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comparison gcc/ada/libgnat/s-carun8.adb @ 111:04ced10e8804

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gcc 7
author kono
date Fri, 27 Oct 2017 22:46:09 +0900
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children 84e7813d76e9
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68:561a7518be6b 111:04ced10e8804
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 _ 8 --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 2002-2017, 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 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
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 pragma Compiler_Unit_Warning;
33
34 with System.Address_Operations; use System.Address_Operations;
35
36 with Ada.Unchecked_Conversion;
37
38 package body System.Compare_Array_Unsigned_8 is
39
40 type Word is mod 2 ** 32;
41 -- Used to process operands by words
42
43 type Big_Words is array (Natural) of Word;
44 type Big_Words_Ptr is access Big_Words;
45 for Big_Words_Ptr'Storage_Size use 0;
46 -- Array type used to access by words
47
48 type Byte is mod 2 ** 8;
49 -- Used to process operands by bytes
50
51 type Big_Bytes is array (Natural) of Byte;
52 type Big_Bytes_Ptr is access Big_Bytes;
53 for Big_Bytes_Ptr'Storage_Size use 0;
54 -- Array type used to access by bytes
55
56 function To_Big_Words is new
57 Ada.Unchecked_Conversion (System.Address, Big_Words_Ptr);
58
59 function To_Big_Bytes is new
60 Ada.Unchecked_Conversion (System.Address, Big_Bytes_Ptr);
61
62 ----------------------
63 -- Compare_Array_U8 --
64 ----------------------
65
66 function Compare_Array_U8
67 (Left : System.Address;
68 Right : System.Address;
69 Left_Len : Natural;
70 Right_Len : Natural) return Integer
71 is
72 Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
73
74 begin
75 -- If operands are non-aligned, or length is too short, go by bytes
76
77 if (ModA (OrA (Left, Right), 4) /= 0) or else Compare_Len < 4 then
78 return Compare_Array_U8_Unaligned (Left, Right, Left_Len, Right_Len);
79 end if;
80
81 -- Here we can go by words
82
83 declare
84 LeftP : constant Big_Words_Ptr :=
85 To_Big_Words (Left);
86 RightP : constant Big_Words_Ptr :=
87 To_Big_Words (Right);
88 Words_To_Compare : constant Natural := Compare_Len / 4;
89 Bytes_Compared_As_Words : constant Natural := Words_To_Compare * 4;
90
91 begin
92 for J in 0 .. Words_To_Compare - 1 loop
93 if LeftP (J) /= RightP (J) then
94 return Compare_Array_U8_Unaligned
95 (AddA (Left, Address (4 * J)),
96 AddA (Right, Address (4 * J)),
97 4, 4);
98 end if;
99 end loop;
100
101 return Compare_Array_U8_Unaligned
102 (AddA (Left, Address (Bytes_Compared_As_Words)),
103 AddA (Right, Address (Bytes_Compared_As_Words)),
104 Left_Len - Bytes_Compared_As_Words,
105 Right_Len - Bytes_Compared_As_Words);
106 end;
107 end Compare_Array_U8;
108
109 --------------------------------
110 -- Compare_Array_U8_Unaligned --
111 --------------------------------
112
113 function Compare_Array_U8_Unaligned
114 (Left : System.Address;
115 Right : System.Address;
116 Left_Len : Natural;
117 Right_Len : Natural) return Integer
118 is
119 Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
120
121 LeftP : constant Big_Bytes_Ptr := To_Big_Bytes (Left);
122 RightP : constant Big_Bytes_Ptr := To_Big_Bytes (Right);
123
124 begin
125 for J in 0 .. Compare_Len - 1 loop
126 if LeftP (J) /= RightP (J) then
127 if LeftP (J) > RightP (J) then
128 return +1;
129 else
130 return -1;
131 end if;
132 end if;
133 end loop;
134
135 if Left_Len = Right_Len then
136 return 0;
137 elsif Left_Len > Right_Len then
138 return +1;
139 else
140 return -1;
141 end if;
142 end Compare_Array_U8_Unaligned;
143
144 end System.Compare_Array_Unsigned_8;