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sp_fdp.c

/* IEEE754 floating point arithmetic
 * single precision
 */
/*
 * 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 "ieee754sp.h"

ieee754sp ieee754sp_fdp(ieee754dp x)
{
      COMPXDP;
      ieee754sp nan;

      EXPLODEXDP;

      CLEARCX;

      FLUSHXDP;

      switch (xc) {
      case IEEE754_CLASS_SNAN:
            SETCX(IEEE754_INVALID_OPERATION);
            return ieee754sp_nanxcpt(ieee754sp_indef(), "fdp");
      case IEEE754_CLASS_QNAN:
            nan = buildsp(xs, SP_EMAX + 1 + SP_EBIAS, (u32)
                        (xm >> (DP_MBITS - SP_MBITS)));
            if (!ieee754sp_isnan(nan))
                  nan = ieee754sp_indef();
            return ieee754sp_nanxcpt(nan, "fdp", x);
      case IEEE754_CLASS_INF:
            return ieee754sp_inf(xs);
      case IEEE754_CLASS_ZERO:
            return ieee754sp_zero(xs);
      case IEEE754_CLASS_DNORM:
            /* can't possibly be sp representable */
            SETCX(IEEE754_UNDERFLOW);
            SETCX(IEEE754_INEXACT);
            if ((ieee754_csr.rm == IEEE754_RU && !xs) ||
                        (ieee754_csr.rm == IEEE754_RD && xs))
                  return ieee754sp_xcpt(ieee754sp_mind(xs), "fdp", x);
            return ieee754sp_xcpt(ieee754sp_zero(xs), "fdp", x);
      case IEEE754_CLASS_NORM:
            break;
      }

      {
            u32 rm;

            /* convert from DP_MBITS to SP_MBITS+3 with sticky right shift
             */
            rm = (xm >> (DP_MBITS - (SP_MBITS + 3))) |
                ((xm << (64 - (DP_MBITS - (SP_MBITS + 3)))) != 0);

            SPNORMRET1(xs, xe, rm, "fdp", x);
      }
}

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