--!
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--!
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--! Copyright (C) 2011 - 2012 Creonic GmbH
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--! Copyright (C) 2011 - 2014 Creonic GmbH
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--!
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--!
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--! This file is part of the Creonic Viterbi Decoder, which is distributed
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--! This file is part of the Creonic Viterbi Decoder, which is distributed
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--! under the terms of the GNU General Public License version 2.
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--! under the terms of the GNU General Public License version 2.
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--!
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--!
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--! @file
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--! @file
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--! @brief Trellis parameter calculations (e.g., transitions, init values).
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--! @brief Trellis parameter calculations (e.g., transitions, init values).
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--! @author Markus Fehrenz
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--! @author Markus Fehrenz
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--! @date 2011/07/27
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--! @date 2011/07/27
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--!
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--!
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--!
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--!
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library ieee;
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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use ieee.numeric_std.all;
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library dec_viterbi;
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library dec_viterbi;
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use dec_viterbi.pkg_param.all;
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use dec_viterbi.pkg_param.all;
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use dec_viterbi.pkg_param_derived.all;
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use dec_viterbi.pkg_param_derived.all;
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use dec_viterbi.pkg_types.all;
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use dec_viterbi.pkg_types.all;
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package pkg_trellis is
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package pkg_trellis is
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type t_prev_base is array (1 downto 0) of std_logic_vector(BW_TRELLIS_STATES - 1 downto 0);
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type t_prev_base is array (1 downto 0) of std_logic_vector(BW_TRELLIS_STATES - 1 downto 0);
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type t_previous_states is array (NUMBER_TRELLIS_STATES - 1 downto 0) of t_prev_base;
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type t_previous_states is array (NUMBER_TRELLIS_STATES - 1 downto 0) of t_prev_base;
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type t_trans_base is array (1 downto 0) of std_logic_vector(NUMBER_PARITY_BITS - 1 downto 0);
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type t_trans_base is array (1 downto 0) of std_logic_vector(NUMBER_PARITY_BITS - 1 downto 0);
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type t_transitions is array (NUMBER_TRELLIS_STATES - 1 downto 0) of t_trans_base;
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type t_transitions is array (NUMBER_TRELLIS_STATES - 1 downto 0) of t_trans_base;
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type t_trans_base_signed is array (1 downto 0) of std_logic_vector(NUMBER_PARITY_BITS downto 0);
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type t_trans_base_signed is array (1 downto 0) of std_logic_vector(NUMBER_PARITY_BITS downto 0);
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type t_transitions_signed is array (NUMBER_TRELLIS_STATES - 1 downto 0) of t_trans_base_signed;
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type t_transitions_signed is array (NUMBER_TRELLIS_STATES - 1 downto 0) of t_trans_base_signed;
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--
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--
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-- This function calculates the previous states of each state.
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-- This function calculates the previous states of each state.
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-- The values are used to connect the ACS units.
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-- The values are used to connect the ACS units.
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--
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--
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function calc_previous_states return t_previous_states;
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function calc_previous_states return t_previous_states;
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--
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--
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-- This function calculates corresponding transitions to a trellis sate.
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-- This function calculates corresponding transitions to a trellis sate.
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-- The values are used to connect branch units to ACS units.
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-- The values are used to connect branch units to ACS units.
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--
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--
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function calc_transitions return t_transitions;
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function calc_transitions return t_transitions;
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--
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--
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-- This function calculates the initialization values for trellis metrics.
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-- This function calculates the initialization values for trellis metrics.
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-- The values are used as a constant and written to the ACS unit, every time a new block arrives.
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-- The values are used as a constant and written to the ACS unit, every time a new block arrives.
