Subversion Repositories astron_r2sdf_fft

--------------------------------------------------------------------------------
--
-- Copyright 2020
-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>
-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands
-- 
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
-- 
--     http://www.apache.org/licenses/LICENSE-2.0
-- 
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
--------------------------------------------------------------------------------
 
library ieee, common_pkg_lib, astron_counter_lib, astron_ram_lib;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
use common_pkg_lib.common_pkg.all;
use astron_ram_lib.common_ram_pkg.all;
 
entity rTwoOrder is
  generic   (
    g_nof_points  : natural := 8;
    g_bit_flip    : boolean := true;
    g_nof_chan    : natural := 0
  );
  port (
    clk     : in  std_logic;
    rst     : in  std_logic;
    in_dat  : in  std_logic_vector;
    in_val  : in  std_logic;
    out_dat : out std_logic_vector;
    out_val : out std_logic
  );
end entity rTwoOrder;
 
architecture rtl of rTwoOrder is
 
  constant c_nof_channels : natural := 2**g_nof_chan;
  constant c_dat_w        : natural := in_dat'length;
  constant c_page_size    : natural := g_nof_points*c_nof_channels;
  constant c_adr_points_w : natural := ceil_log2(g_nof_points); 
  constant c_adr_chan_w   : natural := g_nof_chan; 
  constant c_adr_tot_w    : natural := c_adr_points_w + c_adr_chan_w;
 
  signal adr_points_cnt   : std_logic_vector(c_adr_points_w -1 downto 0);
  signal adr_chan_cnt     : std_logic_vector(c_adr_chan_w   -1 downto 0);
  signal adr_tot_cnt      : std_logic_vector(c_adr_tot_w    -1 downto 0);
 
  signal in_init          : STD_LOGIC;
  signal nxt_in_init      : STD_LOGIC;
  signal in_en            : STD_LOGIC;
 
  signal cnt_ena   : std_logic; 
 
  signal next_page        : STD_LOGIC;
 
  signal wr_en            : STD_LOGIC;
  signal wr_adr           : STD_LOGIC_VECTOR(c_adr_tot_w-1 DOWNTO 0);
  signal wr_dat           : STD_LOGIC_VECTOR(c_dat_w-1 DOWNTO 0);
 
  signal rd_en            : STD_LOGIC;
  signal rd_adr           : STD_LOGIC_VECTOR(c_adr_tot_w-1 DOWNTO 0);
  signal rd_dat           : STD_LOGIC_VECTOR(c_dat_w-1 DOWNTO 0);
  signal rd_val           : STD_LOGIC;
 
begin
 
  out_dat <= rd_dat;
  out_val <= rd_val;
 
  p_clk : process(clk, rst)
  begin
    if rst='1' then
      in_init      <= '1';
    elsif rising_edge(clk) then
      in_init      <= nxt_in_init;
    end if;
  end process;
 
  nxt_in_init <= '0' WHEN next_page='1' ELSE in_init;  -- keep in_init active until the first block has been written
 
  in_en <= NOT in_init;  -- disable reading of the first block for convenience in verification, because it contains undefined values
 
  wr_dat   <= in_dat;
  wr_en    <= in_val;
  rd_en    <= in_val AND in_en;
 
  next_page <= '1' when unsigned(adr_tot_cnt) = c_page_size-1  and wr_en='1' else '0';
 
  adr_tot_cnt <= adr_chan_cnt & adr_points_cnt;
 
  gen_bit_flip : if g_bit_flip=true generate
    wr_adr <= adr_chan_cnt & flip(adr_points_cnt);  -- flip the addresses to perform the reorder
  end generate;
  no_bit_flip : if g_bit_flip=false generate
    wr_adr <= adr_tot_cnt;        -- do not flip the addresses for easier debugging with tb_rTwoOrder
  end generate;
 
  rd_adr <= adr_tot_cnt;
 
  u_adr_point_cnt : entity astron_counter_lib.common_counter
  generic map(
    g_latency   => 1,  
    g_init      => 0,
    g_width     => ceil_log2(g_nof_points)
  )
  PORT MAP (
    rst     => rst,
    clk     => clk,
    cnt_en  => cnt_ena,
    count   => adr_points_cnt
  );
 
  -- Generate on c_nof_channels to avoid simulation warnings on TO_UINT(adr_chan_cnt) when adr_chan_cnt is a NULL array
  one_chan : if c_nof_channels=1 generate
    cnt_ena <= '1' when in_val = '1' else '0';
  end generate;
  more_chan : if c_nof_channels>1 generate
    cnt_ena <= '1' when in_val = '1' and TO_UINT(adr_chan_cnt) = c_nof_channels-1 else '0';
  end generate;
 
  u_adr_chan_cnt : entity astron_counter_lib.common_counter
  generic map(
    g_latency   => 1,  
    g_init      => 0,
    g_width     => g_nof_chan
  )
  PORT MAP (
    rst     => rst,
    clk     => clk,
    cnt_en  => in_val,
    count   => adr_chan_cnt
  ); 
 
  u_buff : ENTITY astron_ram_lib.common_paged_ram_r_w
  GENERIC MAP (
    g_str             => "use_adr",
    g_data_w          => c_dat_w,
    g_nof_pages       => 2,
    g_page_sz         => c_page_size,
    g_wr_start_page   => 0,
    g_rd_start_page   => 1,
    g_rd_latency      => 1
  )
  PORT MAP (
    rst          => rst,
    clk          => clk,
    wr_next_page => next_page,
    wr_adr       => wr_adr,
    wr_en        => wr_en,
    wr_dat       => wr_dat,
    rd_next_page => next_page,
    rd_adr       => rd_adr,
    rd_en        => rd_en,
    rd_dat       => rd_dat,
    rd_val       => rd_val
  );
 
end rtl;