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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME 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) 2002-2005 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;
|
