1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--                       S Y S T E M . P A C K _ 3 1                        --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 1992-2009, 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
32with System.Storage_Elements;
33with System.Unsigned_Types;
34with Ada.Unchecked_Conversion;
35
36package body System.Pack_31 is
37
38   subtype Ofs is System.Storage_Elements.Storage_Offset;
39   subtype Uns is System.Unsigned_Types.Unsigned;
40   subtype N07 is System.Unsigned_Types.Unsigned range 0 .. 7;
41
42   use type System.Storage_Elements.Storage_Offset;
43   use type System.Unsigned_Types.Unsigned;
44
45   type Cluster is record
46      E0, E1, E2, E3, E4, E5, E6, E7 : Bits_31;
47   end record;
48
49   for Cluster use record
50      E0 at 0 range 0 * Bits .. 0 * Bits + Bits - 1;
51      E1 at 0 range 1 * Bits .. 1 * Bits + Bits - 1;
52      E2 at 0 range 2 * Bits .. 2 * Bits + Bits - 1;
53      E3 at 0 range 3 * Bits .. 3 * Bits + Bits - 1;
54      E4 at 0 range 4 * Bits .. 4 * Bits + Bits - 1;
55      E5 at 0 range 5 * Bits .. 5 * Bits + Bits - 1;
56      E6 at 0 range 6 * Bits .. 6 * Bits + Bits - 1;
57      E7 at 0 range 7 * Bits .. 7 * Bits + Bits - 1;
58   end record;
59
60   for Cluster'Size use Bits * 8;
61
62   for Cluster'Alignment use Integer'Min (Standard'Maximum_Alignment,
63     1 +
64     1 * Boolean'Pos (Bits mod 2 = 0) +
65     2 * Boolean'Pos (Bits mod 4 = 0));
66   --  Use maximum possible alignment, given the bit field size, since this
67   --  will result in the most efficient code possible for the field.
68
69   type Cluster_Ref is access Cluster;
70
71   function To_Ref is new
72     Ada.Unchecked_Conversion (System.Address, Cluster_Ref);
73
74   ------------
75   -- Get_31 --
76   ------------
77
78   function Get_31 (Arr : System.Address; N : Natural) return Bits_31 is
79      C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
80   begin
81      case N07 (Uns (N) mod 8) is
82         when 0 => return C.E0;
83         when 1 => return C.E1;
84         when 2 => return C.E2;
85         when 3 => return C.E3;
86         when 4 => return C.E4;
87         when 5 => return C.E5;
88         when 6 => return C.E6;
89         when 7 => return C.E7;
90      end case;
91   end Get_31;
92
93   ------------
94   -- Set_31 --
95   ------------
96
97   procedure Set_31 (Arr : System.Address; N : Natural; E : Bits_31) is
98      C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
99   begin
100      case N07 (Uns (N) mod 8) is
101         when 0 => C.E0 := E;
102         when 1 => C.E1 := E;
103         when 2 => C.E2 := E;
104         when 3 => C.E3 := E;
105         when 4 => C.E4 := E;
106         when 5 => C.E5 := E;
107         when 6 => C.E6 := E;
108         when 7 => C.E7 := E;
109      end case;
110   end Set_31;
111
112end System.Pack_31;
113