minix/lib/libc/quad/floatunditf_ieee754.c

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/* $NetBSD: floatunditf_ieee754.c,v 1.4 2012/08/05 04:28:58 matt 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)floatunsdidf.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: floatunditf_ieee754.c,v 1.4 2012/08/05 04:28:58 matt Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#ifdef SOFTFLOAT
#include "softfloat/softfloat-for-gcc.h"
#endif
#include "quad.h"
#ifdef __vax__
#error vax does not support a distinct long double
#endif
#include <machine/ieee.h>
/*
* Convert (unsigned) quad to long double.
* This is exactly like floatdidf.c except that negatives never occur.
*/
long double
__floatunditf(u_quad_t x)
{
#if 0
long double ld;
union uu u;
u.uq = x;
ld = (long double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0);
ld += u.ul[L];
return (ld);
#else
union ieee_ext_u extu;
quad_t tmp = x; /* must be signed */
unsigned int width = 64;
unsigned int bit = 0;
quad_t mask = ~(quad_t)0;
if (x == 0)
return 0.0L;
if (x == 1)
return 1.0L;
while (mask != 0 && (tmp >= 0)) {
width >>= 1;
mask <<= width;
if ((tmp & mask) == 0) {
tmp <<= width;
bit += width;
}
}
x <<= (bit + 1);
extu.extu_sign = 0;
extu.extu_exp = EXT_EXP_BIAS + (64 - (bit + 1));
extu.extu_frach = (unsigned int)(x >> (64 - EXT_FRACHBITS));
x <<= EXT_FRACHBITS;
#ifdef EXT_FRACHMBITS
extu.extu_frachm =(unsigned int)(x >> (64 - EXT_FRACHMBITS));
x <<= EXT_FRACHMBITS;
#endif
#ifdef EXT_FRACLMBITS
extu.extu_fraclm =(unsigned int)(x >> (64 - EXT_FRACLMBITS));
x <<= EXT_FRACLMBITS;
#endif
extu.extu_fracl =(unsigned int)(x >> (64 - EXT_FRACLBITS));
return extu.extu_ld;
#endif
}