| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNU ADA RUNTIME LIBRARY (GNARL) COMPONENTS -- |
| -- -- |
| -- 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 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 2002 Free Software Foundation, Inc. -- |
| -- -- |
| -- GNAT is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 2, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- |
| -- for more details. You should have received a copy of the GNU General -- |
| -- Public License distributed with GNAT; see file COPYING. If not, write -- |
| -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- |
| -- MA 02111-1307, USA. -- |
| -- -- |
| -- As a special exception, if other files instantiate generics from this -- |
| -- unit, or you link this unit with other files to produce an executable, -- |
| -- this unit does not by itself cause the resulting executable to be -- |
| -- covered by the GNU General Public License. This exception does not -- |
| -- however invalidate any other reasons why the executable file might be -- |
| -- covered by the GNU Public License. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| package body System.Vectors.Boolean_Operations is |
| |
| type Boolean_Array is array (Integer range <>) of Boolean; |
| pragma Assert (Boolean_Array'Component_Size = 8); |
| -- Unfortunately Boolean_Array'Component_Size is not a compile-time-known |
| -- value, so assume it is 8 in order to be able to determine True_Val at |
| -- compile time. |
| |
| -- NOTE: The boolean literals must be qualified here to avoid visibility |
| -- anomalies when this package is compiled through Rtsfind, in a context |
| -- that includes a user-defined type derived from boolean. |
| |
| True_Val : constant Vector := Standard.True'Enum_Rep |
| + Standard.True'Enum_Rep * 2**8 |
| + Standard.True'Enum_Rep * 2**(8 * 2) |
| + Standard.True'Enum_Rep * 2**(8 * 3) |
| + Standard.True'Enum_Rep * 2**(8 * 4) |
| + Standard.True'Enum_Rep * 2**(8 * 5) |
| + Standard.True'Enum_Rep * 2**(8 * 6) |
| + Standard.True'Enum_Rep * 2**(8 * 7); |
| -- This constant represents the bits to be flipped to perform a logical |
| -- "not" on a vector of booleans, independent of the actual |
| -- representation of True. |
| |
| -- The representations of (False, True) are assumed to be zero/one and |
| -- the maximum number of unpacked booleans per Vector is assumed to be 8. |
| |
| pragma Assert (Standard.False'Enum_Rep = 0); |
| pragma Assert (Standard.True'Enum_Rep = 1); |
| pragma Assert (Vector'Size / Storage_Unit <= 8); |
| |
| -- The reason we need to do these gymnastics is that no call to |
| -- Unchecked_Conversion can be made at the library level since this |
| -- unit is pure. Also a conversion from the array type to the Vector type |
| -- inside the body of "not" is inefficient because of alignment issues. |
| |
| ----------- |
| -- "not" -- |
| ----------- |
| |
| function "not" (Item : Vectors.Vector) return Vectors.Vector is |
| begin |
| return Item xor True_Val; |
| end "not"; |
| |
| ---------- |
| -- Nand -- |
| ---------- |
| |
| function Nand (Left, Right : Boolean) return Boolean is |
| begin |
| return not (Left and Right); |
| end Nand; |
| |
| function Nand (Left, Right : Vectors.Vector) return Vectors.Vector is |
| begin |
| return not (Left and Right); |
| end Nand; |
| |
| --------- |
| -- Nor -- |
| --------- |
| |
| function Nor (Left, Right : Boolean) return Boolean is |
| begin |
| return not (Left or Right); |
| end Nor; |
| |
| function Nor (Left, Right : Vectors.Vector) return Vectors.Vector is |
| begin |
| return not (Left or Right); |
| end Nor; |
| |
| ---------- |
| -- Nxor -- |
| ---------- |
| |
| function Nxor (Left, Right : Boolean) return Boolean is |
| begin |
| return not (Left xor Right); |
| end Nxor; |
| |
| function Nxor (Left, Right : Vectors.Vector) return Vectors.Vector is |
| begin |
| return not (Left xor Right); |
| end Nxor; |
| |
| end System.Vectors.Boolean_Operations; |
