable

  start:
        invoke  ShowLastError,HWND_DESKTOP
        invoke  ExitProcess,0

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
          errormsg,'ERRORMSG.DLL'

  import kernel,\
         ExitProcess,'ExitProcess'

  import errormsg,\
         ShowLastError,'ShowLastError'
    

; DLL creation example

format PE GUI 4.0 DLL
entry DllEntryPoint

include 'win32a.inc'

section '.text' code readable executable

proc DllEntryPoint hinstDLL,fdwReason,lpvReserved
        mov     eax,TRUE
        ret
endp

; VOID ShowErrorMessage(HWND hWnd,DWORD dwError);

proc ShowErrorMessage hWnd,dwError
  local lpBuffer:DWORD
        lea     eax,[lpBuffer]
        invoke  FormatMessage,FORMAT_MESSAGE_ALLOCATE_BUFFER+FORMAT_MESSAGE_FROM_SYSTEM,0,[dwError],LANG_NEUTRAL,eax,0,0
        invoke  MessageBox,[hWnd],[lpBuffer],NULL,MB_ICONERROR+MB_OK
        invoke  LocalFree,[lpBuffer]
        ret
endp

; VOID ShowLastError(HWND hWnd);

proc ShowLastError hWnd
        invoke  GetLastError
        stdcall ShowErrorMessage,[hWnd],eax
        ret
endp

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
          user,'USER32.DLL'

  import kernel,\
         GetLastError,'GetLastError',\
         SetLastError,'SetLastError',\
         FormatMessage,'FormatMessageA',\
         LocalFree,'LocalFree'

  import user,\
         MessageBox,'MessageBoxA'

section '.edata' export data readable

  export 'ERRORMSG.DLL',\
         ShowErrorMessage,'ShowErrorMessage',\
         ShowLastError,'ShowLastError'

section '.reloc' fixups data discardable        
    

format PE GUI 4.0
entry start

include 'win32a.inc'

section '.text' code readable executable

  start:
    

include 'winheader.inc'
        invoke  ShowLastError,HWND_DESKTOP
        invoke  ExitProcess,0
include 'imports.inc'
    

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
          errormsg,'ERRORMSG.DLL'

  import kernel,\
         ExitProcess,'ExitProcess'

  import errormsg,\
         ShowLastError,'ShowLastError'
    

...
func:
add eax,1
ret
...
mov eax,3
@@:
call func
sub eax,4 ;here, eax equal 0 the first time, and -3 the second time
je @b ;reloop the first time
...some more code ;it will run here the second time
...
    

Thanks all of you.
JohnFound: So if I put procedures, macros and even data in a source file, then include it in another source file, no procedures, macros or data will be part of the executable if I do not refer to any of the 3 mentioned?

if used MyData
  MyData db 1,2,3,0
end if
    

If I create a procedure and put it in its own source file to be included later. Do I need to put .code operator and segments into that source file or is it enough to just put "name proc and endp" and the code?

Also, do I need to put my procedures at the top of the source file, before I actually call the procedures, or can I put it after the places where I refer and use the procedures?

I see. Is dynamic linking the only way to reuse your old code?

Display MyNum does not work on constants, it translates it to ascii. How can I effectively print a constant as it is?

;Displays a binary representation of a number
macro dispBin num*, padding, leader, trailer, size
{
 local digCount,number,lastdig
       number = size num
   lastdig = number

        if number < 0
            display '-'
               number = -(number shr 1 + number and 1)
             lastdig = -(lastdig + number + number)
      else
                number = number shr 1
               lastdig = lastdig and 1
     end if
      digCount = 0
        while number shr digCount > 0
            digCount = digCount + 1
     end while
   if ~ leader eq
              display leader
      end if
      if ~ padding eq
             if digCount < padding
                    times (padding-digCount-1) display '0'
            end if
      end if
      times digCount display number shr (digCount-%) and 1+'0'
  display lastdig+'0'
       if ~ trailer eq
             display trailer
     end if
}

;Displays a decimal representation of a number
macro dispDec num*, padding, leader, trailer
{
    local digCount,tenPow,number,lastdig
        number = num
        lastdig = number
    
    if number < 0
            display '-'
               number = (-(number shr 1 + number and 1)) / 5
               lastdig = -(lastdig + number*5 + number*5)
  else
                number = number/10
          lastdig = lastdig mod 10
    end if
      digCount = 0
        tenPow = 1
  while tenPow <= number
           tenPow = tenPow*10
          digCount = digCount + 1
     end while
   if ~ leader eq
              display leader
      end if
      if ~ padding eq
             if digCount < padding
                    times (padding-digCount-1) display '0'
            end if
      end if
      repeat digCount
             tenPow = tenPow/10
          display number/tenPow+'0'
         number = number mod tenPow
  end repeat
  display lastdig+'0'
       if ~ trailer eq
             display trailer
     end if
}

;Displays a hexadecimal representation of a number
macro dispHex num*, padding, leader, trailer, size
{
  local digCount,dig,number,lastdig
   number = size num
   lastdig = number
    
    if number < 0
            display '-'
               number = (-(number shr 1 + number and 1)) shr 3
             lastdig = -(lastdig + number shl 3 + number shl 3)
  else
                number = number shr 4
               lastdig = lastdig and 0xF
   end if
      digCount = 0
        while number shr (digCount*4) > 0
                digCount = digCount + 1
     end while
   if ~ leader eq
              display leader
      end if
      if ~ padding eq
             if digCount < padding
                    times (padding-digCount-1) display '0'
            end if
      end if
      repeat digCount
             dig = number shr ((digCount-%)*4) and 0Fh
           if dig > 9
                       dig = dig-'0'+('A'-10)
          end if
              display dig+'0'
   end repeat
  if lastdig > 9
           lastdig = lastdig-'0'+('A'-10)
  end if
      display lastdig+'0'
       if ~ trailer eq
             display trailer
     end if
}

;Displays a string with binary, decimal and hexadecimal values
;usage: display d=number,":",9,b=number,9,h=number,13,10
macro display [token]
{
     forward
             define matched +
            define matched -
            irp type, =b, =d, =h, =bb, =bw, =bd, =bq, =hb, =hw, =hd, =hq \{ match type==n,token \\{ restore matched \\} \}
            match =b==number,token \{ dispBin number,,,'b' \}
             match =d==number,token \{ dispDec number \}
             match =h==number,token \{ dispHex number,,'0x' \}
             match =bb==number,token \{ dispBin number,,,'b',byte \}
               match =bw==number,token \{ dispBin number,,,'b',word \}
               match =bd==number,token \{ dispBin number,,,'b',dword \}
              match =bq==number,token \{ dispBin number,,,'b',qword \}
              match =hb==number,token \{ dispHex number,,'0x',,byte \}
              match =hw==number,token \{ dispHex number,,'0x',,word \}
              match =hd==number,token \{ dispHex number,,'0x',,dword \}
             match =hq==number,token \{ dispHex number,,'0x',,qword \}
             match -,matched \{ display token \}
             match -,matched \{ restore matched \}
           restore matched
}    

Also, do anyone know how I can keep track of build numbering, how many times I've built my program?