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--                                                                            --

--                          V H D L    F I L E                                --

--                          COPYRIGHT (C) 2006                                --

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--

-- Title       : DCT1D

-- Design      : MDCT Core

-- Author      : Michal Krepa

--

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--

-- File        : DCT1D.VHD

-- Created     : Sat Mar 5 7:37 2006

--

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--

--  Description : 1D Discrete Cosine Transform (1st stage)

--

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library IEEE;

  use IEEE.STD_LOGIC_1164.all;

  use IEEE.NUMERIC_STD.all;

library WORK;

  use WORK.MDCT_PKG.all;

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-- ENTITY

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entity DCT1D is

        port(

                  clk          : in STD_LOGIC;

                  rst          : in std_logic;

      dcti         : in std_logic_vector(IP_W-1 downto 0);

      idv          : in STD_LOGIC;

      romedatao    : in T_ROM1DATAO;

      romodatao    : in T_ROM1DATAO;

      odv          : out STD_LOGIC;

      dcto         : out std_logic_vector(OP_W-1 downto 0);

      romeaddro    : out T_ROM1ADDRO;

      romoaddro    : out T_ROM1ADDRO;

      ramwaddro    : out STD_LOGIC_VECTOR(RAMADRR_W-1 downto 0);

      ramdatai     : out STD_LOGIC_VECTOR(RAMDATA_W-1 downto 0);

      ramwe        : out STD_LOGIC;

      wmemsel      : out STD_LOGIC

                );

end DCT1D;

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-- ARCHITECTURE

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architecture RTL of DCT1D is

  type INPUT_DATA is array (N-1 downto 0) of SIGNED(IP_W downto 0);

  signal databuf_reg     : INPUT_DATA;

  signal latchbuf_reg    : INPUT_DATA;

  signal col_reg         : UNSIGNED(RAMADRR_W/2-1 downto 0);

  signal row_reg         : UNSIGNED(RAMADRR_W/2-1 downto 0);

  signal rowr_reg        : UNSIGNED(RAMADRR_W/2-1 downto 0);

  signal inpcnt_reg      : UNSIGNED(RAMADRR_W/2-1 downto 0);

  signal ramwe_s         : STD_LOGIC;

  signal wmemsel_reg     : STD_LOGIC;

  signal stage2_reg      : STD_LOGIC;

  signal stage2_cnt_reg  : UNSIGNED(RAMADRR_W-1 downto 0);

  signal col_2_reg       : UNSIGNED(RAMADRR_W/2-1 downto 0);

  signal ramwaddro_s     : STD_LOGIC_VECTOR(RAMADRR_W-1 downto 0);

  signal even_not_odd    : std_logic;

  signal even_not_odd_d1 : std_logic;

  signal even_not_odd_d2 : std_logic;

  signal even_not_odd_d3 : std_logic;

  signal ramwe_d1        : STD_LOGIC;

  signal ramwe_d2        : STD_LOGIC;

  signal ramwe_d3        : STD_LOGIC;

  signal ramwe_d4        : STD_LOGIC;

  signal ramwaddro_d1    : STD_LOGIC_VECTOR(RAMADRR_W-1 downto 0);

  signal ramwaddro_d2    : STD_LOGIC_VECTOR(RAMADRR_W-1 downto 0);

  signal ramwaddro_d3    : STD_LOGIC_VECTOR(RAMADRR_W-1 downto 0);

  signal ramwaddro_d4    : STD_LOGIC_VECTOR(RAMADRR_W-1 downto 0);

  signal wmemsel_d1      : STD_LOGIC;

  signal wmemsel_d2      : STD_LOGIC;

  signal wmemsel_d3      : STD_LOGIC;

  signal wmemsel_d4      : STD_LOGIC;

  signal romedatao_d1    : T_ROM1DATAO;

  signal romodatao_d1    : T_ROM1DATAO;

  signal romedatao_d2    : T_ROM1DATAO;

  signal romodatao_d2    : T_ROM1DATAO;

  signal romedatao_d3    : T_ROM1DATAO;

  signal romodatao_d3    : T_ROM1DATAO;

  signal dcto_1          : STD_LOGIC_VECTOR(DA_W-1 downto 0);

  signal dcto_2          : STD_LOGIC_VECTOR(DA_W-1 downto 0);

  signal dcto_3          : STD_LOGIC_VECTOR(DA_W-1 downto 0);

  signal dcto_4          : STD_LOGIC_VECTOR(DA_W-1 downto 0);

begin

  ramwaddro <= ramwaddro_d4;

  ramwe     <= ramwe_d4;

  ramdatai  <= dcto_4(DA_W-1 downto 12);

  wmemsel   <= wmemsel_d4;

  process(clk,rst)

  begin

    if rst = '1' then

      inpcnt_reg      <= (others => '0');

      latchbuf_reg    <= (others => (others => '0'));

      databuf_reg     <= (others => (others => '0'));

      stage2_reg      <= '0';

      stage2_cnt_reg  <= (others => '1');

      ramwe_s         <= '0';

      ramwaddro_s     <= (others => '0');

      col_reg         <= (others => '0');

      row_reg         <= (others => '0');

      wmemsel_reg     <= '0';

      col_2_reg       <= (others => '0');

    elsif clk = '1' and clk'event then

      stage2_reg     <= '0';

      ramwe_s        <= '0';

