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------------------------------------------------
--! @file fadd32.vhd
--! @brief RayTrac Floating Point Adder  
--! @author Julián Andrés Guarín Reyes
--------------------------------------------------
 
 
-- RAYTRAC (FP BRANCH)
-- Author Julian Andres Guarin
-- fadd32.vhd
-- This file is part of raytrac.
-- 
--     raytrac is free software: you can redistribute it and/or modify
--     it under the terms of the GNU General Public License as published by
--     the Free Software Foundation, either version 3 of the License, or
--     (at your option) any later version.
-- 
--     raytrac is distributed in the hope that it will be useful,
--     but WITHOUT ANY WARRANTY; without even the implied warranty of
--     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--     GNU General Public License for more details.
-- 
--     You should have received a copy of the GNU General Public License
--     along with raytrac.  If not, see <http://www.gnu.org/licenses/>
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
 
use work.arithpack.all;
 
--! Esta entidad recibe dos n&uacutemeros en formato punto flotante IEEE 754, de precision simple y devuelve las mantissas signadas y corridas, y el exponente correspondiente al resultado antes de normalizarlo al formato float. 
--!\nLas 2 mantissas y el exponente entran despues a la entidad add2 que suma las mantissas y entrega el resultado en formato IEEE 754.
entity fadd32 is
 
	port (
		clk,dpc	: in std_logic;
		a32,b32	: in xfloat32;
		c32		: out xfloat32
	);
end entity;
architecture fadd32_arch of fadd32 is
 
	--! Altera Compiler Directive, to avoid m9k autoinferring thanks to the guys at http://www.alteraforum.com/forum/archive/index.php/t-30784.html .... 
	attribute altera_attribute : string; 
	attribute altera_attribute of fadd32_arch : architecture is "-name AUTO_SHIFT_REGISTER_RECOGNITION OFF";
 
 
	--!TBXSTART:STAGE0
	signal s0delta	: std_logic_vector(7 downto 0);
	signal s0a,s0b	: std_logic_vector(31 downto 0); -- Float 32 bit 
 
	--!TBXEND
	--!TBXSTART:STAGE1
	signal s1zero											: std_logic;
	signal s1delta											: std_logic_vector(5 downto 0);
	signal s1exp											: std_logic_vector(7 downto 0);
	signal s1shifter,s1datab_8x								: std_logic_vector(8 downto 0);
	signal s1pl,s1datab										: std_logic_vector(17 downto 0);
	signal s1umantshift,s1umantfixed,s1postshift,s1xorslab	: std_logic_vector(23 downto 0);
	signal s1ph												: std_logic_vector(26 downto 0); 
	--!TBXEND
	--!TBXSTART:STAGE2
	signal s2exp 						: std_logic_vector(7 downto 0);
	signal s2xorslab 					: std_logic_vector(23 downto 0);
	signal s2umantshift, s2mantfixed	: std_logic_vector(24 downto 0);
	--!TBXEND
	--!TBXSTART:STAGE3
	signal s3exp 					: std_logic_vector(7 downto 0);
	signal s3mantfixed,s3mantshift	: std_logic_vector (24 downto 0);
	--!TBXEND
	--!TBXSTART:STAGE4
	signal s4exp 		: std_logic_vector (7 downto 0);
	signal s4xorslab	: std_logic_vector (24 downto 0);
	signal s4sresult	: std_logic_vector (25 downto 0);
	--!TBXEND
	--!TBXSTART:STAGE5
	signal s5exp		: std_logic_vector (7 downto 0);				
	signal s5result 	: std_logic_vector (25 downto 0);
	--!TBXEND
 
 
 
 
 
 
begin
 
	process (clk)
	begin
		if clk'event and clk='1'  then 
 
			--!Registro de entrada
			s0a <= a32;
			s0b(31) <= dpc xor b32(31);	--! Importante: Integrar el signo en el operando B
			s0b(30 downto 0) <= b32(30 downto 0);
 
			--!Etapa 0,Escoger el mayor exponente que sera el resultado desnormalizado, calcula cuanto debe ser el corrimiento de la mantissa con menor exponente y reorganiza los operandos, si el mayor es b, intercambia las posici&oacute;n si el mayor es a las posiciones la mantiene. Zero check.
			--!signo,exponente,mantissa
			if (s0b(30 downto 23)&s0a(30 downto 23))=x"0000" then 
				s1zero <= '0';
			else
				s1zero <= '1';
			end if;
			s1delta <= s0delta(7) & (s0delta(7) xor s0delta(4))&(s0delta(7) xor s0delta(3)) & s0delta(2 downto 0);			
			case s0delta(7) is
				when '1'  => 
					s1exp <= s0b(30 downto 23);
					s1umantshift <= s0a(31)&s0a(22 downto 0);
					s1umantfixed <= s0b(31)&s0b(22 downto 0);
				when others => 
					s1exp <= s0a(30 downto 23);
					s1umantshift <= s0b(31)&s0b(22 downto 0);
					s1umantfixed <= s0a(31)&s0a(22 downto 0);
			end case;
 
