[hdl] move offset calculation outside of channel generation loop.

This reduces the required resources since we only use one set of adders for all channels (instead of one per). There is no issue with multiple timestamps arriving simultaneously, since the previous stages serialise the delivery of timestamps and this stage is fully pipelined, so it can process one timestamp per cycle.

[hdl] move offset calculation outside of channel generation loop.
This reduces the required resources since we only use one set of adders for all channels (instead of one per). There is no issue with multiple timestamps arriving simultaneously, since the previous stages serialise the delivery of timestamps and this stage is fully pipelined, so it can process one timestamp per cycle.
e66d3b45 · Dimitris Lampridis · d693db67 · e66d3b45 · e66d3b45 · e66d3b45
Commit e66d3b45 authored Sep 29, 2019 by Dimitris Lampridis
Showing with 117 additions and 121 deletions

fmc_tdc_direct_readout.vhd hdl/rtl/fmc_tdc_direct_readout.vhd +1 -1

tdc_ts_addsub.vhd hdl/rtl/tdc_ts_addsub.vhd +25 -26

timestamp_convert_filter.vhd hdl/rtl/timestamp_convert_filter.vhd +91 -94

No files found.
--- a/hdl/rtl/fmc_tdc_direct_readout.vhd
+++ b/hdl/rtl/fmc_tdc_direct_readout.vhd
@@ -65,7 +65,7 @@ begin
  regs_in.fifo_cycles_i  <= timestamp_i(channel_select).coarse;
  regs_in.fifo_edge_i    <= timestamp_i(channel_select).slope;
  regs_in.fifo_seconds_i <= timestamp_i(channel_select).tai;
-  regs_in.fifo_channel_i <= std_logic_vector(to_unsigned(channel_select, 4));
+  regs_in.fifo_channel_i <= '0' & timestamp_i(channel_select).channel;
  regs_in.fifo_bins_i    <= "000000" & timestamp_i(channel_select).frac;
  regs_in.fifo_wr_req_i  <= f_to_std_logic(fifo_wr(channel_select) = '1' and
                                           regs_out.fifo_wr_full_o = '0');

--- a/hdl/rtl/tdc_ts_addsub.vhd
+++ b/hdl/rtl/tdc_ts_addsub.vhd
@@ -61,7 +61,7 @@ entity tdc_ts_addsub is
    a_i : in t_tdc_timestamp;
    b_i : in t_tdc_timestamp;
    valid_o    : out std_logic;
    q_o    : out t_tdc_timestamp
    );
@@ -72,11 +72,12 @@ architecture rtl of tdc_ts_addsub is
  constant c_NUM_PIPELINE_STAGES : integer := 4;
  type t_internal_sum is record
-    tai    : signed(32 downto 0);
+    tai     : signed(32 downto 0);
-    coarse : signed(31 downto 0);
+    coarse  : signed(31 downto 0);
-    frac   : signed(15 downto 0);
+    frac    : signed(15 downto 0);
-    meta : std_logic_vector(31 downto 0);
+    channel : std_logic_vector(2 downto 0);
-    slope : std_logic;
+    meta    : std_logic_vector(31 downto 0);
+    slope   : std_logic;
  end record;
  type t_internal_sum_array is array (integer range <>) of t_internal_sum;
@@ -88,7 +89,7 @@ architecture rtl of tdc_ts_addsub is
  signal unf_frac   : std_logic;
  signal ovf_coarse : std_logic_vector(1 downto 0);
  signal unf_coarse : std_logic_vector(1 downto 0);
 begin  -- rtl
  -- Pipeline stage 0: just subtract the two timestamps field by field
@@ -100,8 +101,9 @@ begin  -- rtl
      elsif(enable_i = '1') then
        pipe(0) <= valid_i;
-        sums(0).slope <= a_i.slope;
+        sums(0).channel <= a_i.channel;
-        sums(0).meta  <= a_i.meta;
+        sums(0).slope   <= a_i.slope;
+        sums(0).meta    <= a_i.meta;
        sums(0).tai    <= signed(resize(unsigned(a_i.tai) + unsigned(b_i.tai), 33));
        sums(0).coarse <= signed(a_i.coarse) + signed(b_i.coarse);
@@ -120,16 +122,16 @@ begin  -- rtl
  p_stage1 : process(clk_i)
  begin
    if rising_edge(clk_i) then
      if rst_n_i = '0' then
        pipe(1) <= '0';
      else
        pipe(1) <= pipe(0);
-        sums(1).meta <= sums(0).meta;
+        sums(1) <= sums(0);
-        sums(1).slope <= sums(0).slope;
+        sums(1) <= sums(0);
+        sums(1) <= sums(0);
        if(ovf_frac = '1') then
          sums(1).frac   <= sums(0).frac - g_frac_range;
          sums(1).coarse <= sums(0).coarse + 1;
@@ -141,7 +143,6 @@ begin  -- rtl
          sums(1).coarse <= sums(0).coarse;
        end if;
-        sums(1).tai <= sums(0).tai;
      end if;
    end if;
  end process;
@@ -173,7 +174,7 @@ begin  -- rtl
        else
          ovf_coarse <= "00";
        end if;
      end if;
    end if;
  end process;
@@ -188,8 +189,7 @@ begin  -- rtl
      else
        pipe(3) <= pipe(2);
-        sums(3).slope <= sums(2).slope;
+        sums(3) <= sums(2);
-        sums(3).meta <= sums(2).meta;
        if(unf_coarse = "10") then
          sums(3).coarse <= sums(2).coarse + g_coarse_range;
@@ -208,17 +208,16 @@ begin  -- rtl
          sums(3).tai    <= sums(2).tai;
        end if;
-        sums(3).frac <= sums(2).frac;
      end if;
    end if;
  end process;
  -- clip the extra bits and output the result
-  valid_o    <= pipe(c_NUM_PIPELINE_STAGES-1);
+  valid_o     <= pipe(c_NUM_PIPELINE_STAGES-1);
-  q_o.tai    <= std_logic_vector(sums(c_NUM_PIPELINE_STAGES-1).tai(31 downto 0));
+  q_o.tai     <= std_logic_vector(sums(c_NUM_PIPELINE_STAGES-1).tai(31 downto 0));
-  q_o.coarse <= std_logic_vector(sums(c_NUM_PIPELINE_STAGES-1).coarse(31 downto 0));
+  q_o.coarse  <= std_logic_vector(sums(c_NUM_PIPELINE_STAGES-1).coarse(31 downto 0));
-  q_o.frac  <= std_logic_vector(sums(c_NUM_PIPELINE_STAGES-1).frac(11 downto 0));
+  q_o.frac    <= std_logic_vector(sums(c_NUM_PIPELINE_STAGES-1).frac(11 downto 0));
-  q_o.slope <= sums(c_NUM_PIPELINE_STAGES-1).slope;
+  q_o.slope   <= sums(c_NUM_PIPELINE_STAGES-1).slope;
-  q_o.meta <=  sums(c_NUM_PIPELINE_STAGES-1).meta;
+  q_o.meta    <= sums(c_NUM_PIPELINE_STAGES-1).meta;
+  q_o.channel <= sums(c_NUM_PIPELINE_STAGES-1).channel;
 end rtl;
--- a/hdl/rtl/timestamp_convert_filter.vhd
+++ b/hdl/rtl/timestamp_convert_filter.vhd