From e44cd87182452ce6220b028c62caa1bdbb9c55e3 Mon Sep 17 00:00:00 2001
From: tmeissner <programming@goodcleanfun.de>
Date: Fri, 5 Jun 2020 13:47:04 +0200
Subject: Synthesis of PSL stable() function.

---
 src/synth/synth-expr.adb | 60 +++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 11 deletions(-)

(limited to 'src/synth')

diff --git a/src/synth/synth-expr.adb b/src/synth/synth-expr.adb
index 677df4454..6f8317831 100644
--- a/src/synth/synth-expr.adb
+++ b/src/synth/synth-expr.adb
@@ -1849,30 +1849,40 @@ package body Synth.Expr is
       return Res;
    end Synth_PSL_Expression;
 
+   function Synth_Psl_Function_Clock
+     (Syn_Inst : Synth_Instance_Acc; Call : Node; Ctxt : Context_Acc)
+     return Net
+   is
+      Clock   : Node;
+      Clk     : Valtyp;
+      Clk_Net : Net;
+   begin
+      Clock := Get_Clock_Expression (Call);
+      if Clock /= Null_Node then
+         Clk := Synth_Expression (Syn_Inst, Clock);
+         Clk_Net := Get_Net (Ctxt, Clk);
+      else
+         Clock := Get_Default_Clock (Call);
+         pragma Assert (Clock /= Null_Node);
+         Clk_Net := Synth_PSL_Expression (Syn_Inst, Get_Psl_Boolean (Clock));
+      end if;
+      return Clk_Net;
+   end Synth_Psl_Function_Clock;
+
    function Synth_Psl_Prev (Syn_Inst : Synth_Instance_Acc; Call : Node)
                             return Valtyp
    is
       Ctxt      : constant Context_Acc := Get_Build (Syn_Inst);
       Count     : constant Node := Get_Count_Expression (Call);
-      Clock     : Node;
       Count_Val : Valtyp;
       Dff       : Net;
-      Clk       : Valtyp;
       Expr      : Valtyp;
       Clk_Net   : Net;
       Num       : Int64;
    begin
       Expr := Synth_Expression (Syn_Inst, Get_Expression (Call));
 
-      Clock := Get_Clock_Expression (Call);
-      if Clock /= Null_Node then
-         Clk := Synth_Expression (Syn_Inst, Clock);
-         Clk_Net := Get_Net (Ctxt, Clk);
-      else
-         Clock := Get_Default_Clock (Call);
-         pragma Assert (Clock /= Null_Node);
-         Clk_Net := Synth_PSL_Expression (Syn_Inst, Get_Psl_Boolean (Clock));
-      end if;
+      Clk_Net := Synth_Psl_Function_Clock(Syn_Inst, Call, Ctxt);
 
       if Count /= Null_Node then
          Count_Val := Synth_Expression (Syn_Inst, Count);
@@ -1891,6 +1901,32 @@ package body Synth.Expr is
       return Create_Value_Net (Dff, Expr.Typ);
    end Synth_Psl_Prev;
 
+   function Synth_Psl_Stable (Syn_Inst : Synth_Instance_Acc; Call : Node)
+                              return Valtyp
+   is
+      Ctxt    : constant Context_Acc := Get_Build (Syn_Inst);
+      DffCurr : Net;
+      Dff     : Net;
+      Expr    : Valtyp;
+      Clk_Net : Net;
+      Res     : Net;
+   begin
+      Expr := Synth_Expression (Syn_Inst, Get_Expression (Call));
+
+      Clk_Net := Synth_Psl_Function_Clock(Syn_Inst, Call, Ctxt);
+
+      DffCurr := Get_Net (Ctxt, Expr);
+      Set_Location (DffCurr, Call);
+      Dff := Build_Dff (Ctxt, Clk_Net, DffCurr);
+      Set_Location (Dff, Call);
+
+      Res := Build_Compare(Ctxt, Id_Eq, DffCurr, Dff);
+      Set_Location (Res, Call);
+
+      return Create_Value_Net (Res, Boolean_Type);
+
+   end Synth_Psl_Stable;
+
    subtype And_Or_Module_Id is Module_Id range Id_And .. Id_Or;
 
    function Synth_Short_Circuit (Syn_Inst : Synth_Instance_Acc;
@@ -2231,6 +2267,8 @@ package body Synth.Expr is
             return No_Valtyp;
          when Iir_Kind_Psl_Prev =>
             return Synth_Psl_Prev (Syn_Inst, Expr);
+         when Iir_Kind_Psl_Stable =>
+            return Synth_Psl_Stable (Syn_Inst, Expr);
          when Iir_Kind_Overflow_Literal =>
             Error_Msg_Synth (+Expr, "out of bound expression");
             return No_Valtyp;
-- 
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