gcc/ada/s-veboop.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUNTIME LIBRARY (GNARL) COMPONENTS                --
   4 --                                                                          --
   5 --    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     --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --             Copyright (C) 2002 Free Software Foundation, Inc.            --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This package contains functions for runtime operations on boolean vectors
  35
  36 package System.Vectors.Boolean_Operations is
  37 pragma Pure (Boolean_Operations);
  38
  39    --  Although in general the boolean operations on arrays of booleans are
  40    --  identical to operations on arrays of unsigned words of the same size,
  41    --  for the "not" operator this is not the case as False is typically
  42    --  represented by 0 and true by 1.
  43
  44    function "not" (Item : Vectors.Vector) return Vectors.Vector;
  45
  46    --  The three boolean operations "nand", "nor" and "nxor" are needed
  47    --  for cases where the compiler moves boolean array operations into
  48    --  the body of the loop that iterates over the array elements.
  49
  50    --  Note the following equivalences:
  51    --    (not X) or  (not Y)  =  not (X and Y)  =  Nand (X, Y)
  52    --    (not X) and (not Y)  =  not (X or Y)   =  Nor  (X, Y)
  53    --    (not X) xor (not Y)  =  X xor Y
  54    --    X       xor (not Y)  =  not (X xor Y)  =  Nxor (X, Y)
  55
  56    function Nand (Left, Right : Boolean) return Boolean;
  57    function Nor  (Left, Right : Boolean) return Boolean;
  58    function Nxor (Left, Right : Boolean) return Boolean;
  59
  60    function Nand (Left, Right : Vectors.Vector) return Vectors.Vector;
  61    function Nor (Left, Right : Vectors.Vector) return Vectors.Vector;
  62    function Nxor (Left, Right : Vectors.Vector) return Vectors.Vector;
  63
  64    pragma Inline_Always ("not");
  65    pragma Inline_Always (Nand);
  66    pragma Inline_Always (Nor);
  67    pragma Inline_Always (Nxor);
  68 end System.Vectors.Boolean_Operations;