1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
4--                                                                          --
5--                       S Y S T E M . B I T _ O P S                        --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2021, 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
32--  Operations on packed bit strings
33
34pragma Compiler_Unit_Warning;
35
36with System;
37
38package System.Bit_Ops is
39
40   --  Note: in all the following routines, the System.Address parameters
41   --  represent the address of the first byte of an array used to represent
42   --  a packed array (of type System.Unsigned_Types.Packed_Bytes{1,2,4})
43   --  The length in bits is passed as a separate parameter. Note that all
44   --  addresses must be of byte aligned arrays.
45
46   procedure Bit_And
47     (Left   : System.Address;
48      Llen   : Natural;
49      Right  : System.Address;
50      Rlen   : Natural;
51      Result : System.Address);
52   --  Bitwise "and" of given bit string with result being placed in Result.
53   --  The and operation is allowed to destroy unused bits in the last byte,
54   --  i.e. to leave them set in an undefined manner. Note that Left, Right
55   --  and Result always have the same length in bits (Len).
56
57   function Bit_Eq
58     (Left  : System.Address;
59      Llen  : Natural;
60      Right : System.Address;
61      Rlen  : Natural) return Boolean;
62   --  Left and Right are the addresses of two bit packed arrays with Llen
63   --  and Rlen being the respective length in bits. The routine compares the
64   --  two bit strings for equality, being careful not to include the unused
65   --  bits in the final byte. Note that the result is always False if Rlen
66   --  is not equal to Llen.
67
68   procedure Bit_Not
69     (Opnd   : System.Address;
70      Len    : Natural;
71      Result : System.Address);
72   --  Bitwise "not" of given bit string with result being placed in Result.
73   --  The not operation is allowed to destroy unused bits in the last byte,
74   --  i.e. to leave them set in an undefined manner. Note that Result and
75   --  Opnd always have the same length in bits (Len).
76
77   procedure Bit_Or
78     (Left   : System.Address;
79      Llen   : Natural;
80      Right  : System.Address;
81      Rlen   : Natural;
82      Result : System.Address);
83   --  Bitwise "or" of given bit string with result being placed in Result.
84   --  The or operation is allowed to destroy unused bits in the last byte,
85   --  i.e. to leave them set in an undefined manner. Note that Left, Right
86   --  and Result always have the same length in bits (Len).
87
88   procedure Bit_Xor
89     (Left   : System.Address;
90      Llen   : Natural;
91      Right  : System.Address;
92      Rlen   : Natural;
93      Result : System.Address);
94   --  Bitwise "xor" of given bit string with result being placed in Result.
95   --  The xor operation is allowed to destroy unused bits in the last byte,
96   --  i.e. to leave them set in an undefined manner. Note that Left, Right
97   --  and Result always have the same length in bits (Len).
98
99end System.Bit_Ops;
100