1------------------------------------------------------------------------------
2--                                                                          --
3--                   GNU ADA RUNTIME LIBRARY COMPONENTS                     --
4--                                                                          --
5--        S Y S T E M . C O M P A R E _ A R R A Y _ S I G N E D _ 6 4       --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--             Copyright (C) 2002 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 2,  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.  See the GNU General Public License --
17-- for  more details.  You should have  received  a copy of the GNU General --
18-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
19-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
20-- MA 02111-1307, USA.                                                      --
21--                                                                          --
22-- As a special exception,  if other files  instantiate  generics from this --
23-- unit, or you link  this unit with other files  to produce an executable, --
24-- this  unit  does not  by itself cause  the resulting  executable  to  be --
25-- covered  by the  GNU  General  Public  License.  This exception does not --
26-- however invalidate  any other reasons why  the executable file  might be --
27-- covered by the  GNU Public License.                                      --
28--                                                                          --
29-- GNAT was originally developed  by the GNAT team at  New York University. --
30-- Extensive contributions were provided by Ada Core Technologies Inc.      --
31--                                                                          --
32------------------------------------------------------------------------------
33
34with Unchecked_Conversion;
35
36package body System.Compare_Array_Signed_64 is
37
38   type Word is range -2**63 .. 2**63 - 1;
39   for Word'Size use 64;
40   --  Used to process operands by words
41
42   type Uword is record
43      W : Word;
44   end record;
45   pragma Pack (Uword);
46   for Uword'Alignment use 1;
47   --  Used to process operands when unaligned
48
49   type WP is access Word;
50   type UP is access Uword;
51
52   function W is new Unchecked_Conversion (Address, WP);
53   function U is new Unchecked_Conversion (Address, UP);
54
55   -----------------------
56   -- Compare_Array_S64 --
57   -----------------------
58
59   function Compare_Array_S64
60     (Left      : System.Address;
61      Right     : System.Address;
62      Left_Len  : Natural;
63      Right_Len : Natural)
64      return      Integer
65   is
66      Clen : Natural := Natural'Min (Left_Len, Right_Len);
67      --  Number of elements left to compare
68
69      L : Address := Left;
70      R : Address := Right;
71      --  Pointers to next elements to compare
72
73   begin
74      --  Case of going by aligned words
75
76      if ((Left or Right) and (8 - 1)) = 0 then
77         while Clen /= 0 loop
78            if W (L).all /= W (R).all then
79               if W (L).all > W (R).all then
80                  return +1;
81               else
82                  return -1;
83               end if;
84            end if;
85
86            Clen := Clen - 1;
87            L := L + 8;
88            R := R + 8;
89         end loop;
90
91      --  Case of going by unaligned words
92
93      else
94         while Clen /= 0 loop
95            if U (L).W /= U (R).W then
96               if U (L).W > U (R).W then
97                  return +1;
98               else
99                  return -1;
100               end if;
101            end if;
102
103            Clen := Clen - 1;
104            L := L + 8;
105            R := R + 8;
106         end loop;
107      end if;
108
109      --  Here if common section equal, result decided by lengths
110
111      if Left_Len = Right_Len then
112         return 0;
113      elsif Left_Len > Right_Len then
114         return +1;
115      else
116         return -1;
117      end if;
118   end Compare_Array_S64;
119
120end System.Compare_Array_Signed_64;
121