STRING REVERSAL ASSEMBLY PROGRAM for MP lab

1. ORG 100h
2.  
3. MOV si,sp ; Save stack pointer!
4.  
5. input_loop:
6.     XOR ax,ax
7.     INT 16h ; Use int16 to get a keystroke
8.  
9.     CMP al,' ' ; is it a space char?
10.      JE input_loop ; if space, get another char
11.  
12.     PUSH ax ; Save current char on stack top!
13.     CMP al,13 ; Terminating CR?
14.      JNE input_loop
15.  
16.     POP ax ; Get rid of last pushed char (terminating CR)
17.      JMP test_stack
18.  
19. disp_loop:
20.     POP dx ; DL will get the pushed char
21.     MOV ah,2
22.     INT 21h
23.  
24. test_stack:
25.     CMP si,sp ; Is the stack back where we started?
26.      JNE disp_loop
27.  
28. done: ; So,exit
29.     MOV ax,0x4C00
30.     INT 0x21