Detailed Description

This modules adds some utility functions to perform atomic accesses.

Usage

The atomic utilitys allow atomic access to regular variables.

uint32_t global_counter;
 
void irq_handler(void)
{
    // No need to use atomic access in IRQ handlers, if other IRQ handlers
    // never touch global_counter: At the beginning and at the end of every
    // ISR a memory barrier is in place, so that at the end of the ISR the
    // memory will be in a state as if all memory accesses within the ISR
    // took place in sequential order.
    //
    // Extra detail only RIOT kernel hackers need to know: If all ISRs
    // accessing the same variable cannot interrupt each other, atomic
    // access is still not needed. (Currently only PendSV on ARM can be
    // interrupted by other IRQs with RIOTs default IRQ priorities. If
    // application developers modifies those, they can be assumed to know
    // what they are doing - or to happily face the consequences otherwise.)
    global_counter++;
}
 
void called_by_thread_a(void) {
    if (atomic_load_u32(&global_counter) > THRESHOLD) {
        on_threshold_reached();
        atomic_store_u32(&global_counter, 0);
    }
}
 
void called_by_thread_b(void) {
    atomic_add_u32(&global_counter, 42);
}

Motivation

There are some reasons why these functions might be chosen over the C11 Atomic Operations Library in some advanced use cases:

The functions allow mixing of atomic and non-atomic accesses. E.g. while IRQs are disabled anyway, even plain accesses cannot be interrupted but are often more efficient.
On platforms not supporting lock-free access, a library call is generated instead. The fallback implementation used here is more efficient in terms of both CPU instructions and ROM size.
On platforms where some operations can be implemented lock free while others can't, at least LLVM will use the library call even for those accesses that can be implemented lock-free. This is because without assuming how the library call implements atomic access for the other functions, mixing library calls and lock free accesses could result in data corruption. But this implementation resorts to disabling IRQs when lock-free implementations are not possible, which mixes well with lock-free accesses. Thus, additional overhead for atomic accesses is only spent where needed.
In some cases the fallback implementation performs better than the lock free implementation. E.g. if a specific platform has an atomic compare and swap instruction, this could be used to perform a read-modify-write in a loop until the value initially read was not changed in between. Just disabling IRQs to implement an atomic read-modify-write operation is likely more efficient. C11 atomics will however always use the lock free implementation (if such exists), assuming that this is more efficient. This assumption was made with desktop class hardware in mind, but is not generally true for bare metal targets. These function allow to optimize for the actual hardware RIOT is running on.
This library provides "semi-atomic" read-modify-write operations, which are useful when at most one thread is ever writing to memory. In that case, only the write part of the read-modify-write operation needs to be performed in an atomic fashion in order for the reading threads to perceive atomic updates of the variable. This is significantly cheaper than atomic read-modify-write operations for many platforms

Guarantees

Every utility function here acts as a barrier for code reordering regarding
For the atomic_*() family of functions: The whole operation will be done in an non-interruptible fashion
For the semi_atomic_*() family of functions: The write part of the operation is done atomically. If at most one thread is ever performing changes to a variable using the semi_atomic_() functions, those changes will appear as if they were atomic to all other threads.

Porting to new CPUs

At the bare minimum, create an empty atomic_utils_arch.h file. This will result in the fallback implementations being used.

To expose lock-free atomic operations, add an implementation to the atomic_utils_arch.h file and disable the fallback implementation by defining HAS_<FN_NAME_ALL_CAPS>, where <FN_NAME_ALL_CAPS> is the name of the function provided in all upper case. E.g. most platforms will be able to provide lock-free reads and writes up to their word size and can expose this as follows for GCC:

// All the user header boilerplate
#define HAS_ATOMIC_LOAD_U8
static inline uint8_t atomic_load_u8(const uint8_t *var)
{
    return __atomic_load_1(var, __ATOMIC_SEQ_CST);
}
 
#define HAS_ATOMIC_STORE_U8
static inline void atomic_store_u8(uint8_t *dest, uint8_t val)
{
    __atomic_store_1(dest, val, __ATOMIC_SEQ_CST);
}

Note: The semi_atomic_*() family of functions is always provided using atomic_*() functions in the cheapest way possible.

