134 lines
4.9 KiB
Ada
134 lines
4.9 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 _ 1 6 --
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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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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_16 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 Half is mod 2 ** 16;
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for Half'Size use 16;
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-- Used to process operands by half words
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type Uhalf is new Half;
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for Uhalf'Alignment use 1;
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-- Used to process operands when unaligned
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type WP is access Word;
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type HP is access Half;
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type UP is access Uhalf;
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function W is new Ada.Unchecked_Conversion (Address, WP);
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function H is new Ada.Unchecked_Conversion (Address, HP);
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function U is new Ada.Unchecked_Conversion (Address, UP);
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-----------------------
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-- Compare_Array_U16 --
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-----------------------
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function Compare_Array_U16
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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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Clen : Natural := Natural'Min (Left_Len, Right_Len);
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-- Number of elements left to compare
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L : Address := Left;
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R : Address := Right;
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-- Pointers to next elements to compare
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begin
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-- Go by words if possible
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if ModA (OrA (Left, Right), 4) = 0 then
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while Clen > 1
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and then W (L).all = W (R).all
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loop
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Clen := Clen - 2;
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L := AddA (L, 4);
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R := AddA (R, 4);
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end loop;
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end if;
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-- Case of going by aligned half words
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if ModA (OrA (Left, Right), 2) = 0 then
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while Clen /= 0 loop
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if H (L).all /= H (R).all then
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if H (L).all > H (R).all 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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Clen := Clen - 1;
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L := AddA (L, 2);
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R := AddA (R, 2);
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end loop;
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-- Case of going by unaligned half words
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else
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while Clen /= 0 loop
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if U (L).all /= U (R).all then
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if U (L).all > U (R).all 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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Clen := Clen - 1;
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L := AddA (L, 2);
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R := AddA (R, 2);
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end loop;
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end if;
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-- Here if common section equal, result decided by lengths
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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_U16;
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end System.Compare_Array_Unsigned_16;
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