From c6ff96cb67935a59fe78f692974cfa5870b5f1d3 Mon Sep 17 00:00:00 2001
From: Tristan Gingold <tgingold@free.fr>
Date: Sat, 28 Aug 2021 10:17:22 +0200
Subject: synth-vhdl_decls.adb: add comments

---
 src/synth/synth-vhdl_decls.adb | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src')

diff --git a/src/synth/synth-vhdl_decls.adb b/src/synth/synth-vhdl_decls.adb
index 779c802c1..c6ada6dba 100644
--- a/src/synth/synth-vhdl_decls.adb
+++ b/src/synth/synth-vhdl_decls.adb
@@ -1123,6 +1123,7 @@ package body Synth.Vhdl_Decls is
             raise Internal_Error;
       end case;
       if Drv = No_Net then
+         --  Undriven signals.
          if Is_Connected (Get_Output (Gate, 0)) then
             --  No warning if the signal is not used.
             --  TODO: maybe simply remove it.
@@ -1135,9 +1136,12 @@ package body Synth.Vhdl_Decls is
             end if;
          end if;
          if Def_Val = No_Net then
+            --  The initial value of an undriven signal is X.
             Def_Val := Build_Const_X (Get_Build (Syn_Inst),
                                       Get_Width (Gate_Net));
          end if;
+
+         --  The value of an undriven signal is its initial value.
          Connect (Get_Input (Gate, 0), Def_Val);
       end if;
 
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