Added quantizer between wpfb and correlator

applications/apertif/designs/apertif_unb1_correlator/src/vhdl/apertif_unb1_correlator.vhd

@@ -161,6 +161,7 @@ ARCHITECTURE str OF apertif_unb1_correlator IS
   CONSTANT c_nof_channels           : NATURAL := 64;
   CONSTANT c_integration_period     : NATURAL := c_nof_blocks_per_sync/c_nof_channels; --12207;
   CONSTANT c_nof_visibilities       : NATURAL := (c_nof_inputs*(c_nof_inputs+1))/2;
+  CONSTANT c_cor_in_dat_w           : NATURAL := 9;  -- 9-bit input data for the correlator: 9b -> mult -> 18b -> accu -> 32b at the corr output. 
   -- . Inter Channel Delay:
   --   . With no inter channel output delay, channels are output back-to-back, creating a short full valid burst of 64 channels (12.8 Gbps burst, 158Mbps on average).
   --     We need to set an appropriate number of inter-channel delay cycles for a constant visibility buffer output rate.
@@ -176,9 +177,9 @@ ARCHITECTURE str OF apertif_unb1_correlator IS
   CONSTANT c_wpfb_nof_chan          : NATURAL := 1;                    -- = default 0, defines the number of channels (=time-m
   CONSTANT c_wpfb_nof_points        : NATURAL := 64;                   -- = 1024, N point FFT
   CONSTANT c_wpfb_nof_taps          : NATURAL := 8;                    -- = 8 nof taps n the filter
-  CONSTANT c_wpfb_coef_w            : NATURAL := 18;                   --FIXME: 9b does not work; needs updated coefficient files.
+  CONSTANT c_wpfb_coef_w            : NATURAL := 16;                   --FIXME: 9b does not work; needs updated coefficient files.
   CONSTANT c_wpfb_in_dat_w          : NATURAL := 8;                    --FIXME: should be 6b at some point
-  CONSTANT c_wpfb_out_dat_w         : NATURAL := 9;                    --FIXME: Could be wider but is currently 9b to avoid the need for quantization: 9b -> mult -> 18b -> accu -> 32b at the corr output.
+  CONSTANT c_wpfb_out_dat_w         : NATURAL := 16;                   --FIXME: Could be wider but is currently 9b to avoid the need for quantization: 9b -> mult -> 18b -> accu -> 32b at the corr output.
   CONSTANT c_wpfb_use_separate      : BOOLEAN := FALSE;                -- = false for complex input, true for two real inputs
   CONSTANT c_wpfb_use_reorder       : BOOLEAN := FALSE;
 
@@ -186,6 +187,37 @@ ARCHITECTURE str OF apertif_unb1_correlator IS
                                 c_wpfb_nof_taps, c_wpfb_in_dat_w, 16, c_wpfb_coef_w,
                                 c_wpfb_use_reorder, c_wpfb_use_separate, 16, c_wpfb_out_dat_w, 18, 2, true, 56, 2,                      
                                 c_fft_pipeline, c_fft_pipeline, c_fil_ppf_pipeline);
+--  type t_wpfb is record  
+--    -- General parameters for the wideband poly phase filter
+--    wb_factor         : natural;        -- = default 4, wideband factor
+--    nof_points        : natural;        -- = 1024, N point FFT (Also the number of subbands for the filter part)
+--    nof_chan          : natural;        -- = default 0, defines the number of channels (=time-multiplexed input signals): nof channels = 2**nof_chan     
+--    nof_wb_streams    : natural;        -- = 1, the number of parallel wideband streams. The filter coefficients are shared on every wb-stream. 
+--    
+--    -- Parameters for the poly phase filter
+--    nof_taps          : natural;        -- = 16, the number of FIR taps per subband
+--    fil_in_dat_w      : natural;        -- = 8, number of input bits
+--    fil_out_dat_w     : natural;        -- = 16, number of output bits
+--    coef_dat_w        : natural;        -- = 16, data width of the FIR coefficients
+--                                      
+--    -- Parameters for the FFT         
+--    use_reorder       : boolean;        -- = false for bit-reversed output, true for normal output
+--    use_separate      : boolean;        -- = false for complex input, true for two real inputs
+--    fft_in_dat_w      : natural;        -- = 16, number of input bits
+--    fft_out_dat_w     : natural;        -- = 16, number of output bits >= (fil_in_dat_w=8) + log2(nof_points=1024)/2 = 13
+--    stage_dat_w       : natural;        -- = 18, number of bits that are used inter-stage
+--    guard_w           : natural;        -- = 2
+--    guard_enable      : boolean;        -- = true
+--    stat_data_w       : positive;       -- = 56
+--    stat_data_sz      : positive;       -- = 2
+--
+--    -- Pipeline parameters for both poly phase filter and FFT. These are heritaged from the filter and fft libraries.  
+--    pft_pipeline      : t_fft_pipeline;     -- Pipeline settings for the pipelined FFT
+--    fft_pipeline      : t_fft_pipeline;     -- Pipeline settings for the parallel FFT
+--    fil_pipeline      : t_fil_ppf_pipeline; -- Pipeline settings for the filter units 
+--    
+--  end record;
+
 
