High precision numerical type, implementing Q64.64 fixed precision. More...

#include <int64x64-128.h>

Public Types
enum	impl_type { int128_impl, cairo_impl, ld_impl }
	Type tag for the underlying implementation. More...

Public Member Functions
	int64x64_t ()
	Default constructor. More...

	int64x64_t (const int64_t hi, const uint64_t lo)
	Construct from explicit high and low values. More...

	int64x64_t (const int64x64_t &o)
	Copy constructor. More...

double	GetDouble (void) const
	Get this value as a double. More...

int64_t	GetHigh (void) const
	Get the integer portion. More...

uint64_t	GetLow (void) const
	Get the fractional portion of this value, unscaled. More...

void	MulByInvert (const int64x64_t &o)
	Multiply this value by a Q0.128 value, presumably representing an inverse, completing a division operation. More...

int64x64_t &	operator= (const int64x64_t &o)
	Assignment. More...


	int64x64_t (const double value)
	Construct from a floating point value. More...

	int64x64_t (const long double value)
	Construct from a floating point value. More...


	int64x64_t (const int v)
	Construct from an integral type. More...

	int64x64_t (const long int v)
	Construct from an integral type. More...

	int64x64_t (const long long int v)
	Construct from an integral type. More...

	int64x64_t (const unsigned int v)
	Construct from an integral type. More...

	int64x64_t (const unsigned long int v)
	Construct from an integral type. More...

	int64x64_t (const unsigned long long int v)
	Construct from an integral type. More...

Static Public Member Functions
static int64x64_t	Invert (const uint64_t v)
	Compute the inverse of an integer value. More...

Static Public Attributes
static enum impl_type	implementation = int128_impl
	Type tag for this implementation. More...

Private Member Functions
	int64x64_t (const int128_t v)
	Construct from an integral type. More...

void	Div (const int64x64_t &o)
	Implement `/=`. More...

void	Mul (const int64x64_t &o)
	Implement `*=`. More...

Static Private Member Functions
static uint128_t	Udiv (const uint128_t a, const uint128_t b)
	Unsigned division of Q64.64 values. More...

static uint128_t	Umul (const uint128_t a, const uint128_t b)
	Unsigned multiplication of Q64.64 values. More...

static uint128_t	UmulByInvert (const uint128_t a, const uint128_t b)
	Unsigned multiplication of Q64.64 and Q0.128 values. More...

Private Attributes
int128_t	_v
	The Q64.64 value. More...

Static Private Attributes
static const uint128_t	HP128_MASK_HI_BIT = (((int128_t)1)<<127)
	uint128_t high bit (sign bit) More...

static const uint64_t	HP_MASK_HI = ~HP_MASK_LO
	Mask for sign + integer part. More...

static const uint64_t	HP_MASK_LO = 0xffffffffffffffffULL
	Mask for fraction part. More...

Friends
int64x64_t	operator! (const int64x64_t &lhs)
	Logical not operator. More...

int64x64_t &	operator*= (int64x64_t &lhs, const int64x64_t &rhs)
	Compound multiplication operator. More...

int64x64_t &	operator+= (int64x64_t &lhs, const int64x64_t &rhs)
	Compound addition operator. More...

int64x64_t	operator- (const int64x64_t &lhs)
	Unary negation operator (change sign operator) More...

int64x64_t &	operator-= (int64x64_t &lhs, const int64x64_t &rhs)
	Compound subtraction operator. More...

int64x64_t &	operator/= (int64x64_t &lhs, const int64x64_t &rhs)
	Compound division operator. More...

bool	operator< (const int64x64_t &lhs, const int64x64_t &rhs)
	Less than operator. More...

bool	operator== (const int64x64_t &lhs, const int64x64_t &rhs)
	Equality operator. More...

bool	operator> (const int64x64_t &lhs, const int64x64_t &rhs)
	Greater operator. More...

Detailed Description

High precision numerical type, implementing Q64.64 fixed precision.

Internal:: The implementation documented here is based on native 128-bit integers.

A Q64.64 fixed precision number consists of:

Bits	Function
1	Sign bit
63	Integer portion
64	Fractional portion

The high word consists of the sign bit and integer value; the low word is the fractional part, unscaled.

All standard arithmetic operations are supported:

Category	Operators
Computation	`+`, `+=`, `-`, `-=`, ``, `=`, `/`, `/=`
Comparison	`==`, `!=`, `<`, `<=`, `>`, `>=`
Unary	`+`, `-`, `!`

Definition at line 20 of file int64x64-128.h.

Member Enumeration Documentation

enum ns3::int64x64_t::impl_type

Type tag for the underlying implementation.

A few testcases are are sensitive to implementation, specifically the double implementation. To handle this, we expose the underlying implementation type here.

Enumerator
int128_impl	Native int128_t implementation.
cairo_impl	cairo wideint implementation
ld_impl	long double implementation

Definition at line 50 of file int64x64-128.h.

Constructor & Destructor Documentation

ns3::int64x64_t::int64x64_t ( )

inline

Default constructor.

Definition at line 60 of file int64x64-128.h.

Referenced by Invert().

