model   tiny,pascal
                .code
                .286
                jumps

                public  rect

rect            proc
                uses    es
                arg     x1,y1,x2,y2:word,color:byte

                cld
                mov     bx,x1
                mov     ax,y1
                mov     cx,ax
                mov     di,ax
                shl     di,6
                shl     ax,8
                add     ax,bx
                add     di,ax
                mov     dx,y2
                sub     dx,cx
                mov     cx,x2
                sub     cx,bx
                push    0a000h
                pop     es
                mov     al,color
                mov     ah,al
                shr     cx,1
                push    cx
                rep     stosw
                jnc     right
                stosb
right:
                mov     cx,dx
                jcxz    down
                pushf
next_right:
                stosb
                add     di,319
                loop    next_right
                popf
down:
                pop     cx
                dec     di
                std
                rep     stosw
                inc     di
                jnc     left
                stosb
left:
                cld
                mov     cx,dx
                jcxz    exit_rect
next_left:
                stosb
                sub     di,321
                loop    next_left
exit_rect:
                ret
rect            endp

                end