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--! @file mul2.vhd

--! @brief RayTrac Mantissa Multiplier  

--! @author Julián Andrés Guarín Reyes

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-- RAYTRAC (FP BRANCH)

-- Author Julian Andres Guarin

-- mmp.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_arith.all;

use ieee.std_logic_unsigned.all;

library lpm;

use lpm.all;

entity mul2 is

        port (

                clk             : in std_logic;

                a32,b32         : in std_logic_vector(31 downto 0);

                p32                     : out std_logic_vector(31 downto 0)

        );

end mul2;

architecture mul2_arch of mul2 is

        component lpm_mult

        generic (

                lpm_hint                        : string;

                lpm_pipeline            : natural;

                lpm_representation      : string;

                lpm_type                        : string;

                lpm_widtha                      : natural;

                lpm_widthb                      : natural;

                lpm_widthp                      : natural

        );

        port (

                dataa   : in std_logic_vector ( lpm_widtha-1 downto 0 );

                datab   : in std_logic_vector ( lpm_widthb-1 downto 0 );

                result  : out std_logic_vector ( lpm_widthp-1 downto 0 )

        );

        end component;

        --Stage 0 signals

        signal s0sga,s0sgb,s0zrs,s1sgr,s2sgr:std_logic;

        signal s0exa,s0exb,s1exp,s2exp:std_logic_vector(7 downto 0);

        signal s0exp : std_logic_vector(8 downto 0);

        signal s0uma,s0umb:std_logic_vector(22 downto 0);

        signal s0ad,s0bc,s1ad,s1bc:std_logic_vector(23 downto 0);

        signal s0ac:std_logic_vector(35 downto 0);

        signal s1ac,s1umu:std_logic_vector(35 downto 0);

        signal s2umu:std_logic_vector(24 downto 0);

begin

        process(clk)

        begin

                if clk'event and clk='1' then

                        --! Registro de entrada

                        s0sga <= a32(31);

                        s0sgb <= b32(31);

                        s0exa <= a32(30 downto 23);

                        s0exb <= b32(30 downto 23);

                        s0uma <= a32(22 downto 0);

                        s0umb <= b32(22 downto 0);

                        --! Etapa 0 multiplicacion de la mantissa, suma de los exponentes y multiplicación de los signos.

                        s1sgr <= s0sga xor s0sgb;

                        s1ad <= s0ad;

                        s1bc <= s0bc;

                        s1ac <= s0ac;

                        s1exp <= s0exp(7 downto 0);

                        --! Etapa 1 Sumas parciales

                        s2umu <= s1umu(35 downto 11);

                        s2sgr <= s1sgr;

                        s2exp <= s1exp;

                        --! Etapa 2 entregar el resultado

                        p32(31) <= s2sgr;

                        p32(30 downto 23) <= s2exp+s2umu(24);

                        if s2umu(24) ='1' then

                                p32(22 downto 0) <= s2umu(23 downto 1);

                        else

                                p32(22 downto 0) <= s2umu(22 downto 0);

                        end if;

                end if;

        end process;

        --! Combinatorial Gremlin Etapa 0 : multiplicacion de la mantissa, suma de los exponentes y multiplicación de los signos.

        --! Multipliers

        mult18x18ac:lpm_mult

        generic map ("DEDICATED_MULTIPLIER_CIRCUITRY=YES,MAXIMIZE_SPEED=9",0,"UNSIGNED","LPM_MULT",18,18,36)

        port    map (s0zrs&s0uma(22 downto 6),s0zrs&s0umb(22 downto 6),s0ac);

        mult18x6ad:lpm_mult

        generic map ("DEDICATED_MULTIPLIER_CIRCUITRY=YES,MAXIMIZE_SPEED=9",0,"UNSIGNED","LPM_MULT",18,6,24)

        port    map (s0zrs&s0uma(22 downto 6),s0umb(5 downto 0),s0ad);

        mult18x6bc:lpm_mult

        generic map ("DEDICATED_MULTIPLIER_CIRCUITRY=YES,MAXIMIZE_SPEED=9",0,"UNSIGNED","LPM_MULT",18,6,24)

        port    map (s0zrs&s0umb(22 downto 6),s0uma(5 downto 0),s0bc);

        --! Exponent Addition 

        process (s0sga,s0sgb,s0exa,s0exb)

                variable i8s0exa,i8s0exb: integer range 0 to 255;

        begin

                i8s0exa:=conv_integer(s0exa);

                i8s0exb:=conv_integer(s0exb);

                if i8s0exa = 0 or i8s0exb = 0  then

                        s0exp <= (others => '0');

                        s0zrs <= '0';

                else

                        s0zrs<='1';

                        s0exp <= conv_std_logic_vector(i8s0exb+i8s0exa+129,9);

                end if;

        end process;

        --! Etapa 1: Suma parcial de la multiplicacion. Suma del exponente      

        process(s1ac,s1ad,s1bc)

        begin

                s1umu <= s1ac+s1ad(23 downto 6)+s1bc(23 downto 6);

        end process;

end mul2_arch;