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skrzyp |
//===========================================================================
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//
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// e_remainder.c
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//
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// Part of the standard mathematical function library
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//
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//===========================================================================
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// ####ECOSGPLCOPYRIGHTBEGIN####
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// -------------------------------------------
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// This file is part of eCos, the Embedded Configurable Operating System.
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// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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//
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// eCos is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 2 or (at your option) any later
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// version.
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//
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// eCos is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with eCos; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// As a special exception, if other files instantiate templates or use
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// macros or inline functions from this file, or you compile this file
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// and link it with other works to produce a work based on this file,
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// this file does not by itself cause the resulting work to be covered by
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// the GNU General Public License. However the source code for this file
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// must still be made available in accordance with section (3) of the GNU
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// General Public License v2.
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//
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// This exception does not invalidate any other reasons why a work based
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// on this file might be covered by the GNU General Public License.
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// -------------------------------------------
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// ####ECOSGPLCOPYRIGHTEND####
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//===========================================================================
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//#####DESCRIPTIONBEGIN####
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//
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// Author(s): jlarmour
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// Contributors: jlarmour
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// Date: 1998-02-13
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// Purpose:
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// Description:
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// Usage:
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//
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//####DESCRIPTIONEND####
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//
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//===========================================================================
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// CONFIGURATION
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#include <pkgconf/libm.h> // Configuration header
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// Include the Math library?
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#ifdef CYGPKG_LIBM
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// Derived from code with the following copyright
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/* @(#)e_remainder.c 1.3 95/01/18 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, 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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*/
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/* __ieee754_remainder(x,p)
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* Return :
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* returns x REM p = x - [x/p]*p as if in infinite
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* precise arithmetic, where [x/p] is the (infinite bit)
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* integer nearest x/p (in half way case choose the even one).
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* Method :
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* Based on fmod() return x-[x/p]chopped*p exactlp.
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*/
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#include "mathincl/fdlibm.h"
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static const double zero = 0.0;
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double __ieee754_remainder(double x, double p)
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{
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int hx,hp;
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unsigned sx,lx,lp;
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double p_half;
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hx = CYG_LIBM_HI(x); /* high word of x */
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lx = CYG_LIBM_LO(x); /* low word of x */
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hp = CYG_LIBM_HI(p); /* high word of p */
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lp = CYG_LIBM_LO(p); /* low word of p */
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sx = hx&0x80000000;
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hp &= 0x7fffffff;
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hx &= 0x7fffffff;
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/* purge off exception values */
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if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */
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if((hx>=0x7ff00000)|| /* x not finite */
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((hp>=0x7ff00000)&& /* p is NaN */
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(((hp-0x7ff00000)|lp)!=0)))
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return (x*p)/(x*p);
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if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */
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if (((hx-hp)|(lx-lp))==0) return zero*x;
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x = fabs(x);
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p = fabs(p);
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if (hp<0x00200000) {
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if(x+x>p) {
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x-=p;
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if(x+x>=p) x -= p;
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}
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} else {
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p_half = 0.5*p;
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if(x>p_half) {
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x-=p;
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if(x>=p_half) x -= p;
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}
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}
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CYG_LIBM_HI(x) ^= sx;
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return x;
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}
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#endif // ifdef CYGPKG_LIBM
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// EOF e_remainder.c
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