1 ------------------------------------------------------------------------------
3 -- GNAT RUNTIME COMPONENTS --
5 -- S Y S T E M . P A C K _ 4 3 --
10 -- Copyright (C) 1992-1999 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT was originally developed by the GNAT team at New York University. --
31 -- Extensive contributions were provided by Ada Core Technologies Inc. --
33 ------------------------------------------------------------------------------
35 with System
.Storage_Elements
;
36 with System
.Unsigned_Types
;
37 with Unchecked_Conversion
;
39 package body System
.Pack_43
is
41 subtype Ofs
is System
.Storage_Elements
.Storage_Offset
;
42 subtype Uns
is System
.Unsigned_Types
.Unsigned
;
43 subtype N07
is System
.Unsigned_Types
.Unsigned
range 0 .. 7;
45 use type System
.Storage_Elements
.Storage_Offset
;
46 use type System
.Unsigned_Types
.Unsigned
;
48 type Cluster
is record
49 E0
, E1
, E2
, E3
, E4
, E5
, E6
, E7
: Bits_43
;
52 for Cluster
use record
53 E0
at 0 range 0 * Bits
.. 0 * Bits
+ Bits
- 1;
54 E1
at 0 range 1 * Bits
.. 1 * Bits
+ Bits
- 1;
55 E2
at 0 range 2 * Bits
.. 2 * Bits
+ Bits
- 1;
56 E3
at 0 range 3 * Bits
.. 3 * Bits
+ Bits
- 1;
57 E4
at 0 range 4 * Bits
.. 4 * Bits
+ Bits
- 1;
58 E5
at 0 range 5 * Bits
.. 5 * Bits
+ Bits
- 1;
59 E6
at 0 range 6 * Bits
.. 6 * Bits
+ Bits
- 1;
60 E7
at 0 range 7 * Bits
.. 7 * Bits
+ Bits
- 1;
63 for Cluster
'Size use Bits
* 8;
65 for Cluster
'Alignment use Integer'Min (Standard
'Maximum_Alignment,
67 1 * Boolean'Pos (Bits
mod 2 = 0) +
68 2 * Boolean'Pos (Bits
mod 4 = 0));
69 -- Use maximum possible alignment, given the bit field size, since this
70 -- will result in the most efficient code possible for the field.
72 type Cluster_Ref
is access Cluster
;
74 function To_Ref
is new
75 Unchecked_Conversion
(System
.Address
, Cluster_Ref
);
81 function Get_43
(Arr
: System
.Address
; N
: Natural) return Bits_43
is
82 C
: constant Cluster_Ref
:= To_Ref
(Arr
+ Bits
* Ofs
(Uns
(N
) / 8));
85 case N07
(Uns
(N
) mod 8) is
86 when 0 => return C
.E0
;
87 when 1 => return C
.E1
;
88 when 2 => return C
.E2
;
89 when 3 => return C
.E3
;
90 when 4 => return C
.E4
;
91 when 5 => return C
.E5
;
92 when 6 => return C
.E6
;
93 when 7 => return C
.E7
;
101 procedure Set_43
(Arr
: System
.Address
; N
: Natural; E
: Bits_43
) is
102 C
: constant Cluster_Ref
:= To_Ref
(Arr
+ Bits
* Ofs
(Uns
(N
) / 8));
105 case N07
(Uns
(N
) mod 8) is