145 lines
5.8 KiB
Ada
145 lines
5.8 KiB
Ada
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------------------------------------------------------------------------------
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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 . C O M P A R E _ A R R A Y _ U N S I G N E D _ 8 --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2002-2013, 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_Warning;
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with System.Address_Operations; use System.Address_Operations;
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with Ada.Unchecked_Conversion;
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package body System.Compare_Array_Unsigned_8 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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-- Compare_Array_U8 --
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----------------------
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function Compare_Array_U8
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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 (ModA (OrA (Left, Right), 4) /= 0) or else Compare_Len < 4 then
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return Compare_Array_U8_Unaligned (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 :=
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To_Big_Words (Left);
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RightP : constant Big_Words_Ptr :=
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To_Big_Words (Right);
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Words_To_Compare : constant Natural := Compare_Len / 4;
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Bytes_Compared_As_Words : constant Natural := Words_To_Compare * 4;
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begin
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for J in 0 .. Words_To_Compare - 1 loop
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if LeftP (J) /= RightP (J) then
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return Compare_Array_U8_Unaligned
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(AddA (Left, Address (4 * J)),
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AddA (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 Compare_Array_U8_Unaligned
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(AddA (Left, Address (Bytes_Compared_As_Words)),
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AddA (Right, Address (Bytes_Compared_As_Words)),
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Left_Len - Bytes_Compared_As_Words,
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Right_Len - Bytes_Compared_As_Words);
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end;
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end Compare_Array_U8;
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--------------------------------
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-- Compare_Array_U8_Unaligned --
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--------------------------------
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function Compare_Array_U8_Unaligned
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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 Compare_Array_U8_Unaligned;
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end System.Compare_Array_Unsigned_8;
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