/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma weak __fmodf = fmodf

#include "libm.h"

/* INDENT OFF */
static const int
        is = (int)0x80000000,
        im = 0x007fffff,
        ii = 0x7f800000,
        iu = 0x00800000;
/* INDENT ON */

static const float zero = 0.0;

float
fmodf(float x, float y) {
        float   w;
        int     hx, ix, iy, iz, k, ny, nd;

        hx = *(int *)&x;
        ix = hx & 0x7fffffff;
        iy = *(int *)&y & 0x7fffffff;

        /* purge off exception values */
        if (ix >= ii || iy > ii || iy == 0) {
                w = x * y;
                w = w / w;
        } else if (ix <= iy) {
                if (ix < iy)
                        w = x;  /* return x if |x|<|y| */
                else
                        w = zero * x;   /* return sign(x)*0.0 */
        } else {
                /* INDENT OFF */
                /*
                 * scale x,y to "normal" with
                 *      ny = exponent of y
                 *      nd = exponent of x minus exponent of y
                 */
                /* INDENT ON */
                ny = iy >> 23;
                k = ix >> 23;

                /* special case for subnormal y or x */
                if (ny == 0) {
                        ny = 1;
                        while (iy < iu) {
                                ny -= 1;
                                iy += iy;
                        }
                        nd = k - ny;
                        if (k == 0) {
                                nd += 1;
                                while (ix < iu) {
                                        nd -= 1;
                                        ix += ix;
                                }
                        } else {
                                ix = iu | (ix & im);
                        }
                } else {
                        nd = k - ny;
                        ix = iu | (ix & im);
                        iy = iu | (iy & im);
                }

                /* fix point fmod for normalized ix and iy */
                /* INDENT OFF */
                /*
                 * while (nd--) {
                 *      iz = ix - iy;
                 * if (iz < 0)
                 *      ix = ix + ix;
                 * else if (iz == 0) {
                 *      *(int *) &w = is & hx;
                 *      return w;
                 * }
                 * else
                 *      ix = iz + iz;
                 * }
                 */
                /* INDENT ON */
                /* unroll the above loop 4 times to gain performance */
                k = nd >> 2;
                nd -= k << 2;
                while (k--) {
                        iz = ix - iy;
                        if (iz >= 0)
                                ix = iz + iz;
                        else
                                ix += ix;
                        iz = ix - iy;
                        if (iz >= 0)
                                ix = iz + iz;
                        else
                                ix += ix;
                        iz = ix - iy;
                        if (iz >= 0)
                                ix = iz + iz;
                        else
                                ix += ix;
                        iz = ix - iy;
                        if (iz >= 0)
                                ix = iz + iz;
                        else
                                ix += ix;
                        if (iz == 0) {
                                *(int *)&w = is & hx;
                                return (w);
                        }
                }
                while (nd--) {
                        iz = ix - iy;
                        if (iz >= 0)
                                ix = iz + iz;
                        else
                                ix += ix;
                }
                /* end of unrolling */

                iz = ix - iy;
                if (iz >= 0)
                        ix = iz;

                /* convert back to floating value and restore the sign */
                if (ix == 0) {
                        *(int *)&w = is & hx;
                        return (w);
                }
                while (ix < iu) {
                        ix += ix;
                        ny -= 1;
                }
                while (ix > (iu + iu)) {
                        ny += 1;
                        ix >>= 1;
                }
                if (ny > 0) {
                        *(int *)&w = (is & hx) | (ix & im) | (ny << 23);
                } else {
                        /* subnormal output */
                        k = -ny + 1;
                        ix >>= k;
                        *(int *)&w = (is & hx) | ix;
                }
        }
        return (w);
}