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/****************************************************************************
* Core Library Version 1.7, August 2004
* Copyright (c) 1995-2004 Exact Computation Project
* All rights reserved.
*
* This file is part of CGAL (www.cgal.org).
*
* File: extLong.cpp
* Synopsis:
* The class extLong is basically a wrapper around the machine
* type long. It is an important class to provide several
* additional facilities to detect overflows and undefined values.
* Future development includes extensions to level arithmetic
* (i.e., if a number overflows level i, we will go to level i+1).
* Level i representation of a number n is just i iterations
* of log_2 applied to n.
*
* Written by
* Chee Yap <yap@cs.nyu.edu>
* Chen Li <chenli@cs.nyu.edu>
* Zilin Du <zilin@cs.nyu.edu>
* Sylvain Pion <pion@cs.nyu.edu>
*
* WWW URL: https://cs.nyu.edu/exact/
* Email: exact@cs.nyu.edu
*
* $URL: https://github.com/CGAL/cgal/blob/v6.1.1/CGAL_Core/include/CGAL/CORE/extLong_impl.h $
* $Id: include/CGAL/CORE/extLong_impl.h 08b27d3db14 $
* SPDX-License-Identifier: LGPL-3.0-or-later
***************************************************************************/
#ifdef CGAL_HEADER_ONLY
#define CGAL_INLINE_FUNCTION inline
#else
#define CGAL_INLINE_FUNCTION
#endif
#include <CGAL/CORE/extLong.h>
namespace CORE {
CGAL_INLINE_FUNCTION
const extLong& extLong::getNaNLong() {
static const extLong NaNLong(true);
return NaNLong;
}
CGAL_INLINE_FUNCTION
const extLong& extLong::getPosInfty() {
static const extLong posInfty(EXTLONG_MAX);
return posInfty;
}
CGAL_INLINE_FUNCTION
const extLong& extLong::getNegInfty() {
static const extLong negInfty(EXTLONG_MIN);
return negInfty;
}
CGAL_INLINE_FUNCTION
void extLong::add(extLong& z, long x, long y) {
if (x > 0 && y > 0 && x >= EXTLONG_MAX - y) {
z.val = EXTLONG_MAX;
z.flag = 1;
} else if (x < 0 && y < 0 && x <= EXTLONG_MIN - y) {
z.val = EXTLONG_MIN;
z.flag = -1;
} else {
z.val = x + y;
z.flag = 0;
}
}
// arithmetic and assignment operators
CGAL_INLINE_FUNCTION
extLong& extLong::operator+= (const extLong& y) {
if (flag == 2 || y.flag == 2 || (flag * y.flag < 0)) {
#ifdef CORE_DEBUG
if (flag * y.flag < 0) //want a message at the first creation of NaN
CGAL_CORE_warning_msg(false, "extLong NaN Error in addition.");
#endif
*this = CORE_NaNLong;
} else if (flag == 1 || y.flag == 1) { // one of them is +Inf
*this = CORE_posInfty;
} else if (flag == -1 || y.flag == -1) { // one of them is -Inf
*this = CORE_negInfty;
} else { // x and y are normal now
add(*this, val, y.val);
}
return *this;
}
CGAL_INLINE_FUNCTION
extLong& extLong::operator-= (const extLong& y) {
if (flag == 2 || y.flag == 2 || (flag * y.flag > 0)) {
#ifdef CORE_DEBUG
if (flag * y.flag > 0) //want a message at the first creation of NaN
CGAL_CORE_warning_msg(false, "extLong NaN Error in subtraction.");
#endif
*this = CORE_NaNLong;
} else if (flag == 1 || y.flag == -1) {
*this = CORE_posInfty;
} else if (flag == -1 || y.flag == 1) {
*this = CORE_negInfty;
} else {
add(*this, val, -y.val);
}
return *this;
}
CGAL_INLINE_FUNCTION
extLong& extLong::operator*= (const extLong& y) {
if (flag == 2 || y.flag == 2) {
*this = CORE_NaNLong;
} else if ((flag != 0) || (y.flag != 0)) {
if (sign() * y.sign() > 0)
*this = CORE_posInfty;
else
*this = CORE_negInfty;
} else { // flag == 0 and y.flag == 0
double d = double(val) * double(y.val);
long p = val * y.val;
if (std::fabs(d - p) <= std::fabs(d) * relEps) {
val = p;
flag = 0;
} else if (d > static_cast<double>(EXTLONG_MAX)) {
*this = CORE_posInfty;
} else if (d < static_cast<double>(EXTLONG_MIN)) {
*this = CORE_negInfty;
} else {
#ifdef CORE_DEBUG
CGAL_CORE_warning_msg(false, "extLong NaN Error in multiplication.");
#endif
*this = CORE_NaNLong;
}
}
return *this;
}
CGAL_INLINE_FUNCTION
extLong& extLong::operator/= (const extLong& y) {
if (flag==2 || y.flag==2 || ((flag != 0) && (y.flag != 0)) || (y.val == 0)) {
#ifdef CORE_DEBUG
if (y.val == 0)
CGAL_CORE_warning_msg(false, "extLong NaN Error, Divide by Zero.");
else if ((flag !=0) && (y.flag !=0))
CGAL_CORE_warning_msg(false, "extLong NaN Error, +/-Inf/Inf.");
#endif
*this = CORE_NaNLong;
} else if ((flag != 0) || (y.flag != 0)) { // y.flag == 0 now and y != 0
if (sign() * y.sign() > 0)
*this = CORE_posInfty;
else
*this = CORE_negInfty;
} else { // flag == 0 and y.flag == 0
val /= y.val; // no overflow in divisions
flag = 0;
}
return *this;
}
// unary minus
CGAL_INLINE_FUNCTION
extLong extLong::operator- () const {
if (flag == 0)
return extLong(-val);
else if (flag == 1)
return CORE_negInfty;
else if (flag == -1)
return CORE_posInfty;
else // NaN
return CORE_NaNLong;
}
// sign
// You should check "flag" before calling this, otherwise
// you cannot interpret the returned value!
CGAL_INLINE_FUNCTION
int extLong::sign() const {
CGAL_CORE_warning_msg(flag != 2, "NaN Sign can not be determined!");
return ((val == 0) ? 0 : ((val > 0) ? 1 : -1));
}
// stream operators
CGAL_INLINE_FUNCTION
std::ostream& operator<< (std::ostream& o, const extLong& x) {
if (x.flag == 1)
o << " infty ";
else if (x.flag == - 1)
o << " tiny ";
else if (x.flag == 2)
o << " NaN ";
else
o << x.val;
return o;
}
} //namespace CORE
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