Subversion Repositories i2s_interface

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----                                                              ----

---- WISHBONE I2S Interface IP Core                               ----

----                                                              ----

---- This file is part of the I2S Interface project               ----

---- http://www.opencores.org/cores/i2s_interface/                ----

----                                                              ----

---- Description                                                  ----

---- I2S receiver Wishbone bus cycle decoder.                     ----

----                                                              ----

---- To Do:                                                       ----

---- -                                                            ----

----                                                              ----

---- Author(s):                                                   ----

---- - Geir Drange, gedra@opencores.org                           ----

----                                                              ----

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---- Copyright (C) 2004 Authors and OPENCORES.ORG                 ----

----                                                              ----

---- 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 General          ----

---- Public License as published by the Free Software Foundation; ----

---- either version 2.0 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 General Public License for more details.----

----                                                              ----

---- You should have received a copy of the GNU General           ----

---- Public License along with this source; if not, download it   ----

---- from http://www.gnu.org/licenses/gpl.txt                     ----

----                                                              ----

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--

-- CVS Revision History

--

-- $Log: not supported by cvs2svn $

-- Revision 1.2  2004/08/06 18:55:43  gedra

-- De-linting.

--

-- Revision 1.1  2004/08/03 18:50:29  gedra

-- Receiver Wishbone cycle decoder.

--

--

--

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

entity rx_i2s_wbd is

  generic (DATA_WIDTH: integer;

           ADDR_WIDTH: integer);

  port (

    wb_clk_i: in std_logic;             -- wishbone clock

    wb_rst_i: in std_logic;             -- reset signal

    wb_sel_i: in std_logic;             -- select input

    wb_stb_i: in std_logic;             -- strobe input

    wb_we_i: in std_logic;              -- write enable

    wb_cyc_i: in std_logic;             -- cycle input

    wb_bte_i: in std_logic_vector(1 downto 0);  -- burts type extension

    wb_cti_i: in std_logic_vector(2 downto 0);  -- cycle type identifier

    wb_adr_i: in std_logic_vector(ADDR_WIDTH - 1 downto 0);  -- address

    data_out: in std_logic_vector(DATA_WIDTH - 1 downto 0); -- internal bus

    wb_ack_o: out std_logic;            -- acknowledge

    wb_dat_o: out std_logic_vector(DATA_WIDTH - 1 downto 0);  -- data out

    version_rd: out std_logic;          -- Version register read 

    config_rd: out std_logic;           -- Config register read

    config_wr: out std_logic;           -- Config register write

    intmask_rd: out std_logic;          -- Interrupt mask register read

    intmask_wr: out std_logic;          -- Interrupt mask register write

    intstat_rd: out std_logic;          -- Interrupt status register read

    intstat_wr: out std_logic;          -- Interrupt status register read

    mem_rd: out std_logic;              -- Sample memory read

    mem_addr: out std_logic_vector(ADDR_WIDTH - 2 downto 0));  -- memory addr.

end rx_i2s_wbd;

architecture rtl of rx_i2s_wbd is

  constant REG_RXVERSION : std_logic_vector(3 downto 0) := "0000";

  constant REG_RXCONFIG  : std_logic_vector(3 downto 0) := "0001";

  constant REG_RXINTMASK : std_logic_vector(3 downto 0) := "0010";

  constant REG_RXINTSTAT : std_logic_vector(3 downto 0) := "0011";

  signal iack, iwr, ird : std_logic;

  signal acnt: integer range 0 to 2**(ADDR_WIDTH - 1) - 1;

  signal all_ones : std_logic_vector(ADDR_WIDTH - 1 downto 0);

  signal rdout : std_logic_vector(DATA_WIDTH - 1 downto 0);

begin

  wb_ack_o <= iack;

