gcc/ada/cuintp.c

/****************************************************************************
 *                                                                          *
 *                        GNAT COMPILER COMPONENTS                          *
 *                                                                          *
 *                               C U I N T P                                *
 *                                                                          *
 *                          C Implementation File                           *
 *                                                                          *
 *                            $Revision: 1.1 $
 *                                                                          *
 *          Copyright (C) 1992-2001 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. *
 * It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). *
 *                                                                          *
 ****************************************************************************/

/* 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 "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.  */

/* Similarly to UI_To_Int, but return a GCC INTEGER_CST.  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 (Input, type)
     Uint Input;
     tree type;
{
  tree gnu_ret;

  if (Input <= Uint_Direct_Last)
    gnu_ret = convert (type, build_int_2 (Input - Uint_Direct_Bias, 
					  Input < Uint_Direct_Bias ? -1 : 0));
  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
	= (TYPE_PRECISION (type) >= TYPE_PRECISION (integer_type_node)
	   ? type : integer_type_node);
      tree gnu_base = convert (comp_type, build_int_2 (Base, 0));

      if (Length <= 0)
	gigi_abort (601);

      gnu_ret = convert (comp_type, build_int_2 (First, First < 0 ? -1 : 0));
      if (First < 0)
	for (Idx++, Length--; Length; Idx++, Length--)
	  gnu_ret = fold (build (MINUS_EXPR, comp_type,
				 fold (build (MULT_EXPR, comp_type,
					      gnu_ret, gnu_base)),
				 convert (comp_type,
					  build_int_2 (Udigits_Ptr[Idx], 0))));
      else
	for (Idx++, Length--; Length; Idx++, Length--)
	  gnu_ret = fold (build (PLUS_EXPR, comp_type,
				 fold (build (MULT_EXPR, comp_type,
					      gnu_ret, gnu_base)),
				 convert (comp_type,
					  build_int_2 (Udigits_Ptr[Idx], 0))));
    }

  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;
}