port/fp/_base_sup.c

	_base_sup.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#include "synonyms.h"
#include <sys/types.h>
#include "base_conversion.h"
#include <sys/isa_defs.h>

/*
 * Miscellaneous support routines used in base conversion
 */

static const union {
    unsigned int    u[2];
    double      d;
} C[] = {
#ifdef _LITTLE_ENDIAN
    { 0x00000000u, 0x00100000u },
    { 0x00000001u, 0x7ff00000u }
#else
    { 0x00100000u, 0x00000000u },
    { 0x7ff00000u, 0x00000001u }
#endif
};

#define minnormal   C[0].d
#define signalingnan    C[1].d

/* raise the floating point exceptions indicated by ef */
void
__base_conversion_set_exception(fp_exception_field_type ef)
{
    double  t;
    volatile double tstored;

    if (ef == (1 << fp_inexact)) {
        t = 9.999999962747097015E-1;
        /*
         * 28 sig bits so product isn't inexact in extended
         * accumulator, causing two inexact traps.
         */
    } else if ((ef & (1 << fp_invalid)) != 0) {
        t = signalingnan;
    } else if ((ef & (1 << fp_overflow)) != 0) {
        t = 4.149515553422842866E+180;
        /*
         * 28 sig bits so product isn't inexact in extended
         * accumulator, causing inexact trap prior to overflow trap
         * on store.
         */
    } else if ((ef & (1 << fp_underflow)) != 0) {
        t = minnormal;
    } else
        return;

    /* Storage forces exception */
    tstored = t * t;
#if defined(__lint)
    tstored = tstored;
#endif
}

/*
 * The following routine is no longer used in libc, but we have
 * to leave it for now because it's still used by Sun's old Fortran
 * runtime libraries.  Today this is a bug; in the days of SunOS 4.x,
 * when the relevant design decisions were made, it was a feature.
 */
enum fp_class_type
__class_quadruple(quadruple *x)
{
    quadruple_equivalence kluge;

    kluge.x = *x;
    if (kluge.f.msw.exponent == 0) {    /* 0 or sub */
        if ((kluge.f.msw.significand == 0) &&
            (kluge.f.significand2 == 0) &&
            (kluge.f.significand3 == 0) &&
            (kluge.f.significand4 == 0))
            return (fp_zero);
        else
            return (fp_subnormal);
    } else if (kluge.f.msw.exponent == 0x7fff) {    /* inf or nan */
        if ((kluge.f.msw.significand == 0) &&
            (kluge.f.significand2 == 0) &&
            (kluge.f.significand3 == 0) &&
            (kluge.f.significand4 == 0))
            return (fp_infinity);
        else if ((kluge.f.msw.significand & 0xffff) >=
                (unsigned int)0x8000)
            return (fp_quiet);
        else
            return (fp_signaling);
    } else
        return (fp_normal);
}