-- Author : Julian Andres Guarin Reyes.
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-- Author : Julian Andres Guarin Reyes.
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-- Project : JART, Just Another Ray Tracer.
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-- Project : JART, Just Another Ray Tracer.
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-- email : jguarin2002 at gmail.com, j.guarin at javeriana.edu.co
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-- email : jguarin2002 at gmail.com, j.guarin at javeriana.edu.co
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-- This code was entirely written by Julian Andres Guarin Reyes.
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-- This code was entirely written by Julian Andres Guarin Reyes.
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-- The following code is licensed under GNU Public License
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-- The following code is licensed under GNU Public License
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-- http://www.gnu.org/licenses/gpl-3.0.txt.
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-- http://www.gnu.org/licenses/gpl-3.0.txt.
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-- This file is part of JART (Just Another Ray Tracer).
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-- This file is part of JART (Just Another Ray Tracer).
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-- JART (Just Another Ray Tracer) is free software: you can redistribute it and/or modify
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-- JART (Just Another Ray Tracer) is free software: you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation, either version 3 of the License, or
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-- the Free Software Foundation, either version 3 of the License, or
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-- (at your option) any later version.
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-- (at your option) any later version.
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-- JART (Just Another Ray Tracer) is distributed in the hope that it will be useful,
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-- JART (Just Another Ray Tracer) is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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-- GNU General Public License for more details.
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-- You should have received a copy of the GNU General Public License
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-- You should have received a copy of the GNU General Public License
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-- along with JART (Just Another Ray Tracer). If not, see <http://www.gnu.org/licenses/>.
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-- along with JART (Just Another Ray Tracer). If not, see <http://www.gnu.org/licenses/>.
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-- A scan flipflop hdl code. Note the logic function q <= (s0 and s ) or (s1 and ~s) its a mux with s as selector and s0 and s1 as selectable inputs.
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-- A scan flipflop hdl code. Note the logic function q <= (s0 and s ) or (s1 and ~s) its a mux with s as selector and s0 and s1 as selectable inputs.
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library ieee;
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_1164.all;
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entity scanFF is
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entity scanFF is
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generic ( W : integer := 8);
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generic ( W : integer := 8);
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port (
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port (
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clk,rst,ena,sel : std_logic; -- The usual control signals
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clk,rst,ena,sel : in std_logic; -- The usual control signals
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d0,d1 : std_logic_vector (W-1 downto 0); -- The two operands.
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d0,d1 : in std_logic_vector (W-1 downto 0); -- The two operands.
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q : std_logic_vector (W-1 downto 0) -- The selected data.
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q : out std_logic_vector (W-1 downto 0) -- The selected data.
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);
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);
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end entity;
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end entity;
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architecture rtl of scanFF is
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architecture rtl of scanFF is
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signal mux: std_logic_vector (W-1 downto 0);
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begin
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begin
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dff_ena_sel :for i in 0 to W-1 generate
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mux(i) <= (d1(i) and sel) or (d0(i) and not(sel));
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dff_ena_sel : process (clk,rst,ena)
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process (clk,rst,ena)
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begin
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begin
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if rst = '0' then
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if rst = '0' then
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q <= '0' & (others => '1');
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q(i) <= '1';
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elsif rising_edge (clk) and ena = '1' then
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elsif rising_edge (clk) and ena = '1' then
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if sel='1' then
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q(i) <= mux(i);
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q <= d1;
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else
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q <= d0;
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end if;
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end if;
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end if;
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end process;
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end process;
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end generate;
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end rtl;
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end rtl;
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