File : s-bitops.ads
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) 1992-2013, 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 -- --
19 -- --
20 -- --
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
34 pragma Compiler_Unit_Warning;
35
36 with System;
37
38 package 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
99 end System.Bit_Ops;