------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- G N A T . B Y T E _ S W A P P I N G -- -- -- -- B o d y -- -- -- -- Copyright (C) 2006-2012, 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 -- -- . -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- This is a general implementation that uses GCC intrinsics to take -- advantage of any machine-specific instructions. with Ada.Unchecked_Conversion; use Ada; package body GNAT.Byte_Swapping is 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 is (X / 256 or X * 256); -- The above is an idiom recognized by GCC 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"); -------------- -- Swapped2 -- -------------- function Swapped2 (Input : Item) return Item is function As_U16 is new Unchecked_Conversion (Item, U16); function As_Item is new Unchecked_Conversion (U16, Item); function Bswap_16 (X : U16) return U16 is (X / 256 or X * 256); -- ??? Need to have function local here to allow inlining pragma Compile_Time_Error (Item'Max_Size_In_Storage_Elements /= 2, "storage size must be 2 bytes"); begin return As_Item (Bswap_16 (As_U16 (Input))); end Swapped2; -------------- -- Swapped4 -- -------------- function Swapped4 (Input : Item) return Item is function As_U32 is new Unchecked_Conversion (Item, U32); function As_Item is new Unchecked_Conversion (U32, Item); pragma Compile_Time_Error (Item'Max_Size_In_Storage_Elements /= 4, "storage size must be 4 bytes"); begin return As_Item (Bswap_32 (As_U32 (Input))); end Swapped4; -------------- -- Swapped8 -- -------------- function Swapped8 (Input : Item) return Item is function As_U64 is new Unchecked_Conversion (Item, U64); function As_Item is new Unchecked_Conversion (U64, Item); pragma Compile_Time_Error (Item'Max_Size_In_Storage_Elements /= 8, "storage size must be 8 bytes"); begin return As_Item (Bswap_64 (As_U64 (Input))); end Swapped8; ----------- -- Swap2 -- ----------- procedure Swap2 (Location : System.Address) is X : U16; for X'Address use Location; begin X := Bswap_16 (X); end Swap2; ----------- -- Swap4 -- ----------- procedure Swap4 (Location : System.Address) is X : U32; for X'Address use Location; begin X := Bswap_32 (X); end Swap4; ----------- -- Swap8 -- ----------- procedure Swap8 (Location : System.Address) is X : U64; for X'Address use Location; begin X := Bswap_64 (X); end Swap8; end GNAT.Byte_Swapping;