Question

IN ASSEMLY LANGUAGE MASM! please show output run. Write a program that ask the user to write a string and reverse a string using indirect addressing (may not use the stack - push/pop). The string will be given by the user and be up to 64 characters long.  
INCLUDE Irvine32.inc
INCLUDE macros.inc

  MAX = 64
 .data

  source       BYTE MAX DUP('#'),0
  destination  BYTE LENGTHOF source DUP('*'),0
  actual_length DWORD ?
  ask BYTE "Enter a String: ",0
 .code
 main proc
    ; ask user for input
    mov edx, OFFSET ask
    call WriteString
    ; read string from keyboard 
    mov edx, OFFSET source                 ; where to put string from keyboard 
    mov ecx, LENGTHOF source        ; max num char to get (dont' over fill) 
    call ReadString                 ; get string 
    mov actual_length, eax          ; how long is the string 

    call WriteString


    mov esi, OFFSET source
    mov ecx, SIZEOF source
    call ShowBuffer

    exit
 main ENDP

Answer 1

.586
.model flat

.data
source byte "This is the source string", 0

.code
_main proc
    mov     esi, offset source   ; load up start pointer.

    mov     edi, offset source   ; set end pointer by finding zero byte.
    dec     edi
find_end:
    inc     edi                  ; advance end pointer.
    mov     al, [edi]            ; look for end of string.
    cmp     al, 0
    jnz     find_end             ; no, keep looking.
    dec     edi                  ; yes, adjust to last character.

swap_loop:
    cmp     esi, edi             ; if start >= end, then we are finished.
    jge     finished

    mov     bl, [esi]            ; swap over start and end characters.
    mov     al, [edi]
    mov     [esi], al
    mov     [edi], bl

    inc     esi                  ; move pointers toward each other and continue.
    dec     edi
    jmp     swap_loop

finished:
    int     3                    ; trap to enter debugger and check string.
                                 ; replace with whatever you need.
_main endp
end _main