74e63df17e
2009-04-17 Robert Dewar <dewar@adacore.com> * g-moreex.adb: Add comments. * s-auxdec.ads: Add ??? comment for uncommented pragma Warnings (Off) * s-auxdec-vms_64.ads: Add ??? comment for uncommented pragma Warnings (Off) * prepcomp.adb: Add ??? comment * a-tasatt.adb: Minor reformatting * g-trasym-vms-alpha.adb: Add ??? comment * g-trasym-vms-ia64.adb: Add ??? comment * xoscons.adb: Minor reformatting * s-tassta.adb: Minor reformatting * s-scaval.adb: Add ??? comment * stand.ads: Minor code clean up (remove junk with of Namet) * s-strcom.adb, s-strcom.ads, s-string.adb, s-string.ads, s-sopco3.adb, s-sopco3.ads, s-strops.adb, s-strops.ads, s-sopco5.adb, s-sopco5.ads, s-wchcnv.adb, s-wchcnv.ads, s-ststop.adb, s-ststop.ads, s-soflin.adb, s-soflin.ads, s-traceb.adb, s-traceb.ads, s-traent.adb, s-traent.ads, s-secsta.adb, s-secsta.ads, s-utf_32.adb, s-utf_32.ads, s-wchcon.adb, s-wchjis.adb, s-wchcon.ads, s-wchjis.ads, s-sopco4.adb, s-sopco4.ads, s-stache.adb, s-stache.ads, s-stoele.adb, s-stoele.ads, s-stalib.adb, s-stalib.ads, s-os_lib.ads, s-purexc.ads: Remove no longer needed Warnings off pragmas. From-SVN: r146262
141 lines
5.3 KiB
Ada
141 lines
5.3 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME LIBRARY COMPONENTS --
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-- --
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-- S Y S T E M . S T R I N G _ C O M P A R E --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2002-2009, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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pragma Compiler_Unit;
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with Ada.Unchecked_Conversion;
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package body System.String_Compare is
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type Word is mod 2 ** 32;
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-- Used to process operands by words
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type Big_Words is array (Natural) of Word;
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type Big_Words_Ptr is access Big_Words;
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for Big_Words_Ptr'Storage_Size use 0;
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-- Array type used to access by words
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type Byte is mod 2 ** 8;
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-- Used to process operands by bytes
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type Big_Bytes is array (Natural) of Byte;
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type Big_Bytes_Ptr is access Big_Bytes;
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for Big_Bytes_Ptr'Storage_Size use 0;
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-- Array type used to access by bytes
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function To_Big_Words is new
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Ada.Unchecked_Conversion (System.Address, Big_Words_Ptr);
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function To_Big_Bytes is new
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Ada.Unchecked_Conversion (System.Address, Big_Bytes_Ptr);
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-----------------
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-- Str_Compare --
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-----------------
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function Str_Compare
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(Left : System.Address;
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Right : System.Address;
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Left_Len : Natural;
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Right_Len : Natural) return Integer
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is
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Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
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begin
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-- If operands are non-aligned, or length is too short, go by bytes
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if (((Left or Right) and 2#11#) /= 0) or else Compare_Len < 4 then
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return Str_Compare_Bytes (Left, Right, Left_Len, Right_Len);
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end if;
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-- Here we can go by words
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declare
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LeftP : constant Big_Words_Ptr := To_Big_Words (Left);
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RightP : constant Big_Words_Ptr := To_Big_Words (Right);
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Clen4 : constant Natural := Compare_Len / 4 - 1;
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Clen4F : constant Natural := Clen4 * 4;
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begin
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for J in 0 .. Clen4 loop
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if LeftP (J) /= RightP (J) then
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return Str_Compare_Bytes
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(Left + Address (4 * J),
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Right + Address (4 * J),
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4, 4);
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end if;
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end loop;
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return Str_Compare_Bytes
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(Left + Address (Clen4F),
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Right + Address (Clen4F),
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Left_Len - Clen4F,
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Right_Len - Clen4F);
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end;
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end Str_Compare;
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-----------------------
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-- Str_Compare_Bytes --
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-----------------------
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function Str_Compare_Bytes
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(Left : System.Address;
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Right : System.Address;
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Left_Len : Natural;
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Right_Len : Natural) return Integer
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is
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Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
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LeftP : constant Big_Bytes_Ptr := To_Big_Bytes (Left);
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RightP : constant Big_Bytes_Ptr := To_Big_Bytes (Right);
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begin
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for J in 0 .. Compare_Len - 1 loop
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if LeftP (J) /= RightP (J) then
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if LeftP (J) > RightP (J) then
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return +1;
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else
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return -1;
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end if;
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end if;
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end loop;
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if Left_Len = Right_Len then
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return 0;
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elsif Left_Len > Right_Len then
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return +1;
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else
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return -1;
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end if;
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end Str_Compare_Bytes;
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end System.String_Compare;
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