73 lines
2.7 KiB
C
73 lines
2.7 KiB
C
/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Sean Eric Fagan.
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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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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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/*
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* ldexp(value, exp): return value * (2 ** exp).
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*
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* Written by Sean Eric Fagan (sef@kithrup.COM)
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* Sun Mar 11 20:27:09 PST 1990
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*/
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/*
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* We do the conversion in C to let gcc optimize it away, if possible.
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* The "fxch ; fstp" stuff is because value is still on the stack
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* (stupid 8087!).
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*/
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double
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ldexp (double value, int exp)
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{
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double temp, texp, temp2;
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texp = exp;
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#ifdef __GNUC__
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#if __GNUC__ >= 2
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asm ("fscale "
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: "=u" (temp2), "=t" (temp)
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: "0" (texp), "1" (value));
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#else
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asm ("fscale ; fxch %%st(1) ; fstp%L1 %1 "
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: "=f" (temp), "=0" (temp2)
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: "0" (texp), "f" (value));
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#endif
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#else
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error unknown asm
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#endif
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return (temp);
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}
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