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dp_flong.c

/* IEEE754 floating point arithmetic
 * double precision: common utilities
 */
/*
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 * http://www.algor.co.uk
 *
 * ########################################################################
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope it will be useful, but WITHOUT
 *  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 this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * ########################################################################
 */


#include "ieee754dp.h"

ieee754dp ieee754dp_flong(s64 x)
{
      u64 xm;
      int xe;
      int xs;

      CLEARCX;

      if (x == 0)
            return ieee754dp_zero(0);
      if (x == 1 || x == -1)
            return ieee754dp_one(x < 0);
      if (x == 10 || x == -10)
            return ieee754dp_ten(x < 0);

      xs = (x < 0);
      if (xs) {
            if (x == (1ULL << 63))
                  xm = (1ULL << 63);      /* max neg can't be safely negated */
            else
                  xm = -x;
      } else {
            xm = x;
      }

      /* normalize */
      xe = DP_MBITS + 3;
      if (xm >> (DP_MBITS + 1 + 3)) {
            /* shunt out overflow bits */
            while (xm >> (DP_MBITS + 1 + 3)) {
                  XDPSRSX1();
            }
      } else {
            /* normalize in grs extended double precision */
            while ((xm >> (DP_MBITS + 3)) == 0) {
                  xm <<= 1;
                  xe--;
            }
      }
      DPNORMRET1(xs, xe, xm, "dp_flong", x);
}

ieee754dp ieee754dp_fulong(u64 u)
{
      if ((s64) u < 0)
            return ieee754dp_add(ieee754dp_1e63(),
                             ieee754dp_flong(u & ~(1ULL << 63)));
      return ieee754dp_flong(u);
}

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