1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- G N A T . B Y T E _ S W A P P I N G --
9 -- Copyright (C) 2006-2012, AdaCore --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 -- This is a general implementation that uses GCC intrinsics to take
33 -- advantage of any machine-specific instructions.
35 with Ada.Unchecked_Conversion; use Ada;
37 package body GNAT.Byte_Swapping is
39 type U16 is mod 2**16;
40 type U32 is mod 2**32;
41 type U64 is mod 2**64;
43 function Bswap_16 (X : U16) return U16 is (X / 256 or X * 256);
44 -- The above is an idiom recognized by GCC
46 function Bswap_32 (X : U32) return U32;
47 pragma Import (Intrinsic, Bswap_32, "__builtin_bswap32");
49 function Bswap_64 (X : U64) return U64;
50 pragma Import (Intrinsic, Bswap_64, "__builtin_bswap64");
56 function Swapped2 (Input : Item) return Item is
57 function As_U16 is new Unchecked_Conversion (Item, U16);
58 function As_Item is new Unchecked_Conversion (U16, Item);
60 function Bswap_16 (X : U16) return U16 is (X / 256 or X * 256);
61 -- ??? Need to have function local here to allow inlining
62 pragma Compile_Time_Error (Item'Max_Size_In_Storage_Elements /= 2,
63 "storage size must be 2 bytes");
65 return As_Item (Bswap_16 (As_U16 (Input)));
72 function Swapped4 (Input : Item) return Item is
73 function As_U32 is new Unchecked_Conversion (Item, U32);
74 function As_Item is new Unchecked_Conversion (U32, Item);
75 pragma Compile_Time_Error (Item'Max_Size_In_Storage_Elements /= 4,
76 "storage size must be 4 bytes");
78 return As_Item (Bswap_32 (As_U32 (Input)));
85 function Swapped8 (Input : Item) return Item is
86 function As_U64 is new Unchecked_Conversion (Item, U64);
87 function As_Item is new Unchecked_Conversion (U64, Item);
88 pragma Compile_Time_Error (Item'Max_Size_In_Storage_Elements /= 8,
89 "storage size must be 8 bytes");
91 return As_Item (Bswap_64 (As_U64 (Input)));
98 procedure Swap2 (Location : System.Address) is
100 for X'Address use Location;
109 procedure Swap4 (Location : System.Address) is
111 for X'Address use Location;
120 procedure Swap8 (Location : System.Address) is
122 for X'Address use Location;
126 end GNAT.Byte_Swapping;