80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
/* Round double to integer away from zero.
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Copyright (C) 2011-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 2011.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* Based on a version which carries the following copyright: */
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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 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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*/
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#include <math.h>
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#include <math_private.h>
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#include <stdint.h>
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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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static const double huge = 1.0e300;
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double
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__floor (double x)
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{
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int64_t i0;
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EXTRACT_WORDS64(i0,x);
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int32_t j0 = ((i0>>52)&0x7ff)-0x3ff;
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if(__builtin_expect(j0<52, 1)) {
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if(j0<0) { /* raise inexact if x != 0 */
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math_force_eval(huge+x);/* return 0*sign(x) if |x|<1 */
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if(i0>=0) {i0=0;}
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else if((i0&0x7fffffffffffffffl)!=0)
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{ i0=0xbff0000000000000l;}
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} else {
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uint64_t i = (0x000fffffffffffffl)>>j0;
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if((i0&i)==0) return x; /* x is integral */
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math_force_eval(huge+x); /* raise inexact flag */
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if(i0<0) i0 += (0x0010000000000000l)>>j0;
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i0 &= (~i);
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}
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INSERT_WORDS64(x,i0);
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} else if (j0==0x400)
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return x+x; /* inf or NaN */
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return x;
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}
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#ifndef __floor
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weak_alias (__floor, floor)
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# ifdef NO_LONG_DOUBLE
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strong_alias (__floor, __floorl)
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weak_alias (__floor, floorl)
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# endif
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#endif
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