common/m9x/llroundl.c

/*
 * 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 __llroundl = llroundl
#if defined(__sparcv9) || defined(__amd64)
#pragma weak lroundl = llroundl
#pragma weak __lroundl = llroundl
#endif

#include "libm.h"

#if defined(__sparc)
long long
llroundl(long double x) {
    union {
        unsigned i[4];
        long double q;
    } xx;
    union {
        unsigned i[2];
        long long l;
    } zz;
    union {
        unsigned i;
        float f;
    } tt;
    unsigned hx, sx, frac;
    int j;

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

    /* handle trivial cases */
    if (hx > 0x403e0000) { /* |x| > 2^63 + ... or x is nan */
        /* convert an out-of-range float */
        tt.i = sx | 0x7f000000;
        return ((long long) tt.f);
    }

    /* handle |x| < 1 */
    if (hx < 0x3fff0000) {
        if (hx >= 0x3ffe0000)
            return (sx ? -1LL : 1LL);
        return (0LL);
    }

    /* extract the integer and fractional parts of x */
    j = 0x406f - (hx >> 16);
    xx.i[0] = 0x10000 | (xx.i[0] & 0xffff);
    if (j >= 96) {
        zz.i[0] = 0;
        zz.i[1] = xx.i[0] >> (j - 96);
        frac = ((xx.i[0] << 1) << (127 - j)) | (xx.i[1] >> (j - 96));
        if (((xx.i[1] << 1) << (127 - j)) | xx.i[2] | xx.i[3])
            frac |= 1;
    } else if (j >= 64) {
        zz.i[0] = xx.i[0] >> (j - 64);
        zz.i[1] = ((xx.i[0] << 1) << (95 - j)) | (xx.i[1] >> (j - 64));
        frac = ((xx.i[1] << 1) << (95 - j)) | (xx.i[2] >> (j - 64));
        if (((xx.i[2] << 1) << (95 - j)) | xx.i[3])
            frac |= 1;
    } else {
        zz.i[0] = ((xx.i[0] << 1) << (63 - j)) | (xx.i[1] >> (j - 32));
        zz.i[1] = ((xx.i[1] << 1) << (63 - j)) | (xx.i[2] >> (j - 32));
        frac = ((xx.i[2] << 1) << (63 - j)) | (xx.i[3] >> (j - 32));
        if ((xx.i[3] << 1) << (63 - j))
            frac |= 1;
    }

    /* round */
    if (frac >= 0x80000000u) {
        if (++zz.i[1] == 0)
            zz.i[0]++;
    }

    /* check for result out of range (note that z is |x| at this point) */
    if (zz.i[0] > 0x80000000u || (zz.i[0] == 0x80000000 && (zz.i[1] ||
        !sx))) {
        tt.i = sx | 0x7f000000;
        return ((long long) tt.f);
    }

    /* negate result if need be */
    if (sx) {
        zz.i[0] = ~zz.i[0];
        zz.i[1] = -zz.i[1];
        if (zz.i[1] == 0)
            zz.i[0]++;
    }

    return (zz.l);
}
#elif defined(__x86)
long long
llroundl(long double x) {
    union {
        unsigned i[3];
        long double e;
    } xx;
    int ex, sx, i;

    xx.e = x;
    ex = xx.i[2] & 0x7fff;
    sx = xx.i[2] & 0x8000;

    if (ex < 0x403e) { /* |x| < 2^63 */
        /* handle |x| < 1 */
        if (ex < 0x3fff) {
            if (ex >= 0x3ffe)
                return (sx ? -1LL : 1LL);
            return (0LL);
        }

        /* round x at the integer bit */
        if (ex < 0x401e) {
            i = 1 << (0x401d - ex);
            xx.i[1] = (xx.i[1] + i) & ~(i | (i - 1));
            xx.i[0] = 0;
        } else {
            i = 1 << (0x403d - ex);
            xx.i[0] += i;
            if (xx.i[0] < i)
                xx.i[1]++;
            xx.i[0] &= ~(i | (i - 1));
        }
        if (xx.i[1] == 0) {
            xx.i[2] = sx | ++ex;
            xx.i[1] = 0x80000000U;
        }
    }

    /* now x is nan, inf, or integral */
    return ((long long) xx.e);
}
#else
#error Unknown architecture
#endif