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

/*      $OpenBSD: sfrem.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: sfrem.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 Remainder
 */
int
sgl_frem(sgl_floating_point *srcptr1, sgl_floating_point *srcptr2,
    sgl_floating_point *dstptr, unsigned int *status)
{
        register unsigned int opnd1, opnd2, result;
        register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
        register int roundup = false;

        opnd1 = *srcptr1;
        opnd2 = *srcptr2;
        /*
         * check first operand for NaN's or infinity
         */
        if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) {
                if (Sgl_iszero_mantissa(opnd1)) {
                        if (Sgl_isnotnan(opnd2)) {
                                /* invalid since first operand is infinity */
                                if (Is_invalidtrap_enabled())
                                        return(INVALIDEXCEPTION);
                                Set_invalidflag();
                                Sgl_makequietnan(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 ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) {
                if (Sgl_iszero_mantissa(opnd2)) {
                        /*
                         * return first operand
                         */
                        *dstptr = opnd1;
                        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);
        }
        /*
         * check second operand for zero
         */
        if (Sgl_iszero_exponentmantissa(opnd2)) {
                /* invalid since second operand is zero */
                if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                Set_invalidflag();
                Sgl_makequietnan(result);
                *dstptr = result;
                return(NOEXCEPTION);
        }

        /*
         * get sign of result
         */
        result = opnd1;

        /*
         * check for denormalized operands
         */
        if (opnd1_exponent == 0) {
                /* check for zero */
                if (Sgl_iszero_mantissa(opnd1)) {
                        *dstptr = opnd1;
                        return(NOEXCEPTION);
                }
                /* normalize, then continue */
                opnd1_exponent = 1;
                Sgl_normalize(opnd1,opnd1_exponent);
        }
        else {
                Sgl_clear_signexponent_set_hidden(opnd1);
        }
        if (opnd2_exponent == 0) {
                /* normalize, then continue */
                opnd2_exponent = 1;
                Sgl_normalize(opnd2,opnd2_exponent);
        }
        else {
                Sgl_clear_signexponent_set_hidden(opnd2);
        }

        /* find result exponent and divide step loop count */
        dest_exponent = opnd2_exponent - 1;
        stepcount = opnd1_exponent - opnd2_exponent;

        /*
         * check for opnd1/opnd2 < 1
         */
        if (stepcount < 0) {
                /*
                 * check for opnd1/opnd2 > 1/2
                 *
                 * In this case n will round to 1, so
                 *    r = opnd1 - opnd2
                 */
                if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) {
                        Sgl_all(result) = ~Sgl_all(result);   /* set sign */
                        /* align opnd2 with opnd1 */
                        Sgl_leftshiftby1(opnd2);
                        Sgl_subtract(opnd2,opnd1,opnd2);
                        /* now normalize */
                        while (Sgl_iszero_hidden(opnd2)) {
                                Sgl_leftshiftby1(opnd2);
                                dest_exponent--;
                        }
                        Sgl_set_exponentmantissa(result,opnd2);
                        goto testforunderflow;
                }
                /*
                 * opnd1/opnd2 <= 1/2
                 *
                 * In this case n will round to zero, so
                 *    r = opnd1
                 */
                Sgl_set_exponentmantissa(result,opnd1);
                dest_exponent = opnd1_exponent;
                goto testforunderflow;
        }

        /*
         * Generate result
         *
         * Do iterative subtract until remainder is less than operand 2.
         */
        while (stepcount-- > 0 && Sgl_all(opnd1)) {
                if (Sgl_isnotlessthan(opnd1,opnd2))
                        Sgl_subtract(opnd1,opnd2,opnd1);
                Sgl_leftshiftby1(opnd1);
        }
        /*
         * Do last subtract, then determine which way to round if remainder
         * is exactly 1/2 of opnd2
         */
        if (Sgl_isnotlessthan(opnd1,opnd2)) {
                Sgl_subtract(opnd1,opnd2,opnd1);
                roundup = true;
        }
        if (stepcount > 0 || Sgl_iszero(opnd1)) {
                /* division is exact, remainder is zero */
                Sgl_setzero_exponentmantissa(result);
                *dstptr = result;
                return(NOEXCEPTION);
        }

        /*
         * Check for cases where opnd1/opnd2 < n
         *
         * In this case the result's sign will be opposite that of
         * opnd1.  The mantissa also needs some correction.
         */
        Sgl_leftshiftby1(opnd1);
        if (Sgl_isgreaterthan(opnd1,opnd2)) {
                Sgl_invert_sign(result);
                Sgl_subtract((opnd2<<1),opnd1,opnd1);
        }
        /* check for remainder being exactly 1/2 of opnd2 */
        else if (Sgl_isequal(opnd1,opnd2) && roundup) {
                Sgl_invert_sign(result);
        }

        /* normalize result's mantissa */
        while (Sgl_iszero_hidden(opnd1)) {
                dest_exponent--;
                Sgl_leftshiftby1(opnd1);
        }
        Sgl_set_exponentmantissa(result,opnd1);

        /*
         * Test for underflow
         */
    testforunderflow:
        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;
                        /* frem is always exact */
                        return(UNDERFLOWEXCEPTION);
                }
                /*
                 * denormalize result or set to signed zero
                 */
                if (dest_exponent >= (1 - SGL_P)) {
                        Sgl_rightshift_exponentmantissa(result,1-dest_exponent);
                } else {
                        Sgl_setzero_exponentmantissa(result);
                }
        }
        else Sgl_set_exponent(result,dest_exponent);
        *dstptr = result;
        return(NOEXCEPTION);
}