gc_pulse_synchronizer2: add comments.

68ccc8ed · Tristan Gingold · 8796fa8e · 68ccc8ed
Commit 68ccc8ed authored Mar 03, 2020 by Tristan Gingold
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gc_pulse_synchronizer2.vhd modules/common/gc_pulse_synchronizer2.vhd +6 -0

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--- a/modules/common/gc_pulse_synchronizer2.vhd
+++ b/modules/common/gc_pulse_synchronizer2.vhd
@@ -89,12 +89,18 @@ begin  -- rtl
      d_ack_d0 <= d_ack;

      if ready = '1' and d_p_i = '1' and d_p_d0 = '0'then
+        --  Incoming pulse detected and the system is ready.
+        --  Transfer it.
        in_ext <= '1';
+        --  Clear ack and ready!
        d_ack  <= '0';
        ready  <= '0';
      elsif in_ext = '1' and out_feedback = '1' then
+        --  Pulse has been transfered, clear the input.
        in_ext <= '0';
      elsif in_ext = '0' and out_feedback = '0' then
+        --  Clear transfered.  Done.
+        --  This is also the steady state.
        d_ack <= '1';
        ready <= '1';
      end if;