Use almost_equal(sum_of_bins, g_nof_data_per_sync, c_sum_delta) to work around...

Use almost_equal(sum_of_bins, g_nof_data_per_sync, c_sum_delta) to work around missed counts due to block RAM mixed_port_feed_through_mode = DONT_CARE.

libraries/dsp/st/tb/vhdl/tb_st_histogram.vhd

@@ -90,6 +90,7 @@ architecture tb of tb_st_histogram is
   constant c_nof_levels_per_bin           : natural := (2**g_data_w) / g_nof_bins;  -- e.g. 2 values per bin if g_data_w=9 (512 levels) and g_nof_bins=256
   constant c_ram_dat_w                    : natural := ceil_log2(g_nof_data_per_sync + 1);
   constant c_ram_adr_w                    : natural := ceil_log2(g_nof_bins);
+  constant c_sum_delta                    : natural := largest(g_nof_data_per_sync / 100, 1);  -- 1 % margin
 
   ---------------------------------------------------------------------------
   -- Clocks and resets
@@ -342,6 +343,9 @@ begin
       if i > 0 then  -- Skip sync 0 (histogram still all zeros)
         assert sum_of_bins = g_nof_data_per_sync
           report "Sum of bins not equal to g_nof_data_per_sync (expected " & integer'image(g_nof_data_per_sync) & ", actual " & integer'image(sum_of_bins) & ")"
+          severity WARNING;  -- Delta caused by block RAM mixed_port_feed_through_mode = DONT_CARE and wr and rd access at same address
+        assert almost_equal(sum_of_bins, g_nof_data_per_sync, c_sum_delta)
+          report "Sum of bins not within g_nof_data_per_sync +- c_sum_delta (expected " & integer'image(g_nof_data_per_sync) & ", actual " & integer'image(sum_of_bins) & ")"
           severity ERROR;
       end if;
     end loop;