string db 'd', 'a', 'b', 'e', 'c', 0Dh, 0Ah, '$'

string db 'e', 'c', 'b', 'd', 'a', 0Dh, 0Ah, '$'

org 100h

jmp main

string db 'd', 'a', 'b', 'e', 'c', 0Dh, 0Ah, '$'
length dw 3

main:
    xor ax, ax
    xor bx, bx
    xor dx, dx
    xor cx, cx
    xor si, si
    xor bp, bp

    lea bx, string
    mov ax, bx
    print "Before string: "
    call print_ax_str

    lea ax, [bx]
    push ax

    lea ax, [bx + 3]
    push ax

    call swap ;swap the chars.

    lea ax, string
    print "After string: "
    call print_ax_str
    jmp end
swap:
    printn "swap!"
    push cx
    push bx
    push dx
    push ax
    push bp


    mov bp, sp

    mov ax, [bp + 12]; ax = ptr char 2

    mov cx, [bp + 14]; cx = ptr char 1

    mov bx, ax
    mov ax, [bx] ;ax = char 2

    mov bx, cx
    mov dx, [bx] ;dx = char 1
    mov [bx], ax ;char 1 = char 2


    mov bx, [bp + 12]
    mov [bx], dx ;char 2 = char 1
    mov ax, [bx]

    mov sp, bp
    pop bp
    pop ax
    pop dx
    pop bx
    pop cx
    retn 4


end:
    mov ah, 0
    int 16h
    ret

include prints.inc