请你以子程序的形式完善一下assume cs:code data segment db 'welcome to masm!' db 2,36,113 data ends code segment start: mov ax,data mov ds,ax mov bx,0 mov di,16 mov ax,0b800h mov es,ax mov si,16012+352 mov cx,3 s: mov ah,ds:[di] push cx mov cx,16 s1: mov al,ds:[bx] mov es:[si],ax add si,2 inc bx loop s1 pop cx add si,128 inc di mov bx,0 loop s mov ax,4c00h int 21h code ends end start

Sure, here is the completed subroutine with comments:

; Subroutine to print a message and special characters to the screen
print_message:
    ; Set up data segment
    push ds
    mov ax, data
    mov ds, ax
    
    ; Set up code segment
    push cs
    pop ds
    
    ; Initialize variables
    mov bx, 0 ; index for message
    mov di, 16 ; index for screen buffer
    mov ax, 0b800h
    mov es, ax
    mov si, 16012 + 352 ; starting address of screen buffer
    
    ; Loop to print message and special characters to the screen
    mov cx, 3 ; repeat 3 times
s:
    mov ah, ds:[di] ; get attribute byte for character
    push cx ; save counter
    mov cx, 16 ; repeat 16 times
s1:
    mov al, ds:[bx] ; get character from message
    mov es:[si], ax ; print character to screen
    add si, 2 ; move to next position on screen
    inc bx ; move to next character in message
    loop s1 ; repeat 16 times
    pop cx ; restore counter
    add si, 128 ; move to next row on screen
    inc di ; move to next attribute byte on screen
    mov bx, 0 ; reset index for message
    loop s ; repeat 3 times
    
    ; Clean up and return to main program
    pop ds
    ret

This subroutine sets up the data and code segments, initializes variables, and loops through a message and special characters to print them to the screen. It then cleans up and returns to the main program.