------------------------------------------------------------------------------ -- -- -- 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;