File : s-memcom.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- S Y S T E M . M E M O R Y _ C O M P A R E --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 2006-2014, 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 Ada.Unchecked_Conversion;
33 with Interfaces.C; use Interfaces.C;
34
35 package body System.Memory_Compare is
36
37 subtype mem is char_array (size_t);
38 type memptr is access mem;
39
40 function to_memptr is new Ada.Unchecked_Conversion (Address, memptr);
41
42 ------------
43 -- memcmp --
44 ------------
45
46 function memcmp (S1 : Address; S2 : Address; N : size_t) return int is
47 s1_p : constant memptr := to_memptr (S1);
48 s2_p : constant memptr := to_memptr (S2);
49
50 begin
51 if N = 0 then
52 return 0;
53 end if;
54
55 for J in 0 .. N - 1 loop
56 if s1_p (J) < s2_p (J) then
57 return -1;
58 elsif s1_p (J) > s2_p (J) then
59 return 1;
60 end if;
61 end loop;
62
63 return 0;
64 end memcmp;
65
66 end System.Memory_Compare;