atomic_uint64_t Class Reference

A 64-bit integer with support for atomic operations. More...

#include <atomic.hh>

Public Member Functions
uint64_t	value () const
	Return the value.
uint64_t	nonatomic_value () const
	Return the value.
	operator uint64_t () const
	Return the value.
atomic_uint64_t &	operator= (uint64_t x)
	Set the value to x.
atomic_uint64_t &	operator+= (int64_t delta)
	Atomically add delta to the value.
atomic_uint64_t &	operator-= (int64_t delta)
	Atomically subtract delta from the value.
void	nonatomic_inc ()
	Increment the value.
void	operator++ ()
	Atomically increment the value.
void	operator++ (int)
	Atomically increment the value.
void	nonatomic_dec ()
	Decrement the value.
void	operator-- ()
	Atomically decrement the value.
void	operator-- (int)
	Atomically decrement the value.
uint64_t	compare_swap (uint64_t expected, uint64_t desired) CLICK_BUILTINS_DEPRECATED
uint64_t	fetch_and_add (uint64_t delta)
	Perform a compare-and-swap operation.

Static Public Member Functions
static void	add (volatile uint64_t &x, uint64_t delta)
	Atomically increment value x.
static uint64_t	compare_swap (volatile uint64_t &x, uint64_t expected, uint64_t desired) CLICK_BUILTINS_DEPRECATED
static bool	use_builtins ()

Detailed Description

A 64-bit integer with support for atomic operations.

The atomic_uint64_t class represents a 64-bit integer, with support for atomic operations. The +=, -=, &=, |=, ++, and – operations are implemented using atomic instructions. There are also atomic swap(), fetch_and_add(), dec_and_test(), and compare_swap() operations.

Because of some issues with compiler implementations, atomic_uint64_t has no explicit constructor; to set an atomic_uint64_t to a value, use operator=.

The atomic_uint64_t only provides true atomic semantics when that has been implemented. It has been implemented in the Linux kernel, and at userlevel (when –enable-multithread has been defined) for x86 machines. In other situations, it's not truly atomic (because it doesn't need to be).

Member Function Documentation

value()

uint64_t atomic_uint64_t::value ( ) const

inline

Return the value.

nonatomic_value()

uint64_t atomic_uint64_t::nonatomic_value ( ) const

inline

Return the value.

operator uint64_t()

atomic_uint64_t::operator uint64_t ( ) const

inline

Return the value.

operator=()

atomic_uint64_t & atomic_uint64_t::operator= ( uint64_t  x )

inline

Set the value to x.

operator+=()

atomic_uint64_t & atomic_uint64_t::operator+= ( int64_t  delta )

inline

Atomically add delta to the value.

operator-=()

atomic_uint64_t & atomic_uint64_t::operator-= ( int64_t  delta )

inline

Atomically subtract delta from the value.

nonatomic_inc()

void atomic_uint64_t::nonatomic_inc ( )

inline

Increment the value.

operator++() [1/2]

void atomic_uint64_t::operator++ ( )

inline

Atomically increment the value.

operator++() [2/2]

void atomic_uint64_t::operator++ ( int  )

inline

Atomically increment the value.

nonatomic_dec()

void atomic_uint64_t::nonatomic_dec ( )

inline

Decrement the value.

operator--() [1/2]

void atomic_uint64_t::operator-- ( )

inline

Atomically decrement the value.

operator--() [2/2]

void atomic_uint64_t::operator-- ( int  )

inline

Atomically decrement the value.

fetch_and_add()

uint64_t atomic_uint64_t::fetch_and_add ( uint64_t  delta )

inline

Perform a compare-and-swap operation.

Parameters

x	value
expected	test value
desired	new value

Returns

The actual old value. If it equaled expected, x has been set to desired.

Behaves like this, but in one atomic step:

uint62_t actual = x;
if (x == expected)
    x = desired;
return actual;

Also acts as a memory barrier.

Atomically add delta to the value, returning the old value.

Behaves like this, but in one atomic step:

uint32_t old_value = value();
*this += delta;
return old_value;

add()

void atomic_uint64_t::add ( volatile uint64_t &  x, uint64_t  delta  )

inlinestatic

Atomically increment value x.

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

• include/click/atomic.hh