Files
file	atomic_utils.h
	API of the utility functions for atomic accesses.

Data Structures
struct	atomic_bit_u8_t
	Type specifying a bit in an `uint8_t` More...

struct	atomic_bit_u16_t
	Type specifying a bit in an `uint16_t` More...

struct	atomic_bit_u32_t
	Type specifying a bit in an `uint32_t` More...

struct	atomic_bit_u64_t
	Type specifying a bit in an `uint64_t` More...

Macros
#define	CONCAT(a, b) a ## b
	Concatenate two tokens.

#define	CONCAT4(a, b, c, d) a ## b ## c ## d
	Concatenate four tokens.

#define	ATOMIC_LOAD_IMPL(name, type)
	Generates a static inline function implementing `atomic_load_u<width>()` More...

#define	ATOMIC_STORE_IMPL(name, type)
	Generates a static inline function implementing `atomic_store_u<width>()` More...

#define	ATOMIC_FETCH_OP_IMPL(opname, op, name, type)
	Generates a static inline function implementing `atomic_fecth_<op>_u<width>()` More...

Atomic Loads
static uint8_t	atomic_load_u8 (const uint8_t *var)
	Load an `uint8_t` atomically. More...

static uint16_t	atomic_load_u16 (const uint16_t *var)
	Load an `uint16_t` atomically. More...

static uint32_t	atomic_load_u32 (const uint32_t *var)
	Load an `uint32_t` atomically. More...

static uint64_t	atomic_load_u64 (const uint64_t *var)
	Load an `uint64_t` atomically. More...

Atomic Stores
static void	atomic_store_u8 (uint8_t *dest, uint8_t val)
	Store an `uint8_t` atomically. More...

static void	atomic_store_u16 (uint16_t *dest, uint16_t val)
	Store an `uint16_t` atomically. More...

static void	atomic_store_u32 (uint32_t *dest, uint32_t val)
	Store an `uint32_t` atomically. More...

static void	atomic_store_u64 (uint64_t *dest, uint64_t val)
	Store an `uint64_t` atomically. More...

Atomic In-Place Addition
static void	atomic_fetch_add_u8 (uint8_t *dest, uint8_t summand)
	Atomically add a value onto a given value. More...

static void	atomic_fetch_add_u16 (uint16_t *dest, uint16_t summand)
	Atomically add a value onto a given value. More...

static void	atomic_fetch_add_u32 (uint32_t *dest, uint32_t summand)
	Atomically add a value onto a given value. More...

static void	atomic_fetch_add_u64 (uint64_t *dest, uint64_t summand)
	Atomically add a value onto a given value. More...

Atomic In-Place Subtraction
static void	atomic_fetch_sub_u8 (uint8_t *dest, uint8_t subtrahend)
	Atomically subtract a value from a given value. More...

static void	atomic_fetch_sub_u16 (uint16_t *dest, uint16_t subtrahend)
	Atomically subtract a value from a given value. More...

static void	atomic_fetch_sub_u32 (uint32_t *dest, uint32_t subtrahend)
	Atomically subtract a value from a given value. More...

static void	atomic_fetch_sub_u64 (uint64_t *dest, uint64_t subtrahend)
	Atomically subtract a value from a given value. More...

Atomic In-Place Bitwise OR
static void	atomic_fetch_or_u8 (uint8_t *dest, uint8_t val)
	Atomic version of `*dest \|= val` More...

static void	atomic_fetch_or_u16 (uint16_t *dest, uint16_t val)
	Atomic version of `*dest \|= val` More...

static void	atomic_fetch_or_u32 (uint32_t *dest, uint32_t val)
	Atomic version of `*dest \|= val` More...

static void	atomic_fetch_or_u64 (uint64_t *dest, uint64_t val)
	Atomic version of `*dest \|= val` More...

