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https://github.com/Nuand/bladeRF-wiphy.git
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80 lines
2.6 KiB
VHDL
80 lines
2.6 KiB
VHDL
-- This file is part of bladeRF-wiphy.
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--
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-- Copyright (C) 2020 Nuand, LLC.
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--
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-- This program 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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-- the Free Software Foundation; either version 2 of the License, or
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-- (at your option) any later version.
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--
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-- This program 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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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License along
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-- with this program; if not, write to the Free Software Foundation, Inc.,
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-- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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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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entity wlan_lfsr is
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generic (
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WIDTH : positive := 8
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) ;
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port (
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clock : in std_logic ;
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reset : in std_logic ;
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init : in unsigned(6 downto 0) ;
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init_valid : in std_logic ;
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advance : in std_logic ;
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data : out std_logic_vector(WIDTH-1 downto 0) ;
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data_valid : out std_logic
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) ;
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end entity ;
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architecture arch of wlan_lfsr is
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signal state : unsigned(6 downto 0) := (others =>'0') ;
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begin
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lfsr : process(clock, reset)
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variable tempstate : unsigned(6 downto 0) := (others =>'0') ;
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begin
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if( reset = '1' ) then
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state <= (others =>'0') ;
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data <= (others =>'0') ;
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data_valid <= '0' ;
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tempstate := (others =>'0') ;
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elsif( rising_edge(clock) ) then
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data_valid <= '0' ;
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if( init_valid = '1' ) then
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tempstate := init ;
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-- Initialize output to the first word, like a look-ahead FIFO
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for i in 0 to data'high loop
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tempstate := tempstate(5 downto 0) & (tempstate(6) xor tempstate(3)) ;
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data(i) <= tempstate(0) ;
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end loop ;
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state <= tempstate ;
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else
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data_valid <= advance ;
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if( advance = '1' ) then
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tempstate := state ;
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for i in 0 to data'high loop
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tempstate := tempstate(5 downto 0) & (tempstate(6) xor tempstate(3)) ;
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data(i) <= tempstate(0) ;
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end loop ;
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state <= tempstate ;
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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 architecture ;
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