			--! Etapa 1: Denormalizaci&oacute;n de la mantissas.
			case s1delta(4 downto 3) is
				when "00" =>	s2umantshift <= s1umantshift(23)&s1postshift(23 downto 0);
				when "01" =>	s2umantshift <= s1umantshift(23)&x"00"&s1postshift(23 downto 8);
				when "10" =>	s2umantshift <= s1umantshift(23)&x"0000"&s1postshift(23 downto 16);
				when others => 	s2umantshift <= (others => '0');		
			end case;
 
			s2mantfixed <= s1umantfixed(23) & ( ( ('1'&s1umantfixed(22 downto 0)) xor s1xorslab) + ( x"00000"&"000"&s1umantfixed(23)  )   ); 
			s2exp  <= s1exp;
 
			--! Etapa2: Signar la mantissa denormalizada.
			s3mantfixed <= s2mantfixed;
			s3mantshift <= s2umantshift(24)&         (  (      s2umantshift(23 downto 0)  xor s2xorslab)   + ( x"00000"&"000"&s2umantshift(24)  )   ); 
			s3exp 		<= s2exp;
 
			--! Etapa 3: Etapa 3 Realizar la suma, entre la mantissa corrida y la fija.
			s4sresult	<= (s3mantshift(24)&s3mantshift)+(s3mantfixed(24)&s3mantfixed);
			s4exp 		<= s3exp; 
 
			--! Etapa 4: Quitar el signo a la mantissa resultante.
			s5result	<= s4sresult(25)&((s4sresult(24 downto 0) xor s4xorslab)  +(x"000000"&s4sresult(25)));
			s5exp		<= s4exp; 
 
 
 
 
 
 
		end if;
	end process;
	--! Etapa 5: Codificar el corrimiento para la normalizacion de la mantissa resultante y entregar el resultado.
	c32(31) <= s5result(25);
	process (s5result(24 downto 0))
	begin 
		case s5result(24) is
			when '1' => 
				c32 (22 downto 00) <= s5result(23 downto 1);
				c32 (30 downto 23) <= s5exp+1;
			when others => 
				c32 (22 downto 00) <= s5result(22 downto 0);
				c32 (30 downto 23) <= s5exp;
		end case;
	end process;
 
 
	--! Combinatorial gremlin, Etapa 0 el corrimiento de la mantissa con menor exponente y reorganiza los operandos,\n
	--! si el mayor es b, intercambia las posici&oacute;n si el mayor es a las posiciones la mantiene. 
	s0delta <=  s0a(30 downto 23)-s0b(30 downto 23);
	--! Combinatorial Gremlin, Etapa 1 Codificar el factor de corrimiento de denormalizacion y denormalizar la mantissa no fija. Signar la mantissa que se queda fija.
	decodeshiftfactor:
	process (s1delta(2 downto 0))
	begin
		case s1delta(2 downto 0) is
			when "111" =>  s1shifter(8 downto 0) <= '0'&s1delta(5)&"00000"&not(s1delta(5))&'0';
			when "110" =>  s1shifter(8 downto 0) <= "00"&s1delta(5)&"000"&not(s1delta(5))&"00";
			when "101" =>  s1shifter(8 downto 0) <= "000"&s1delta(5)&'0'&not(s1delta(5))&"000";
			when "100" =>  s1shifter(8 downto 0) <= '0'&x"10";
			when "011" =>  s1shifter(8 downto 0) <= "000"&not(s1delta(5))&'0'&s1delta(5)&"000";
			when "010" =>  s1shifter(8 downto 0) <= "00"&not(s1delta(5))&"000"&s1delta(5)&"00";
			when "001" =>  s1shifter(8 downto 0) <= '0'&not(s1delta(5))&"00000"&s1delta(5)&'0';
			when others => s1shifter(8 downto 0) <=    not(s1delta(5))&"0000000"&s1delta(5);
		end case;
	end process;
	s1datab <= s1zero&s1umantshift(22 downto 06);
	denormhighshiftermult:lpm_mult
	generic	map (
		lpm_hint => "DEDICATED_MULTIPLIER_CIRCUITRY=YES,MAXIMIZE_SPEED=9",
		lpm_pipeline => 0,
		lpm_representation => "UNSIGNED",
		lpm_type => "LPM_MULT",
		lpm_widtha => 9,
		lpm_widthb => 18,
		lpm_widthp => 27
	)
	port map (
		dataa => s1shifter,
		datab => s1datab,
		result => s1ph
	);	
	s1datab_8x <= s1umantshift(5 downto 0)&"000";
	denormlowshiftermult:lpm_mult
	generic map (
		lpm_hint => "DEDICATED_MULTIPLIER_CIRCUITRY=YES,MAXIMIZE_SPEED=9",
		lpm_pipeline => 0,
		lpm_representation => "UNSIGNED",
		lpm_type => "LPM_MULT",
		lpm_widtha => 9,
		lpm_widthb => 9,
		lpm_widthp => 18
	)
	port map (
		dataa => s1shifter,
		datab(8 downto 0) => s1datab_8x,
		result => s1pl
	);	
 
	s1postshift(23 downto 7) <= s1ph(25 downto 9);
	s1postshift(06 downto 0) <= s1ph(08 downto 2) or s1pl(17 downto 11);
	s1xorslab(23 downto 0) <= (others => s1umantfixed(23)); 
 
	--! Combinatorial Gremlin, Etapa 2: Signar la mantissa denormalizada. 
	s2xorslab <= (others => s2umantshift(24));
 
	--! Combinatorial Gremlin, Etapa 4: Quitar el signo de la mantissa resultante.
	s4xorslab <= (others => s4sresult(25));
 
 
 
 
 
 
 
end architecture;