.model small
.stack 100h
video equ 0B800h
.data
linepack label word
x1 dw 159
y1 dw 99
x2 dw ?
y2 dw ?
color db 3
len dw 0
skip dw 0
mask_table label word
db 3fh,0
db 3fh,40h
db 3fh,80h
db 3fh,0c0h
db 0cfh,0
db 0cfh,10h
db 0cfh,20h
db 0cfh,30h
db 0f3h,0
db 0f3h,4
db 0f3h,8
db 0f3h,12
db 0fch,0
db 0fch,1
db 0fch,2
db,0fch,3
short_step dw ?
long
_step dw ?
line_start dw ?
line_stop dw ?
; x1 equ [word ptr si]
; y1 equ [word ptr si+2]
; x2 equ [word ptr si+4]
; y2 equ [word ptr si+6
; color equ [word ptr si+8]
; len equ [word ptr si+10]
; skip equ [word ptr si+12]
codeseg
;public plotdot
.386
plotdot proc near
pusha
mov di,3
and di,cx
shl di,2
and bx,3
add di,bx
;shl di,1
mov bx,mask_table[di]
mov di,dx
and di,0ffeh
shl di,3
mov ax,di
shl di,2
add di,ax
test dx,1
jz pd1
add di,2000h
pd1:
mov ax,cx
shr ax,2
add di,ax
and es:[di],bl
or es:[di],bh
popa
ret
plotdot endp
plotline proc near
pusha
mov long_step,1
mov bp,x2
sub bp,x1
jge pl1
neg long_step
neg bp
pl1:
mov short_step,1
mov ax,y2
sub ax,y1
jge pl2
neg short_step
neg ax
pl2:
mov line_start,0
mov di,skip
cmp di,0
je pl3
mov line_start,di
pl3:
mov bl,color
mov cx,x1
mov dx,y1
cmp ax,bp
ja alt_code
mov line_sto
p,di
pl4:
mov di,bp
shr di,1
xor si,si
norm_loop:
cmp si,line_start
jl pl5
call plotdot
pl5:
add cx,long_step
add di,ax
cmp di,bp
jl pl6
add dx,short_step
pl6:
inc si
cmp si,line_stop
jbe norm_loop
jmp pl_exit
alt_code:
xchg ax,bp
mov di,long_step
xchg short_step,di
&nbs
p;mov long_step,di
mov line_stop,bp
mov di,len
cmp di,0
je pl7
mov line_stop,di
pl7:
mov di,bp
shr di,1
xor si,si
alt_loop:
cmp si,line_start
jl pl8
call plotdot
pl8:
add dx,long_step
add di,ax
cmp di,bp
jl pl9
add cx,short_step
pl9:
inc si
cmp si,line_stop
jbe alt_loop
pl_exit:
popa
ret
plotline endp
draw proc near
mov ax,@data
mov ds,ax
mov ax, video
mov es,ax
mov ax,4 ;med res interrupt
int 10h
mov si,offset linepack
mov x2,0
mov y2,0
top_side:
call plotline
inc color
and color,3
inc x2
cmp x2,320
jb top_side
dec x2
right_side:
call plotli
ne
inc color
and color,3
inc y2
cmp y2,200
jb right_side
dec y2
bot_side:
call plotline
inc color
and color,3
dec x2
cmp x2,0
jg bot_side
inc x2
left_side:
call plotline
inc color
and color,3
dec y2
cmp y2,0
jg left_side
mov ah,1
int 21h
mov ax,2
int 10h
dosRET:
mov ax,4c00h
int 21h
draw endp
ends
end draw