----------------------------------------------------------
--	bloc divisor d'un nombre de 30 bits entre un de 16	--
-- creat per: Lluís Magí		1999							--
----------------------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
 
ENTITY divi30bi IS

	PORT
	(
		clear_n			: in Std_Logic;
		ck				: in Std_Logic;
		dividend_in 	: in integer range 0 to (2**30)-1; -- 30 bits
		divisor_in 		: in integer range 0 to (2**16)-1; -- 16 bits
		output_enable	: out Std_Logic;
		quocient_out 	: out integer range 0 to (2**16)-1 -- 16 bits
	);
	
END divi30bi;

ARCHITECTURE divisor OF divi30bi IS

signal N 		: integer range 0 to 17 := 0;
signal flag		: std_logic;
signal dividend	: integer range -(2**30)+1 to (2**30)-1; -- 31 bits
signal divisor	: integer range -(2**30)+1 to (2**30)-1; -- 31 bits
signal quocient : integer range 0 to (2**16)-1;          -- 16 bits

BEGIN

----------------------------------------------------------
-- Mentres ens mantinguem en l'estat N=0 no es fara cap --
-- operacio. En el moment que hi ha start=1 i un flanc  --
-- de pujada del clock estarem 16 cicles fent la divisio--
-- Si en qualsevol moment clear=1, s'atura la divisio   --
-- i es torna a l'estat N=0                             --
-- Amb clear=1, el proces s'engega si en el raise del   --
-- clock start=1.      									--
----------------------------------------------------------

Proces_N:
	process (clear_n, ck)

	begin
		if clear_n = '0' then
			N <= 0;
		elsif ck'event and ck = '1' then
			if N = 17 then 
				N <= 0;
				quocient_out <= quocient;
				output_enable <= '1';
			else
				output_enable <= '0';	
				N <= N + 1;
			end if;
		end if;
	end process;

Proces_Div:
	process(clear_n, ck)
	begin
		if clear_n = '0' then
			quocient <= 0;
			dividend <= 0;
			divisor <= 0;
			output_enable <= '0';
		elsif ck'event and ck = '1' then
			if N = 0 then
				quocient <= 0;
				divisor <= divisor_in * 2**15;
				dividend <= dividend_in;
				flag <= '0';
			elsif N = 1 THEN
				dividend <= 2*dividend - divisor;
			elsif N < 16 then
				if dividend >= 0 then
					dividend <= 2*dividend - divisor;  
					quocient <= 2*quocient + 1; 
				else
					dividend <= 2*dividend + divisor; 
					quocient <= 2*quocient + 0; 
				end if;
			elsif N = 16 THEN
				if dividend < 0 then
					quocient <= 2*quocient + 0;
					dividend <= dividend + divisor;
					flag <= '1';
				else
					quocient <= 2*quocient + 1;
				end if;
				if divisor = 0 then
					quocient <= 0;
				END IF;
			end if;
		end if;
	end process;

-----------------------------------------------------------------
-- output_enable sempre val 0, excepte el últim/primer  cicle  --
-- de rellotge en el qual el quocient de la divisio es         --
-- valid, en que fa un pols d'un cicle a '1' 			       --
-----------------------------------------------------------------
	
END divisor;