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129 lines
4.0 KiB
C
129 lines
4.0 KiB
C
/*
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* $Id: math_llrint.c,v 1.1 2007-01-06 10:09:48 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) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
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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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/* Adding a double, x, to 2^52 will cause the result to be rounded based on
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the fractional part of x, according to the implementation's current rounding
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mode. 2^52 is the smallest double that can be represented using all 52 significant
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digits. */
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static const double TWO52[2]={
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4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
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-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
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};
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/****************************************************************************/
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long long int
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llrint(double x)
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{
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LONG i0,j0,sx;
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ULONG i1;
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double t;
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volatile double w;
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long long int result;
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EXTRACT_WORDS(i0,i1,x);
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/* Extract sign bit. */
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sx = (i0>>31)&1;
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/* Extract exponent field. */
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j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
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if(j0 < 20)
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{
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if(j0 < -1)
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return 0;
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else
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{
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w = TWO52[sx] + x;
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t = w - TWO52[sx];
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GET_HIGH_WORD(i0, t);
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/* Detect the all-zeros representation of plus and
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minus zero, which fails the calculation below. */
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if ((i0 & ~(1 << 31)) == 0)
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return 0;
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j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
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i0 &= 0x000fffff;
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i0 |= 0x00100000;
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result = i0 >> (20 - j0);
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}
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}
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else if (j0 < (int)(8 * sizeof (long long int)) - 1)
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{
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if (j0 >= 52)
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result = ((long long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) |
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(i1 << (j0 - 52));
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else
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{
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w = TWO52[sx] + x;
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t = w - TWO52[sx];
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EXTRACT_WORDS (i0, i1, t);
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j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
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i0 &= 0x000fffff;
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i0 |= 0x00100000;
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result = ((long long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
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}
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}
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else
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{
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return (long long int) x;
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}
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return sx ? -result : result;
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT */
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