82 lines
2.5 KiB
C
82 lines
2.5 KiB
C
/* $NetBSD: floatunditf_ieee754.c,v 1.1 2014/01/30 15:06:18 joerg Exp $ */
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/*-
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* Copyright (c) 2014 Joerg Sonnenberger <joerg@NetBSD.org>.
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* All rights reserved.
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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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*
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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
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* 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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__RCSID("$NetBSD: floatunditf_ieee754.c,v 1.1 2014/01/30 15:06:18 joerg Exp $");
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#include <math.h>
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#include <machine/ieee.h>
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#include <limits.h>
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#ifdef __HAVE_LONG_DOUBLE
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long double __floatunditf(uint64_t x);
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/*
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* Convert uint64_t to long double.
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*/
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long double
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__floatunditf(uint64_t x)
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{
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int exponent, zeros;
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union ieee_ext_u ux;
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/* Use the easier conversion routine for uint32_t if possible. */
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if (x <= UINT32_MAX)
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return (long double)(uint32_t)x;
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zeros = __builtin_clzll(x);
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#ifdef LDBL_IMPLICIT_NBIT
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exponent = 64 - zeros;
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x <<= zeros + 1;
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#else
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exponent = 63 - zeros;
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x <<= zeros;
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#endif
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ux.extu_exp = EXT_EXP_BIAS + exponent;
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ux.extu_frach = (x >> (64 - EXT_FRACHBITS));
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x <<= EXT_FRACHBITS;
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#ifdef EXT_FRACHMBITS
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ux.extu_frachm = (x >> (64 - EXT_FRACHMBITS));
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x <<= EXT_FRACHMBITS;
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#endif
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#ifdef EXT_FRACLMBITS
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ux.extu_fraclm = (x >> (64 - EXT_FRACLMBITS));
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x <<= EXT_FRACLMBITS;
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#endif
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ux.extu_fracl = (x >> (64 - EXT_FRACLBITS));
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ux.extu_sign = 0;
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return ux.extu_ld;
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}
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#endif /* __HAVE_LONG_DOUBLE */
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