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------------------------------------------------------------------------------
-- --
-- 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) 2006-2007, 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 2, 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. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- 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 does not take advantage of
-- any machine-specific instructions.
with Interfaces; use Interfaces;
with Ada.Unchecked_Conversion;
package body GNAT.Byte_Swapping is
--------------
-- Swapped2 --
--------------
function Swapped2 (Input : Item) return Item is
function As_U16 is new Ada.Unchecked_Conversion
(Source => Item, Target => Unsigned_16);
function As_Item is new Ada.Unchecked_Conversion
(Source => Unsigned_16, Target => Item);
X : constant Unsigned_16 := As_U16 (Input);
begin
return As_Item ((Shift_Left (X, 8) and 16#FF00#) or
(Shift_Right (X, 8) and 16#00FF#));
end Swapped2;
--------------
-- Swapped4 --
--------------
function Swapped4 (Input : Item) return Item is
function As_U32 is new Ada.Unchecked_Conversion
(Source => Item, Target => Unsigned_32);
function As_Item is new Ada.Unchecked_Conversion
(Source => Unsigned_32, Target => Item);
X : constant Unsigned_32 := As_U32 (Input);
begin
return As_Item ((Shift_Right (X, 24) and 16#0000_00FF#) or
(Shift_Right (X, 8) and 16#0000_FF00#) or
(Shift_Left (X, 8) and 16#00FF_0000#) or
(Shift_Left (X, 24) and 16#FF00_0000#));
end Swapped4;
--------------
-- Swapped8 --
--------------
function Swapped8 (Input : Item) return Item is
function As_U64 is new Ada.Unchecked_Conversion
(Source => Item, Target => Unsigned_64);
function As_Item is new Ada.Unchecked_Conversion
(Source => Unsigned_64, Target => Item);
X : constant Unsigned_64 := As_U64 (Input);
Low, High : aliased Unsigned_32;
begin
Low := Unsigned_32 (X and 16#0000_0000_FFFF_FFFF#);
Swap4 (Low'Address);
High := Unsigned_32 (Shift_Right (X, 32));
Swap4 (High'Address);
return As_Item
(Shift_Left (Unsigned_64 (Low), 32) or Unsigned_64 (High));
end Swapped8;
-----------
-- Swap2 --
-----------
procedure Swap2 (Location : System.Address) is
X : Unsigned_16;
for X'Address use Location;
begin
X := (Shift_Left (X, 8) and 16#FF00#) or
(Shift_Right (X, 8) and 16#00FF#);
end Swap2;
-----------
-- Swap4 --
-----------
procedure Swap4 (Location : System.Address) is
X : Unsigned_32;
for X'Address use Location;
begin
X := (Shift_Right (X, 24) and 16#0000_00FF#) or
(Shift_Right (X, 8) and 16#0000_FF00#) or
(Shift_Left (X, 8) and 16#00FF_0000#) or
(Shift_Left (X, 24) and 16#FF00_0000#);
end Swap4;
-----------
-- Swap8 --
-----------
procedure Swap8 (Location : System.Address) is
X : Unsigned_64;
for X'Address use Location;
Low, High : aliased Unsigned_32;
begin
Low := Unsigned_32 (X and 16#0000_0000_FFFF_FFFF#);
Swap4 (Low'Address);
High := Unsigned_32 (Shift_Right (X, 32));
Swap4 (High'Address);
X := Shift_Left (Unsigned_64 (Low), 32) or Unsigned_64 (High);
end Swap8;
end GNAT.Byte_Swapping;
|