Atomic In-Place Bitwise XOR
static void	atomic_fetch_xor_u8 (uint8_t *dest, uint8_t val)
	Atomic version of `*dest ^= val` More...

static void	atomic_fetch_xor_u16 (uint16_t *dest, uint16_t val)
	Atomic version of `*dest ^= val` More...

static void	atomic_fetch_xor_u32 (uint32_t *dest, uint32_t val)
	Atomic version of `*dest ^= val` More...

static void	atomic_fetch_xor_u64 (uint64_t *dest, uint64_t val)
	Atomic version of `*dest ^= val` More...

Atomic In-Place Bitwise AND
static void	atomic_fetch_and_u8 (uint8_t *dest, uint8_t val)
	Atomic version of `*dest &= val` More...

static void	atomic_fetch_and_u16 (uint16_t *dest, uint16_t val)
	Atomic version of `*dest &= val` More...

static void	atomic_fetch_and_u32 (uint32_t *dest, uint32_t val)
	Atomic version of `*dest &= val` More...

static void	atomic_fetch_and_u64 (uint64_t *dest, uint64_t val)
	Atomic version of `*dest &= val` More...

Helper Functions to Handle Atomic Bit References
static atomic_bit_u8_t	atomic_bit_u8 (uint8_t *dest, uint8_t bit)
	Create a reference to a bit in an `uint8_t` More...

static atomic_bit_u16_t	atomic_bit_u16 (uint16_t *dest, uint8_t bit)
	Create a reference to a bit in an `uint16_t` More...

static atomic_bit_u32_t	atomic_bit_u32 (uint32_t *dest, uint8_t bit)
	Create a reference to a bit in an `uint32_t` More...

static atomic_bit_u64_t	atomic_bit_u64 (uint64_t *dest, uint8_t bit)
	Create a reference to a bit in an `uint64_t` More...

Atomic Bit Setting
static void	atomic_set_bit_u8 (atomic_bit_u8_t bit)
	Atomic version of `*dest \|= (1 << bit)` More...

static void	atomic_set_bit_u16 (atomic_bit_u16_t bit)
	Atomic version of `*dest \|= (1 << bit)` More...

static void	atomic_set_bit_u32 (atomic_bit_u32_t bit)
	Atomic version of `*dest \|= (1 << bit)` More...

static void	atomic_set_bit_u64 (atomic_bit_u64_t bit)
	Atomic version of `*dest \|= (1 << bit)` More...

Atomic Bit Clearing
static void	atomic_clear_bit_u8 (atomic_bit_u8_t bit)
	Atomic version of `*dest &= ~(1 << bit)` More...

static void	atomic_clear_bit_u16 (atomic_bit_u16_t bit)
	Atomic version of `*dest &= ~(1 << bit)` More...

static void	atomic_clear_bit_u32 (atomic_bit_u32_t bit)
	Atomic version of `*dest &= ~(1 << bit)` More...

static void	atomic_clear_bit_u64 (atomic_bit_u64_t bit)
	Atomic version of `*dest &= ~(1 << bit)` More...

Semi-Atomic In-Place Addition
static void	semi_atomic_fetch_add_u8 (uint8_t *dest, uint8_t summand)
	Semi-atomically add a value onto a given value. More...

static void	semi_atomic_fetch_add_u16 (uint16_t *dest, uint16_t summand)
	Semi-atomically add a value onto a given value. More...

static void	semi_atomic_fetch_add_u32 (uint32_t *dest, uint32_t summand)
	Semi-atomically add a value onto a given value. More...

static void	semi_atomic_fetch_add_u64 (uint64_t *dest, uint64_t summand)
	Semi-atomically add a value onto a given value. More...

