------------------------------------------------------------------------------ | |

-- -- | |

-- 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) 2002-2009, 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 3, 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. -- | |

-- -- | |

-- As a special exception under Section 7 of GPL version 3, you are granted -- | |

-- additional permissions described in the GCC Runtime Library Exception, -- | |

-- version 3.1, as published by the Free Software Foundation. -- | |

-- -- | |

-- You should have received a copy of the GNU General Public License and -- | |

-- a copy of the GCC Runtime Library Exception along with this program; -- | |

-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- | |

-- <http://www.gnu.org/licenses/>. -- | |

-- -- | |

-- 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 | |

SU : constant := Storage_Unit; | |

-- Convenient short hand, used throughout | |

-- The coding of this unit depends on the fact that the Component_Size | |

-- of a normally declared array of Boolean is equal to Storage_Unit. We | |

-- can't use the Component_Size directly since it is non-static. The | |

-- following declaration checks that this declaration is correct | |

type Boolean_Array is array (Integer range <>) of Boolean; | |

pragma Compile_Time_Error | |

(Boolean_Array'Component_Size /= SU, "run time compile failure"); | |

-- 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**SU | |

+ Standard.True'Enum_Rep * 2**(SU * 2) | |

+ Standard.True'Enum_Rep * 2**(SU * 3) | |

+ Standard.True'Enum_Rep * 2**(SU * 4) | |

+ Standard.True'Enum_Rep * 2**(SU * 5) | |

+ Standard.True'Enum_Rep * 2**(SU * 6) | |

+ Standard.True'Enum_Rep * 2**(SU * 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; |