/*      $NetBSD: sfmpy.c,v 1.5 2012/02/04 17:03:10 skrll Exp $  */

/*      $OpenBSD: sfmpy.c,v 1.4 2001/03/29 03:58:19 mickey Exp $        */

/*
 * Copyright 1996 1995 by Open Software Foundation, Inc.
 *              All Rights Reserved
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby granted,
 * provided that the above copyright notice appears in all copies and
 * that both the copyright notice and this permission notice appear in
 * supporting documentation.
 *
 * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
 * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */
/*
 * pmk1.1
 */
/*
 * (c) Copyright 1986 HEWLETT-PACKARD COMPANY
 *
 * To anyone who acknowledges that this file is provided "AS IS"
 * without any express or implied warranty:
 *     permission to use, copy, modify, and distribute this file
 * for any purpose is hereby granted without fee, provided that
 * the above copyright notice and this notice appears in all
 * copies, and that the name of Hewlett-Packard Company not be
 * used in advertising or publicity pertaining to distribution
 * of the software without specific, written prior permission.
 * Hewlett-Packard Company makes no representations about the
 * suitability of this software for any purpose.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sfmpy.c,v 1.5 2012/02/04 17:03:10 skrll Exp $");

#include "../spmath/float.h"
#include "../spmath/sgl_float.h"

/*
 *  Single Precision Floating-point Multiply
 */
int
sgl_fmpy(sgl_floating_point *srcptr1, sgl_floating_point *srcptr2,
    sgl_floating_point *dstptr, unsigned int *status)
{
        register unsigned int opnd1, opnd2, opnd3, result;
        register int dest_exponent, count;
        register int inexact = false, guardbit = false, stickybit = false;
        int is_tiny;

        opnd1 = *srcptr1;
        opnd2 = *srcptr2;
        /*
         * set sign bit of result
         */
        if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result);
        else Sgl_setzero(result);
        /*
         * check first operand for NaN's or infinity
         */
        if (Sgl_isinfinity_exponent(opnd1)) {
                if (Sgl_iszero_mantissa(opnd1)) {
                        if (Sgl_isnotnan(opnd2)) {
                                if (Sgl_iszero_exponentmantissa(opnd2)) {
                                        /*
                                         * invalid since operands are infinity
                                         * and zero
                                         */
                                        if (Is_invalidtrap_enabled())
                                                return(INVALIDEXCEPTION);
                                        Set_invalidflag();
                                        Sgl_makequietnan(result);
                                        *dstptr = result;
                                        return(NOEXCEPTION);
                                }
                                /*
                                 * return infinity
                                 */
                                Sgl_setinfinity_exponentmantissa(result);
                                *dstptr = result;
                                return(NOEXCEPTION);
                        }
                }
                else {
                        /*
                         * is NaN; signaling or quiet?
                         */
                        if (Sgl_isone_signaling(opnd1)) {
                                /* trap if INVALIDTRAP enabled */
                                if (Is_invalidtrap_enabled())
                                        return(INVALIDEXCEPTION);
                                /* make NaN quiet */
                                Set_invalidflag();
                                Sgl_set_quiet(opnd1);
                        }
                        /*
                         * is second operand a signaling NaN?
                         */
                        else if (Sgl_is_signalingnan(opnd2)) {
                                /* trap if INVALIDTRAP enabled */
                                if (Is_invalidtrap_enabled())
                                        return(INVALIDEXCEPTION);
                                /* make NaN quiet */
                                Set_invalidflag();
                                Sgl_set_quiet(opnd2);
                                *dstptr = opnd2;
                                return(NOEXCEPTION);
                        }
                        /*
                         * return quiet NaN
                         */
                        *dstptr = opnd1;
                        return(NOEXCEPTION);
                }
        }
        /*
         * check second operand for NaN's or infinity
         */
        if (Sgl_isinfinity_exponent(opnd2)) {
                if (Sgl_iszero_mantissa(opnd2)) {
                        if (Sgl_iszero_exponentmantissa(opnd1)) {
                                /* invalid since operands are zero & infinity */
                                if (Is_invalidtrap_enabled())
                                        return(INVALIDEXCEPTION);
                                Set_invalidflag();
                                Sgl_makequietnan(opnd2);
                                *dstptr = opnd2;
                                return(NOEXCEPTION);
                        }
                        /*
                         * return infinity
                         */
                        Sgl_setinfinity_exponentmantissa(result);
                        *dstptr = result;
                        return(NOEXCEPTION);
                }
                /*
                 * is NaN; signaling or quiet?
                 */
                if (Sgl_isone_signaling(opnd2)) {
                        /* trap if INVALIDTRAP enabled */
                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);

