c06-03.asm

[org 0x100]

jmp start 

data:   dw  60, 55, 45, 50 
swapflag:   db  0 


swap: 
    push ax  ; -------------------------; 
    ; push cx  ; ------------------;      ;  
                                 ;      ; 
    mov  ax, [bx + si]           ;      ; 
    xchg ax, [bx + si + 2]       ;      ; 
    mov  [bx + si], ax           ;      ; 
                                 ;      ; 
    dec  cx                      ;      ; 
    ; do some storage here       ;      ; 
    ; pop cx   ; ------------------;      ; 
    pop ax   ; -------------------------; 

    ret       


bubblesort: 
    push ax         ; three new pushes 
    push cx 
    push si 


    dec  cx 
    shl  cx, 1                   

    mainloop:  
        mov  si, 0                   ; use as array index 
        mov  byte[swapflag], 0       ; reset swap flag for this iteration 

        innerloop: 
            mov  ax, [bx + si]
            cmp  ax, [bx + si + 2]
            jbe  noswap 

               call swap    ; another call here 
               mov  byte[swapflag], 1

            noswap: 
            add  si, 2 
            cmp  si, cx
            jne  innerloop

        cmp  byte[swap], 1 
        je   mainloop 


    ; pops in reverse order 
    pop si 
    pop cx 
    pop ax 
    ret    ; notice this!! 




start: 
    mov  bx, data 
    mov  cx, 4 

    ; make a function call 
    call bubblesort 

    ; data is now sorted! 

    mov ax, 0x4c00 
    int 0x21