1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . B I T _ O P S --
9 -- Copyright (C) 1992-2009, 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 -- Operations on packed bit strings
36 package System.Bit_Ops is
38 -- Note: in all the following routines, the System.Address parameters
39 -- represent the address of the first byte of an array used to represent
40 -- a packed array (of type System.Unsigned_Types.Packed_Bytes{1,2,4})
41 -- The length in bits is passed as a separate parameter. Note that all
42 -- addresses must be of byte aligned arrays.
45 (Left : System.Address;
47 Right : System.Address;
49 Result : System.Address);
50 -- Bitwise "and" of given bit string with result being placed in Result.
51 -- The and operation is allowed to destroy unused bits in the last byte,
52 -- i.e. to leave them set in an undefined manner. Note that Left, Right
53 -- and Result always have the same length in bits (Len).
56 (Left : System.Address;
58 Right : System.Address;
59 Rlen : Natural) return Boolean;
60 -- Left and Right are the addresses of two bit packed arrays with Llen
61 -- and Rlen being the respective length in bits. The routine compares the
62 -- two bit strings for equality, being careful not to include the unused
63 -- bits in the final byte. Note that the result is always False if Rlen
64 -- is not equal to Llen.
67 (Opnd : System.Address;
69 Result : System.Address);
70 -- Bitwise "not" of given bit string with result being placed in Result.
71 -- The not operation is allowed to destroy unused bits in the last byte,
72 -- i.e. to leave them set in an undefined manner. Note that Result and
73 -- Opnd always have the same length in bits (Len).
76 (Left : System.Address;
78 Right : System.Address;
80 Result : System.Address);
81 -- Bitwise "or" of given bit string with result being placed in Result.
82 -- The or operation is allowed to destroy unused bits in the last byte,
83 -- i.e. to leave them set in an undefined manner. Note that Left, Right
84 -- and Result always have the same length in bits (Len).
87 (Left : System.Address;
89 Right : System.Address;
91 Result : System.Address);
92 -- Bitwise "xor" of given bit string with result being placed in Result.
93 -- The xor operation is allowed to destroy unused bits in the last byte,
94 -- i.e. to leave them set in an undefined manner. Note that Left, Right
95 -- and Result always have the same length in bits (Len).