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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

        --!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 s5tokena,s5tokenb,s5tokenc       : std_logic;

        signal s5token                                          : std_logic_vector (2 downto 0);

        signal s5exp,s5factor                           : std_logic_vector (7 downto 0);

        signal s5factorhot9                                     : std_logic_vector (8 downto 0);

        signal s5factorhot24                            : std_logic_vector (23 downto 0);

        signal s5result                                         : std_logic_vector (25 downto 0);

        --!TBXEND

        --!TBXSTART:STAGE6

        signal s6exp,s6factor                   : std_logic_vector(7 downto 0);

        signal s6factorhot9,s6datab_4x  : std_logic_vector(8 downto 0);

        signal s6pl,s6datab                             : std_logic_vector(17 downto 0);

        signal s6postshift                              : std_logic_vector(22 downto 0);

        signal s6result                                 : std_logic_vector(25 downto 0); -- Signed mantissa result

        signal s6ph                                             : std_logic_vector(26 downto 0);

        --!TBXEND

        --!TBXSTART:STAGE7

        signal s7sign                                   : std_logic;

        signal s7exp,s7factor                   : std_logic_vector(7 downto 0);

        signal s7postshift                              : std_logic_vector(22 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 posición 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: Denormalización 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;

                        --! Etapa 5: Codificar el corrimiento para la normalizacion de la mantissa resultante.

                        s6result                <= s5result;

                        s6exp                   <= s5exp;

                        s6factor                <= s5factor;

                        s6factorhot9    <= s5factorhot9;

                        --! Etapa 6: Ejecutar el corrimiento de la mantissa.

                        s7sign                  <= s6result(25);

                        s7exp                   <= s6exp;

                        s7factor                <= s6factor;

                        s7postshift             <= s6postshift;

                end if;

        end process;

        --! Etapa 7: Entregar el resultado.

        c32(31) <= s7sign;

        process(s7exp,s7postshift,s7factor)

        begin

                c32(30 downto 23)       <= s7exp+s7factor;

                case s7factor(4 downto 3) is

                        when "01"       => c32(22 downto 0) <= s7postshift(14 downto 00)&x"00";

                        when "10"       => c32(22 downto 0) <= s7postshift(06 downto 00)&x"0000";

                        when others => c32(22 downto 0)  <= s7postshift;

                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 posición 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));

        --! Combinatorial Gremlin, Etapa 5: Codificar el factor de normalizacion de la mantissa resultante.

        normalizerdecodeshift:

        process (s5result,s5factorhot24,s5token,s5tokena,s5tokenb,s5tokenc,s5factorhot9)

        begin

                s5tokena <= not(s5result(24));

                s5tokenb <= not(s5result(24));

                s5tokenc <= not(s5result(24));

                s5factor(7 downto 5) <= (others => s5result(24));

                s5factorhot24 <= x"000000";

                for i in 23 downto 16 loop

                        if s5result(i)='1' then

                                s5factorhot24(23-i) <= s5tokena;

                                s5tokenb <= '0';

                                s5tokenc <= '0';

                                exit;

                        end if;

                end loop;

                for i in 15 downto 8 loop

                        if s5result(i)='1' then

                                s5factorhot24(23-i) <= s5tokenb;

                                s5tokenc <= '0';

                                exit;

                        end if;

                end loop;

                for i in 7 downto 0 loop

                        if s5result(i)='1' then

                                s5factorhot24(23-i) <= s5tokenc;

                                exit;

                        end if;

                end loop;

                s5token <=s5tokena&s5tokenb&s5tokenc;

                case (s5token) is

                        when "100"  => s5factor(4 downto 3) <= "00";

                        when "110"  => s5factor(4 downto 3) <= "01";

                        when "111"      => s5factor(4 downto 3) <= "10";

                        when others => s5factor(4 downto 3) <= (others => s5result(24));

                end case;

                s5factorhot9 <= (s5factorhot24(7 downto 0)or s5factorhot24(15 downto 8)or s5factorhot24(23 downto 16)) & s5result(24);

                case s5factorhot9 is

                        when "100000000" => s5factor(2 downto 0) <= "111";

                        when "010000000" => s5factor(2 downto 0) <= "110";

                        when "001000000" => s5factor(2 downto 0) <= "101";

                        when "000100000" => s5factor(2 downto 0) <= "100";

                        when "000010000" => s5factor(2 downto 0) <= "011";

                        when "000001000" => s5factor(2 downto 0) <= "010";

                        when "000000100" => s5factor(2 downto 0) <= "001";

                        when "000000010" => s5factor(2 downto 0) <= "000";

                        when others => s5factor (2 downto 0) <= (others => s5result(24));

                end case;

        end process;

        --! Etapa 6: Ejecutar el corrimiento para normalizar la mantissa.

        s6datab <= s6result(24 downto 7);

        normhighshiftermult: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 => s6factorhot9,

                datab => s6datab,

                result => s6ph

        );

        s6datab_4x <= s6result(06 downto 0)&"00";

        normlowshiftermult: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 => s6factorhot9,

                datab => s6datab_4x,

                result => s6pl

        );

        s6postshift(22 downto 15) <= s6ph(16 downto 09);

        s6postshift(14 downto 06) <= s6ph(08 downto 00) + s6pl(17 downto 09);

        s6postshift(05 downto 00) <= s6pl(08 downto 03);

end architecture;