initvars.asm

;Initializes AMOUNT_OF_SQUARES_HORIZONTAL, HORIZONTAL_OFFSET, AMOUNT_OF_SQUARES_VERTICAL, VERTICAL_OFFSET
proc InitVars
	xor dx, dx
	mov ax, SCREEN_WIDTH
	div [SQUARE_SIZE]
	mov [AMOUNT_OF_SQUARES_HORIZONTAL], ax; SCREEN_WIDTH / SQUARE_SIZE 
	mov [HORIZONTAL_OFFSET], dl; SCREEN_WIDTH % SQUARE_SIZE
	
	xor dx, dx
	mov ax, SCREEN_HEIGHT
	div [SQUARE_SIZE]
	mov [AMOUNT_OF_SQUARES_VERTICAL], ax; SCREEN_HEIGHT / SQUARE_SIZE
	mov [VERTICAL_OFFSET], dl; SCREEN_HEIGHT % SQUARE_SIZE
	
	
	mov ax, SCREEN_HEIGHT
	sub al, dl; dl == VERTICAL_OFFSET from previus calculation
	mov [LEN_VERTICAL], ax; SCREEN_HEIGHT - (SCREEN_HEIGHT % SQUARE_SIZE)
	
	;SCREEN_WIDTH > FFH, calculation needs to occur inside a word
	mov ax, SCREEN_WIDTH
	xor bh, bh
	mov bl, [HORIZONTAL_OFFSET]
	sub ax, bx
	mov [LEN_HORIZONTAL], ax; 
ret
endp initVars