library ieee;
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use ieee.std_logic_1164.all;
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entity sequencer is
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generic (
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seq : string
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);
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port (
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clk : in std_logic;
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data : out std_logic
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);
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end entity sequencer;
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architecture rtl of sequencer is
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signal index : natural := seq'low;
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signal ch : character;
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function to_bit (a : in character) return std_logic is
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variable ret : std_logic;
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begin
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case a is
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when '0' | '_' => ret := '0';
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when '1' | '-' => ret := '1';
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when others => ret := 'X';
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end case;
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return ret;
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end function to_bit;
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begin
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process (clk) is
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begin
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if rising_edge(clk) then
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if (index < seq'high) then
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index <= index + 1;
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end if;
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end if;
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end process;
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ch <= seq(index);
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data <= to_bit(ch);
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end architecture rtl;
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library ieee;
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use ieee.std_logic_1164.all;
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entity issue is
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port (
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clk : in std_logic
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);
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end entity issue;
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architecture psl of issue is
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component sequencer is
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generic (
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seq : string
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);
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port (
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clk : in std_logic;
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data : out std_logic
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);
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end component sequencer;
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signal a, b, c : std_logic;
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begin
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-- 012345678901234
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SEQ_A : sequencer generic map ("_-______-______") port map (clk, a);
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SEQ_B : sequencer generic map ("___-__-___-__-_") port map (clk, b);
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SEQ_C : sequencer generic map ("______-___-____") port map (clk, c);
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-- All is sensitive to rising edge of clk
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default clock is rising_edge(clk);
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-- This assertion holds
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NEXT_EVENT_a : assert always (a -> next_event_e(b)[1 to 2](c));
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end architecture psl;
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