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to doubles as bits. fdlibm-1.1 had similar aliasing bugs, but these were fixed by NetBSD or Cygnus before a modified version of fdlibm was imported in 1994. TRUNC() is only used by tgamma() and some implementation-detail functions. The aliasing bugs were detected by compiling with gcc -O2 but don't seem to have broken tgamma() on i386's or amd64's. They broke my modified version of tgamma(). Moved the definition of TRUNC() to mathimpl.h so that it can be fixed in one place, although the general version is even slower than necessary because it has to operate on pointers to volatiles to handle its arg sometimes being volatile. Inefficiency of the fdlibm macros slows down libm generally, and tgamma() is a relatively unimportant part of libm. The macros act as if on 32-bit words in memory, so they are hard to optimize to direct actions on 64-bit double registers for (non-i386) machines where this is possible. The optimization is too hard for gcc on amd64's, and declaring variables as volatile makes it impossible.
73 lines
2.7 KiB
C
73 lines
2.7 KiB
C
/*
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* Copyright (c) 1988, 1993
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* The Regents of the University of California. 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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* 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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* @(#)mathimpl.h 8.1 (Berkeley) 6/4/93
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* $FreeBSD$
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*/
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#ifndef _MATHIMPL_H_
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#define _MATHIMPL_H_
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#include <sys/cdefs.h>
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#include <math.h>
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#include "../src/math_private.h"
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/*
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* TRUNC() is a macro that sets the trailing 27 bits in the mantissa of an
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* IEEE double variable to zero. It must be expression-like for syntactic
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* reasons, and we implement this expression using an inline function
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* instead of a pure macro to avoid depending on the gcc feature of
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* statement-expressions.
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*/
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#define TRUNC(d) (_b_trunc(&(d)))
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static __inline void
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_b_trunc(volatile double *_dp)
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{
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uint32_t _lw;
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GET_LOW_WORD(_lw, *_dp);
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SET_LOW_WORD(*_dp, _lw & 0xf8000000);
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}
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/*
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* Functions internal to the math package, yet not static.
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*/
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extern double __exp__E();
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struct Double {double a, b;};
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double __exp__D(double, double);
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struct Double __log__D(double);
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#endif /* !_MATHIMPL_H_ */
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