sp_fdp.c

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/* IEEE754 floating point arithmetic
 * single precision
 */
/*
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 *
 * ########################################################################
 *
 *  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);
    }
}