      --------------------------------

      -- 1st stage

      --------------------------------

      if idv = '1' then

        inpcnt_reg    <= inpcnt_reg + 1;

        -- right shift input data

        latchbuf_reg(N-2 downto 0) <= latchbuf_reg(N-1 downto 1);

        latchbuf_reg(N-1)          <= SIGNED('0' & dcti) - LEVEL_SHIFT;

        if inpcnt_reg = N-1 then

          -- after this sum databuf_reg is in range of -256 to 254 (min to max) 

          databuf_reg(0)  <= latchbuf_reg(1)+(SIGNED('0' & dcti) - LEVEL_SHIFT);

          databuf_reg(1)  <= latchbuf_reg(2)+latchbuf_reg(7);

          databuf_reg(2)  <= latchbuf_reg(3)+latchbuf_reg(6);

          databuf_reg(3)  <= latchbuf_reg(4)+latchbuf_reg(5);

          databuf_reg(4)  <= latchbuf_reg(1)-(SIGNED('0' & dcti) - LEVEL_SHIFT);

          databuf_reg(5)  <= latchbuf_reg(2)-latchbuf_reg(7);

          databuf_reg(6)  <= latchbuf_reg(3)-latchbuf_reg(6);

          databuf_reg(7)  <= latchbuf_reg(4)-latchbuf_reg(5);

          stage2_reg      <= '1';

        end if;

      end if;

      --------------------------------

      --------------------------------

      -- 2nd stage

      --------------------------------

      if stage2_cnt_reg < N then

        stage2_cnt_reg <= stage2_cnt_reg + 1;

        -- write RAM

        ramwe_s   <= '1';

        -- reverse col/row order for transposition purpose

        ramwaddro_s <= STD_LOGIC_VECTOR(col_2_reg & row_reg);

        -- increment column counter

        col_reg   <= col_reg + 1;

        col_2_reg <= col_2_reg + 1;

        -- finished processing one input row

        if col_reg = 0 then

          row_reg         <= row_reg + 1;

          -- switch to 2nd memory

          if row_reg = N - 1 then

            wmemsel_reg <= not wmemsel_reg;

            col_reg         <= (others => '0');

          end if;

        end if;

      end if;

      if stage2_reg = '1' then

        stage2_cnt_reg <= (others => '0');

        col_reg        <= (0=>'1',others => '0');

        col_2_reg      <= (others => '0');

      end if;

      ----------------------------------   

    end if;

  end process;

  -- output data pipeline

  p_data_out_pipe : process(CLK, RST)

  begin

    if RST = '1' then

      even_not_odd    <= '0';

      even_not_odd_d1 <= '0';

      even_not_odd_d2 <= '0';

      even_not_odd_d3 <= '0';

      ramwe_d1        <= '0';

      ramwe_d2        <= '0';

      ramwe_d3        <= '0';

      ramwe_d4        <= '0';

      ramwaddro_d1    <= (others => '0');

      ramwaddro_d2    <= (others => '0');

      ramwaddro_d3    <= (others => '0');

      ramwaddro_d4    <= (others => '0');

      wmemsel_d1      <= '0';

      wmemsel_d2      <= '0';

      wmemsel_d3      <= '0';

      wmemsel_d4      <= '0';

      dcto_1          <= (others => '0');

      dcto_2          <= (others => '0');

      dcto_3          <= (others => '0');

      dcto_4          <= (others => '0');

    elsif CLK'event and CLK = '1' then

      even_not_odd    <= stage2_cnt_reg(0);

      even_not_odd_d1 <= even_not_odd;

      even_not_odd_d2 <= even_not_odd_d1;

      even_not_odd_d3 <= even_not_odd_d2;

      ramwe_d1        <= ramwe_s;

      ramwe_d2        <= ramwe_d1;

      ramwe_d3        <= ramwe_d2;

      ramwe_d4        <= ramwe_d3;

      ramwaddro_d1    <= ramwaddro_s;

      ramwaddro_d2    <= ramwaddro_d1;

      ramwaddro_d3    <= ramwaddro_d2;

      ramwaddro_d4    <= ramwaddro_d3;

      wmemsel_d1      <= wmemsel_reg;

      wmemsel_d2      <= wmemsel_d1;