   CONSTANT c_wpfb_coefs_file_prefix : STRING  := "mif/coefs_wide1_p64_t8";
 
@@ -331,6 +363,8 @@ ARCHITECTURE str OF apertif_unb1_correlator IS
   SIGNAL wpfb_snk_in_ctrl                            : t_dp_sosi;                    
   SIGNAL wpfb_snk_in_arr                             : t_dp_sosi_arr(c_nof_input_streams-1 DOWNTO 0);
   SIGNAL wpfb_src_out_arr                            : t_dp_sosi_arr(c_nof_input_streams-1 DOWNTO 0);
+  SIGNAL requantize_snk_in_arr                       : t_dp_sosi_arr(c_nof_input_streams-1 DOWNTO 0);
+  SIGNAL requantize_src_out_arr                      : t_dp_sosi_arr(1-1 DOWNTO 0);
   SIGNAL correlator_snk_in_arr                       : t_dp_sosi_arr(c_nof_input_streams-1 DOWNTO 0);
   SIGNAL correlator_src_out_arr                      : t_dp_sosi_arr(1-1 DOWNTO 0);
   
@@ -958,9 +992,9 @@ BEGIN
   -----------------------------------------------------------------------------
   p_bsn_filter : PROCESS(wpfb_src_out_arr)
   BEGIN
-    correlator_snk_in_arr <= (OTHERS=>c_dp_sosi_rst);
+    requantize_snk_in_arr <= (OTHERS=>c_dp_sosi_rst);
     IF TO_UINT(wpfb_src_out_arr(0).bsn)>=5 THEN
-      correlator_snk_in_arr <= wpfb_src_out_arr;
+      requantize_snk_in_arr <= wpfb_src_out_arr;
     END IF;
   END PROCESS;
 
@@ -983,6 +1017,34 @@ BEGIN
     src_in  => c_dp_siso_rdy
   );
   
+  -----------------------------------------------------------------------------
+  -- Requantize output of wpfb for correlator input
+  -----------------------------------------------------------------------------
+  gen_requantizer : FOR I IN 0 TO c_nof_input_streams-1 GENERATE
+    u_dp_requantize_out : ENTITY dp_lib.dp_requantize
+    GENERIC MAP (
+      g_complex             => TRUE,
+      g_representation      => "SIGNED",      
+      g_lsb_w               => c_wpfb_out_dat_w-c_cor_in_dat_w,               
+      g_lsb_round           => FALSE,           
+      g_lsb_round_clip      => FALSE,      
+      g_msb_clip            => FALSE,  
+      g_msb_clip_symmetric  => FALSE,  
+      g_gain_w              => 0,
+      g_pipeline_remove_lsb => 1, 
+      g_pipeline_remove_msb => 0, 
+      g_in_dat_w            => c_wpfb_out_dat_w,            
+      g_out_dat_w           => c_cor_in_dat_w           
+    )
+    PORT MAP (
+      rst        => dp_rst,
+      clk        => dp_clk,
+      snk_in     => requantize_snk_in_arr(I),
+      src_out    => correlator_snk_in_arr(I),
+      out_ovr    => OPEN
+    );
+  END GENERATE;
+  
   -----------------------------------------------------------------------------
   -- Correlator
   -----------------------------------------------------------------------------
@@ -992,7 +1054,7 @@ BEGIN
     g_nof_input_streams   => c_nof_input_streams,
     g_input_unfold_factor => c_nof_input_folds,
     g_nof_pre_mult_folds  => c_nof_pre_mult_folds,
-    g_data_w              => c_wpfb_out_dat_w,
+    g_data_w              => c_cor_in_dat_w,
     g_conjugate           => c_conjugate,
     g_nof_channels        => c_nof_channels,
     g_integration_period  => c_integration_period,