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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
------------------------------------------------------------------------------
-- --
-- GNAT RUNTIME COMPONENTS --
-- --
-- S Y S T E M . P A C K _ 2 6 --
-- --
-- B o d y --
-- --
-- $Revision: 1.4 $
-- --
-- Copyright (C) 1992-1999 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. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
with System.Storage_Elements;
with System.Unsigned_Types;
with Unchecked_Conversion;
package body System.Pack_26 is
subtype Ofs is System.Storage_Elements.Storage_Offset;
subtype Uns is System.Unsigned_Types.Unsigned;
subtype N07 is System.Unsigned_Types.Unsigned range 0 .. 7;
use type System.Storage_Elements.Storage_Offset;
use type System.Unsigned_Types.Unsigned;
type Cluster is record
E0, E1, E2, E3, E4, E5, E6, E7 : Bits_26;
end record;
for Cluster use record
E0 at 0 range 0 * Bits .. 0 * Bits + Bits - 1;
E1 at 0 range 1 * Bits .. 1 * Bits + Bits - 1;
E2 at 0 range 2 * Bits .. 2 * Bits + Bits - 1;
E3 at 0 range 3 * Bits .. 3 * Bits + Bits - 1;
E4 at 0 range 4 * Bits .. 4 * Bits + Bits - 1;
E5 at 0 range 5 * Bits .. 5 * Bits + Bits - 1;
E6 at 0 range 6 * Bits .. 6 * Bits + Bits - 1;
E7 at 0 range 7 * Bits .. 7 * Bits + Bits - 1;
end record;
for Cluster'Size use Bits * 8;
for Cluster'Alignment use Integer'Min (Standard'Maximum_Alignment,
1 +
1 * Boolean'Pos (Bits mod 2 = 0) +
2 * Boolean'Pos (Bits mod 4 = 0));
-- Use maximum possible alignment, given the bit field size, since this
-- will result in the most efficient code possible for the field.
type Cluster_Ref is access Cluster;
function To_Ref is new
Unchecked_Conversion (System.Address, Cluster_Ref);
-- The following declarations are for the case where the address
-- passed to GetU_26 or SetU_26 is not guaranteed to be aligned.
-- These routines are used when the packed array is itself a
-- component of a packed record, and therefore may not be aligned.
type ClusterU is new Cluster;
for ClusterU'Alignment use 1;
type ClusterU_Ref is access ClusterU;
function To_Ref is new
Unchecked_Conversion (System.Address, ClusterU_Ref);
------------
-- Get_26 --
------------
function Get_26 (Arr : System.Address; N : Natural) return Bits_26 is
C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
begin
case N07 (Uns (N) mod 8) is
when 0 => return C.E0;
when 1 => return C.E1;
when 2 => return C.E2;
when 3 => return C.E3;
when 4 => return C.E4;
when 5 => return C.E5;
when 6 => return C.E6;
when 7 => return C.E7;
end case;
end Get_26;
-------------
-- GetU_26 --
-------------
function GetU_26 (Arr : System.Address; N : Natural) return Bits_26 is
C : constant ClusterU_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
begin
case N07 (Uns (N) mod 8) is
when 0 => return C.E0;
when 1 => return C.E1;
when 2 => return C.E2;
when 3 => return C.E3;
when 4 => return C.E4;
when 5 => return C.E5;
when 6 => return C.E6;
when 7 => return C.E7;
end case;
end GetU_26;
------------
-- Set_26 --
------------
procedure Set_26 (Arr : System.Address; N : Natural; E : Bits_26) is
C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
begin
case N07 (Uns (N) mod 8) is
when 0 => C.E0 := E;
when 1 => C.E1 := E;
when 2 => C.E2 := E;
when 3 => C.E3 := E;
when 4 => C.E4 := E;
when 5 => C.E5 := E;
when 6 => C.E6 := E;
when 7 => C.E7 := E;
end case;
end Set_26;
-------------
-- SetU_26 --
-------------
procedure SetU_26 (Arr : System.Address; N : Natural; E : Bits_26) is
C : constant ClusterU_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
begin
case N07 (Uns (N) mod 8) is
when 0 => C.E0 := E;
when 1 => C.E1 := E;
when 2 => C.E2 := E;
when 3 => C.E3 := E;
when 4 => C.E4 := E;
when 5 => C.E5 := E;
when 6 => C.E6 := E;
when 7 => C.E7 := E;
end case;
end SetU_26;
end System.Pack_26;
|