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/* $OpenBSD: fixunssfdi.c,v 1.5 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 float to (unsigned) quad. We do most of our work in double,
* out of sheer paranoia.
*
* Not sure what to do with negative numbers---for now, anything out
* of range becomes UQUAD_MAX.
*
* N.B.: must use new ANSI syntax (sorry).
*/
u_quad_t __fixunssfdi(float f)
{
double x, toppart;
union uu t;
if (f < 0) {
return (UQUAD_MAX); /* ??? should be 0? ERANGE??? */
}
#ifdef notdef /* this falls afoul of a GCC bug */
if (f >= UQUAD_MAX) {
return UQUAD_MAX;
}
#else /* so we wire in 2^64-1 instead */
if (f >= 18446744073709551615.0) { /* XXX */
return (UQUAD_MAX);
}
#endif
x = f;
/*
* Get the upper part of the result. Note that the divide
* may round up; we want to avoid this if possible, so we
* subtract `1/2' first.
*/
toppart = (x - ONE_HALF) / ONE;
/*
* Now build a u_quad_t out of the top part. The difference
* between x and this is the bottom part (this may introduce
* a few fuzzy bits, but what the heck). With any luck this
* difference will be nonnegative: x should wind up in the
* range [0..UINT_MAX]. For paranoia, we assume [INT_MIN..
* 2*UINT_MAX] instead.
*/
t.ul[H] = (unsigned int) toppart;
t.ul[L] = 0;
x -= (double) t.uq;
if (x < 0) {
t.ul[H]--;
x += UINT_MAX;
}
if (x > UINT_MAX) {
t.ul[H]++;
x -= UINT_MAX;
}
t.ul[L] = (u_int)x;
return t.uq;
}
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