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91 lines
3 KiB
C
91 lines
3 KiB
C
/*
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* Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code 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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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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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 "fdlibm.h"
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#ifdef __STDC__
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static const double huge = 1.0e300;
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#else
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static double huge = 1.0e300;
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#endif
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#ifdef __STDC__
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double floor(double x)
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#else
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double floor(x)
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double x;
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#endif
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{
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int i0,i1,j0;
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unsigned i,j;
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i0 = __HI(x);
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i1 = __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<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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__HI(x) = i0;
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__LO(x) = i1;
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return x;
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}
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