Atomic Services APIs

Macros
#define	ATOMIC_INIT(i)
	Initialize an atomic variable.
#define	ATOMIC_PTR_INIT(p)
	Initialize an atomic pointer variable.
#define	ATOMIC_BITMAP_SIZE(num_bits)
	This macro computes the number of atomic variables necessary to represent a bitmap with num_bits.
#define	ATOMIC_DEFINE(name, num_bits)
	Define an array of atomic variables.

Functions
static bool	atomic_test_bit (const atomic_t *target, int bit)
	Atomically get and test a bit.
static bool	atomic_test_and_clear_bit (atomic_t *target, int bit)
	Atomically clear a bit and test it.
static bool	atomic_test_and_set_bit (atomic_t *target, int bit)
	Atomically set a bit and test it.
static void	atomic_clear_bit (atomic_t *target, int bit)
	Atomically clear a bit.
static void	atomic_set_bit (atomic_t *target, int bit)
	Atomically set a bit.
static void	atomic_set_bit_to (atomic_t *target, int bit, bool val)
	Atomically set a bit to a given value.
bool	atomic_cas (atomic_t *target, atomic_val_t old_value, atomic_val_t new_value)
	Atomic compare-and-set.
bool	atomic_ptr_cas (atomic_ptr_t *target, atomic_ptr_val_t old_value, atomic_ptr_val_t new_value)
	Atomic compare-and-set with pointer values.
atomic_val_t	atomic_add (atomic_t *target, atomic_val_t value)
	Atomic addition.
atomic_val_t	atomic_sub (atomic_t *target, atomic_val_t value)
	Atomic subtraction.
atomic_val_t	atomic_inc (atomic_t *target)
	Atomic increment.
atomic_val_t	atomic_dec (atomic_t *target)
	Atomic decrement.
atomic_val_t	atomic_get (const atomic_t *target)
	Atomic get.
atomic_ptr_val_t	atomic_ptr_get (const atomic_ptr_t *target)
	Atomic get a pointer value.
atomic_val_t	atomic_set (atomic_t *target, atomic_val_t value)
	Atomic get-and-set.
atomic_ptr_val_t	atomic_ptr_set (atomic_ptr_t *target, atomic_ptr_val_t value)
	Atomic get-and-set for pointer values.
atomic_val_t	atomic_clear (atomic_t *target)
	Atomic clear.
atomic_ptr_val_t	atomic_ptr_clear (atomic_ptr_t *target)
	Atomic clear of a pointer value.
atomic_val_t	atomic_or (atomic_t *target, atomic_val_t value)
	Atomic bitwise inclusive OR.
atomic_val_t	atomic_xor (atomic_t *target, atomic_val_t value)
	Atomic bitwise exclusive OR (XOR).
atomic_val_t	atomic_and (atomic_t *target, atomic_val_t value)
	Atomic bitwise AND.
atomic_val_t	atomic_nand (atomic_t *target, atomic_val_t value)
	Atomic bitwise NAND.

Detailed Description

Macro Definition Documentation

ATOMIC_BITMAP_SIZE

#define ATOMIC_BITMAP_SIZE

(

num_bits

)

#include <zephyr/sys/atomic.h>

Value:

(ROUND_UP(num_bits, ATOMIC_BITS) / ATOMIC_BITS)

This macro computes the number of atomic variables necessary to represent a bitmap with num_bits.

Parameters

num_bits

Number of bits.

ATOMIC_DEFINE

#define ATOMIC_DEFINE	(		name,
			num_bits )

#include <zephyr/sys/atomic.h>

Value:

        atomic_t name[ATOMIC_BITMAP_SIZE(num_bits)]

Define an array of atomic variables.

This macro defines an array of atomic variables containing at least num_bits bits.

Note

If used from file scope, the bits of the array are initialized to zero; if used from within a function, the bits are left uninitialized.

