/* $OpenBSD: fixunsdfdi.c,v 1.7 2005/08/08 08:05:35 espie Exp $ */
/*-
 * Copyright (c) 1992, 1993
 * The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "quad.h"

#define ONE_FOURTH  ((int) 1 << (INT_BITS - 2))
#define ONE_HALF    (ONE_FOURTH * 2.0)
#define ONE     (ONE_FOURTH * 4.0)

/*
 * Convert double to (unsigned) quad.
 * Not sure what to do with negative numbers---for now, anything out
 * of range becomes UQUAD_MAX.
 */
u_quad_t __fixunsdfdi(double x)
{
    union uu t;
    unsigned int tmp;

    if (x < 0) {
        return (UQUAD_MAX); /* ??? should be 0?  ERANGE??? */
    }

#ifdef notdef               /* this falls afoul of a GCC bug */
    if (x >= UQUAD_MAX) {
        return (UQUAD_MAX);
    }
#else                   /* so we wire in 2^64-1 instead */
    if (x >= 18446744073709551615.0) {   /* XXX */
        return (UQUAD_MAX);
    }
#endif

    /*
     * Now we know that 0 <= x <= 18446744073709549568.  The upper
     * limit is one ulp less than 18446744073709551615 tested for above.
     * Dividing this by 2^32 will *not* round irrespective of any
     * rounding modes (except if the result is an IEEE denorm).
     * Furthermore, the quotient will fit into a 32-bit integer.
     */
    tmp = x / ONE;
    t.ul[L] = (unsigned int) (x - tmp * ONE);
    t.ul[H] = tmp;
    return (t.uq);
}
