File : s-casi32.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 _ S I G N E D _ 3 2 --
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_Signed_32 is
37
38 type Word is range -2**31 .. 2**31 - 1;
39 for Word'Size use 32;
40 -- Used to process operands by words
41
42 type Uword is new Word;
43 for Uword'Alignment use 1;
44 -- Used to process operands when unaligned
45
46 type WP is access Word;
47 type UP is access Uword;
48
49 function W is new Ada.Unchecked_Conversion (Address, WP);
50 function U is new Ada.Unchecked_Conversion (Address, UP);
51
52 -----------------------
53 -- Compare_Array_S32 --
54 -----------------------
55
56 function Compare_Array_S32
57 (Left : System.Address;
58 Right : System.Address;
59 Left_Len : Natural;
60 Right_Len : Natural) return Integer
61 is
62 Clen : Natural := Natural'Min (Left_Len, Right_Len);
63 -- Number of elements left to compare
64
65 L : Address := Left;
66 R : Address := Right;
67 -- Pointers to next elements to compare
68
69 begin
70 -- Case of going by aligned words
71
72 if ModA (OrA (Left, Right), 4) = 0 then
73 while Clen /= 0 loop
74 if W (L).all /= W (R).all then
75 if W (L).all > W (R).all then
76 return +1;
77 else
78 return -1;
79 end if;
80 end if;
81
82 Clen := Clen - 1;
83 L := AddA (L, 4);
84 R := AddA (R, 4);
85 end loop;
86
87 -- Case of going by unaligned words
88
89 else
90 while Clen /= 0 loop
91 if U (L).all /= U (R).all then
92 if U (L).all > U (R).all then
93 return +1;
94 else
95 return -1;
96 end if;
97 end if;
98
99 Clen := Clen - 1;
100 L := AddA (L, 4);
101 R := AddA (R, 4);
102 end loop;
103 end if;
104
105 -- Here if common section equal, result decided by lengths
106
107 if Left_Len = Right_Len then
108 return 0;
109 elsif Left_Len > Right_Len then
110 return +1;
111 else
112 return -1;
113 end if;
114 end Compare_Array_S32;
115
116 end System.Compare_Array_Signed_32;