/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2006 INRIA
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation;
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
*/
#ifndef HIGH_PRECISION_CAIRO_H
#define HIGH_PRECISION_CAIRO_H
#include <stdint.h>
#include <math.h>
#include <iostream>
#include "cairo-wideint-private.h"
/**
* This file contains an implementation of the HighPrecision class.
* Each instance of the Time class also contains an instance of this
* class which is used to perform all the arithmetic operations of
* the Time class.
*
* This code is a bit ugly with a lot of inline methods for speed:
* profiling this code on anything but the simplest scenarios shows
* that it is a big bottleneck if great care in its implementation
* is not performed. My observations are that what dominates are
* Division operations (there are really really super costly)
* and Comparison operations (because there are typically a lot of
* these in any complex timekeeping code).
*/
namespace ns3 {
class HighPrecision
{
public:
inline HighPrecision ();
explicit inline HighPrecision (int64_t value, bool dummy);
explicit inline HighPrecision (double value);
inline int64_t GetInteger (void) const;
inline double GetDouble (void) const;
inline void Add (HighPrecision const &o);
inline void Sub (HighPrecision const &o);
void Mul (HighPrecision const &o);
void Div (HighPrecision const &o);
void MulByInvert (const HighPrecision &o);
static HighPrecision Invert (uint64_t v);
inline int Compare (HighPrecision const &o) const;
inline static HighPrecision Zero (void);
int64_t GetHigh (void) const;
uint64_t GetLow (void) const;
private:
static cairo_uint128_t Umul (cairo_uint128_t a, cairo_uint128_t b);
static cairo_uint128_t Udiv (cairo_uint128_t a, cairo_uint128_t b);
static cairo_uint128_t UmulByInvert (cairo_uint128_t a, cairo_uint128_t b);
inline bool IsNegative (void) const;
cairo_int128_t m_value;
};
std::ostream &operator << (std::ostream &os, const HighPrecision &hp);
std::istream &operator >> (std::istream &is, HighPrecision &hp);
} // namespace ns3
namespace ns3 {
HighPrecision::HighPrecision ()
{
m_value.hi = 0;
m_value.lo = 0;
}
HighPrecision::HighPrecision (int64_t value, bool dummy)
{
m_value.hi = value;
m_value.lo = 0;
}
bool
HighPrecision::IsNegative (void) const
{
int64_t hi = m_value.hi;
return hi < 0;
}
int64_t
HighPrecision::GetInteger (void) const
{
return m_value.hi;
}
void
HighPrecision::Add (HighPrecision const &o)
{
m_value.hi += o.m_value.hi;
m_value.lo += o.m_value.lo;
if (m_value.lo < o.m_value.lo)
{
m_value.hi++;
}
}
void
HighPrecision::Sub (HighPrecision const &o)
{
m_value.hi -= o.m_value.hi;
m_value.lo -= o.m_value.lo;
if (m_value.lo > o.m_value.lo)
{
m_value.hi--;
}
}
int
HighPrecision::Compare (HighPrecision const &o) const
{
HighPrecision tmp = *this;
tmp.Sub (o);
return tmp.IsNegative ()?-1:(tmp.m_value.hi == 0 && tmp.m_value.lo == 0)?0:1;
}
HighPrecision
HighPrecision::Zero (void)
{
return HighPrecision ();
}
#define HPCAIRO_MAX_64 18446744073709551615.0
double HighPrecision::GetDouble (void) const
{
bool is_negative = IsNegative ();
cairo_int128_t value = is_negative ? _cairo_int128_negate (m_value) : m_value;
double flo = value.lo;
flo /= HPCAIRO_MAX_64;
double retval = value.hi;
retval += flo;
retval = is_negative ? -retval: retval;
return retval;
}
#undef HPCAIRO_MAX_64
#define HPCAIRO_MAX_64 18446744073709551615.0
HighPrecision::HighPrecision (double value)
{
double fhi = floor (value);
int64_t hi = static_cast<int64_t> (fhi);
uint64_t lo = (uint64_t) ((value - fhi) * HPCAIRO_MAX_64);
m_value.hi = hi;
m_value.lo = lo;
}
#undef HPCAIRO_MAX_64
} // namespace ns3
#endif /* HIGH_PRECISION_CAIRO_H */