                        /* make NaN quiet */
                        Set_invalidflag();
                        Sgl_set_quiet(opnd2);
                }
                /*
                 * return quiet NaN
                 */
                *dstptr = opnd2;
                return(NOEXCEPTION);
        }
        /*
         * Generate exponent
         */
        dest_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS;

        /*
         * Generate mantissa
         */
        if (Sgl_isnotzero_exponent(opnd1)) {
                /* set hidden bit */
                Sgl_clear_signexponent_set_hidden(opnd1);
        }
        else {
                /* check for zero */
                if (Sgl_iszero_mantissa(opnd1)) {
                        Sgl_setzero_exponentmantissa(result);
                        *dstptr = result;
                        return(NOEXCEPTION);
                }
                /* is denormalized, adjust exponent */
                Sgl_clear_signexponent(opnd1);
                Sgl_leftshiftby1(opnd1);
                Sgl_normalize(opnd1,dest_exponent);
        }
        /* opnd2 needs to have hidden bit set with msb in hidden bit */
        if (Sgl_isnotzero_exponent(opnd2)) {
                Sgl_clear_signexponent_set_hidden(opnd2);
        }
        else {
                /* check for zero */
                if (Sgl_iszero_mantissa(opnd2)) {
                        Sgl_setzero_exponentmantissa(result);
                        *dstptr = result;
                        return(NOEXCEPTION);
                }
                /* is denormalized; want to normalize */
                Sgl_clear_signexponent(opnd2);
                Sgl_leftshiftby1(opnd2);
                Sgl_normalize(opnd2,dest_exponent);
        }

        /* Multiply two source mantissas together */

        Sgl_leftshiftby4(opnd2);     /* make room for guard bits */
        Sgl_setzero(opnd3);
        /*
         * Four bits at a time are inspected in each loop, and a
         * simple shift and add multiply algorithm is used.
         */
        for (count=1;count<SGL_P;count+=4) {
                stickybit |= Slow4(opnd3);
                Sgl_rightshiftby4(opnd3);
                if (Sbit28(opnd1)) Sall(opnd3) += (Sall(opnd2) << 3);
                if (Sbit29(opnd1)) Sall(opnd3) += (Sall(opnd2) << 2);
                if (Sbit30(opnd1)) Sall(opnd3) += (Sall(opnd2) << 1);
                if (Sbit31(opnd1)) Sall(opnd3) += Sall(opnd2);
                Sgl_rightshiftby4(opnd1);
        }
        /* make sure result is left-justified */
        if (Sgl_iszero_sign(opnd3)) {
                Sgl_leftshiftby1(opnd3);
        }
        else {
                /* result mantissa >= 2. */
                dest_exponent++;
        }
        /* check for denormalized result */
        while (Sgl_iszero_sign(opnd3)) {
                Sgl_leftshiftby1(opnd3);
                dest_exponent--;
        }
        /*
         * check for guard, sticky and inexact bits
         */
        stickybit |= Sgl_all(opnd3) << (SGL_BITLENGTH - SGL_EXP_LENGTH + 1);
        guardbit = Sbit24(opnd3);
        inexact = guardbit | stickybit;

        /* re-align mantissa */
        Sgl_rightshiftby8(opnd3);

