cs401 assignment 3 solution fall 2019 2020
Question:
Suppose we want to draw a square on our computer screen as shown below.
name “vga”
; this program draws a square in vga mode.
org 100h
jmp code
; dimensions of the square:
; width: 50 pixels
; height: 50 pixels
w equ 50
h equ 50
; set video mode 13h – 320×200
code: mov ah, 0
mov al, 13h
int 10h
; draw upper line:
mov cx, 100+w ; column
mov dx, 20 ; row
mov al, 0010 ; green
u1: mov ah, 0ch ; put pixel
int 10h
dec cx
cmp cx, 100
jae u1
; draw bottom line:
mov cx, 100+w ; column
mov dx, 20+h ; row
mov al, 0001 ; blue
u2: mov ah, 0ch ; put pixel
int 10h
dec cx
cmp cx, 100
ja u2
; draw left line:
mov cx, 100 ; column
mov dx, 20+h ; row
mov al, 35 ; pink
u3: mov ah, 0ch ; put pixel
int 10h
dec dx
cmp dx, 20
ja u3
; draw right line:
mov cx, 100+w ; column
mov dx, 20+h ; row
mov al, 20 ; gray
u4: mov ah, 0ch ; put pixel
int 10h
dec dx
cmp dx, 20
ja u4
; pause the screen for dos compatibility:
;wait for keypress
mov ah,00
int 16h
; return to text mode:
mov ah,00
mov al,03 ;text mode 3
int 10h
ret