      wmemsel_d3      <= wmemsel_d2;

      wmemsel_d4      <= wmemsel_d3;

      if even_not_odd = '0' then

        dcto_1 <= STD_LOGIC_VECTOR(RESIZE

          (RESIZE(SIGNED(romedatao(0)),DA_W) +

          (RESIZE(SIGNED(romedatao(1)),DA_W-1) & '0') +

          (RESIZE(SIGNED(romedatao(2)),DA_W-2) & "00"),

          DA_W));

      else

        dcto_1 <= STD_LOGIC_VECTOR(RESIZE

          (RESIZE(SIGNED(romodatao(0)),DA_W) +

          (RESIZE(SIGNED(romodatao(1)),DA_W-1) & '0') +

          (RESIZE(SIGNED(romodatao(2)),DA_W-2) & "00"),

          DA_W));

      end if;

      if even_not_odd_d1 = '0' then

        dcto_2 <= STD_LOGIC_VECTOR(RESIZE

          (signed(dcto_1) +

          (RESIZE(SIGNED(romedatao_d1(3)),DA_W-3) & "000") +

          (RESIZE(SIGNED(romedatao_d1(4)),DA_W-4) & "0000"),

          DA_W));

      else

        dcto_2 <= STD_LOGIC_VECTOR(RESIZE

          (signed(dcto_1) +

          (RESIZE(SIGNED(romodatao_d1(3)),DA_W-3) & "000") +

          (RESIZE(SIGNED(romodatao_d1(4)),DA_W-4) & "0000"),

          DA_W));

      end if;

      if even_not_odd_d2 = '0' then

        dcto_3 <= STD_LOGIC_VECTOR(RESIZE

          (signed(dcto_2) +

          (RESIZE(SIGNED(romedatao_d2(5)),DA_W-5) & "00000") +

          (RESIZE(SIGNED(romedatao_d2(6)),DA_W-6) & "000000"),

          DA_W));

      else

        dcto_3 <= STD_LOGIC_VECTOR(RESIZE

          (signed(dcto_2) +

          (RESIZE(SIGNED(romodatao_d2(5)),DA_W-5) & "00000") +

          (RESIZE(SIGNED(romodatao_d2(6)),DA_W-6) & "000000"),

          DA_W));

      end if;

      if even_not_odd_d3 = '0' then

        dcto_4 <= STD_LOGIC_VECTOR(RESIZE

          (signed(dcto_3) +

          (RESIZE(SIGNED(romedatao_d3(7)),DA_W-7) & "0000000") -

          (RESIZE(SIGNED(romedatao_d3(8)),DA_W-8) & "00000000"),

          DA_W));

      else

        dcto_4 <= STD_LOGIC_VECTOR(RESIZE

          (signed(dcto_3) +

          (RESIZE(SIGNED(romodatao_d3(7)),DA_W-7) & "0000000") -

          (RESIZE(SIGNED(romodatao_d3(8)),DA_W-8) & "00000000"),

          DA_W));

      end if;

    end if;

  end process;

  -- read precomputed MAC results from LUT

  p_romaddr : process(CLK, RST)

  begin

    if RST = '1' then

      romeaddro   <= (others => (others => '0'));

      romoaddro   <= (others => (others => '0'));

    elsif CLK'event and CLK = '1' then

      for i in 0 to 8 loop

        -- even

        romeaddro(i) <= STD_LOGIC_VECTOR(col_reg(RAMADRR_W/2-1 downto 1)) &

                 databuf_reg(0)(i) &

                 databuf_reg(1)(i) &

                 databuf_reg(2)(i) &

                 databuf_reg(3)(i);

        -- odd

        romoaddro(i) <= STD_LOGIC_VECTOR(col_reg(RAMADRR_W/2-1 downto 1)) &

                 databuf_reg(4)(i) &

                 databuf_reg(5)(i) &

                 databuf_reg(6)(i) &

                 databuf_reg(7)(i);

      end loop;

    end if;

  end process;

  p_romdatao_d1 : process(CLK, RST)

  begin

    if RST = '1' then

      romedatao_d1    <= (others => (others => '0'));

      romodatao_d1    <= (others => (others => '0'));

      romedatao_d2    <= (others => (others => '0'));

      romodatao_d2    <= (others => (others => '0'));

      romedatao_d3    <= (others => (others => '0'));

      romodatao_d3    <= (others => (others => '0'));

    elsif CLK'event and CLK = '1' then

      romedatao_d1   <= romedatao;

      romodatao_d1   <= romodatao;

      romedatao_d2   <= romedatao_d1;

      romodatao_d2   <= romodatao_d1;

      romedatao_d3   <= romedatao_d2;

      romodatao_d3   <= romodatao_d2;

    end if;

  end process;

end RTL;

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