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git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14685 87f5fb63-7c3d-0410-a384-fd976d0f7a62
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Olaf Barthel
175
library/math_ldexp.c
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175
library/math_ldexp.c
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/*
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* $Id: math_ldexp.c,v 1.1.1.1 2004-07-26 16:30:48 obarthel Exp $
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*
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* :ts=4
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*
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* Portable ISO 'C' (1994) runtime library for the Amiga computer
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* Copyright (c) 2002-2004 by Olaf Barthel <olsen@sourcery.han.de>
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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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* - 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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*
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* - Neither the name of Olaf Barthel nor the names of contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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*
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* PowerPC math library based in part on work by Sun Microsystems
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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*/
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#ifndef _MATH_HEADERS_H
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#include "math_headers.h"
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#endif /* _MATH_HEADERS_H */
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/****************************************************************************/
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#if defined(FLOATING_POINT_SUPPORT)
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/****************************************************************************/
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#if defined(IEEE_FLOATING_POINT_SUPPORT)
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#define MANT_MASK 0x800FFFFF /* Mantissa extraction mask */
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#define ZPOS_MASK 0x3FF00000 /* Positive # mask for exp = 0 */
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#define ZNEG_MASK 0x3FF00000 /* Negative # mask for exp = 0 */
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#define EXP_MASK 0x7FF00000 /* Mask for exponent */
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#define EXP_SHIFTS 20 /* Shifts to get into LSB's */
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#define EXP_BIAS 1023 /* Exponent bias */
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union dtol
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{
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double dval;
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long ival[2];
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};
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INLINE static const double
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__ldexp(double x,int n)
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{
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union dtol number;
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long *iptr, cn;
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number.dval = x;
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iptr = &number.ival[0];
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cn = (((*iptr) & EXP_MASK) >> EXP_SHIFTS) - EXP_BIAS;
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(*iptr) &= ~EXP_MASK;
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n += EXP_BIAS;
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/* ZZZ we can't just muck with the exponent, we
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* have to check for underflow and overflow, too!
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*/
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(*iptr) |= ((n + cn) << EXP_SHIFTS) & EXP_MASK;
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return(number.dval);
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}
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#endif /* IEEE_FLOATING_POINT_SUPPORT */
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/****************************************************************************/
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#if defined(M68881_FLOATING_POINT_SUPPORT)
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INLINE static const double
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__ldexp(double x,int n)
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{
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double result;
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__asm ("fscale%.l %2,%0"
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: "=f" (result)
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: "0" (x),
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"dmi" (n));
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return(result);
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}
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#endif /* M68881_FLOATING_POINT_SUPPORT */
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/****************************************************************************/
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#if defined(PPC_FLOATING_POINT_SUPPORT)
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#define MANT_MASK 0x800FFFFF /* Mantissa extraction mask */
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#define ZPOS_MASK 0x3FF00000 /* Positive # mask for exp = 0 */
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#define ZNEG_MASK 0x3FF00000 /* Negative # mask for exp = 0 */
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#define EXP_MASK 0x7FF00000 /* Mask for exponent */
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#define EXP_SHIFTS 20 /* Shifts to get into LSB's */
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#define EXP_BIAS 1023 /* Exponent bias */
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union dtol
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{
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double dval;
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long ival[2];
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};
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INLINE static const double
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__ldexp(double x,int n)
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{
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union dtol number;
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long *iptr, cn;
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number.dval = x;
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iptr = &number.ival[0];
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cn = (((*iptr) & EXP_MASK) >> EXP_SHIFTS) - EXP_BIAS;
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(*iptr) &= ~EXP_MASK;
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n += EXP_BIAS;
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/* ZZZ we can't just muck with the exponent, we
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* have to check for underflow and overflow, too!
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*/
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(*iptr) |= ((n + cn) << EXP_SHIFTS) & EXP_MASK;
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return(number.dval);
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}
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#endif /* PPC_FLOATING_POINT_SUPPORT */
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/****************************************************************************/
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double
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ldexp(double x,int n)
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{
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double result;
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if(x != 0.0)
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result = __ldexp(x,n);
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else
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result = 0.0;
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return(result);
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT */
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