Parameters

name	Name of array of atomic variables.
num_bits	Number of bits needed.

ATOMIC_INIT

#define ATOMIC_INIT

(

i

)

#include <zephyr/sys/atomic.h>

Value:

(i)

Initialize an atomic variable.

This macro can be used to initialize an atomic variable. For example,

atomic_t my_var = ATOMIC_INIT(75); 

Parameters

i	Value to assign to atomic variable.

ATOMIC_PTR_INIT

#define ATOMIC_PTR_INIT

(

p

)

#include <zephyr/sys/atomic.h>

Value:

(p)

Initialize an atomic pointer variable.

This macro can be used to initialize an atomic pointer variable. For example,

atomic_ptr_t my_ptr = ATOMIC_PTR_INIT(&data); 

Parameters

p	Pointer value to assign to atomic pointer variable.

Function Documentation

atomic_add()

atomic_val_t atomic_add	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic addition.

This routine performs an atomic addition on target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to add.

Returns

Previous value of target.

atomic_and()

atomic_val_t atomic_and	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic bitwise AND.

This routine atomically sets target to the bitwise AND of target and value.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to AND.

Returns

Previous value of target.

atomic_cas()

bool atomic_cas	(	atomic_t *	target,
		atomic_val_t	old_value,
		atomic_val_t	new_value )

#include <zephyr/sys/atomic.h>

Atomic compare-and-set.

This routine performs an atomic compare-and-set on target. If the current value of target equals old_value, target is set to new_value. If the current value of target does not equal old_value, target is left unchanged.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
old_value	Original value to compare against.
new_value	New value to store.

Returns

true if new_value is written, false otherwise.

atomic_clear()

atomic_val_t atomic_clear

(

atomic_t *

target

)

#include <zephyr/sys/atomic.h>

Atomic clear.

This routine atomically sets target to zero and returns its previous value. (Hence, it is equivalent to atomic_set(target, 0).)

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target

Address of atomic variable.

Returns

Previous value of target.

atomic_clear_bit()

static void atomic_clear_bit ( atomic_t * target, int bit )

inlinestatic

#include <zephyr/sys/atomic.h>

Atomically clear a bit.

Atomically clear bit number bit of target. The target may be a single atomic variable or an array of them.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable or array.
bit	Bit number (starting from 0).

atomic_dec()

atomic_val_t atomic_dec

(

atomic_t *

target

)

#include <zephyr/sys/atomic.h>

Atomic decrement.

This routine performs an atomic decrement by 1 on target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target

Address of atomic variable.

Returns

Previous value of target.

atomic_get()

atomic_val_t atomic_get

(

const atomic_t *

target

)

#include <zephyr/sys/atomic.h>

Atomic get.

This routine performs an atomic read on target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target

Address of atomic variable.

Returns

Value of target.

atomic_inc()

atomic_val_t atomic_inc

(

atomic_t *

target

)

#include <zephyr/sys/atomic.h>

Atomic increment.

This routine performs an atomic increment by 1 on target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target

Address of atomic variable.

Returns

Previous value of target.

atomic_nand()

atomic_val_t atomic_nand	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic bitwise NAND.

This routine atomically sets target to the bitwise NAND of target and value. (This operation is equivalent to target = ~(target & value).)

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to NAND.

Returns

Previous value of target.

atomic_or()

atomic_val_t atomic_or	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic bitwise inclusive OR.

This routine atomically sets target to the bitwise inclusive OR of target and value.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to OR.

Returns

Previous value of target.

atomic_ptr_cas()

bool atomic_ptr_cas	(	atomic_ptr_t *	target,
		atomic_ptr_val_t	old_value,
		atomic_ptr_val_t	new_value )

#include <zephyr/sys/atomic.h>

Atomic compare-and-set with pointer values.

This routine performs an atomic compare-and-set on target. If the current value of target equals old_value, target is set to new_value. If the current value of target does not equal old_value, target is left unchanged.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
old_value	Original value to compare against.
new_value	New value to store.

