common/m9x/llrintl.c

	llrintl.c revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af
/*
 * 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 __llrintl = llrintl
#if defined(__sparcv9) || defined(__amd64)
#pragma weak lrintl = llrintl
#pragma weak __lrintl = llrintl
#endif

#include "libm.h"

#if defined(__sparc)

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

long long
llrintl(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 int hx, sx, frac, 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 > 0x403e0000) { /* |x| > 2^63 + ... or x is nan */
        /* convert an out-of-range float */
        tt.i = sx | 0x7f000000;
        return ((long long) tt.f);
    } else if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0) /* x is zero */
        return (0LL);

    /* 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) {
        dummy = 1.0e30f; /* x is nonzero, so raise inexact */
        dummy += 1.0e-30f;
        if (rm == FSR_RP || (rm == FSR_RN && (hx >= 0x3ffe0000 &&
            ((hx & 0xffff) | xx.i[1] | xx.i[2] | xx.i[3]))))
            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 && (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
        (frac == 0x80000000 && (zz.i[1] & 1)))))) {
        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);
    }

    /* raise inexact if need be */
    if (frac) {
        dummy = 1.0e30F;
        dummy += 1.0e-30F;
    }

    /* 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
llrintl(long double x) {
    /*
     * Note: The following code works on x86 (in the default rounding
     * precision mode), but one ought to just use the fistpll instruction
     * instead.
     */
    union {
        unsigned i[3];
        long double e;
    } xx, yy;
    int ex;

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

    if (ex < 0x403e) { /* |x| < 2^63 */
        /* add and subtract a power of two to round x to an integer */
        yy.i[2] = (xx.i[2] & 0x8000) | 0x403e;
        yy.i[1] = 0x80000000;
        yy.i[0] = 0;
        x = (x + yy.e) - yy.e;
    }

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