/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma weak __remquof = remquof

/* INDENT OFF */
/*
 * float remquof(float x, float y, int *quo) return remainderf(x,y) and an
 * integer pointer quo such that *quo = N mod (2**31),  where N is the
 * exact integeral part of x/y rounded to nearest even.
 *
 * remquof call internal fmodquof
 */

#include "libm.h"
#include "libm_protos.h"
#include <math.h>
extern float fabsf(float);

static const int
        is = (int) 0x80000000,
        im = 0x007fffff,
        ii = 0x7f800000,
        iu = 0x00800000;

static const float zero = 0.0F, half = 0.5F;
/* INDENT ON */

static float
fmodquof(float x, float y, int *quo) {
        float w;
        int hx, ix, iy, iz, k, ny, nd, m, sq;

        hx = *(int *) &x;
        ix = hx & 0x7fffffff;
        iy = *(int *) &y;
        sq = (iy ^ hx) & is;    /* sign of x/y */
        iy &= 0x7fffffff;

        /* purge off exception values */
        *quo = 0;
        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 {
                        *quo = 1 + (sq >> 30);
                        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);
                }
                /* INDENT OFF */
                /* fix point fmod for normalized ix and iy */
                /*
                 * 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 */
                m = 0;
                k = nd >> 2;
                nd -= (k << 2);
                while (k--) {
                        iz = ix - iy;
                        if (iz >= 0) {
                                m += 1;
                                ix = iz + iz;
                        } else
                                ix += ix;
                        m += m;
                        iz = ix - iy;
                        if (iz >= 0) {
                                m += 1;
                                ix = iz + iz;
                        } else
                                ix += ix;
                        m += m;
                        iz = ix - iy;
                        if (iz >= 0) {
                                m += 1;
                                ix = iz + iz;
                        } else
                                ix += ix;
                        m += m;
                        iz = ix - iy;
                        if (iz >= 0) {
                                m += 1;
                                ix = iz + iz;
                        } else
                                ix += ix;
                        m += m;
                        if (iz == 0) {
                                iz = (k << 2) + nd;
                                if (iz < 32)
                                        m <<= iz;
                                else
                                        m = 0;
                                m &= 0x7fffffff;
                                *quo = sq >= 0 ? m : -m;
                                *(int *) &w = is & hx;
                                return (w);
                        }
                }
                while (nd--) {
                        iz = ix - iy;
                        if (iz >= 0) {
                                m += 1;
                                ix = iz + iz;
                        } else
                                ix += ix;
                        m += m;
                }
                /* end of unrolling */

                iz = ix - iy;
                if (iz >= 0) {
                        m += 1;
                        ix = iz;
                }
                m &= 0x7fffffff;
                *quo = sq >= 0 ? m : -m;

                /* 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);
}

float
remquof(float x, float y, int *quo) {
        int hx, hy, sx, sq;
        float v;

        hx = *(int *) &x;       /* high word of x */
        hy = *(int *) &y;       /* high word of y */
        sx = hx & is;           /* sign of x */
        sq = (hx ^ hy) & is;    /* sign of x/y */
        hx ^= sx;               /* |x| */
        hy &= 0x7fffffff;       /* |y| */

        /* purge off exception values: y is 0 or NaN, x is Inf or NaN */
        *quo = 0;
        if (hx >= ii || hy > ii || hy == 0) {
                v = x * y;
                return (v / v);
        }

        y = fabsf(y);
        x = fabsf(x);
        if (hy <= 0x7f7fffff) {
                x = fmodquof(x, y + y, quo);
                *quo = ((*quo) & 0x3fffffff) << 1;
        }
        if (hy < 0x01000000) {
                if (x + x > y) {
                        *quo += 1;
                        if (x == y)
                                x = zero;
                        else
                                x -= y;
                        if (x + x >= y) {
                                x -= y;
                                *quo += 1;
                        }
                }
        } else {
                v = half * y;
                if (x > v) {
                        *quo += 1;
                        if (x == y)
                                x = zero;
                        else
                                x -= y;
                        if (x >= v) {
                                x -= y;
                                *quo += 1;
                        }
                }
        }
        if (sq != 0)
                *quo = -(*quo);
        return (sx == 0 ? x : -x);
}