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) 2002-2018, 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
32with System.Address_Operations; use System.Address_Operations;
33
34with Ada.Unchecked_Conversion;
35
36package 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
115end System.Compare_Array_Unsigned_64;
116