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-- Copyright (c) 2003 Mentor Graphics Corporation
-- This model is a component of the Mentor Graphics VHDL-AMS educational open 
-- source model library, and is covered by this license agreement. This model,
-- including any updates, modifications, revisions, copies, and documentation 
-- are copyrighted works of Mentor Graphics. USE OF THIS MODEL INDICATES YOUR 
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-- notice that this model has been modified and the date of modification; and 
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-- THIS MODEL IS LICENSED TO YOU "AS IS" AND WITH NO WARRANTIES, EXPRESS OR 
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-- File       : controller_totem.vhd
-- Author     : Mentor Graphics
-- Created    : 2003-05-30
-- Last update: 
-------------------------------------------------------------------------------
-- Description: Driver control logic with tri-state capability. Controls pull-up and
-- pull-down modules (switches) arranged as a totem-pole output stage. For input
-- d_input = '1', the non-inverting output d_output_ninv <= '1' (turns the pull-up
-- element "On") and the inverting output d_output_inv <= '0' (turns the pull-down
-- element "Off"). If the input is '0', the opposite happens. For any other input
-- value (e.g. 'Z'), both outputs go to '0', which turns both the pull-up and pull-down 
-- modules "Off", to produce a high impedance (analog) output condition.
-- Note: The Pull-up and Pull-down modules can be switch_nonlinear.vhd, switch_pwl_iv.vhd, 
-- or any other user-defined switch model.
-------------------------------------------------------------------------------
-- Revisions  :
-- Date        Version     Author              Description
-- 2003-05-30  1.0         Mentor Graphics     Created
-------------------------------------------------------------------------------

library IEEE;
use IEEE.std_logic_1164.all;

entity controller_totem is
	port (
    	d_input      : in  std_logic;
		d_output_ninv  : out std_logic;  -- Non-inverting output (goes to pull-up)
    	d_output_inv : out std_logic     -- Inverting output (goes to pull-down)
		);
end entity controller_totem;

architecture behavioral of controller_totem is  
begin  
	process (d_input) is
	begin
    	if (d_input = '1') then
			d_output_ninv <= '1';
      		d_output_inv <= '0';
		elsif (d_input = '0') then
			d_output_ninv <= '0';
      		d_output_inv <= '1';
		else		-- High-impedance or "weak" input state ('Z' or 'L' or 'H' or other)
	 		d_output_ninv <= '0';
     		d_output_inv <= '0';
     	end if;
  	end process; 
end architecture behavioral;

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-- Copyright (c) 2003 Mentor Graphics Corporation
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