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/****************************************************************************

 *                                                                          *

 *                        GNAT COMPILER COMPONENTS                          *

 *                                                                          *

 *                               C U I N T P                                *

 *                                                                          *

 *                          C Implementation File                           *

 *                                                                          *

 *          Copyright (C) 1992-2009, 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.  See the GNU General Public License *

 * for  more details.  You should have received a copy of the GNU General   *

 * Public License along with GCC; see the file COPYING3.  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 file corresponds to the Ada package body Uintp. It was created

   manually from the files uintp.ads and uintp.adb. */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "tree.h"

#include "ada.h"

#include "types.h"

#include "uintp.h"

#include "atree.h"

#include "elists.h"

#include "nlists.h"

#include "stringt.h"

#include "fe.h"

#include "ada-tree.h"

#include "gigi.h"

/* Universal integers are represented by the Uint type which is an index into

   the Uints_Ptr table containing Uint_Entry values.  A Uint_Entry contains an

   index and length for getting the "digits" of the universal integer from the

   Udigits_Ptr table.

   For efficiency, this method is used only for integer values larger than the

   constant Uint_Bias.  If a Uint is less than this constant, then it contains

   the integer value itself.  The origin of the Uints_Ptr table is adjusted so

   that a Uint value of Uint_Bias indexes the first element.

   First define a utility function that operates like build_int_cst for

   integral types and does a conversion to floating-point for real types.  */

static tree

build_cst_from_int (tree type, HOST_WIDE_INT low)

{

  if (TREE_CODE (type) == REAL_TYPE)

    return convert (type, build_int_cst (NULL_TREE, low));

  else

    return build_int_cst_type (type, low);

}

/* Similar to UI_To_Int, but return a GCC INTEGER_CST or REAL_CST node,

   depending on whether TYPE is an integral or real type.  Overflow is tested

   by the constant-folding used to build the node.  TYPE is the GCC type of

   the resulting node.  */

tree

UI_To_gnu (Uint Input, tree type)

{

  tree gnu_ret;

  /* We might have a TYPE with biased representation and be passed an

     unbiased value that doesn't fit.  We always use an unbiased type able

     to hold any such possible value for intermediate computations, and

     then rely on a conversion back to TYPE to perform the bias adjustment

     when need be.  */

  int biased_type_p

    = (TREE_CODE (type) == INTEGER_TYPE

       && TYPE_BIASED_REPRESENTATION_P (type));

  tree comp_type = biased_type_p ? get_base_type (type) : type;

  if (Input <= Uint_Direct_Last)

    gnu_ret = build_cst_from_int (comp_type, Input - Uint_Direct_Bias);

  else

    {

      Int Idx = Uints_Ptr[Input].Loc;

      Pos Length = Uints_Ptr[Input].Length;

      Int First = Udigits_Ptr[Idx];

      tree gnu_base;

      gcc_assert (Length > 0);

      /* The computations we perform below always require a type at least as

         large as an integer not to overflow.  REAL types are always fine, but

         INTEGER or ENUMERAL types we are handed may be too short.  We use a

         base integer type node for the computations in this case and will

         convert the final result back to the incoming type later on.

         The base integer precision must be superior than 16.  */

      if (TREE_CODE (comp_type) != REAL_TYPE

          && TYPE_PRECISION (comp_type) < TYPE_PRECISION (long_integer_type_node))

        {

          comp_type = long_integer_type_node;

          gcc_assert (TYPE_PRECISION (comp_type) > 16);

        }

      gnu_base = build_cst_from_int (comp_type, Base);

      gnu_ret = build_cst_from_int (comp_type, First);

      if (First < 0)

        for (Idx++, Length--; Length; Idx++, Length--)

          gnu_ret = fold_build2 (MINUS_EXPR, comp_type,

                                 fold_build2 (MULT_EXPR, comp_type,

                                              gnu_ret, gnu_base),

                                 build_cst_from_int (comp_type,

                                                     Udigits_Ptr[Idx]));

      else

        for (Idx++, Length--; Length; Idx++, Length--)

          gnu_ret = fold_build2 (PLUS_EXPR, comp_type,

                                 fold_build2 (MULT_EXPR, comp_type,

                                              gnu_ret, gnu_base),

                                 build_cst_from_int (comp_type,

                                                     Udigits_Ptr[Idx]));

    }

  gnu_ret = convert (type, gnu_ret);

  /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on GNU_RET.  */

  while ((TREE_CODE (gnu_ret) == NOP_EXPR

          || TREE_CODE (gnu_ret) == NON_LVALUE_EXPR)

         && TREE_TYPE (TREE_OPERAND (gnu_ret, 0)) == TREE_TYPE (gnu_ret))

    gnu_ret = TREE_OPERAND (gnu_ret, 0);

  return gnu_ret;

}