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--
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--
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function calc_initialize return t_node_s;
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function calc_initialize return t_node_s;
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constant PREVIOUS_STATES : t_previous_states;
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constant PREVIOUS_STATES : t_previous_states;
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constant TRANSITIONS : t_transitions;
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constant TRANSITIONS : t_transitions;
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constant INITIALIZE_TRELLIS : t_node_s;
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constant INITIALIZE_TRELLIS : t_node_s;
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end package pkg_trellis;
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end package pkg_trellis;
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package body pkg_trellis is
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package body pkg_trellis is
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function calc_previous_states return t_previous_states is
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function calc_previous_states return t_previous_states is
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variable v_prev_states : t_previous_states := (others=>(others=>(others => '0')));
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variable v_prev_states : t_previous_states := (others=>(others=>(others => '0')));
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variable v_state0, v_state1 : std_logic_vector(BW_TRELLIS_STATES - 1 downto 0);
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variable v_state0, v_state1 : std_logic_vector(BW_TRELLIS_STATES - 1 downto 0);
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begin
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begin
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for i in NUMBER_TRELLIS_STATES - 1 downto 0 loop
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for i in NUMBER_TRELLIS_STATES - 1 downto 0 loop
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v_state0 := std_logic_vector(to_unsigned(i,BW_TRELLIS_STATES));
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v_state0 := std_logic_vector(to_unsigned(i,BW_TRELLIS_STATES));
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v_state1 := v_state0(BW_TRELLIS_STATES - 2 downto 0) & '0';
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v_state1 := v_state0(BW_TRELLIS_STATES - 2 downto 0) & '0';
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v_prev_states(i)(0) := v_state1;
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v_prev_states(i)(0) := v_state1;
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v_state1 := v_state0(BW_TRELLIS_STATES - 2 downto 0) & '1';
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v_state1 := v_state0(BW_TRELLIS_STATES - 2 downto 0) & '1';
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v_prev_states(i)(1) := v_state1;
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v_prev_states(i)(1) := v_state1;
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end loop;
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end loop;
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return v_prev_states;
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return v_prev_states;
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end function calc_previous_states;
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end function calc_previous_states;
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function calc_transitions return t_transitions is
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function calc_transitions return t_transitions is
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variable v_transitions : t_transitions_signed := (others => (others => (others => '0')));
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variable v_transitions : t_transitions_signed := (others => (others => (others => '0')));
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variable v_transitions_out : t_transitions := (others => (others => (others => '0')));
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variable v_transitions_out : t_transitions := (others => (others => (others => '0')));
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variable v_one_transition : std_logic_vector(NUMBER_PARITY_BITS - 1 downto 0);
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variable v_one_transition : std_logic_vector(NUMBER_PARITY_BITS - 1 downto 0);
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variable v_next_state : unsigned(ENCODER_MEMORY_DEPTH - 1 downto 0) := (others => '0');
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variable v_next_state : unsigned(ENCODER_MEMORY_DEPTH - 1 downto 0) := (others => '0');
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variable v_state, v_states : unsigned(ENCODER_MEMORY_DEPTH downto 0);
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variable v_state, v_states : unsigned(ENCODER_MEMORY_DEPTH downto 0);
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variable v_bit : std_logic := '0';
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variable v_bit : std_logic := '0';
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begin
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begin
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--
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--
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-- It is possible to reduce code size at this stage, if feedback is handled differently,
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-- It is possible to reduce code size at this stage, if feedback is handled differently,
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-- but the complexity will increase.
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-- but the complexity will increase.
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--
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--
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for i in NUMBER_TRELLIS_STATES - 1 downto 0 loop
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for i in NUMBER_TRELLIS_STATES - 1 downto 0 loop
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--
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--
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-- for input : 0
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-- for input : 0
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-- determine correct input with feedback
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-- determine correct input with feedback
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--
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--
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v_next_state := to_unsigned(i,ENCODER_MEMORY_DEPTH) and to_unsigned(FEEDBACK_POLYNOMIAL, ENCODER_MEMORY_DEPTH);
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v_next_state := to_unsigned(i,ENCODER_MEMORY_DEPTH) and to_unsigned(FEEDBACK_POLYNOMIAL, ENCODER_MEMORY_DEPTH);
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for k in ENCODER_MEMORY_DEPTH - 1 downto 0 loop
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for k in ENCODER_MEMORY_DEPTH - 1 downto 0 loop
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v_bit := v_bit xor v_next_state(k);
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v_bit := v_bit xor v_next_state(k);
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end loop;
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end loop;
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v_state(ENCODER_MEMORY_DEPTH) := v_bit;
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v_state(ENCODER_MEMORY_DEPTH) := v_bit;
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v_state(ENCODER_MEMORY_DEPTH - 1 downto 0) := to_unsigned(i,ENCODER_MEMORY_DEPTH);
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v_state(ENCODER_MEMORY_DEPTH - 1 downto 0) := to_unsigned(i,ENCODER_MEMORY_DEPTH);
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v_next_state := v_state(ENCODER_MEMORY_DEPTH downto 1);
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v_next_state := v_state(ENCODER_MEMORY_DEPTH downto 1);
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v_bit := '0';
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v_bit := '0';
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-- determine paritybits
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-- determine paritybits
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for j in NUMBER_PARITY_BITS - 1 downto 0 loop
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for j in NUMBER_PARITY_BITS - 1 downto 0 loop
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v_states := v_state and to_unsigned(PARITY_POLYNOMIALS(j), ENCODER_MEMORY_DEPTH + 1);
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v_states := v_state and to_unsigned(PARITY_POLYNOMIALS(j), ENCODER_MEMORY_DEPTH + 1);
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for k in ENCODER_MEMORY_DEPTH downto 0 loop
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for k in ENCODER_MEMORY_DEPTH downto 0 loop
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v_bit := v_bit xor v_states(k);
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v_bit := v_bit xor v_states(k);
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end loop;
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end loop;
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v_one_transition(j) := v_bit;
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v_one_transition(j) := v_bit;
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v_bit := '0';
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v_bit := '0';
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end loop;
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end loop;
