141 lines
5.4 KiB
Ada
141 lines
5.4 KiB
Ada
------------------------------------------------------------------------------
|
|
-- --
|
|
-- GNAT RUN-TIME LIBRARY COMPONENTS --
|
|
-- --
|
|
-- S Y S T E M . S T R I N G _ C O M P A R E --
|
|
-- --
|
|
-- 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, 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. --
|
|
-- --
|
|
------------------------------------------------------------------------------
|
|
|
|
with Unchecked_Conversion;
|
|
|
|
package body System.String_Compare is
|
|
|
|
type Word is mod 2 ** 32;
|
|
-- Used to process operands by words
|
|
|
|
type Big_Words is array (Natural) of Word;
|
|
type Big_Words_Ptr is access Big_Words;
|
|
-- Array type used to access by words
|
|
|
|
type Byte is mod 2 ** 8;
|
|
-- Used to process operands by bytes
|
|
|
|
type Big_Bytes is array (Natural) of Byte;
|
|
type Big_Bytes_Ptr is access Big_Bytes;
|
|
-- Array type used to access by bytes
|
|
|
|
function To_Big_Words is new
|
|
Unchecked_Conversion (System.Address, Big_Words_Ptr);
|
|
|
|
function To_Big_Bytes is new
|
|
Unchecked_Conversion (System.Address, Big_Bytes_Ptr);
|
|
|
|
-----------------
|
|
-- Str_Compare --
|
|
-----------------
|
|
|
|
function Str_Compare
|
|
(Left : System.Address;
|
|
Right : System.Address;
|
|
Left_Len : Natural;
|
|
Right_Len : Natural)
|
|
return Integer
|
|
is
|
|
Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
|
|
|
|
begin
|
|
-- If operands are non-aligned, or length is too short, go by bytes
|
|
|
|
if (((Left or Right) and 2#11#) /= 0) or else Compare_Len < 4 then
|
|
return Str_Compare_Bytes (Left, Right, Left_Len, Right_Len);
|
|
end if;
|
|
|
|
-- Here we can go by words
|
|
|
|
declare
|
|
LeftP : constant Big_Words_Ptr := To_Big_Words (Left);
|
|
RightP : constant Big_Words_Ptr := To_Big_Words (Right);
|
|
Clen4 : constant Natural := Compare_Len / 4 - 1;
|
|
Clen4F : constant Natural := Clen4 * 4;
|
|
|
|
begin
|
|
for J in 0 .. Clen4 loop
|
|
if LeftP (J) /= RightP (J) then
|
|
return Str_Compare_Bytes
|
|
(Left + Address (4 * J),
|
|
Right + Address (4 * J),
|
|
4, 4);
|
|
end if;
|
|
end loop;
|
|
|
|
return Str_Compare_Bytes
|
|
(Left + Address (Clen4F),
|
|
Right + Address (Clen4F),
|
|
Left_Len - Clen4F,
|
|
Right_Len - Clen4F);
|
|
end;
|
|
end Str_Compare;
|
|
|
|
-----------------------
|
|
-- Str_Compare_Bytes --
|
|
-----------------------
|
|
|
|
function Str_Compare_Bytes
|
|
(Left : System.Address;
|
|
Right : System.Address;
|
|
Left_Len : Natural;
|
|
Right_Len : Natural)
|
|
return Integer
|
|
is
|
|
Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
|
|
|
|
LeftP : constant Big_Bytes_Ptr := To_Big_Bytes (Left);
|
|
RightP : constant Big_Bytes_Ptr := To_Big_Bytes (Right);
|
|
|
|
begin
|
|
for J in 0 .. Compare_Len - 1 loop
|
|
if LeftP (J) /= RightP (J) then
|
|
if LeftP (J) > RightP (J) then
|
|
return +1;
|
|
else
|
|
return -1;
|
|
end if;
|
|
end if;
|
|
end loop;
|
|
|
|
if Left_Len = Right_Len then
|
|
return 0;
|
|
elsif Left_Len > Right_Len then
|
|
return +1;
|
|
else
|
|
return -1;
|
|
end if;
|
|
end Str_Compare_Bytes;
|
|
|
|
end System.String_Compare;
|