/****************************************************************************
 *                                                                          *
 *                        GNAT COMPILER COMPONENTS                          *
 *                                                                          *
 *                               C U I N T P                                *
 *                                                                          *
 *                          C Implementation File                           *
 *                                                                          *
 *          Copyright (C) 1992-2003 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.                                                      *
 *                                                                          *
 * 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 "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 force_fit_type (build_int_cst (type, low), false, false, false);
}

/* 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;

  if (Input <= Uint_Direct_Last)
    gnu_ret = build_cst_from_int (type, Input - Uint_Direct_Bias);
  else
    {
      Int Idx = Uints_Ptr[Input].Loc;
      Pos Length = Uints_Ptr[Input].Length;
      Int First = Udigits_Ptr[Idx];
      /* Do computations in integer type or TYPE whichever is wider, then
	 convert later.  This avoid overflow if type is short integer.  */
      tree comp_type
	= ((TREE_CODE (type) == REAL_TYPE
	    || TYPE_PRECISION (type) >= TYPE_PRECISION (integer_type_node))
	   ? type : integer_type_node);
      tree gnu_base = build_cst_from_int (comp_type, Base);

      gcc_assert (Length > 0);
      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;
}