port/gen/_ftoll.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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "lint.h"
#include <sys/isa_defs.h>
#include <floatingpoint.h>
#include <limits.h>
#include "libc.h"

/*
 * Ensure that this "portable" code is only used on big-endian ISAs
 */
#if !defined(_BIG_ENDIAN) || defined(_LITTLE_ENDIAN)
#error  "big-endian only!"
#endif

/*
 * Convert a double precision floating point number into a 64-bit int.
 */
long long
__dtoll(double dval)
{
    int i0, i1;     /* bitslam */
    int exp;        /* exponent */
    int m0;         /* most significant word of mantissa */
    unsigned int m1;    /* least sig. word of mantissa */
    unsigned int _fp_current_exceptions = 0;
    union {
        int i[2];
        double d;
    } u;

    /*
     * Extract the exponent and check boundary conditions.
     * Notice that the exponent is equal to the bit number where
     * we want the most significant bit to live.
     */
    u.d = dval;
    i0 = u.i[0];
    i1 = u.i[1];

    exp = ((i0 >> 20) & 0x7ff) - 0x3ff;
    if (exp < 0) {
        return ((long long)0); /* abs(x) < 1.0, so round to 0 */
    } else if (exp > 62) {
        /*
         * fp_invalid NOT raised if <i0,i1> == LLONG_MIN
         */
        if (i0 >= 0 || exp != 63 || (i0 & 0xfffff) != 0 || i1 != 0) {
            /*
             * abs(x) > MAXLLONG; return {MIN,MAX}LLONG and as
             * overflow, Inf, NaN set fp_invalid exception
             */
            _fp_current_exceptions |= (1 << (int)fp_invalid);
            (void) _Q_set_exception(_fp_current_exceptions);
        }
        if (i0 < 0)
            return (LLONG_MIN);
        else
            return (LLONG_MAX); /* MAXLONG */
    }

    /* Extract the mantissa. */

    m0 = 0x40000000 | ((i0 << 10) & 0x3ffffc00) | ((i1 >> 22) & 0x3ff);
    m1 = i1 << 10;

    /*
     * The most significant bit of the mantissa is now in bit 62 of m0:m1.
     * Shift right by (62 - exp) bits.
     */
    switch (exp) {
    case 62:
        break;
    case 30:
        m1 = m0;
        m0 = 0;
        break;
    default:
        if (exp > 30) {
            m1 = (m0 << (exp - 30)) |
                (m1 >> (62 - exp)) & ~(-1 << (exp - 30));
            m0 >>= 62 - exp;
        } else {
            m1 = m0 >> (30 - exp);
            m0 = 0;
        }
        break;
    }

    if (i0 < 0) {
        m0 = ~m0;
        m1 = ~m1;
        if (++m1 == 0)
            m0++;
    }

    (void) _Q_set_exception(_fp_current_exceptions);
    return ((long long)(((unsigned long long)m0 << 32) | m1));
}

/*
 * Convert a floating point number into a 64-bit int.
 */
long long
__ftoll(float fval)
{
    int i0;
    int exp;        /* exponent */
    int m0;         /* most significant word of mantissa */
    unsigned int m1;    /* least sig. word of mantissa */
    unsigned int _fp_current_exceptions = 0;
    union {
        int i;
        float f;
    } u;

    /*
     * Extract the exponent and check boundary conditions.
     * Notice that the exponent is equal to the bit number where
     * we want the most significant bit to live.
     */
    u.f = fval;
    i0 = u.i;

    exp = ((i0 >> 23) & 0xff) - 0x7f;
    if (exp < 0) {
        return ((long long) 0); /* abs(x) < 1.0, so round to 0 */
    } else if (exp > 62)  {
        /*
         * fp_invalid NOT raised if <i0> == LLONG_MIN
         */
        if (i0 >= 0 || exp != 63 || (i0 & 0x7fffff) != 0) {
            /*
             * abs(x) > MAXLLONG; return {MIN,MAX}LLONG and as
             * overflow, Inf, NaN set fp_invalid exception
             */
            _fp_current_exceptions |= (1 << (int)fp_invalid);
            (void) _Q_set_exception(_fp_current_exceptions);
        }
        if (i0 < 0)
            return (LLONG_MIN);
        else
            return (LLONG_MAX); /* MAXLONG */
    }

