problem with variables values

[nulon]

Hi!

I'm writing a program in VHDL which should draw a line on the monitor. I have implemented vga_sync module, RAM memory and other necesarry things. Almost everything is OK. So i don't know what is happening with variables values

I have a process which is writing to memory pixel coordinates in resolution 80x60 at the Altera UP-2 (Flex 10K) Board.

bresenham :process

variable punkt1_x : std_logic_vector(6 downto 0) 	:= CONV_STD_LOGIC_VECTOR(20,7);
variable punkt2_x : std_logic_vector(6 downto 0)	:= CONV_STD_LOGIC_VECTOR(20,7);
variable punkt1_y : std_logic_vector(6 downto 0)	:= CONV_STD_LOGIC_VECTOR(40,7);
variable punkt2_y : std_logic_vector(6 downto 0)	:= CONV_STD_LOGIC_VECTOR(40,7);

variable i	:integer;

variable delta_x : std_logic_vector (6 downto 0) ;
variable delta_y : std_logic_vector (6 downto 0) ;

variable det  : std_logic_vector (6 downto 0) ;

variable flag2 : std_logic ;

begin
WAIT UNTIL flag'event and flag='1';

if punkt2_y >= punkt1_y then
	flag2 := '0';
	delta_y := punkt2_y - punkt1_y;
else 
	flag2 := '1';
	delta_y := punkt1_y - punkt2_y;
end if;

delta_x := punkt2_x - punkt1_x;
pixels_to_save <= "1";
if delta_x = "0000000" and delta_y = "0000000" then
	adres_pixela_w <= "0100101001010";	
else
	adres_pixela_w <= "0110111001110";	

	if delta_x = "0000000" then 
			if punkt2_y >= punkt1_y  then 
				punkt1_y := punkt1_y + 1;
				--p1_y <= punkt1_y;
			else 
				punkt1_y := punkt1_y - 1;
				--p1_y <= punkt1_y;
			end if;		
	elsif delta_y = "0000000" then 
			if punkt2_x >= punkt1_x then 
				punkt1_x := punkt1_x + 1;
				--p1_x <= punkt1_x;
			else 
				punkt1_x := punkt1_x + 1;
				--p1_x <= punkt1_x;
			end if;
	else 

	if delta_x >"0000000" then
		if flag2= '0' then 
			if delta_x >= delta_y then 
				det  := delta_y(5 downto 0)&"0" - delta_x;
				if det >= "0000000" then 
						punkt1_x := punkt1_x + "0000001";
						punkt1_y := punkt1_y + "0000001";
						--p1_x <= punkt1_x;
						--p1_y <= punkt1_y;	
				else
					punkt1_x := punkt1_x +1;
					--p1_x <= punkt1_x;
				end if;		
			else
				det  := delta_x(5 downto 0)&"0" - delta_y;
				if det >= "0000000"  then 
					punkt1_x := punkt1_x + "0000001";
					punkt1_y := punkt1_y + "0000001";
					--p1_x <= punkt1_x;
					--p1_y <= punkt1_y;		
				else
					punkt1_y := punkt1_y + "0000001";
					--p1_y <= punkt1_y;		
				end if;
			end if;		
			
		else --delta_y < 0
			if delta_x >= delta_y then 
				det  := delta_y(5 downto 0)&"0" - delta_x;
				if det >= "0000000"  then 
					punkt1_x := punkt1_x + "0000001";
					punkt1_y := punkt1_y - "0000001";
					--p1_x <= punkt1_x;
					--p1_y <= punkt1_y;	
				else
					punkt1_x := punkt1_x + "0000001";
					--p1_x <= punkt1_x;
				end if;	
					
			else --przyrasta po y
				det  := delta_x(5 downto 0)&"0" - delta_y;
				if det >= "0000000"  then 
					punkt1_x := punkt1_x + "0000001";
					punkt1_y := punkt1_y - "0000001";
					--p1_x <= punkt1_x;
					--p1_y <= punkt1_y;	
				else 
					punkt1_y := punkt1_y - "0000001";
					--p1_y <= punkt1_y;			
				end if;
						
			end if;
   		 end if;
end if ;	
end if ;
end if;

end process bresenham;

Siganl flag in the high is determining that we can write to the memory.

And the main problem is here :
if delta_x = "0000000" and delta_y = "0000000" then
	adres_pixela_w <= "0110111001110";
else
      adres_pixela_w <= "0110111001110";
end if;

As you can see the value of delta_x and delta_y is constant and equal 0. So WHY this process is writing two points not one.

The adres_pixela_w is a signal which is determining the address in memory.

link to the complete project is here

http://student.agh.edu.pl/~dzmuda/put_pixel.zip

Can anybody say me why it is happening?

Thanks a lot,
Daniel.