Assembly Program to Draw a line in Graphic Mode of Video

Write an assembly language program for drawing a line in graphic mode of video service?

; draw line in graphics mode
[org 0x0100]
mov ax, 0x000D ; set 320x200 graphics mode
int 0x10 ; bios video services
mov ax, 0x0C07 ; put pixel in white color
xor bx, bx ; page number 0
mov cx, 200 ; x position 200
mov dx, 200 ; y position 200
l1: int 0x10 ; bios video services
dec dx ; decrease y position
loop l1 ; decrease x position and repeat
mov ah, 0 ; service 0 – get keystroke
int 0x16 ; bios keyboard services
mov ax, 0x0003 ; 80x25 text mode
int 0x10 ; bios video services
mov ax, 0x4c00 ; terminate program
int 0x21