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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 |
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-- 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. |
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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 |
-- 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. |
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-- 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. |
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-- 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/>. |
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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. |
library ieee; |
use ieee.std_logic_1164.all; |
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entity scanFF is |
generic ( W : integer := 8); |
port ( |
clk,rst,ena,sel : std_logic; -- The usual control signals |
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d0,d1 : std_logic_vector (W-1 downto 0); -- The two operands. |
q : std_logic_vector (W-1 downto 0) -- The selected data. |
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); |
end entity; |
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architecture rtl of scanFF is |
begin |
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dff_ena_sel : process (clk,rst,ena) |
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begin |
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if rst = '0' then |
q <= '0' & (others => '1'); |
elsif rising_edge (clk) and ena = '1' then |
if sel='1' then |
q <= d1; |
else |
q <= d0; |
end if; |
end if; |
end process; |
end rtl; |
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end process; |
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end rtl; |
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