mirror of https://gitlab.com/rnger/amath
112 lines
3.6 KiB
C
112 lines
3.6 KiB
C
/*-
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* Copyright (c) 2014-2017 Carsten Sonne Larsen <cs@innolan.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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* 1. 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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Project homepage:
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* https://amath.innolan.net
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*
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* The original source code can be obtained from:
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* http://www.netlib.org/fdlibm/s_ceil.c
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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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* @file ceil.c
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* @brief Ceiling function
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*/
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#include "prim.h"
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static const double huge = 1.0e300;
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/**
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* @brief Ceiling function
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* @param x
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* @returns x rounded toward -inf to integral value
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* @details
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* <pre>
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* Method
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* Bit twiddling
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*
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* Exception
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* Inexact flag raised if x not equal to ceil(x).
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* </pre>
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*/
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double ceil(double x)
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{
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int32_t i0,i1,j0;
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uint32_t i,j;
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EXTRACT_WORDS(i0,i1,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) {
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i0=0x80000000;
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i1=0;
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}
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else if((i0|i1)!=0) {
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i0=0x3ff00000;
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i1=0;
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}
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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);
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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 = ((uint32_t)(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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// NOTICE: Is this a correct cast?
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if((int32_t)j<(int32_t)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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INSERT_WORDS(x,i0,i1);
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return x;
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}
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