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

-- -- | |

-- 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 -- | |

-- -- | |

-- S p e c -- | |

-- -- | |

-- Copyright (C) 2002-2021, 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. -- | |

-- -- | |

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

-- This package contains functions for runtime operations on boolean vectors | |

package System.Vectors.Boolean_Operations is | |

pragma Pure; | |

-- Although in general the boolean operations on arrays of booleans are | |

-- identical to operations on arrays of unsigned words of the same size, | |

-- for the "not" operator this is not the case as False is typically | |

-- represented by 0 and true by 1. | |

function "not" (Item : Vectors.Vector) return Vectors.Vector; | |

-- The three boolean operations "nand", "nor" and "nxor" are needed | |

-- for cases where the compiler moves boolean array operations into | |

-- the body of the loop that iterates over the array elements. | |

-- Note the following equivalences: | |

-- (not X) or (not Y) = not (X and Y) = Nand (X, Y) | |

-- (not X) and (not Y) = not (X or Y) = Nor (X, Y) | |

-- (not X) xor (not Y) = X xor Y | |

-- X xor (not Y) = not (X xor Y) = Nxor (X, Y) | |

function Nand (Left, Right : Boolean) return Boolean; | |

function Nor (Left, Right : Boolean) return Boolean; | |

function Nxor (Left, Right : Boolean) return Boolean; | |

function Nand (Left, Right : Vectors.Vector) return Vectors.Vector; | |

function Nor (Left, Right : Vectors.Vector) return Vectors.Vector; | |

function Nxor (Left, Right : Vectors.Vector) return Vectors.Vector; | |

pragma Inline_Always ("not"); | |

pragma Inline_Always (Nand); | |

pragma Inline_Always (Nor); | |

pragma Inline_Always (Nxor); | |

end System.Vectors.Boolean_Operations; |