108 lines
3.7 KiB
C
108 lines
3.7 KiB
C
/* $NetBSD: fixunssfdi.c,v 1.5 2002/10/20 10:15:47 scw Exp $ */
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/*-
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This software was developed by the Computer Systems Engineering group
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* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
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* contributed to Berkeley.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)fixunssfdi.c 8.1 (Berkeley) 6/4/93";
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#else
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__RCSID("$NetBSD: fixunssfdi.c,v 1.5 2002/10/20 10:15:47 scw Exp $");
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#endif
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#endif /* LIBC_SCCS and not lint */
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#include "quad.h"
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#define ONE_FOURTH ((int)1 << (INT_BITS - 2))
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#define ONE_HALF (ONE_FOURTH * 2.0)
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#define ONE (ONE_FOURTH * 4.0)
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/*
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* Convert float to (unsigned) quad. We do most of our work in double,
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* out of sheer paranoia.
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*
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* Not sure what to do with negative numbers---for now, anything out
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* of range becomes UQUAD_MAX.
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*
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* N.B.: must use new ANSI syntax (sorry).
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*/
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u_quad_t
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__fixunssfdi(float f)
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{
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double x, toppart;
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union uu t;
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if (f < 0)
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return (UQUAD_MAX); /* ??? should be 0? ERANGE??? */
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#ifdef notdef /* this falls afoul of a GCC bug */
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if (f >= UQUAD_MAX)
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return (UQUAD_MAX);
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#else /* so we wire in 2^64-1 instead */
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if (f >= 18446744073709551615.0) /* XXX */
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return (UQUAD_MAX);
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#endif
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x = f;
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/*
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* Get the upper part of the result. Note that the divide
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* may round up; we want to avoid this if possible, so we
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* subtract `1/2' first.
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*/
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toppart = (x - ONE_HALF) / ONE;
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/*
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* Now build a u_quad_t out of the top part. The difference
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* between x and this is the bottom part (this may introduce
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* a few fuzzy bits, but what the heck). With any luck this
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* difference will be nonnegative: x should wind up in the
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* range [0..UINT_MAX]. For paranoia, we assume [INT_MIN..
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* 2*UINT_MAX] instead.
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*/
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t.ul[H] = (unsigned int)toppart;
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t.ul[L] = 0;
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x -= (double)t.uq;
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if (x < 0) {
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t.ul[H]--;
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x += UINT_MAX;
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}
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if (x > UINT_MAX) {
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t.ul[H]++;
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x -= UINT_MAX;
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}
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t.ul[L] = (u_int)x;
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return (t.uq);
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}
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