-- acknowledge generation

  ACK: process (wb_clk_i, wb_rst_i)

  begin

    if wb_rst_i = '1' then

      iack <= '0';

    elsif rising_edge(wb_clk_i) then

      if wb_cyc_i = '1' and wb_sel_i = '1' and wb_stb_i = '1' then

        case wb_cti_i is

          when "010" => -- incrementing burst

            case wb_bte_i is -- burst extension

              when "00" => -- linear burst

                iack <= '1';

              when others => -- all other treated assert classic cycle

                iack <= not iack;

            end case;

          when "111" => -- end of burst

            iack <= not iack;

          when others => -- all other treated assert classic cycle 

            iack <= not iack;

        end case;

      else

        iack <= '0';

      end if;

    end if;

  end process ACK;

-- write generation      

  WR: process (wb_clk_i, wb_rst_i)

  begin

    if wb_rst_i = '1' then

      iwr <= '0';

    elsif rising_edge(wb_clk_i) then

      if wb_cyc_i = '1' and wb_sel_i = '1' and wb_stb_i = '1' and

        wb_we_i = '1' then

        case wb_cti_i is

          when "010" => -- incrementing burst

            case wb_bte_i is -- burst extension

              when "00" => -- linear burst

                iwr <= '1';

              when others => -- all other treated assert classic cycle

                iwr <= not iwr;

            end case;

          when "111" => -- end of burst

            iwr <= not iwr;

          when others => -- all other treated assert classic cycle   

            iwr <= not iwr;

        end case;

      else

        iwr <= '0';

      end if;

    end if;

  end process WR;

-- read generation

  ird <= '1' when wb_cyc_i = '1' and wb_sel_i = '1' and wb_stb_i = '1' and

         wb_we_i = '0' else '0';

  wb_dat_o <= data_out when wb_adr_i(ADDR_WIDTH - 1) = '1' else rdout;

  DREG: process (wb_clk_i)              -- clock data from registers

  begin

    if rising_edge(wb_clk_i) then

      rdout <= data_out;

    end if;

  end process DREG;

-- sample memory read address. This needs special attention due to read latency

  mem_addr <= std_logic_vector(to_unsigned(acnt, ADDR_WIDTH - 1)) when

              wb_cti_i = "010" and wb_we_i = '0' and iack = '1' and

              wb_bte_i = "00" else wb_adr_i(ADDR_WIDTH - 2 downto 0);

  all_ones(ADDR_WIDTH - 1 downto 0) <= (others => '1');

  SMA: process (wb_clk_i, wb_rst_i)

  begin

    if wb_rst_i = '1' then

      acnt <= 0;

    elsif rising_edge(wb_clk_i) then

      if wb_cti_i = "010" and wb_we_i = '0' and wb_bte_i = "00" then

        if iack = '0' then

          if wb_adr_i = all_ones then

            acnt <= 0;

          else

            acnt <= to_integer(unsigned(wb_adr_i)) + 1;

          end if;

        else

          if acnt < 2**(ADDR_WIDTH - 1) - 1 then

            acnt <= acnt + 1;

          else

            acnt <= 0;

          end if;

        end if;

      end if;

    end if;

  end process SMA;

-- read and write strobe generation

  version_rd <= '1' when wb_adr_i(3 downto 0) = REG_RXVERSION and ird = '1'

                and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  config_rd <= '1' when wb_adr_i(3 downto 0) = REG_RXCONFIG and ird = '1'

               and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  config_wr <= '1' when wb_adr_i(3 downto 0) = REG_RXCONFIG and iwr = '1'

               and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  intmask_rd <= '1' when wb_adr_i(3 downto 0) = REG_RXINTMASK and ird = '1'

                and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  intmask_wr <= '1' when wb_adr_i(3 downto 0) = REG_RXINTMASK and iwr = '1'

                and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  intstat_rd <= '1' when wb_adr_i(3 downto 0) = REG_RXINTSTAT and ird = '1'

                and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  intstat_wr <= '1' when wb_adr_i(3 downto 0) = REG_RXINTSTAT and iwr = '1'

                and wb_adr_i(ADDR_WIDTH - 1) = '0' else '0';

  mem_rd <= '1' when wb_adr_i(ADDR_WIDTH - 1) = '1' and ird = '1' else '0';

end rtl;