File : 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 -- --
19 -- --
20 -- --
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;