f14fb60209
* Updating common/lib * Updating lib/csu * Updating lib/libc * Updating libexec/ld.elf_so * Corrected test on __minix in featuretest to actually follow the meaning of the comment. * Cleaned up _REENTRANT-related defintions. * Disabled -D_REENTRANT for libfetch * Removing some unneeded __NBSD_LIBC defines and tests Change-Id: Ic1394baef74d11b9f86b312f5ff4bbc3cbf72ce2
112 lines
3.7 KiB
C
112 lines
3.7 KiB
C
/* $NetBSD: fixunsgen_ieee754.c,v 1.3 2012/03/25 19:53:41 christos 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. 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(FIXUNSNAME) && defined(LIBC_SCCS) && !defined(lint)
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__RCSID("$NetBSD: fixunsgen_ieee754.c,v 1.3 2012/03/25 19:53:41 christos Exp $");
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#endif /* LIBC_SCCS and not lint */
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#include <stddef.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <float.h>
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#ifndef FIXUNSNAME
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#define FIXUNSNAME(n) n##32
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#define UINTXX_T uint32_t
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#endif
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__dso_hidden UINTXX_T
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FIXUNSNAME(__fixunsgen)(int, bool, size_t, size_t, const uint32_t *);
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/*
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* Convert double to (unsigned) int. All operations are done module 2^32.
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*/
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UINTXX_T
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FIXUNSNAME(__fixunsgen)(int exp, bool sign, size_t mant_dig, size_t fracbits,
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const uint32_t *frac)
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{
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UINTXX_T tmp;
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/*
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* If it's less than 1 (negative exponent), it's going to round
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* to zero. If the exponent is so large that it is a multiple of
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* 2^N, then x module 2^N will be 0. (we use the fact treating a
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* negative value as unsigned will be greater than nonnegative value)
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*/
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if (__predict_false((size_t)exp >= mant_dig + sizeof(UINTXX_T)*8))
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return 0;
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/*
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* This is simplier than it seems. Basically we are constructing
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* fixed binary representation of the floating point number tossing
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* away bits that wont be in the modulis we return.
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*/
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tmp = 1;
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for (size_t ebits = exp;;) {
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if (ebits <= fracbits) {
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/*
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* The current fraction has more bits than we need.
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* Shift the current value over and insert the bits
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* we want. We're done.
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*/
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tmp <<= (unsigned int)ebits;
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tmp |= *frac >> (fracbits - ebits);
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break;
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}
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if (fracbits == sizeof(tmp)*4) {
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/*
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* Shifts must be < sizeof(type). If it's going to be
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* sizeof(type), just replace the value.
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*/
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tmp = *frac--;
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} else {
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tmp <<= (unsigned int)fracbits;
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tmp |= *frac--;
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}
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ebits -= fracbits;
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fracbits = sizeof(frac[0]) * 4;
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}
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/*
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* If the input was negative, make tmp negative module 2^32.
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*/
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if (sign)
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tmp = -tmp;
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return tmp;
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}
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