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skrzyp |
//===========================================================================
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//
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// s_floor.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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/* @(#)s_floor.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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/*
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* floor(x)
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* Return x rounded toward -inf to integral value
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* Method:
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* Bit twiddling.
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* Exception:
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* Inexact flag raised if x not equal to floor(x).
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*/
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#include "mathincl/fdlibm.h"
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static const double huge = 1.0e300;
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double floor(double x)
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{
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int i0,i1,j0;
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unsigned i,j;
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i0 = CYG_LIBM_HI(x);
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i1 = CYG_LIBM_LO(x);
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j0 = ((i0>>20)&0x7ff)-0x3ff;
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if(j0<20) {
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if(j0<0) { /* raise inexact if x != 0 */
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if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
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if(i0>=0) {i0=i1=0;}
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else if(((i0&0x7fffffff)|i1)!=0)
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{ i0=0xbff00000;i1=0;}
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}
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} else {
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i = (0x000fffff)>>j0;
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if(((i0&i)|i1)==0) return x; /* x is integral */
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if(huge+x>0.0) { /* raise inexact flag */
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if(i0<0) i0 += (0x00100000)>>j0;
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i0 &= (~i); i1=0;
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}
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}
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} else if (j0>51) {
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if(j0==0x400) return x+x; /* inf or NaN */
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else return x; /* x is integral */
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} else {
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i = ((unsigned)(0xffffffff))>>(j0-20);
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if((i1&i)==0) return x; /* x is integral */
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if(huge+x>0.0) { /* raise inexact flag */
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if(i0<0) {
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if(j0==20) i0+=1;
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else {
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j = i1+(1<<(52-j0));
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if(j<(unsigned)i1) i0 +=1 ; /* got a carry */
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i1=j;
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}
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}
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i1 &= (~i);
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}
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}
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CYG_LIBM_HI(x) = i0;
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CYG_LIBM_LO(x) = i1;
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return x;
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}
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#endif // ifdef CYGPKG_LIBM
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// EOF s_floor.c
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