NASM Rectangle

org 256

mov ax, 0x0013
int 0x10
push 15
push 20
push 50
push 150
push 149
call rectangle
add sp, 10

while:
        mov ah, 0
        int 0x16
        cmp al, 'q'
jnz while

mov ah, 0x00
mov al, 0x03
int 0x10
ret

rectangle:
        push bp
        mov bp, sp
        push bx
        push ds
        push si
        push ax
        push cx
        mov bx, 0xA000 ; Сегмент с видеопамятью
        mov ds, bx
        mov ax, [bp + 8] ; y1
        mov bx, 320
        mul bx
        mov bx, ax ; in bx — zeroth byte of line y1
        mov cl, [bp + 12] ; color
        mov ax, [bp + 4]  ; y2
        mov si, 320
        mul si
        mov si, ax
        sub si, bx ; si — offset between top and bottom lines
        mov ax, bx
        add ax, [bp + 6]  ; add x2, in ax — x2 byte of line y1
        add bx, [bp + 10] ; add x1, in bx — x1 byte of line y1
        rect_while1:
                mov [bx], cl
                mov [bx + si], cl
                inc bx
                cmp bx, ax
        jnz rect_while1
        mov ax, [bp + 8] ; y1
        mov bx, 320
        mul bx
        mov bx, ax
        add bx, [bp + 10] ; add x1, in bx — x1 byte of line y1
        mov si, 320
        mov ax, [bp + 4]  ; y2
        mul si
        add si, [bp + 6]  ; x2
        sub si, [bp + 10] ; sub x1, now si — offset between left and right lines
        add ax, [bp + 10] ; add x1
        rect_while2:
                mov [bx], cl
                mov [bx + si], cl
                add bx, 320
                cmp bx, ax
        jnz rect_while2
        pop cx
        pop ax
        pop si
        pop ds
        pop bx
        pop bp
ret