Semi-Atomic In-Place Subtraction
static void	semi_atomic_fetch_sub_u8 (uint8_t *dest, uint8_t subtrahend)
	Semi-atomically subtract a value from a given value. More...

static void	semi_atomic_fetch_sub_u16 (uint16_t *dest, uint16_t subtrahend)
	Semi-atomically subtract a value from a given value. More...

static void	semi_atomic_fetch_sub_u32 (uint32_t *dest, uint32_t subtrahend)
	Semi-atomically subtract a value from a given value. More...

static void	semi_atomic_fetch_sub_u64 (uint64_t *dest, uint64_t subtrahend)
	Semi-atomically subtract a value from a given value. More...

Semi-atomic In-Place Bitwise OR
static void	semi_atomic_fetch_or_u8 (uint8_t *dest, uint8_t val)
	Semi-atomic version of `*dest \|= val` More...

static void	semi_atomic_fetch_or_u16 (uint16_t *dest, uint16_t val)
	Semi-atomic version of `*dest \|= val` More...

static void	semi_atomic_fetch_or_u32 (uint32_t *dest, uint32_t val)
	Semi-atomic version of `*dest \|= val` More...

static void	semi_atomic_fetch_or_u64 (uint64_t *dest, uint64_t val)
	Semi-atomic version of `*dest \|= val` More...

Semi-Atomic In-Place Bitwise XOR
static void	semi_atomic_fetch_xor_u8 (uint8_t *dest, uint8_t val)
	Semi-atomic version of `*dest ^= val` More...

static void	semi_atomic_fetch_xor_u16 (uint16_t *dest, uint16_t val)
	Semi-atomic version of `*dest ^= val` More...

static void	semi_atomic_fetch_xor_u32 (uint32_t *dest, uint32_t val)
	Semi-atomic version of `*dest ^= val` More...

static void	semi_atomic_fetch_xor_u64 (uint64_t *dest, uint64_t val)
	Semi-atomic version of `*dest ^= val` More...

Semi-Atomic In-Place Bitwise AND
static void	semi_atomic_fetch_and_u8 (uint8_t *dest, uint8_t val)
	Semi-atomic version of `*dest &= val` More...

static void	semi_atomic_fetch_and_u16 (uint16_t *dest, uint16_t val)
	Semi-atomic version of `*dest &= val` More...

static void	semi_atomic_fetch_and_u32 (uint32_t *dest, uint32_t val)
	Semi-atomic version of `*dest &= val` More...

static void	semi_atomic_fetch_and_u64 (uint64_t *dest, uint64_t val)
	Semi-atomic version of `*dest &= val` More...

Macro Definition Documentation

◆ ATOMIC_FETCH_OP_IMPL

#define ATOMIC_FETCH_OP_IMPL	(	opname,
		op,
		name,
		type
	)

Value:

    static inline void CONCAT4(atomic_fetch_, opname, _, name)(type *dest,     \
                                                               type val)       \
    {                                                                          \
        unsigned state = irq_disable();                                        \
        /* dest can be register allocated, hence the memory barrier of         \
         * irq_disable() and irq_restore() may not apply here. Using volatile  \
         * ensures that the compiler allocates it in memory and that the       \
         * memory access is not optimized out. */                              \
        volatile type *tmp = dest;                                             \
        *tmp = *tmp op val;                                                    \
        irq_restore(state);                                                    \
    }

Generates a static inline function implementing atomic_fecth_<op>_u<width>()

Parameters

opname	Name of the operator in `op`, e.g. "and" for `+`
op	Operator to implement atomically, e.g. `+`
name	Name of the variable type, e.g. "u8"
type	Variable type, e.g. `uint8_t`

Definition at line 775 of file atomic_utils.h.

