1 ------------------------------------------------------------------------------
3 -- GNAT RUNTIME COMPONENTS --
5 -- S Y S T E M . P A C K _ 6 3 --
11 -- Copyright (C) 1992-1999 Free Software Foundation, Inc. --
13 -- GNAT is free software; you can redistribute it and/or modify it under --
14 -- terms of the GNU General Public License as published by the Free Soft- --
15 -- ware Foundation; either version 2, or (at your option) any later ver- --
16 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
17 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
18 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
19 -- for more details. You should have received a copy of the GNU General --
20 -- Public License distributed with GNAT; see file COPYING. If not, write --
21 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
22 -- MA 02111-1307, USA. --
24 -- As a special exception, if other files instantiate generics from this --
25 -- unit, or you link this unit with other files to produce an executable, --
26 -- this unit does not by itself cause the resulting executable to be --
27 -- covered by the GNU General Public License. This exception does not --
28 -- however invalidate any other reasons why the executable file might be --
29 -- covered by the GNU Public License. --
31 -- GNAT was originally developed by the GNAT team at New York University. --
32 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
34 ------------------------------------------------------------------------------
36 with System.Storage_Elements;
37 with System.Unsigned_Types;
38 with Unchecked_Conversion;
40 package body System.Pack_63 is
42 subtype Ofs is System.Storage_Elements.Storage_Offset;
43 subtype Uns is System.Unsigned_Types.Unsigned;
44 subtype N07 is System.Unsigned_Types.Unsigned range 0 .. 7;
46 use type System.Storage_Elements.Storage_Offset;
47 use type System.Unsigned_Types.Unsigned;
49 type Cluster is record
50 E0, E1, E2, E3, E4, E5, E6, E7 : Bits_63;
53 for Cluster use record
54 E0 at 0 range 0 * Bits .. 0 * Bits + Bits - 1;
55 E1 at 0 range 1 * Bits .. 1 * Bits + Bits - 1;
56 E2 at 0 range 2 * Bits .. 2 * Bits + Bits - 1;
57 E3 at 0 range 3 * Bits .. 3 * Bits + Bits - 1;
58 E4 at 0 range 4 * Bits .. 4 * Bits + Bits - 1;
59 E5 at 0 range 5 * Bits .. 5 * Bits + Bits - 1;
60 E6 at 0 range 6 * Bits .. 6 * Bits + Bits - 1;
61 E7 at 0 range 7 * Bits .. 7 * Bits + Bits - 1;
64 for Cluster'Size use Bits * 8;
66 for Cluster'Alignment use Integer'Min (Standard'Maximum_Alignment,
68 1 * Boolean'Pos (Bits mod 2 = 0) +
69 2 * Boolean'Pos (Bits mod 4 = 0));
70 -- Use maximum possible alignment, given the bit field size, since this
71 -- will result in the most efficient code possible for the field.
73 type Cluster_Ref is access Cluster;
75 function To_Ref is new
76 Unchecked_Conversion (System.Address, Cluster_Ref);
82 function Get_63 (Arr : System.Address; N : Natural) return Bits_63 is
83 C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
86 case N07 (Uns (N) mod 8) is
87 when 0 => return C.E0;
88 when 1 => return C.E1;
89 when 2 => return C.E2;
90 when 3 => return C.E3;
91 when 4 => return C.E4;
92 when 5 => return C.E5;
93 when 6 => return C.E6;
94 when 7 => return C.E7;
102 procedure Set_63 (Arr : System.Address; N : Natural; E : Bits_63) is
103 C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
106 case N07 (Uns (N) mod 8) is