    /* Extract the mantissa. */

    m0 = 0x40000000 | (i0 << 7) & 0x3fffff80;
    m1 = 0;

    /*
     * The most significant bit of the mantissa is now in bit 62 of m0:m1.
     * Shift right by (62 - exp) bits.
     */
    switch (exp) {
    case 62:
        break;
    case 30:
        m1 = m0;
        m0 = 0;
        break;
    default:
        if (exp > 30) {
            m1 = m0 << (exp - 30);
            m0 >>= 62 - exp;
        } else {
            m1 = m0 >> (30 - exp);
            m0 = 0;
        }
        break;
    }

    if (i0 < 0) {
        m0 = ~m0;
        m1 = ~m1;
        if (++m1 == 0)
            m0++;
    }

    (void) _Q_set_exception(_fp_current_exceptions);
    return ((long long)(((unsigned long long)m0 << 32) | m1));
}

/*
 * Convert an extended precision floating point number into a 64-bit int.
 */
long long
_Q_qtoll(long double longdbl)
{
    int i0;
    unsigned int i1, i2;    /* a long double is 128-bit in length */
    int *plngdbl = (int *)&longdbl;
    int exp;        /* exponent */
    int m0;         /* most significant word of mantissa */
    unsigned int m1;    /* least sig. word of mantissa */
    unsigned int _fp_current_exceptions = 0;

    /*
     * Only 96-bits of precision used
     */
    i0 = plngdbl[0];
    i1 = plngdbl[1];
    i2 = plngdbl[2];

    /*
     * Extract the exponent and check boundary conditions.
     * Notice that the exponent is equal to the bit number where
     * we want the most significant bit to live.
     */
    exp = ((i0 >> 16) & 0x7fff) - 0x3fff;
    if (exp < 0) {
        return ((long long)0); /* abs(x) < 1.0, so round to 0 */
    } else if (exp > 62)    {
        /*
         * fp_invalid NOT raised if <i0,i1,i2,i3> when chopped to
         * 64 bits == LLONG_MIN
         */
        if (i0 >= 0 || exp != 63 || (i0 & 0xffff) != 0 || i1 != 0 ||
            (i2 & 0xfffe0000) != 0) {
            /*
             * abs(x) > MAXLLONG; return {MIN,MAX}LLONG and as
             * overflow, Inf, NaN set fp_invalid exception
             */
            _fp_current_exceptions |= (1 << (int)fp_invalid);
            (void) _Q_set_exception(_fp_current_exceptions);
        }
        if (i0 < 0)
            return (LLONG_MIN);
        else
            return (LLONG_MAX); /* MAXLONG */
    }

    /* Extract the mantissa. */

    m0 = 0x40000000 | ((i0 << 14) & 0x3fffc000) | ((i1 >> 18) & 0x3fff);
    m1 = (i1 << 14) | ((i2 >> 18) & 0x3fff);

    /*
     * The most significant bit of the mantissa is now in bit 62 of m0:m1.
     * Shift right by (62 - exp) bits.
     */
    switch (exp) {
    case 62:
        break;
    case 30:
        m1 = m0;
        m0 = 0;
        break;
    default:
        if (exp > 30) {
            m1 = (m0 << (exp - 30)) |
                (m1 >> (62 - exp)) & ~(-1 << (exp - 30));
            m0 >>= 62 - exp;
        } else {
            m1 = m0 >> (30 - exp);
            m0 = 0;
        }
        break;
    }

    if (i0 < 0) {
        m0 = ~m0;
        m1 = ~m1;
        if (++m1 == 0)
            m0++;
    }

    (void) _Q_set_exception(_fp_current_exceptions);
    return ((long long)(((unsigned long long)m0 << 32) | m1));
}