##########################################################################                                                              ########  coder.py                                                    ########                                                              ########  This file is part of the turbo decoder IP core project      ########  http://www.opencores.org/projects/turbocodes/               ########                                                              ########  Author(s):                                                  ########      - David Brochart(dbrochart@opencores.org)               ########                                                              ########  All additional information is available in the README.txt   ########  file.                                                       ########                                                              ##############################################################################                                                              ######## Copyright (C) 2005 Authors                                   ########                                                              ######## This source file may be used and distributed without         ######## restriction provided that this copyright statement is not    ######## removed from the file and that any derivative work contains  ######## the original copyright notice and the associated disclaimer. ########                                                              ######## This source file is free software; you can redistribute it   ######## and/or modify it under the terms of the GNU Lesser General   ######## Public License as published by the Free Software Foundation; ######## either version 2.1 of the License, or (at your option) any   ######## later version.                                               ########                                                              ######## This source 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 Lesser General Public License for more  ######## details.                                                     ########                                                              ######## You should have received a copy of the GNU Lesser General    ######## Public License along with this source; if not, download it   ######## from http://www.opencores.org/lgpl.shtml                     ########                                                              ##########################################################################from myhdl import Signal, posedge, negedge, always_comb, instancesdef coderState(clk, rst, a, b, q1, q2, q3):    """ Coder state registers.    clk, rst    -- in  : clock and negative reset    a, b        -- in  : original data    q1, q2, q3  -- out : coder registers    """    while 1:        if rst.val == 0:            q1.next = 0            q2.next = 0            q3.next = 0        else:            q1.next = a.val ^ b.val ^ q1.val ^ q3.val            q2.next = q1.val ^ b.val            q3.next = q2.val ^ b.val        yield posedge(clk), negedge(rst)def coderY1Y2(a, b, q1, q2, q3, y1, y2):    """ Coder redundant output generation.    a, b        -- in  : original data signals    q1, q2, q3  -- in  : coder registers    y1, y2      -- out : coder redundant data signals    """    def coderY1Y2Logic():        y1.next = a.val ^ b.val ^ q1.val ^ q3.val ^ q2.val ^ q3.val        y2.next = a.val ^ b.val ^ q1.val ^ q3.val ^ q3.val    return always_comb(coderY1Y2Logic)def coder(clk, rst, a, b, y1, y2):    """ Coder top level.    clk, rst    -- in  : clock and negative reset    a, b        -- in  : original data signals (= systematic data)    y1, y2      -- out : coder redundant data signals    """    q1 = Signal(bool(0))    q2 = Signal(bool(0))    q3 = Signal(bool(0))    coderState_i0 = coderState(clk, rst, a, b, q1, q2, q3)    coderY1Y2_i0  = coderY1Y2(a, b, q1, q2, q3, y1, y2)    return instances()