MFP lab7

;Fibonacci (passing through register)

data segment

        m db 08
        ans dw ?
        n1 db 01
        n2 db 01

data ends

mystack segment

    dw 100 dup(0)
    TOS Label word

mystack ends

code segment

    assume cs:code,ds:data,ss:mystack

        mov ax,data
        mov ds,ax
        xor ax,ax

        mov ax,mystack
        mov ss,ax
        lea sp,TOS
        xor ax,ax
    call fibo
    mov ax,ans
    int 03H


fibo proc near
        PUSHF
        mov al,02
        cmp al,m
        jnc next
        mov cl,m
        dec cl
        dec cl
       mov al,0
          mov bl,1
       p:
          add al,bl
          mov dl,al
          mov al,bl
          mov bl,dl
          LOOP p
          mov byte ptr[ans],dl
          jmp q
       next :
           mov bl,01
           cmp bl,m
           jz first

           mov ans,01
           jmp q
         first:
            mov ans,0

         q: POPF
            ret

   fibo endp
 code ends
 end



;reverse string(passing through pointers)
data segment
 str1 db 'hello'
 b dw ($-str1)
 str2 db 10 dup(0)
data ends

s_seg segment
 dw 100 dup(0)
 tos label WORD
s_seg ends

code segment
 assume cs:code,ds:data,ss:s_seg
 mov ax,data
 mov ds,ax
 xor ax,ax
 mov ax,s_seg
 mov ss,ax
 lea sp,tos
 lea si,str1
 add si,b
 lea di,str2
 call reverse
 int 3

reverse proc near
pushf
mov cx,b
inc cx
x1: mov al,byte ptr[si]
    mov byte ptr[di],al
    dec si
    inc di
    loop x1

  popf
  ret
  reverse endp
  code ends
  end


NOTE:
;even if we are not initializing stack segment, we can call the procedure. It's not compulsory to initialize the stack segment.
;we can use base pointer as an offset inside procedure.
;we can also use push and pop as many as we want in main line code.

;some program 3: factorial (passing by stack)

;assignment: given a decimal number, implement a procedure to find out whether it is armstrong number or not. Pass the value by stack