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ns3::int64x64_t::int64x64_t ( const double value )

inline

Construct from a floating point value.

Parameters

[in] value floating value to represent

Definition at line 68 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const long double value )

inline

Construct from a floating point value.

Parameters

[in] value floating value to represent

Definition at line 73 of file int64x64-128.h.

References _v, and HP_MAX_64.

ns3::int64x64_t::int64x64_t ( const int v )

inline

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 109 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const long int v )

inline

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 114 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const long long int v )

inline

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 119 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const unsigned int v )

inline

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 124 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const unsigned long int v )

inline

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 129 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const unsigned long long int v )

inline

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 134 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t	(	const int64_t	hi,
		const uint64_t	lo
	)

inlineexplicit

Construct from explicit high and low values.

Parameters

[in]	hi	Integer portion.
[in]	lo	Fractional portion, already scaled to HP_MAX_64.

Definition at line 146 of file int64x64-128.h.

References _v.

ns3::int64x64_t::int64x64_t ( const int64x64_t & o )

inline

Copy constructor.

Parameters

[in] o Value to copy.

Definition at line 157 of file int64x64-128.h.

ns3::int64x64_t::int64x64_t ( const int128_t v )

inlineprivate

Construct from an integral type.

Parameters

[in] v integer value to represent

Definition at line 307 of file int64x64-128.h.

Member Function Documentation

void ns3::int64x64_t::Div ( const int64x64_t & o )

private

Implement /=.

Parameters

[in] o The divisor.

Definition at line 78 of file int64x64-128.cc.

References _v, ns3::output_sign(), and Udiv().

Referenced by ns3::operator/=().

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double ns3::int64x64_t::GetDouble ( void ) const

inline

Get this value as a double.

Returns: This value in floating form.

Definition at line 175 of file int64x64-128.h.

References _v, HP_MASK_LO, and HP_MAX_64.

Referenced by ns3::int64x64::test::Int64x64Bug455TestCase::DoRun(), ns3::int64x64::test::Int64x64Bug863TestCase::DoRun(), and ns3::Time::ToDouble().

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int64_t ns3::int64x64_t::GetHigh ( void ) const

inline

Get the integer portion.

Returns: The integer portion of this value.

Definition at line 191 of file int64x64-128.h.

References _v.

Referenced by ns3::OnOffApplication::CancelEvents(), ns3::int64x64::test::Int64x64HiLoTestCase::Check(), ns3::DelayJitterEstimation::GetLastJitter(), Invert(), and ns3::operator<<().

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uint64_t ns3::int64x64_t::GetLow ( void ) const

inline

Get the fractional portion of this value, unscaled.

Returns: The fractional portion, unscaled, as an integer.

Definition at line 201 of file int64x64-128.h.

References _v, and HP_MASK_LO.

Referenced by ns3::int64x64::test::Int64x64HiLoTestCase::Check(), ns3::int64x64::test::Int64x64InputTestCase::Check(), ns3::operator<<(), and ns3::ReadLoDigits().

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int64x64_t ns3::int64x64_t::Invert ( const uint64_t v )

static

Compute the inverse of an integer value.

Ordinary division by an integer would be limited to 64 bits of precsion. Instead, we multiply by the 128-bit inverse of the divisor. This function computes the inverse to 128-bit precision. MulByInvert() then completes the division.

(Really this should be a separate type representing Q0.128.)

Parameters

[in] v The value to compute the inverse of.

Returns: A Q0.128 representation of the inverse.

Definition at line 182 of file int64x64-128.cc.

References _v, GetHigh(), int64x64_t(), MulByInvert(), NS_ASSERT, and Udiv().

Referenced by ns3::int64x64::test::Int64x64InvertTestCase::Check(), and ns3::Time::SetResolution().

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void ns3::int64x64_t::Mul ( const int64x64_t & o )

private

Implement *=.

Parameters

[in] o The other factor.

Definition at line 29 of file int64x64-128.cc.

References _v, ns3::output_sign(), and Umul().

Referenced by ns3::operator*=().

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void ns3::int64x64_t::MulByInvert ( const int64x64_t & o )

Multiply this value by a Q0.128 value, presumably representing an inverse, completing a division operation.

Parameters

[in] o The inverse operand.

See also: Invert

Definition at line 156 of file int64x64-128.cc.

References _v, and UmulByInvert().

Referenced by ns3::int64x64::test::Int64x64InvertTestCase::Check(), ns3::Time::From(), Invert(), and ns3::Time::To().

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int64x64_t& ns3::int64x64_t::operator= ( const int64x64_t & o )

inline

Assignment.

Parameters

[in] o Value to assign to this int64x64_t.

Definition at line 164 of file int64x64-128.h.

References _v.

cairo_uint128_t ns3::int64x64_t::Udiv	(	const uint128_t	a,
		const uint128_t	b
	)

staticprivate

Unsigned division of Q64.64 values.

Parameters

[in]	a	Numerator.
[in]	b	Denominator.

Returns: The Q64.64 representation of a / b

Definition at line 87 of file int64x64-128.cc.

References HP128_MASK_HI_BIT, and NS_ASSERT_MSG.

