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-- Author : Julian Andres Guarin Reyes.

-- Project : JART, Just Another Ray Tracer.

-- email : jguarin2002 at gmail.com, j.guarin at javeriana.edu.co

-- This code was entirely written by Julian Andres Guarin Reyes.

-- The following code is licensed under GNU Public License

-- http://www.gnu.org/licenses/gpl-3.0.txt.

 -- This file is part of JART (Just Another Ray Tracer).

    -- JART (Just Another Ray Tracer) 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.

    -- JART (Just Another Ray Tracer) 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 JART (Just Another Ray Tracer).  If not, see <http://www.gnu.org/licenses/>.

-- A single dot product cell.

library ieee;

use ieee.std_logic_1164.all;

use work.powerGrid.all;

entity dotCell is

        generic (       levelW  : integer := 18;        -- Actual Level Width

                                nLevelW : integer := 32);       -- Next Level Width

        port    (       clk             : in std_logic;

                                rst             : in std_logic;

                                -- Object control.

                                nxtSphere       : in std_logic; -- This signal controls when the sphere center goes to the next row.

                                nxtRay          : in std_logic; -- This signal controls when the ray goes to the next column.

                                -- First Side.

                                vxInput         : in std_logic_vector(levelW-1 downto 0);

                                vyInput         : in std_logic_vector(levelW-1 downto 0);

                                vzInput         : in std_logic_vector(levelW-1 downto 0);

                                -- Second Side (Opposite to the first one)

                                vxOutput                : out std_logic_vector(levelW-1 downto 0);

                                vyOutput                : out std_logic_vector(levelW-1 downto 0);

                                vzOutput                : out std_logic_vector(levelW-1 downto 0);

                                -- Third Side (Perpendicular to the first and second ones)

                                dxInput         : in std_logic_vector(levelW-1 downto 0);

                                dyInput         : in std_logic_vector(levelW-1 downto 0);

                                dzInput         : in std_logic_vector(levelW-1 downto 0);

                                --Fourth Side (Opposite to the third one)

                                dxOutput                : out std_logic_vector(levelW-1 downto 0);

                                dyOutput                : out std_logic_vector(levelW-1 downto 0);

                                dzOutput                : out std_logic_vector(levelW-1 downto 0);

                                --Fifth Side (Going to the floor right upstairs!)

                                vdOutput                : out std_logic_vector(nLevelW-1 downto 0) -- Dot product.

        );

end entity;

architecture rtl of dotCell is

        signal s36vd    : std_logic_vector (2*LevelW-1 downto 0);

        signal s36m0    : std_logic_vector (2*levelW-1 downto 0);

        signal s36m1    : std_logic_vector (2*levelW-1 downto 0);

        signal s36m2    : std_logic_vector (2*levelW-1 downto 0);

        signal pAdd     : std_logic_vector (levelW-1 downto 0);

begin

        -- The Dotprod Machine

        -- 18x18 1 stage pipe Multipliers.

        m0      : p1m18 port map (

                aclr    => not(rst),

                clken   => nxtRay,

                clock   => clk,

                dataa   => vxInput,

                datab   => dxInput,

                result  => s36m0

                );

        m1      : p1m18 port map (

                aclr    => not(rst),

                clken   => nxtRay,

                clock   => clk,

                dataa   => vyInput,

                datab   => dyInput,

                result  => s36m1

                );

        m2      : p1m18 port map (

                aclr    => not(rst),

                clken   => nxtRay,

                clock   => clk,

                dataa   => vzInput,

                datab   => dzInput,

                result  => s36m2

                );

        --  36 bits a+b+c 1 stage pipe Adder. 

        a0      : p1ax  generic map ( W = 36 )

                                port map (

                clk             => clk,

                rst             => rst,

                enable  => nxtRay,

                dataa   => s36m0,

                datab   => s36m1,

                datac   => s36m2,

                result  => s36vd

                );

        -- Truncate the less signifcative 4 bits 35 downto 4.

        vdOutput <= s36vd (2*levelW-1 downto 2*levelW-nLevelW);

        -- Ray PipeLine

        rayPipeStage : process (clk,rst,nxtRay)

        begin

                if rst = '0' then

                        -- There is no ray load yet.

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

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

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

                elsif rising_edge (clk) and nxtRay='1' then

                        -- Set 

                        dxOutput <= dxInput;

                        dyOutput <= dyInput;

                        dzOutput <= dzInput;

                end if;

        end process;

        -- Sphere Pipe Line

        spherePipeStage : process (clk,rst,nxtSphere)

        begin

                if rst = '0' then

                -- There is no object center yet.

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

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

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

                elsif rising_edge (clk) and nxtSphere ='1' then

                        -- Shift sphere to the next row.

                        vxOutput <= vxInput;

                        vyOutput <= vyInput;

                        vzOutput <= vzInput;

                end if;

        end process;

end rtl;