Displaying asterisk triangles

Another version with two triangles connected at one point

Source Code:

jmp start
mess1 db 10,13, "Enter a value [0-9 only]: $"
mess2 db 10,13, "There is nothing to display $"
mess3 db 10,13, "Do you want to continue (y/n): $"
space db " $"
lincar db 10,13, "$"
value db 0
counter db 0

start:
xor ax,ax
xor bx,bx
xor cx,cx

mov ax,3
int 10h

lea dx,mess1
mov ah,9
int 21h

mov ah,1
int 21h
sub al,30h

cmp al,0
je zero_bridge
cmp al,0
jl start
cmp al,9
jg start

mov value,al

lea dx,lincar
mov ah,9
int 21h

mov ah,0
mov al,value

mov cx,ax
mov counter,1
mov bh,counter
mov bl,1
jmp display
zero_bridge:
call zero
display:
cmp bh,bl
jg next

mov dl,'*'
mov ah,2
int 21h

lea dx,space
mov ah,9
int 21h

inc bh
jmp display

next:
inc bl
mov bh,counter

lea dx,lincar
mov ah,9
int 21h

loop display

;-----------------------------------second half-------------------------------------

mov al,value
sub al,1
cmp al,0
je continue
mov ah,0

mov cx,ax
mov counter,1
mov bh,counter
mov bl,al
mov al,0

display2:
cmp bh,bl
jg next2

mov dl,'*'
mov ah,2
int 21h

lea dx,space
mov ah,9
int 21h

inc bh
jmp display2

next2:
dec bl
inc al
mov bh,counter

lea dx,lincar
mov ah,9
int 21h

loop display2
jmp continue
zero:
lea dx, mess2
mov ah,9
int 21h
continue:
xor dx,dx

lea dx,mess3
mov ah,9
int 21h

mov ah,1
int 21h

cmp al,'y'
je start_bridge
cmp al,'n'
je quit

jmp continue

start_bridge:
call start

quit:
int 20h