common/m9x/nearbyintl.c

	nearbyintl.c revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
 * 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.
 */

#if defined(ELFOBJ)
#pragma weak nearbyintl = __nearbyintl
#endif

#include "libm.h"
#include "fma.h"
#include "fenv_inlines.h"

#if defined(__sparc)

static union {
    unsigned i;
    float f;
} snan = { 0x7f800001 };

long double
__nearbyintl(long double x) {
    union {
        unsigned i[4];
        long double q;
    } xx;
    unsigned hx, sx, i, frac;
    unsigned int fsr;
    int rm, j;
    volatile float  dummy;

    xx.q = x;
    sx = xx.i[0] & 0x80000000;
    hx = xx.i[0] & ~0x80000000;

    /* handle trivial cases */
    if (hx >= 0x406f0000) { /* x is nan, inf, or already integral */
        /* check for signaling nan */
        if ((hx > 0x7fff0000 || (hx == 0x7fff0000 &&
            (xx.i[1] | xx.i[2] | xx.i[3]))) && !(hx & 0x8000)) {
            dummy = snan.f;
            dummy += snan.f;
            xx.i[0] = sx | hx | 0x8000;
        }
        return (xx.q);
    } else if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0) /* x is zero */
        return (x);

    /* get the rounding mode */
    __fenv_getfsr32(&fsr);
    rm = fsr >> 30;

    /* flip the sense of directed roundings if x is negative */
    if (sx)
        rm ^= rm >> 1;

    /* handle |x| < 1 */
    if (hx < 0x3fff0000) {
        if (rm == FSR_RP || (rm == FSR_RN && (hx >= 0x3ffe0000 &&
            ((hx & 0xffff) | xx.i[1] | xx.i[2] | xx.i[3]))))
            xx.i[0] = sx | 0x3fff0000;
        else
            xx.i[0] = sx;
        xx.i[1] = xx.i[2] = xx.i[3] = 0;
        return (xx.q);
    }

    /* round x at the integer bit */
    j = 0x406f - (hx >> 16);
    if (j >= 96) {
        i = 1 << (j - 96);
        frac = ((xx.i[0] << 1) << (127 - j)) | (xx.i[1] >> (j - 96));
        if ((xx.i[1] & (i - 1)) | xx.i[2] | xx.i[3])
            frac |= 1;
        if (!frac)
            return (x);
        xx.i[1] = xx.i[2] = xx.i[3] = 0;
        xx.i[0] &= ~(i - 1);
        if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
            (frac == 0x80000000 && (xx.i[0] & i)))))
            xx.i[0] += i;
    } else if (j >= 64) {
        i = 1 << (j - 64);
        frac = ((xx.i[1] << 1) << (95 - j)) | (xx.i[2] >> (j - 64));
        if ((xx.i[2] & (i - 1)) | xx.i[3])
            frac |= 1;
        if (!frac)
            return (x);
        xx.i[2] = xx.i[3] = 0;
        xx.i[1] &= ~(i - 1);
        if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
            (frac == 0x80000000 && (xx.i[1] & i))))) {
            xx.i[1] += i;
            if (xx.i[1] == 0)
                xx.i[0]++;
        }
    } else if (j >= 32) {
        i = 1 << (j - 32);
        frac = ((xx.i[2] << 1) << (63 - j)) | (xx.i[3] >> (j - 32));
        if (xx.i[3] & (i - 1))
            frac |= 1;
        if (!frac)
            return (x);
        xx.i[3] = 0;
        xx.i[2] &= ~(i - 1);
        if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
            (frac == 0x80000000 && (xx.i[2] & i))))) {
            xx.i[2] += i;
            if (xx.i[2] == 0)
                if (++xx.i[1] == 0)
                    xx.i[0]++;
        }
    } else {
        i = 1 << j;
        frac = (xx.i[3] << 1) << (31 - j);
        if (!frac)
            return (x);
        xx.i[3] &= ~(i - 1);
        if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
            (frac == 0x80000000 && (xx.i[3] & i))))) {
            xx.i[3] += i;
            if (xx.i[3] == 0)
                if (++xx.i[2] == 0)
                    if (++xx.i[1] == 0)
                        xx.i[0]++;
        }
    }

    return (xx.q);
}

#elif defined(__x86)

/* inline template */
extern long double frndint(long double);

long double
__nearbyintl(long double x) {
    long double z;
    unsigned oldcwsw, cwsw;

    /* save the control and status words, mask the inexact exception */
    __fenv_getcwsw(&oldcwsw);
    cwsw = oldcwsw | 0x00200000;
    __fenv_setcwsw(&cwsw);

    z = frndint(x);

    /*
     * restore the control and status words, preserving all but the
     * inexact flag
     */
    __fenv_getcwsw(&cwsw);
    oldcwsw |= (cwsw & 0x1f);
    __fenv_setcwsw(&oldcwsw);

    return (z);
}

#else
#error Unknown architecture
#endif