gcc/ada/s-caun64.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                    GNAT RUN-TIME LIBRARY COMPONENTS                      --
   4 --                                                                          --
   5 --      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 _ 6 4     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2002-2009, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 with System.Address_Operations; use System.Address_Operations;
  33
  34 with Ada.Unchecked_Conversion;
  35
  36 package body System.Compare_Array_Unsigned_64 is
  37
  38    type Word is mod 2 ** 64;
  39    --  Used to process operands by words
  40
  41    type Uword is new Word;
  42    for Uword'Alignment use 1;
  43    --  Used to process operands when unaligned
  44
  45    type WP is access Word;
  46    type UP is access Uword;
  47
  48    function W is new Ada.Unchecked_Conversion (Address, WP);
  49    function U is new Ada.Unchecked_Conversion (Address, UP);
  50
  51    -----------------------
  52    -- Compare_Array_U64 --
  53    -----------------------
  54
  55    function Compare_Array_U64
  56      (Left      : System.Address;
  57       Right     : System.Address;
  58       Left_Len  : Natural;
  59       Right_Len : Natural) return Integer
  60    is
  61       Clen : Natural := Natural'Min (Left_Len, Right_Len);
  62       --  Number of elements left to compare
  63
  64       L : Address := Left;
  65       R : Address := Right;
  66       --  Pointers to next elements to compare
  67
  68    begin
  69       --  Case of going by aligned double words
  70
  71       if ModA (OrA (Left, Right), 8) = 0 then
  72          while Clen /= 0 loop
  73             if W (L).all /= W (R).all then
  74                if W (L).all > W (R).all then
  75                   return +1;
  76                else
  77                   return -1;
  78                end if;
  79             end if;
  80
  81             Clen := Clen - 1;
  82             L := AddA (L, 8);
  83             R := AddA (R, 8);
  84          end loop;
  85
  86       --  Case of going by unaligned double words
  87
  88       else
  89          while Clen /= 0 loop
  90             if U (L).all /= U (R).all then
  91                if U (L).all > U (R).all then
  92                   return +1;
  93                else
  94                   return -1;
  95                end if;
  96             end if;
  97
  98             Clen := Clen - 1;
  99             L := AddA (L, 8);
 100             R := AddA (R, 8);
 101          end loop;
 102       end if;
 103
 104       --  Here if common section equal, result decided by lengths
 105
 106       if Left_Len = Right_Len then
 107          return 0;
 108       elsif Left_Len > Right_Len then
 109          return +1;
 110       else
 111          return -1;
 112       end if;
 113    end Compare_Array_U64;
 114
 115 end System.Compare_Array_Unsigned_64;