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-- decide where to save the parity result
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-- decide where to save the parity result
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if v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) = '0' then
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if v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) = '0' then
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) := '1';
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) := '1';
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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else
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else
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v_transitions(to_integer(v_next_state))(0)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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v_transitions(to_integer(v_next_state))(0)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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end if;
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end if;
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--
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--
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-- for input: 1
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-- for input: 1
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-- determine correct input with feedback
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-- determine correct input with feedback
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--
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--
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v_next_state := to_unsigned(i,ENCODER_MEMORY_DEPTH) and to_unsigned(FEEDBACK_POLYNOMIAL, ENCODER_MEMORY_DEPTH);
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v_next_state := to_unsigned(i,ENCODER_MEMORY_DEPTH) and to_unsigned(FEEDBACK_POLYNOMIAL, ENCODER_MEMORY_DEPTH);
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for k in ENCODER_MEMORY_DEPTH - 1 downto 0 loop
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for k in ENCODER_MEMORY_DEPTH - 1 downto 0 loop
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v_bit := v_bit xor v_next_state(k);
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v_bit := v_bit xor v_next_state(k);
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end loop;
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end loop;
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v_state(ENCODER_MEMORY_DEPTH) := '1' xor v_bit;
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v_state(ENCODER_MEMORY_DEPTH) := '1' xor v_bit;
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v_state(ENCODER_MEMORY_DEPTH - 1 downto 0) := to_unsigned(i,ENCODER_MEMORY_DEPTH);
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v_state(ENCODER_MEMORY_DEPTH - 1 downto 0) := to_unsigned(i,ENCODER_MEMORY_DEPTH);
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v_next_state := v_state(ENCODER_MEMORY_DEPTH downto 1);
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v_next_state := v_state(ENCODER_MEMORY_DEPTH downto 1);
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v_bit := '0';
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v_bit := '0';
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-- determine paritybits
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-- determine paritybits
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for j in NUMBER_PARITY_BITS - 1 downto 0 loop
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for j in NUMBER_PARITY_BITS - 1 downto 0 loop
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v_states := v_state and to_unsigned(PARITY_POLYNOMIALS(j), ENCODER_MEMORY_DEPTH + 1);
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v_states := v_state and to_unsigned(PARITY_POLYNOMIALS(j), ENCODER_MEMORY_DEPTH + 1);
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for k in ENCODER_MEMORY_DEPTH downto 0 loop
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for k in ENCODER_MEMORY_DEPTH downto 0 loop
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v_bit := v_bit xor v_states(k);
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v_bit := v_bit xor v_states(k);
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end loop;
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end loop;
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v_one_transition(j) := v_bit;
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v_one_transition(j) := v_bit;
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v_bit := '0';
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v_bit := '0';
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end loop;
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end loop;
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-- decide where to save parity result
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-- decide where to save parity result
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if v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) = '0' then
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if v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) = '0' then
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) := '1';
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS) := '1';
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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v_transitions(to_integer(v_next_state))(1)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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else
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else
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v_transitions(to_integer(v_next_state))(0)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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v_transitions(to_integer(v_next_state))(0)(NUMBER_PARITY_BITS - 1 downto 0) := v_one_transition;
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end if;
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end if;
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end loop;
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end loop;
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-- truncate, the bit, used to decide where to save parity result
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-- truncate, the bit, used to decide where to save parity result
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for i in NUMBER_TRELLIS_STATES - 1 downto 0 loop
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for i in NUMBER_TRELLIS_STATES - 1 downto 0 loop
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v_transitions_out(i)(1) := v_transitions(i)(1)(NUMBER_PARITY_BITS - 1 downto 0);
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v_transitions_out(i)(1) := v_transitions(i)(1)(NUMBER_PARITY_BITS - 1 downto 0);
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v_transitions_out(i)(0) := v_transitions(i)(0)(NUMBER_PARITY_BITS - 1 downto 0);
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v_transitions_out(i)(0) := v_transitions(i)(0)(NUMBER_PARITY_BITS - 1 downto 0);
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end loop;
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end loop;
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return v_transitions_out;
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return v_transitions_out;
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end function calc_transitions;
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end function calc_transitions;
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function calc_initialize return t_node_s is
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function calc_initialize return t_node_s is
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variable v_initialize : t_node_s;
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variable v_initialize : t_node_s;
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begin
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begin
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v_initialize(0) := to_signed(0, BW_MAX_PROBABILITY);
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v_initialize(0) := to_signed(0, BW_MAX_PROBABILITY);
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for i in NUMBER_TRELLIS_STATES - 1 downto 1 loop
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for i in NUMBER_TRELLIS_STATES - 1 downto 1 loop
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v_initialize(i) := to_signed(- 2 ** (BW_MAX_PROBABILITY - 2), BW_MAX_PROBABILITY);
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v_initialize(i) := to_signed(- 2 ** (BW_MAX_PROBABILITY - 2), BW_MAX_PROBABILITY);
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end loop;
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end loop;
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return v_initialize;
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return v_initialize;
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end function calc_initialize;
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end function calc_initialize;
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constant PREVIOUS_STATES : t_previous_states := calc_previous_states;
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constant PREVIOUS_STATES : t_previous_states := calc_previous_states;
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constant TRANSITIONS : t_transitions := calc_transitions;
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constant TRANSITIONS : t_transitions := calc_transitions;
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constant INITIALIZE_TRELLIS : t_node_s := calc_initialize;
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constant INITIALIZE_TRELLIS : t_node_s := calc_initialize;
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end package body pkg_trellis;
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end package body pkg_trellis;
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