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lustrec-tests / vhdl_json / vhdl_files / 2-exportOK / cnes_guidelines / rule / data / STD_06100_good.vhd @ 2051e520

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1 2051e520 Arnaud Dieumegard
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-- Company   : CNES
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-- Author    : Mickael Carl (CNES)
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-- Copyright : Copyright (c) CNES.
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-- Licensing : GNU GPLv3
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-- Version         : V1
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-- Version history :
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--    V1 : 2015-04-08 : Mickael Carl (CNES): Creation
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-- File name          : STD_06100_good.vhd
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-- File Creation date : 2015-04-08
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-- Project name       : VHDL Handbook CNES Edition
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-- Softwares             :  Microsoft Windows (Windows 7) - Editor (Eclipse + VEditor)
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-- Description : Handbook example: Range direction for std_logic_vector: good example
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--
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-- Limitations : This file is an example of the VHDL handbook made by CNES. It is a stub aimed at
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--               demonstrating good practices in VHDL and as such, its design is minimalistic.
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--               It is provided as is, without any warranty.
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--               This example is compliant with the Handbook version 1.
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--
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-- Naming conventions:
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--
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-- i_Port: Input entity port
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-- o_Port: Output entity port
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-- b_Port: Bidirectional entity port
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-- g_My_Generic: Generic entity port
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--
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-- c_My_Constant: Constant definition
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-- t_My_Type: Custom type definition
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--
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-- My_Signal_n: Active low signal
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-- v_My_Variable: Variable
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-- sm_My_Signal: FSM signal
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-- pkg_Param: Element Param coming from a package
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--
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-- My_Signal_re: Rising edge detection of My_Signal
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-- My_Signal_fe: Falling edge detection of My_Signal
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-- My_Signal_rX: X times registered My_Signal signal
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--
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-- P_Process_Name: Process
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--
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library IEEE;
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use IEEE.std_logic_1164.all;
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use IEEE.numeric_std.all;
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--CODE
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entity STD_06100_good is
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   port (
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      i_Clock   : in  std_logic;        -- Main clock signal
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      i_Reset_n : in  std_logic;        -- Main reset signal
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      i_Enable  : in  std_logic;        -- Enables the counter
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      i_Length  : in  std_logic_vector(3 downto 0);  -- Unsigned Value for Counter Period
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      o_Count   : out std_logic_vector(3 downto 0)  -- Counter (unsigned value)
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      );
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end STD_06100_good;
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architecture Behavioral of STD_06100_good is
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   signal Count        : unsigned(3 downto 0);  -- Counter output signal (unsigned converted)
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   signal Count_Length : unsigned(3 downto 0);  -- Length input signal (unsigned converted)
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begin
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--CODE
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   Count_Length <= unsigned(i_Length);
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   -- Will count undefinitely from 0 to i_Length while i_Enable is asserted
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   P_Count : process(i_Reset_n, i_Clock)
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   begin
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      if (i_Reset_n = '0') then
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         Count <= (others => '0');
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      elsif (rising_edge(i_Clock)) then
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            if (Count >= Count_Length) then  -- Counter restarts from 0
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               Count <= (others => '0');
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            elsif (i_Enable = '1') then      -- Increment counter value
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               Count <= Count + 1;
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            end if;
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      end if;
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   end process;
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   o_Count <= std_logic_vector(Count);
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end Behavioral;