        /*
         * round result
         */
        if (inexact && (dest_exponent>0 || Is_underflowtrap_enabled())) {
                Sgl_clear_signexponent(opnd3);
                switch (Rounding_mode()) {
                        case ROUNDPLUS:
                                if (Sgl_iszero_sign(result))
                                        Sgl_increment(opnd3);
                                break;
                        case ROUNDMINUS:
                                if (Sgl_isone_sign(result))
                                        Sgl_increment(opnd3);
                                break;
                        case ROUNDNEAREST:
                                if (guardbit &&
                                    (stickybit || Sgl_isone_lowmantissa(opnd3)))
                                        Sgl_increment(opnd3);
                                break;
                }
                if (Sgl_isone_hidden(opnd3)) dest_exponent++;
        }
        Sgl_set_mantissa(result,opnd3);

        /*
         * Test for overflow
         */
        if (dest_exponent >= SGL_INFINITY_EXPONENT) {
                /* trap if OVERFLOWTRAP enabled */
                if (Is_overflowtrap_enabled()) {
                        /*
                         * Adjust bias of result
                         */
                        Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
                        *dstptr = result;
                        if (inexact) {
                            if (Is_inexacttrap_enabled())
                                return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
                            else Set_inexactflag();
                        }
                        return(OVERFLOWEXCEPTION);
                }
                inexact = true;
                Set_overflowflag();
                /* set result to infinity or largest number */
                Sgl_setoverflow(result);
        }
        /*
         * Test for underflow
         */
        else if (dest_exponent <= 0) {
                /* trap if UNDERFLOWTRAP enabled */
                if (Is_underflowtrap_enabled()) {
                        /*
                         * Adjust bias of result
                         */
                        Sgl_setwrapped_exponent(result,dest_exponent,unfl);
                        *dstptr = result;
                        if (inexact) {
                            if (Is_inexacttrap_enabled())
                                return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION);
                            else Set_inexactflag();
                        }
                        return(UNDERFLOWEXCEPTION);
                }

                /* Determine if should set underflow flag */
                is_tiny = true;
                if (dest_exponent == 0 && inexact) {
                        switch (Rounding_mode()) {
                        case ROUNDPLUS:
                                if (Sgl_iszero_sign(result)) {
                                        Sgl_increment(opnd3);
                                        if (Sgl_isone_hiddenoverflow(opnd3))
                                                is_tiny = false;
                                        Sgl_decrement(opnd3);
                                }
                                break;
                        case ROUNDMINUS:
                                if (Sgl_isone_sign(result)) {
                                        Sgl_increment(opnd3);
                                        if (Sgl_isone_hiddenoverflow(opnd3))
                                                is_tiny = false;
                                        Sgl_decrement(opnd3);
                                }
                                break;
                        case ROUNDNEAREST:
                                if (guardbit && (stickybit ||
                                    Sgl_isone_lowmantissa(opnd3))) {
                                        Sgl_increment(opnd3);
                                        if (Sgl_isone_hiddenoverflow(opnd3))
                                                is_tiny = false;
                                        Sgl_decrement(opnd3);
                                }
                                break;
                        }
                }

                /*
                 * denormalize result or set to signed zero
                 */
                stickybit = inexact;
                Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact);

                /* return zero or smallest number */
                if (inexact) {
                        switch (Rounding_mode()) {
                        case ROUNDPLUS:
                                if (Sgl_iszero_sign(result))
                                        Sgl_increment(opnd3);
                                break;
                        case ROUNDMINUS:
                                if (Sgl_isone_sign(result))
                                        Sgl_increment(opnd3);
                                break;
                        case ROUNDNEAREST:
                                if (guardbit && (stickybit ||
                                    Sgl_isone_lowmantissa(opnd3)))
                                        Sgl_increment(opnd3);
                                break;
                        }
                if (is_tiny) Set_underflowflag();
                }
                Sgl_set_exponentmantissa(result,opnd3);
        }
        else Sgl_set_exponent(result,dest_exponent);
        *dstptr = result;

        /* check for inexact */
        if (inexact) {
                if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
                else Set_inexactflag();
        }
        return(NOEXCEPTION);
}