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entactogen |
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-- Copyright (c) 2013 Antonio de la Piedra
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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 3 of the License, or
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-- (at your option) any later version.
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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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-- You should have received a copy of the GNU General Public License
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-- along with this program. If not, see <http://www.gnu.org/licenses/>.
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library IEEE;
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use IEEE.STD_LOGIC_1164.ALL;
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use IEEE.STD_LOGIC_ARITH.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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entity diffPhaseEncoder is
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port(clk_18_KHz: in std_logic;
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rst: in std_logic;
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en: in std_logic;
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a_k : in std_logic;
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b_k : in std_logic;
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i_k : out std_logic_vector(7 downto 0);
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q_k : out std_logic_vector(7 downto 0));
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end diffPhaseEncoder;
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architecture Behavioral of diffPhaseEncoder is
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-- constellation values arranged as fixed point 8-bit, 6-bit fractional.
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constant c_minus_0_7 : std_logic_vector(7 downto 0) := "10100101";
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constant c_plus_0_7 : std_logic_vector(7 downto 0) := "01011011";
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constant c_plus_1 : std_logic_vector(7 downto 0) := "01111111";
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constant c_minus_1 : std_logic_vector(7 downto 0) := "10000000";
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constant c_plus_0 : std_logic_vector(7 downto 0) := "00000000";
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type state is (plus_0_plus_1,
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plus_0_7_plus_0_7,
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plus_1_plus_0,
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plus_0_7_minus_0_7,
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plus_0_minus_1,
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minus_0_7_minus_0_7,
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minus_1_plus_0,
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minus_0_7_plus_0_7);
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signal pr_state : state;
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signal nx_state : state;
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begin
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fsm_seq: process(clk_18_KHz, rst)
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begin
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if falling_edge(clk_18_KHz) then
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if rst = '1' then
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pr_state <= plus_1_plus_0;
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else
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pr_state <= nx_state;
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end if;
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end if;
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end process;
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fsm_comb: process(pr_state, a_k, b_k, en)
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begin
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case pr_state is
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when plus_0_plus_1 =>
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i_k <= c_plus_0;
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q_k <= c_plus_1;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= minus_0_7_plus_0_7;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= minus_0_7_minus_0_7;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= plus_0_7_plus_0_7;
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else -- 1, 1
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nx_state <= plus_0_7_minus_0_7;
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end if;
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else
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nx_state <= plus_0_plus_1;
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end if;
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when plus_0_7_plus_0_7 =>
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i_k <= c_plus_0_7;
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q_k <= c_plus_0_7;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= plus_0_plus_1;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= minus_1_plus_0;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= plus_1_plus_0;
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else -- 1, 1
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nx_state <= plus_0_minus_1;
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end if;
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else
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nx_state <= plus_0_7_plus_0_7;
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end if;
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when plus_1_plus_0 =>
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i_k <= c_plus_1;
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q_k <= c_plus_0;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= plus_0_7_plus_0_7;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= minus_0_7_plus_0_7;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= plus_0_7_minus_0_7;
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else -- 1, 1
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nx_state <= minus_0_7_minus_0_7;
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end if;
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else
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nx_state <= plus_1_plus_0;
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end if;
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when plus_0_7_minus_0_7 =>
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i_k <= c_plus_0_7;
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q_k <= c_minus_0_7;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= plus_1_plus_0;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= plus_0_plus_1;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= plus_0_minus_1;
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else -- 1, 1
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nx_state <= minus_1_plus_0;
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end if;
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else
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nx_state <= plus_0_7_minus_0_7;
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end if;
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when plus_0_minus_1 =>
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i_k <= c_plus_0;
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q_k <= c_minus_1;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= plus_0_7_minus_0_7;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= plus_0_7_plus_0_7;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= minus_0_7_minus_0_7;
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else -- 1, 1
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nx_state <= minus_0_7_plus_0_7;
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end if;
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else
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nx_state <= plus_0_minus_1;
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end if;
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when minus_0_7_minus_0_7 =>
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i_k <= c_minus_0_7;
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q_k <= c_minus_0_7;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= plus_0_minus_1;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= plus_1_plus_0;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= minus_1_plus_0;
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else -- 1, 1
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nx_state <= plus_0_plus_1;
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end if;
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else
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nx_state <= minus_0_7_minus_0_7;
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end if;
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when minus_1_plus_0 =>
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i_k <= c_minus_1;
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q_k <= c_plus_0;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= minus_0_7_minus_0_7;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= plus_0_7_minus_0_7;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= minus_0_7_plus_0_7;
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else -- 1, 1
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nx_state <= plus_0_7_plus_0_7;
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end if;
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else
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nx_state <= minus_1_plus_0;
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end if;
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when minus_0_7_plus_0_7 =>
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i_k <= c_minus_0_7;
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q_k <= c_plus_0_7;
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if en = '1' then
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if (a_k = '0' and b_k = '0') then
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nx_state <= minus_1_plus_0;
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elsif (a_k = '0' and b_k = '1') then
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nx_state <= plus_0_minus_1;
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elsif (a_k = '1' and b_k = '0') then
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nx_state <= plus_0_plus_1;
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else -- 1, 1
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nx_state <= plus_1_plus_0;
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end if;
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else
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nx_state <= minus_0_7_plus_0_7;
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end if;
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end case;
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end process;
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end Behavioral;
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