netlists-butils: extract synth_case from synth.stmts.

1 files changed, 55 insertions, 0 deletions

diff --git a/src/synth/netlists-butils.ads b/src/synth/netlists-butils.ads
new file mode 100644
index 000000000..c0d79734a
--- /dev/null
+++ b/src/synth/netlists-butils.ads
@@ -0,0 +1,55 @@
+--  Build utilities
+--  Copyright (C) 2019 Tristan Gingold
+--
+--  This file is part of GHDL.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 2 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program; if not, write to the Free Software
+--  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+--  MA 02110-1301, USA.
+
+with Ada.Unchecked_Deallocation;
+
+with Netlists.Builders; use Netlists.Builders;
+
+with Synth.Source; use Synth.Source;
+
+package Netlists.Butils is
+   type Case_Element is record
+      Sel : Uns64;
+      Val : Net;
+   end record;
+
+   type Case_Element_Array is array (Natural range <>) of Case_Element;
+   type Case_Element_Array_Acc is access Case_Element_Array;
+   procedure Free_Case_Element_Array is new Ada.Unchecked_Deallocation
+     (Case_Element_Array, Case_Element_Array_Acc);
+
+   --  Generate a netlist for a 'big' mux selected by SEL.  The inputs are
+   --  described by ELS: E.Val must be selected when SEL = E.Sel; if there
+   --  is no E in Els for a value, DEFAULT is selected.
+   --  The result of the netlist is stored in RES.
+   --
+   --  A tree of MUX4 is built.
+   --
+   --  ELS must be sorted by SEL values.
+   --  ELS is overwritten/modified so after the call it contains garbage.  The
+   --  reason is that ELS might be large, so temporary arrays are not allocated
+   --  on the stack, and ELS is expected to be built only for this subprogram.
+   procedure Synth_Case (Ctxt : Context_Acc;
+                         Sel : Net;
+                         Els : in out Case_Element_Array;
+                         Default : Net;
+                         Res : out Net;
+                         Sel_Loc : Syn_Src);
+end Netlists.Butils;