1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . P A C K _ 2 0 --
9 -- Copyright (C) 1992-2020, Free Software Foundation, Inc. --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with System.Storage_Elements;
33 with System.Unsigned_Types;
35 package body System.Pack_20 is
37 subtype Bit_Order is System.Bit_Order;
38 Reverse_Bit_Order : constant Bit_Order :=
39 Bit_Order'Val (1 - Bit_Order'Pos (System.Default_Bit_Order));
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_20;
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 type Rev_Cluster is new Cluster
75 with Bit_Order => Reverse_Bit_Order,
76 Scalar_Storage_Order => Reverse_Bit_Order;
77 type Rev_Cluster_Ref is access Rev_Cluster;
79 -- The following declarations are for the case where the address
80 -- passed to GetU_20 or SetU_20 is not guaranteed to be aligned.
81 -- These routines are used when the packed array is itself a
82 -- component of a packed record, and therefore may not be aligned.
84 type ClusterU is new Cluster;
85 for ClusterU'Alignment use 1;
87 type ClusterU_Ref is access ClusterU;
89 type Rev_ClusterU is new ClusterU
90 with Bit_Order => Reverse_Bit_Order,
91 Scalar_Storage_Order => Reverse_Bit_Order;
92 type Rev_ClusterU_Ref is access Rev_ClusterU;
99 (Arr : System.Address;
101 Rev_SSO : Boolean) return Bits_20
103 A : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
104 C : Cluster_Ref with Address => A'Address, Import;
105 RC : Rev_Cluster_Ref with Address => A'Address, Import;
108 case N07 (Uns (N) mod 8) is
109 when 0 => return RC.E0;
110 when 1 => return RC.E1;
111 when 2 => return RC.E2;
112 when 3 => return RC.E3;
113 when 4 => return RC.E4;
114 when 5 => return RC.E5;
115 when 6 => return RC.E6;
116 when 7 => return RC.E7;
120 case N07 (Uns (N) mod 8) is
121 when 0 => return C.E0;
122 when 1 => return C.E1;
123 when 2 => return C.E2;
124 when 3 => return C.E3;
125 when 4 => return C.E4;
126 when 5 => return C.E5;
127 when 6 => return C.E6;
128 when 7 => return C.E7;
138 (Arr : System.Address;
140 Rev_SSO : Boolean) return Bits_20
142 A : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
143 C : ClusterU_Ref with Address => A'Address, Import;
144 RC : Rev_ClusterU_Ref with Address => A'Address, Import;
147 case N07 (Uns (N) mod 8) is
148 when 0 => return RC.E0;
149 when 1 => return RC.E1;
150 when 2 => return RC.E2;
151 when 3 => return RC.E3;
152 when 4 => return RC.E4;
153 when 5 => return RC.E5;
154 when 6 => return RC.E6;
155 when 7 => return RC.E7;
159 case N07 (Uns (N) mod 8) is
160 when 0 => return C.E0;
161 when 1 => return C.E1;
162 when 2 => return C.E2;
163 when 3 => return C.E3;
164 when 4 => return C.E4;
165 when 5 => return C.E5;
166 when 6 => return C.E6;
167 when 7 => return C.E7;
177 (Arr : System.Address;
182 A : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
183 C : Cluster_Ref with Address => A'Address, Import;
184 RC : Rev_Cluster_Ref with Address => A'Address, Import;
187 case N07 (Uns (N) mod 8) is
188 when 0 => RC.E0 := E;
189 when 1 => RC.E1 := E;
190 when 2 => RC.E2 := E;
191 when 3 => RC.E3 := E;
192 when 4 => RC.E4 := E;
193 when 5 => RC.E5 := E;
194 when 6 => RC.E6 := E;
195 when 7 => RC.E7 := E;
198 case N07 (Uns (N) mod 8) is
216 (Arr : System.Address;
221 A : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
222 C : ClusterU_Ref with Address => A'Address, Import;
223 RC : Rev_ClusterU_Ref with Address => A'Address, Import;
226 case N07 (Uns (N) mod 8) is
227 when 0 => RC.E0 := E;
228 when 1 => RC.E1 := E;
229 when 2 => RC.E2 := E;
230 when 3 => RC.E3 := E;
231 when 4 => RC.E4 := E;
232 when 5 => RC.E5 := E;
233 when 6 => RC.E6 := E;
234 when 7 => RC.E7 := E;
237 case N07 (Uns (N) mod 8) is