Returns

true if new_value is written, false otherwise.

atomic_ptr_clear()

atomic_ptr_val_t atomic_ptr_clear

(

atomic_ptr_t *

target

)

#include <zephyr/sys/atomic.h>

Atomic clear of a pointer value.

This routine atomically sets target to zero and returns its previous value. (Hence, it is equivalent to atomic_set(target, 0).)

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target

Address of atomic variable.

Returns

Previous value of target.

atomic_ptr_get()

atomic_ptr_val_t atomic_ptr_get

(

const atomic_ptr_t *

target

)

#include <zephyr/sys/atomic.h>

Atomic get a pointer value.

This routine performs an atomic read on target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target

Address of pointer variable.

Returns

Value of target.

atomic_ptr_set()

atomic_ptr_val_t atomic_ptr_set	(	atomic_ptr_t *	target,
		atomic_ptr_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic get-and-set for pointer values.

This routine atomically sets target to value and returns the previous value of target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to write to target.

Returns

Previous value of target.

atomic_set()

atomic_val_t atomic_set	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic get-and-set.

This routine atomically sets target to value and returns the previous value of target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to write to target.

Returns

Previous value of target.

atomic_set_bit()

static void atomic_set_bit ( atomic_t * target, int bit )

inlinestatic

#include <zephyr/sys/atomic.h>

Atomically set a bit.

Atomically set bit number bit of target. The target may be a single atomic variable or an array of them.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable or array.
bit	Bit number (starting from 0).

atomic_set_bit_to()

static void atomic_set_bit_to ( atomic_t * target, int bit, bool val )

inlinestatic

#include <zephyr/sys/atomic.h>

Atomically set a bit to a given value.

Atomically set bit number bit of target to value val. The target may be a single atomic variable or an array of them.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable or array.
bit	Bit number (starting from 0).
val	true for 1, false for 0.

atomic_sub()

atomic_val_t atomic_sub	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic subtraction.

This routine performs an atomic subtraction on target.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable.
value	Value to subtract.

Returns

Previous value of target.

atomic_test_and_clear_bit()

static bool atomic_test_and_clear_bit ( atomic_t * target, int bit )

inlinestatic

#include <zephyr/sys/atomic.h>

Atomically clear a bit and test it.

Atomically clear bit number bit of target and return its old value. The target may be a single atomic variable or an array of them.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable or array.
bit	Bit number (starting from 0).

Returns

false if the bit was already cleared, true if it wasn't.

atomic_test_and_set_bit()

static bool atomic_test_and_set_bit ( atomic_t * target, int bit )

inlinestatic

#include <zephyr/sys/atomic.h>

Atomically set a bit and test it.

Atomically set bit number bit of target and return its old value. The target may be a single atomic variable or an array of them.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable or array.
bit	Bit number (starting from 0).

Returns

true if the bit was already set, false if it wasn't.

atomic_test_bit()

static bool atomic_test_bit ( const atomic_t * target, int bit )

inlinestatic

#include <zephyr/sys/atomic.h>

Atomically get and test a bit.

Atomically get a value and then test whether bit number bit of target is set or not. The target may be a single atomic variable or an array of them.

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

Parameters

target	Address of atomic variable or array.
bit	Bit number (starting from 0).

Returns

true if the bit was set, false if it wasn't.

atomic_xor()

atomic_val_t atomic_xor	(	atomic_t *	target,
		atomic_val_t	value )

#include <zephyr/sys/atomic.h>

Atomic bitwise exclusive OR (XOR).

Note

As for all atomic APIs, includes a full/sequentially-consistent memory barrier (where applicable).

This routine atomically sets target to the bitwise exclusive OR (XOR) of target and value.

Parameters

target	Address of atomic variable.
value	Value to XOR

Returns

Previous value of target.