◆ ATOMIC_LOAD_IMPL

#define ATOMIC_LOAD_IMPL	(	name,
		type
	)

Value:

    static inline type CONCAT(atomic_load_, name)(const type *var)             \
    {                                                                          \
        unsigned state = irq_disable();                                        \
        /* var can be register allocated, hence the memory barrier of          \
         * irq_disable() and irq_restore() may not apply here. Using volatile  \
         * ensures that the compiler allocates it in memory and that the       \
         * memory access is not optimized out. */                              \
        type result = *((const volatile type *)var);                           \
        irq_restore(state);                                                    \
        return result;                                                         \
    }

Generates a static inline function implementing atomic_load_u<width>()

Parameters

name	Name of the variable type, e.g. "u8"
type	Variable type, e.g. `uint8_t`

Definition at line 714 of file atomic_utils.h.

◆ ATOMIC_STORE_IMPL

#define ATOMIC_STORE_IMPL	(	name,
		type
	)

Value:

    static inline void CONCAT(atomic_store_, name)(type *dest, type val)       \
    {                                                                          \
        unsigned state = irq_disable();                                        \
        /* dest can be register allocated, hence the memory barrier of         \
         * irq_disable() and irq_restore() may not apply here. Using volatile  \
         * ensures that the compiler allocates it in memory and that the       \
         * memory access is not optimized out. */                              \
        *((volatile type *)dest) = val;                                        \
        irq_restore(state);                                                    \
    }

Generates a static inline function implementing atomic_store_u<width>()

Parameters

name	Name of the variable type, e.g. "u8"
type	Variable type, e.g. `uint8_t`

Definition at line 744 of file atomic_utils.h.

Function Documentation

◆ atomic_bit_u16()

static atomic_bit_u16_t atomic_bit_u16	(	uint16_t *	dest,
		uint8_t	bit
	)

inlinestatic

Create a reference to a bit in an uint16_t

Parameters

[in]	dest	Memory containing the bit
[in]	bit	Bit number (`0` refers to the least significant)

Definition at line 857 of file atomic_utils.h.

◆ atomic_bit_u32()

static atomic_bit_u32_t atomic_bit_u32	(	uint32_t *	dest,
		uint8_t	bit
	)

inlinestatic

Create a reference to a bit in an uint32_t

Parameters

[in]	dest	Memory containing the bit
[in]	bit	Bit number (`0` refers to the least significant)

Definition at line 862 of file atomic_utils.h.

◆ atomic_bit_u64()

static atomic_bit_u64_t atomic_bit_u64	(	uint64_t *	dest,
		uint8_t	bit
	)

inlinestatic

Create a reference to a bit in an uint64_t

Parameters

[in]	dest	Memory containing the bit
[in]	bit	Bit number (`0` refers to the least significant)

Definition at line 867 of file atomic_utils.h.

◆ atomic_bit_u8()

static atomic_bit_u8_t atomic_bit_u8	(	uint8_t *	dest,
		uint8_t	bit
	)

inlinestatic

Create a reference to a bit in an uint8_t

Parameters

[in]	dest	Memory containing the bit
[in]	bit	Bit number (`0` refers to the least significant)

Definition at line 852 of file atomic_utils.h.

◆ atomic_clear_bit_u16()

static void atomic_clear_bit_u16 ( atomic_bit_u16_t bit )

inlinestatic

Atomic version of *dest &= ~(1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 892 of file atomic_utils.h.

◆ atomic_clear_bit_u32()

static void atomic_clear_bit_u32 ( atomic_bit_u32_t bit )

inlinestatic

Atomic version of *dest &= ~(1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 896 of file atomic_utils.h.

◆ atomic_clear_bit_u64()

static void atomic_clear_bit_u64 ( atomic_bit_u64_t bit )

inlinestatic

Atomic version of *dest &= ~(1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 900 of file atomic_utils.h.

◆ atomic_clear_bit_u8()

static void atomic_clear_bit_u8 ( atomic_bit_u8_t bit )

inlinestatic

Atomic version of *dest &= ~(1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 888 of file atomic_utils.h.

