/*
 * 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 (c) 1994-1997, by Sun Microsystems, Inc.
 * All rights reserved.
 */

#include "quad.h"

#ifdef __sparcv9
#define _Q_qtod _Qp_qtod
#endif

/*
 * _Q_qtod(x) returns (double)*x.
 */
double
_Q_qtod(const union longdouble *x)
{
        union xdouble   u;
        unsigned int    xm, round, sticky, fsr, rm;
        int             subnormal, e;

        xm = x->l.msw & 0x7fffffff;

        /* get the rounding mode, fudging directed rounding modes */
        /* as though the result were positive */
        __quad_getfsrp(&fsr);
        rm = fsr >> 30;
        if (x->l.msw & 0x80000000)
                rm ^= (rm >> 1);

        /* handle nan, inf, and out-of-range cases */
        if (xm >= 0x43ff0000) {
                if (xm >= 0x7fff0000) {
                        if ((xm & 0xffff) | x->l.frac2 | x->l.frac3 |
                            x->l.frac4) {
                                /* x is nan */
                                u.l.hi = (x->l.msw & 0x80000000) | 0x7ff80000;
                                u.l.hi |= ((xm & 0x7fff) << 4) |
                                    (x->l.frac2 >> 28);
                                u.l.lo = (x->l.frac2 << 4) |
                                    (x->l.frac3 >> 28);
                                if (!(xm & 0x8000)) {
                                        /* snan, signal invalid */
                                        if (fsr & FSR_NVM) {
                                                __quad_fqtod(x, &u.d);
                                        } else {
                                                fsr = (fsr & ~FSR_CEXC) |
                                                    FSR_NVA | FSR_NVC;
                                                __quad_setfsrp(&fsr);
                                        }
                                }
                                return (u.d);
                        }
                        /* x is inf */
                        u.l.hi = (x->l.msw & 0x80000000) | 0x7ff00000;
                        u.l.lo = 0;
                        return (u.d);
                }
                /* x is too big, overflow */
                if (rm == FSR_RN || rm == FSR_RP) {
                        u.l.hi = 0x7ff00000;
                        u.l.lo = 0;
                } else {
                        u.l.hi = 0x7fefffff;
                        u.l.lo = 0xffffffff;
                }
                u.l.hi |= (x->l.msw & 0x80000000);
                if (fsr & (FSR_OFM | FSR_NXM)) {
                        __quad_fqtod(x, &u.d);
                } else {
                        fsr = (fsr & ~FSR_CEXC) | FSR_OFA | FSR_OFC |
                            FSR_NXA | FSR_NXC;
                        __quad_setfsrp(&fsr);
                }
                return (u.d);
        }

        subnormal = 0;
        if (xm < 0x3c010000) {
                if (xm < 0x3bcc0000) {
                        if (QUAD_ISZERO(*x)) {
                                u.l.hi = (x->l.msw & 0x80000000);
                                u.l.lo = 0;
                                return (u.d);
                        }
                        /* x is too small, underflow */
                        u.l.hi = (x->l.msw & 0x80000000);
                        u.l.lo = ((rm == FSR_RP)? 1 : 0);
                        if (fsr & (FSR_UFM | FSR_NXM)) {
                                __quad_fqtod(x, &u.d);
                        } else {
                                fsr = (fsr & ~FSR_CEXC) | FSR_UFA | FSR_UFC |
                                    FSR_NXA | FSR_NXC;
                                __quad_setfsrp(&fsr);
                        }
                        return (u.d);
                }

                /* x is in the subnormal range for double */
                subnormal = 1;
                u.l.hi = 0x80000 | ((xm & 0xffff) << 3) | (x->l.frac2 >> 29);
                u.l.lo = (x->l.frac2 << 3) | (x->l.frac3 >> 29);
                round = x->l.frac3 & 0x10000000;
                sticky = (x->l.frac3 & 0xfffffff) | x->l.frac4;
                e = 0x3c00 - (xm >> 16);
                if (e >= 32) {
                        sticky |= round | (u.l.lo & 0x7fffffff);
                        round = u.l.lo & 0x80000000;
                        u.l.lo = u.l.hi;
                        u.l.hi = 0;
                        e -= 32;
                }
                if (e) {
                        sticky |= round | (u.l.lo & ((1 << (e - 1)) - 1));
                        round = u.l.lo & (1 << (e - 1));
                        u.l.lo = (u.l.lo >> e) | (u.l.hi << (32 - e));
                        u.l.hi >>= e;
                }
        } else {
                /* x is in the normal range for double */
                u.l.hi = ((xm - 0x3c000000) << 4) | (x->l.frac2 >> 28);
                u.l.lo = (x->l.frac2 << 4) | (x->l.frac3 >> 28);
                round = x->l.frac3 & 0x8000000;
                sticky = (x->l.frac3 & 0x7ffffff) | x->l.frac4;
        }

        /* see if we need to round */
        fsr &= ~FSR_CEXC;
        if (round | sticky) {
                fsr |= FSR_NXC;
                if (subnormal)
                        fsr |= FSR_UFC;

                /* round up if necessary */
                if (rm == FSR_RP || (rm == FSR_RN && round && (sticky ||
                    (u.l.lo & 1)))) {
                        /* round up and check for overflow */
                        if (++u.l.lo == 0)
                                if (++u.l.hi >= 0x7ff00000)
                                        fsr |= FSR_OFC;
                }
        }

        /* if result is exact and subnormal but underflow trapping is */
        /* enabled, signal underflow */
        else if (subnormal && (fsr & FSR_UFM))
                fsr |= FSR_UFC;

        /* attach the sign and raise exceptions as need be */
        u.l.hi |= (x->l.msw & 0x80000000);
        if ((fsr & FSR_CEXC) & (fsr >> 23)) {
                __quad_setfsrp(&fsr);
                __quad_fqtod(x, &u.d);
        } else {
                fsr |= (fsr & 0x1f) << 5;
                __quad_setfsrp(&fsr);
        }
        return (u.d);
}