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library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_signed.all;
use ieee.std_logic_arith.all;
entity AlphaBlender is
generic (
PixelWidth : natural := 8;
AlphaWidth : natural := 8
);
port(
clk : in std_logic;
alpha : in std_logic_vector(AlphaWidth-1 downto 0);
pixel1 : in std_logic_vector(PixelWidth-1 downto 0);
pixel2 : in std_logic_vector(PixelWidth-1 downto 0);
pixelout : out std_logic_vector(PixelWidth-1 downto 0)
);
end AlphaBlender;
architecture behavioral of AlphaBlender is
constant DspDataWidth : natural := 18;
constant DspCascadeWidth : natural := 48;
constant AlphaPadding : std_logic_vector(AlphaWidth-1 downto 0) := (others => '0');
signal ain : std_logic_vector(DspDataWidth-1 downto 0);
signal ain_r1 : std_logic_vector(DspDataWidth-1 downto 0) := (others => '0');
signal ain_r2 : std_logic_vector(DspDataWidth-1 downto 0) := (others => '0');
signal bin : std_logic_vector(DspDataWidth-1 downto 0);
signal cin : std_logic_vector(DspCascadeWidth-1 downto 0);
signal din : std_logic_vector(DspDataWidth-1 downto 0);
signal bin_r : std_logic_vector(DspDataWidth-1 downto 0) := (others => '0');
signal din_r : std_logic_vector(DspDataWidth-1 downto 0) := (others => '0');
signal cin_r1 : std_logic_vector(DspCascadeWidth-1 downto 0) := (others => '0');
signal cin_r2 : std_logic_vector(DspCascadeWidth-1 downto 0) := (others => '0');
signal cin_r3 : std_logic_vector(DspCascadeWidth-1 downto 0) := (others => '0');
signal preadd_r : std_logic_vector(DspDataWidth-1 downto 0) := (others => '0');
signal mult_r : std_logic_vector(2*DspDataWidth-1 downto 0) := (others => '0');
signal sum_r : std_logic_vector(DspCascadeWidth-1 downto 0) := (others => '0');
begin
bin <= ext(pixel1 & AlphaPadding, DspDataWidth);
cin <= ext(pixel1 & AlphaPadding & AlphaPadding, DspCascadeWidth);
din <= ext(pixel2 & AlphaPadding, DspDataWidth);
ain <= ext(alpha, DspDataWidth);
addmultadd : process (clk)
begin
if rising_edge(clk) then
ain_r1 <= ain;
ain_r2 <= ain_r1;
bin_r <= bin;
din_r <= din;
cin_r1 <= cin;
cin_r2 <= cin_r1;
cin_r3 <= cin_r2;
preadd_r <= din_r - bin_r;
mult_r <= preadd_r * ain_r2;
sum_r <= mult_r + cin_r3;
end if;
end process addmultadd;
pixelout <= sum_r(2*AlphaWidth+PixelWidth-1 downto 2*AlphaWidth);
end behavioral;
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