◆ atomic_fetch_add_u16()

static void atomic_fetch_add_u16	(	uint16_t *	dest,
		uint16_t	summand
	)

inlinestatic

Atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value atomically in-place
[in]	summand	Value to add onto `dest`

◆ atomic_fetch_add_u32()

static void atomic_fetch_add_u32	(	uint32_t *	dest,
		uint32_t	summand
	)

inlinestatic

Atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value atomically in-place
[in]	summand	Value to add onto `dest`

◆ atomic_fetch_add_u64()

static void atomic_fetch_add_u64	(	uint64_t *	dest,
		uint64_t	summand
	)

inlinestatic

Atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value atomically in-place
[in]	summand	Value to add onto `dest`

◆ atomic_fetch_add_u8()

static void atomic_fetch_add_u8	(	uint8_t *	dest,
		uint8_t	summand
	)

inlinestatic

Atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value atomically in-place
[in]	summand	Value to add onto `dest`

◆ atomic_fetch_and_u16()

static void atomic_fetch_and_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

◆ atomic_fetch_and_u32()

static void atomic_fetch_and_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

◆ atomic_fetch_and_u64()

static void atomic_fetch_and_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

◆ atomic_fetch_and_u8()

static void atomic_fetch_and_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

◆ atomic_fetch_or_u16()

static void atomic_fetch_or_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

◆ atomic_fetch_or_u32()

static void atomic_fetch_or_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

◆ atomic_fetch_or_u64()

static void atomic_fetch_or_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

◆ atomic_fetch_or_u8()

static void atomic_fetch_or_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

◆ atomic_fetch_sub_u16()

static void atomic_fetch_sub_u16	(	uint16_t *	dest,
		uint16_t	subtrahend
	)

inlinestatic

Atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value atomically in-place
[in]	subtrahend	Value to subtract from `dest`

◆ atomic_fetch_sub_u32()

static void atomic_fetch_sub_u32	(	uint32_t *	dest,
		uint32_t	subtrahend
	)

inlinestatic

Atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value atomically in-place
[in]	subtrahend	Value to subtract from `dest`

◆ atomic_fetch_sub_u64()

static void atomic_fetch_sub_u64	(	uint64_t *	dest,
		uint64_t	subtrahend
	)

inlinestatic

Atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value atomically in-place
[in]	subtrahend	Value to subtract from `dest`

◆ atomic_fetch_sub_u8()

static void atomic_fetch_sub_u8	(	uint8_t *	dest,
		uint8_t	subtrahend
	)

inlinestatic

Atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value atomically in-place
[in]	subtrahend	Value to subtract from `dest`

◆ atomic_fetch_xor_u16()

static void atomic_fetch_xor_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

◆ atomic_fetch_xor_u32()

static void atomic_fetch_xor_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

◆ atomic_fetch_xor_u64()

static void atomic_fetch_xor_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

◆ atomic_fetch_xor_u8()

static void atomic_fetch_xor_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

◆ atomic_load_u16()

static uint16_t atomic_load_u16 ( const uint16_t * var )

inlinestatic

Load an uint16_t atomically.

Parameters

[in] var Variable to load atomically

Returns: The value stored in var

◆ atomic_load_u32()

static uint32_t atomic_load_u32 ( const uint32_t * var )

inlinestatic

Load an uint32_t atomically.

Parameters

[in] var Variable to load atomically

Returns: The value stored in var

◆ atomic_load_u64()

static uint64_t atomic_load_u64 ( const uint64_t * var )

inlinestatic

Load an uint64_t atomically.

Parameters

[in] var Variable to load atomically

Returns: The value stored in var

◆ atomic_load_u8()

static uint8_t atomic_load_u8 ( const uint8_t * var )

inlinestatic

Load an uint8_t atomically.

Parameters

[in] var Variable to load atomically

Returns: The value stored in var

◆ atomic_set_bit_u16()

static void atomic_set_bit_u16 ( atomic_bit_u16_t bit )

inlinestatic

Atomic version of *dest |= (1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 876 of file atomic_utils.h.

◆ atomic_set_bit_u32()

static void atomic_set_bit_u32 ( atomic_bit_u32_t bit )

inlinestatic

Atomic version of *dest |= (1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 880 of file atomic_utils.h.

