------------------------------------------------------------------------------ -- -- -- 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;