Subversion Repositories astron_multiplexer

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

--

-- Copyright (C) 2012

-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>

-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands

--

-- This program 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 3 of the License, or

-- (at your option) any later version.

--

-- This program 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 program.  If not, see <http://www.gnu.org/licenses/>.

--

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

LIBRARY IEEE, common_pkg_lib, common_components_lib;

USE IEEE.STD_LOGIC_1164.ALL;

USE common_pkg_lib.common_pkg.ALL;

USE common_components_lib.common_components_pkg.ALL;

-- Purpose: Assign input to one of g_nof_out output streams based on out_sel input

-- Description: The output streams are concatenated into one SLV.

-- Remarks:

-- . Same scheme for pipeline handling and g_nof_out=1 handling as in common_select_symbol

ENTITY common_demultiplexer IS

  GENERIC (

    g_pipeline_in  : NATURAL := 0;

    g_pipeline_out : NATURAL := 0;

    g_nof_out      : NATURAL;

    g_dat_w        : NATURAL

 );

  PORT (

    rst         : IN  STD_LOGIC := '0';

    clk         : IN  STD_LOGIC := '0';  -- for g_pipeline_* = 0 no rst and clk are needed, because then the demultiplexer works combinatorialy

    in_dat      : IN  STD_LOGIC_VECTOR(g_dat_w-1 DOWNTO 0);

    in_val      : IN  STD_LOGIC;

    out_sel     : IN  STD_LOGIC_VECTOR(ceil_log2(g_nof_out)-1 DOWNTO 0);

    out_dat     : OUT STD_LOGIC_VECTOR(g_nof_out*g_dat_w-1 DOWNTO 0);

    out_val     : OUT STD_LOGIC_VECTOR(g_nof_out        -1 DOWNTO 0)

  );

END;

ARCHITECTURE rtl OF common_demultiplexer IS

  CONSTANT c_sel_w    : NATURAL := out_sel'LENGTH;

  SIGNAL in_dat_reg    : STD_LOGIC_VECTOR(in_dat'RANGE);

  SIGNAL in_val_reg    : STD_LOGIC;

  SIGNAL out_sel_reg   : STD_LOGIC_VECTOR(out_sel'RANGE);

  SIGNAL sel_dat       : STD_LOGIC_VECTOR(g_nof_out*g_dat_w-1 DOWNTO 0);

  SIGNAL sel_val       : STD_LOGIC_VECTOR(g_nof_out        -1 DOWNTO 0);

BEGIN

  -- pipeline input

  u_pipe_in_dat  : common_pipeline    GENERIC MAP ("SIGNED", g_pipeline_in, 0, g_dat_w, g_dat_w) PORT MAP (rst, clk, '1', '0', '1', in_dat,  in_dat_reg);

  u_pipe_in_val  : common_pipeline_sl GENERIC MAP (          g_pipeline_in, 0, FALSE)            PORT MAP (rst, clk, '1', '0', '1', in_val,  in_val_reg);

  u_pipe_out_sel : common_pipeline    GENERIC MAP ("SIGNED", g_pipeline_in, 0, c_sel_w, c_sel_w) PORT MAP (rst, clk, '1', '0', '1', out_sel, out_sel_reg);

  -- select combinatorialy

  no_sel : IF g_nof_out=1 GENERATE

    sel_dat    <= in_dat_reg;

    sel_val(0) <= in_val_reg;

  END GENERATE;

  gen_sel : IF g_nof_out>1 GENERATE

    p_sel : PROCESS(out_sel_reg, in_dat_reg, in_val_reg)

    BEGIN

      sel_val <= (OTHERS=>'0');

      FOR I IN g_nof_out-1 DOWNTO 0 LOOP

        sel_dat((I+1)*g_dat_w-1 DOWNTO I*g_dat_w) <= in_dat_reg;  -- replicate in_dat to all outputs, this requires less logic than default forcing invalid outputs to 0

        IF TO_UINT(out_sel_reg)=I THEN

          sel_val(I) <= in_val_reg;                               -- let out_sel determine which output is valid

        END IF;

      END LOOP;

    END PROCESS;

  END GENERATE;

  -- pipeline output

  u_pipe_out_dat : common_pipeline GENERIC MAP ("SIGNED", g_pipeline_out, 0, g_nof_out*g_dat_w, g_nof_out*g_dat_w) PORT MAP (rst, clk, '1', '0', '1', sel_dat, out_dat);

  u_pipe_out_val : common_pipeline GENERIC MAP ("SIGNED", g_pipeline_out, 0, g_nof_out        , g_nof_out        ) PORT MAP (rst, clk, '1', '0', '1', sel_val, out_val);

END rtl;