Referenced by Div(), and Invert().

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cairo_uint128_t ns3::int64x64_t::Umul	(	const uint128_t	a,
		const uint128_t	b
	)

staticprivate

Unsigned multiplication of Q64.64 values.

Mathematically this should produce a Q128.128 value; we keep the central 128 bits, representing the Q64.64 result. We assert on integer overflow beyond the 64-bit integer portion.

Parameters

[in]	a	First factor.
[in]	b	Second factor.

Returns: The Q64.64 product.

Internal:

It might be tempting to just use a * b and be done with it, but it's not that simple. With a and b as 128-bit integers, a * b mathematically produces a 256-bit result, which the computer truncates to the lowest 128 bits. In our case, where a and b are interpreted as Q64.64 fixed point numbers, the multiplication mathematically produces a Q128.128 fixed point number. We want the middle 128 bits from the result, truncating both the high and low 64 bits. To achieve this, we carry out the multiplication explicitly with 64-bit operands and 128-bit intermediate results.

Definition at line 38 of file int64x64-128.cc.

References HP_MASK_HI, HP_MASK_LO, and NS_ABORT_MSG_IF.

Referenced by Mul().

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cairo_uint128_t ns3::int64x64_t::UmulByInvert	(	const uint128_t	a,
		const uint128_t	b
	)

staticprivate

Unsigned multiplication of Q64.64 and Q0.128 values.

Parameters

[in]	a	The numerator, a Q64.64 value.
[in]	b	The inverse of the denominator, a Q0.128 value

Returns: The product a * b, representing the ration a / b^-1

See also: Invert

Definition at line 166 of file int64x64-128.cc.

References HP_MASK_LO.

Referenced by MulByInvert().

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Friends And Related Function Documentation

int64x64_t operator! ( const int64x64_t & lhs )

friend

Logical not operator.

Definition at line 397 of file int64x64-128.h.

int64x64_t& operator*=	(	int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Compound multiplication operator.

Definition at line 362 of file int64x64-128.h.

int64x64_t& operator+=	(	int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Compound addition operator.

Definition at line 344 of file int64x64-128.h.

int64x64_t operator- ( const int64x64_t & lhs )

friend

Unary negation operator (change sign operator)

Definition at line 389 of file int64x64-128.h.

int64x64_t& operator-=	(	int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Compound subtraction operator.

Definition at line 353 of file int64x64-128.h.

int64x64_t& operator/=	(	int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Compound division operator.

Definition at line 371 of file int64x64-128.h.

bool operator<	(	const int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Less than operator.

Definition at line 327 of file int64x64-128.h.

bool operator==	(	const int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Equality operator.

Definition at line 319 of file int64x64-128.h.

bool operator>	(	const int64x64_t &	lhs,
		const int64x64_t &	rhs
	)

friend

Greater operator.

Definition at line 335 of file int64x64-128.h.

Member Data Documentation

int128_t ns3::int64x64_t::_v

private

The Q64.64 value.

Definition at line 310 of file int64x64-128.h.

Referenced by Div(), GetDouble(), GetHigh(), GetLow(), int64x64_t(), Invert(), Mul(), MulByInvert(), ns3::operator!(), ns3::operator+=(), ns3::operator-(), ns3::operator-=(), ns3::operator<(), operator=(), ns3::operator==(), and ns3::operator>().

const uint128_t ns3::int64x64_t::HP128_MASK_HI_BIT = (((int128_t)1)<<127)

staticprivate

uint128_t high bit (sign bit)

Definition at line 23 of file int64x64-128.h.

Referenced by Udiv().

const uint64_t ns3::int64x64_t::HP_MASK_HI = ~HP_MASK_LO

staticprivate

Mask for sign + integer part.

Definition at line 27 of file int64x64-128.h.

Referenced by Umul().

const uint64_t ns3::int64x64_t::HP_MASK_LO = 0xffffffffffffffffULL

staticprivate

Mask for fraction part.

Definition at line 25 of file int64x64-128.h.

Referenced by GetDouble(), GetLow(), Umul(), and UmulByInvert().

enum impl_type ns3::int64x64_t::implementation = int128_impl

static

Type tag for this implementation.

Definition at line 57 of file int64x64-128.h.

Referenced by ns3::int64x64::test::Int64x64HiLoTestCase::Check(), ns3::int64x64::test::Int64x64InvertTestCase::Check(), ns3::int64x64::test::Int64x64DoubleTestCase::Check(), ns3::int64x64::test::Int64x64HiLoTestCase::DoRun(), ns3::int64x64::test::Int64x64InputTestCase::DoRun(), ns3::int64x64::test::Int64x64InputOutputTestCase::DoRun(), ns3::int64x64::test::Int64x64Bug1786TestCase::DoRun(), and ns3::int64x64::test::Int64x64ImplTestCase::DoRun().

The documentation for this class was generated from the following files:

src/core/model/int64x64-128.h
src/core/model/int64x64-128.cc
src/core/model/int64x64-cairo.cc

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Private Member Functions

Static Private Member Functions

Private Attributes

Static Private Attributes

Friends

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation