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[official-gcc.git] / gcc / ada / s-pack51.adb
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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUNTIME COMPONENTS --
4 -- --
5 -- S Y S T E M . P A C K _ 5 1 --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-1999 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 2, 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. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
21 -- --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
28 -- --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
31 -- --
32 ------------------------------------------------------------------------------
34 with System.Storage_Elements;
35 with System.Unsigned_Types;
36 with Unchecked_Conversion;
38 package body System.Pack_51 is
40 subtype Ofs is System.Storage_Elements.Storage_Offset;
41 subtype Uns is System.Unsigned_Types.Unsigned;
42 subtype N07 is System.Unsigned_Types.Unsigned range 0 .. 7;
44 use type System.Storage_Elements.Storage_Offset;
45 use type System.Unsigned_Types.Unsigned;
47 type Cluster is record
48 E0, E1, E2, E3, E4, E5, E6, E7 : Bits_51;
49 end record;
51 for Cluster use record
52 E0 at 0 range 0 * Bits .. 0 * Bits + Bits - 1;
53 E1 at 0 range 1 * Bits .. 1 * Bits + Bits - 1;
54 E2 at 0 range 2 * Bits .. 2 * Bits + Bits - 1;
55 E3 at 0 range 3 * Bits .. 3 * Bits + Bits - 1;
56 E4 at 0 range 4 * Bits .. 4 * Bits + Bits - 1;
57 E5 at 0 range 5 * Bits .. 5 * Bits + Bits - 1;
58 E6 at 0 range 6 * Bits .. 6 * Bits + Bits - 1;
59 E7 at 0 range 7 * Bits .. 7 * Bits + Bits - 1;
60 end record;
62 for Cluster'Size use Bits * 8;
64 for Cluster'Alignment use Integer'Min (Standard'Maximum_Alignment,
65 1 +
66 1 * Boolean'Pos (Bits mod 2 = 0) +
67 2 * Boolean'Pos (Bits mod 4 = 0));
68 -- Use maximum possible alignment, given the bit field size, since this
69 -- will result in the most efficient code possible for the field.
71 type Cluster_Ref is access Cluster;
73 function To_Ref is new
74 Unchecked_Conversion (System.Address, Cluster_Ref);
76 ------------
77 -- Get_51 --
78 ------------
80 function Get_51 (Arr : System.Address; N : Natural) return Bits_51 is
81 C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
83 begin
84 case N07 (Uns (N) mod 8) is
85 when 0 => return C.E0;
86 when 1 => return C.E1;
87 when 2 => return C.E2;
88 when 3 => return C.E3;
89 when 4 => return C.E4;
90 when 5 => return C.E5;
91 when 6 => return C.E6;
92 when 7 => return C.E7;
93 end case;
94 end Get_51;
96 ------------
97 -- Set_51 --
98 ------------
100 procedure Set_51 (Arr : System.Address; N : Natural; E : Bits_51) is
101 C : constant Cluster_Ref := To_Ref (Arr + Bits * Ofs (Uns (N) / 8));
103 begin
104 case N07 (Uns (N) mod 8) is
105 when 0 => C.E0 := E;
106 when 1 => C.E1 := E;
107 when 2 => C.E2 := E;
108 when 3 => C.E3 := E;
109 when 4 => C.E4 := E;
110 when 5 => C.E5 := E;
111 when 6 => C.E6 := E;
112 when 7 => C.E7 := E;
113 end case;
114 end Set_51;
116 end System.Pack_51;