--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/s-bytswa.ads	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,53 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT RUN-TIME COMPONENTS                         --
+--                                                                          --
+--                  S Y S T E M . B Y T E _ S W A P P I N G                 --
+--                                                                          --
+--                                 S p e c                                  --
+--                                                                          --
+--                     Copyright (C) 2006-2017, AdaCore                     --
+--                                                                          --
+-- GNAT is free software;  you can  redistribute it  and/or modify it under --
+-- terms of the  GNU General Public License as published  by the Free Soft- --
+-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
+-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
+--                                                                          --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception,   --
+-- version 3.1, as published by the Free Software Foundation.               --
+--                                                                          --
+-- You should have received a copy of the GNU General Public License and    --
+-- a copy of the GCC Runtime Library Exception along with this program;     --
+-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
+-- <http://www.gnu.org/licenses/>.                                          --
+--                                                                          --
+-- GNAT was originally developed  by the GNAT team at  New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc.      --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  Intrinsic routines for byte swapping. These are used by the expanded code
+--  (supporting alternative byte ordering), and by the GNAT.Byte_Swapping run
+--  time package which provides user level routines for byte swapping.
+
+package System.Byte_Swapping is
+
+   pragma Pure;
+
+   type U16 is mod 2**16;
+   type U32 is mod 2**32;
+   type U64 is mod 2**64;
+
+   function Bswap_16 (X : U16) return U16;
+   pragma Import (Intrinsic, Bswap_16, "__builtin_bswap16");
+
+   function Bswap_32 (X : U32) return U32;
+   pragma Import (Intrinsic, Bswap_32, "__builtin_bswap32");
+
+   function Bswap_64 (X : U64) return U64;
+   pragma Import (Intrinsic, Bswap_64, "__builtin_bswap64");
+
+end System.Byte_Swapping;