1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . V E C T O R S . B O O L E A N _ O P E R A T I O N S --
9 -- Copyright (C) 2002-2005 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 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, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
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. --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 package body System
.Vectors
.Boolean_Operations
is
36 type Boolean_Array
is array (Integer range <>) of Boolean;
37 pragma Assert
(Boolean_Array
'Component_Size = 8);
38 -- Unfortunately Boolean_Array'Component_Size is not a compile-time-known
39 -- value, so assume it is 8 in order to be able to determine True_Val at
42 -- NOTE: The boolean literals must be qualified here to avoid visibility
43 -- anomalies when this package is compiled through Rtsfind, in a context
44 -- that includes a user-defined type derived from boolean.
46 True_Val
: constant Vector
:= Standard
.True'Enum_Rep
47 + Standard
.True'Enum_Rep * 2**8
48 + Standard
.True'Enum_Rep * 2**(8 * 2)
49 + Standard
.True'Enum_Rep * 2**(8 * 3)
50 + Standard
.True'Enum_Rep * 2**(8 * 4)
51 + Standard
.True'Enum_Rep * 2**(8 * 5)
52 + Standard
.True'Enum_Rep * 2**(8 * 6)
53 + Standard
.True'Enum_Rep * 2**(8 * 7);
54 -- This constant represents the bits to be flipped to perform a logical
55 -- "not" on a vector of booleans, independent of the actual
56 -- representation of True.
58 -- The representations of (False, True) are assumed to be zero/one and
59 -- the maximum number of unpacked booleans per Vector is assumed to be 8.
61 pragma Assert
(Standard
.False'Enum_Rep = 0);
62 pragma Assert
(Standard
.True'Enum_Rep = 1);
63 pragma Assert
(Vector
'Size / Storage_Unit
<= 8);
65 -- The reason we need to do these gymnastics is that no call to
66 -- Unchecked_Conversion can be made at the library level since this
67 -- unit is pure. Also a conversion from the array type to the Vector type
68 -- inside the body of "not" is inefficient because of alignment issues.
74 function "not" (Item
: Vectors
.Vector
) return Vectors
.Vector
is
76 return Item
xor True_Val
;
83 function Nand
(Left
, Right
: Boolean) return Boolean is
85 return not (Left
and Right
);
88 function Nand
(Left
, Right
: Vectors
.Vector
) return Vectors
.Vector
is
90 return not (Left
and Right
);
97 function Nor
(Left
, Right
: Boolean) return Boolean is
99 return not (Left
or Right
);
102 function Nor
(Left
, Right
: Vectors
.Vector
) return Vectors
.Vector
is
104 return not (Left
or Right
);
111 function Nxor
(Left
, Right
: Boolean) return Boolean is
113 return not (Left
xor Right
);
116 function Nxor
(Left
, Right
: Vectors
.Vector
) return Vectors
.Vector
is
118 return not (Left
xor Right
);
121 end System
.Vectors
.Boolean_Operations
;