summaryrefslogtreecommitdiff
path: root/gcc/ada/s-carsi8.adb
blob: 9a6ea466eb4c14f38287fdf19b83db4342c1e5b6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
------------------------------------------------------------------------------
--                                                                          --
--                   GNU ADA RUNTIME LIBRARY COMPONENTS                     --
--                                                                          --
--         S Y S T E M . C O M P A R E _ A R R A Y _ S I G N E D _ 8        --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 2002-2004 Free Software Foundation, Inc.          --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 2,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
-- for  more details.  You should have  received  a copy of the GNU General --
-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
-- MA 02111-1307, USA.                                                      --
--                                                                          --
-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
-- this  unit  does not  by itself cause  the resulting  executable  to  be --
-- covered  by the  GNU  General  Public  License.  This exception does not --
-- however invalidate  any other reasons why  the executable file  might be --
-- covered by the  GNU Public License.                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

with System.Address_Operations; use System.Address_Operations;

with Unchecked_Conversion;

package body System.Compare_Array_Signed_8 is

   type Word is mod 2 ** 32;
   --  Used to process operands by words

   type Big_Words is array (Natural) of Word;
   type Big_Words_Ptr is access Big_Words;
   --  Array type used to access by words

   type Byte is range -128 .. +127;
   for Byte'Size use 8;
   --  Used to process operands by bytes

   type Big_Bytes is array (Natural) of Byte;
   type Big_Bytes_Ptr is access Big_Bytes;
   --  Array type used to access by bytes

   function To_Big_Words is new
     Unchecked_Conversion (System.Address, Big_Words_Ptr);

   function To_Big_Bytes is new
     Unchecked_Conversion (System.Address, Big_Bytes_Ptr);

   ----------------------
   -- Compare_Array_S8 --
   ----------------------

   function Compare_Array_S8
     (Left      : System.Address;
      Right     : System.Address;
      Left_Len  : Natural;
      Right_Len : Natural) return Integer
   is
      Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);

   begin
      --  If operands are non-aligned, or length is too short, go by bytes

      if ModA (OrA (Left, Right), 4) /= 0 or else Compare_Len < 4 then
         return Compare_Array_S8_Unaligned (Left, Right, Left_Len, Right_Len);
      end if;

      --  Here we can go by words

      declare
         LeftP  : constant Big_Words_Ptr := To_Big_Words (Left);
         RightP : constant Big_Words_Ptr := To_Big_Words (Right);
         Clen4  : constant Natural       := Compare_Len / 4 - 1;
         Clen4F : constant Natural       := Clen4 * 4;

      begin
         for J in 0 .. Clen4 loop
            if LeftP (J) /= RightP (J) then
               return Compare_Array_S8_Unaligned
                        (AddA (Left,  Address (4 * J)),
                         AddA (Right, Address (4 * J)),
                         4, 4);
            end if;
         end loop;

         return Compare_Array_S8_Unaligned
                  (AddA (Left,  Address (Clen4F)),
                   AddA (Right, Address (Clen4F)),
                   Left_Len  - Clen4F,
                   Right_Len - Clen4F);
      end;
   end Compare_Array_S8;

   --------------------------------
   -- Compare_Array_S8_Unaligned --
   --------------------------------

   function Compare_Array_S8_Unaligned
     (Left      : System.Address;
      Right     : System.Address;
      Left_Len  : Natural;
      Right_Len : Natural) return Integer
   is
      Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);

      LeftP  : constant Big_Bytes_Ptr := To_Big_Bytes (Left);
      RightP : constant Big_Bytes_Ptr := To_Big_Bytes (Right);

   begin
      for J in 0 .. Compare_Len - 1 loop
         if LeftP (J) /= RightP (J) then
            if LeftP (J) > RightP (J) then
               return +1;
            else
               return -1;
            end if;
         end if;
      end loop;

      if Left_Len = Right_Len then
         return 0;
      elsif Left_Len > Right_Len then
         return +1;
      else
         return -1;
      end if;
   end Compare_Array_S8_Unaligned;

end System.Compare_Array_Signed_8;