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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME LIBRARY COMPONENTS --
-- --
-- S Y S T E M . C O M P A R E _ A R R A Y _ U N S I G N E D _ 16 --
-- --
-- B o d y --
-- --
-- Copyright (C) 2002-2005 Free Software Foundation, Inc. --
-- --
-- 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. --
-- --
------------------------------------------------------------------------------
with System.Address_Operations; use System.Address_Operations;
with Unchecked_Conversion;
package body System.Compare_Array_Unsigned_16 is
type Word is mod 2 ** 32;
-- Used to process operands by words
type Half is mod 2 ** 16;
for Half'Size use 16;
-- Used to process operands by half words
type Uhalf is record
H : Half;
end record;
pragma Pack (Uhalf);
for Uhalf'Alignment use 1;
-- Used to process operands when unaligned
type WP is access Word;
type HP is access Half;
type UP is access Uhalf;
function W is new Unchecked_Conversion (Address, WP);
function H is new Unchecked_Conversion (Address, HP);
function U is new Unchecked_Conversion (Address, UP);
-----------------------
-- Compare_Array_U16 --
-----------------------
function Compare_Array_U16
(Left : System.Address;
Right : System.Address;
Left_Len : Natural;
Right_Len : Natural) return Integer
is
Clen : Natural := Natural'Min (Left_Len, Right_Len);
-- Number of elements left to compare
L : Address := Left;
R : Address := Right;
-- Pointers to next elements to compare
begin
-- Go by words if possible
if ModA (OrA (Left, Right), 4) = 0 then
while Clen > 1
and then W (L).all = W (R).all
loop
Clen := Clen - 2;
L := AddA (L, 4);
R := AddA (R, 4);
end loop;
end if;
-- Case of going by aligned half words
if ModA (OrA (Left, Right), 2) = 0 then
while Clen /= 0 loop
if H (L).all /= H (R).all then
if H (L).all > H (R).all then
return +1;
else
return -1;
end if;
end if;
Clen := Clen - 1;
L := AddA (L, 2);
R := AddA (R, 2);
end loop;
-- Case of going by unaligned half words
else
while Clen /= 0 loop
if U (L).H /= U (R).H then
if U (L).H > U (R).H then
return +1;
else
return -1;
end if;
end if;
Clen := Clen - 1;
L := AddA (L, 2);
R := AddA (R, 2);
end loop;
end if;
-- Here if common section equal, result decided by lengths
if Left_Len = Right_Len then
return 0;
elsif Left_Len > Right_Len then
return +1;
else
return -1;
end if;
end Compare_Array_U16;
end System.Compare_Array_Unsigned_16;
|
