common/m9x/frexpl.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 frexpl = __frexpl

#include "libm.h"

#if defined(__sparc)

long double
__frexpl(long double x, int *exp) {
    union {
        unsigned i[4];
        long double q;
    } xx;
    unsigned hx;
    int e, s;

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

    if (hx >= 0x7fff0000) { /* x is infinite or NaN */
        *exp = 0;
        return (x);
    }

    e = 0;
    if (hx < 0x00010000) {  /* x is subnormal or zero */
        if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0) {
            *exp = 0;
            return (x);
        }

        /* normalize x */
        s = xx.i[0] & 0x80000000;
        while ((hx | (xx.i[1] & 0xffff0000)) == 0) {
            hx = xx.i[1];
            xx.i[1] = xx.i[2];
            xx.i[2] = xx.i[3];
            xx.i[3] = 0;
            e -= 32;
        }
        while (hx < 0x10000) {
            hx = (hx << 1) | (xx.i[1] >> 31);
            xx.i[1] = (xx.i[1] << 1) | (xx.i[2] >> 31);
            xx.i[2] = (xx.i[2] << 1) | (xx.i[3] >> 31);
            xx.i[3] <<= 1;
            e--;
        }
        xx.i[0] = s | hx;
    }

    /* now xx.q is normal */
    xx.i[0] = (xx.i[0] & ~0x7fff0000) | 0x3ffe0000;
    *exp = e + (hx >> 16) - 0x3ffe;
    return (xx.q);
}

#elif defined(__x86)

long double
__frexpl(long double x, int *exp) {
    union {
        unsigned i[3];
        long double e;
    } xx;
    unsigned hx;
    int e;

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

    if (hx >= 0x7fff) { /* x is infinite or NaN */
        *exp = 0;
        return (x);
    }

    e = 0;
    if (hx < 0x0001) {  /* x is subnormal or zero */
        if ((xx.i[0] | xx.i[1]) == 0) {
            *exp = 0;
            return (x);
        }

        /* normalize x */
        xx.e *= 18446744073709551616.0L;    /* 2^64 */
        hx = xx.i[2] & 0x7fff;
        e = -64;
    }

    /* now xx.e is normal */
    xx.i[2] = (xx.i[2] & 0x8000) | 0x3ffe;
    *exp = e + hx - 0x3ffe;
    return (xx.e);
}

#else
#error Unknown architecture
#endif