◆ atomic_set_bit_u64()

static void atomic_set_bit_u64 ( atomic_bit_u64_t bit )

inlinestatic

Atomic version of *dest |= (1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 884 of file atomic_utils.h.

◆ atomic_set_bit_u8()

static void atomic_set_bit_u8 ( atomic_bit_u8_t bit )

inlinestatic

Atomic version of *dest |= (1 << bit)

Parameters

[in,out] bit bit to set

Definition at line 872 of file atomic_utils.h.

◆ atomic_store_u16()

static void atomic_store_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Store an uint16_t atomically.

Parameters

[out]	dest	Location to atomically write the new value to
[in]	val	Value to write

◆ atomic_store_u32()

static void atomic_store_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Store an uint32_t atomically.

Parameters

[out]	dest	Location to atomically write the new value to
[in]	val	Value to write

◆ atomic_store_u64()

static void atomic_store_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Store an uint64_t atomically.

Parameters

[out]	dest	Location to atomically write the new value to
[in]	val	Value to write

◆ atomic_store_u8()

static void atomic_store_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Store an uint8_t atomically.

Parameters

[out]	dest	Location to atomically write the new value to
[in]	val	Value to write

◆ semi_atomic_fetch_add_u16()

static void semi_atomic_fetch_add_u16	(	uint16_t *	dest,
		uint16_t	summand
	)

inlinestatic

Semi-atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value semi-atomically in-place
[in]	summand	Value to add onto `dest`

Definition at line 930 of file atomic_utils.h.

◆ semi_atomic_fetch_add_u32()

static void semi_atomic_fetch_add_u32	(	uint32_t *	dest,
		uint32_t	summand
	)

inlinestatic

Semi-atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value semi-atomically in-place
[in]	summand	Value to add onto `dest`

Definition at line 940 of file atomic_utils.h.

◆ semi_atomic_fetch_add_u64()

static void semi_atomic_fetch_add_u64	(	uint64_t *	dest,
		uint64_t	summand
	)

inlinestatic

Semi-atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value semi-atomically in-place
[in]	summand	Value to add onto `dest`

Definition at line 950 of file atomic_utils.h.

◆ semi_atomic_fetch_add_u8()

static void semi_atomic_fetch_add_u8	(	uint8_t *	dest,
		uint8_t	summand
	)

inlinestatic

Semi-atomically add a value onto a given value.

Parameters

[in,out]	dest	Add `summand` onto this value semi-atomically in-place
[in]	summand	Value to add onto `dest`

Definition at line 920 of file atomic_utils.h.

◆ semi_atomic_fetch_and_u16()

static void semi_atomic_fetch_and_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Semi-atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

Definition at line 1094 of file atomic_utils.h.

◆ semi_atomic_fetch_and_u32()

static void semi_atomic_fetch_and_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Semi-atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

Definition at line 1104 of file atomic_utils.h.

◆ semi_atomic_fetch_and_u64()

static void semi_atomic_fetch_and_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Semi-atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

Definition at line 1114 of file atomic_utils.h.

◆ semi_atomic_fetch_and_u8()

static void semi_atomic_fetch_and_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Semi-atomic version of *dest &= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest & val`
[in]	val	Value to bitwise and into `dest` in-place

Definition at line 1084 of file atomic_utils.h.

◆ semi_atomic_fetch_or_u16()

static void semi_atomic_fetch_or_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Semi-atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

Definition at line 1012 of file atomic_utils.h.

◆ semi_atomic_fetch_or_u32()

static void semi_atomic_fetch_or_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Semi-atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

Definition at line 1022 of file atomic_utils.h.

◆ semi_atomic_fetch_or_u64()

static void semi_atomic_fetch_or_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Semi-atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

Definition at line 1032 of file atomic_utils.h.

◆ semi_atomic_fetch_or_u8()

static void semi_atomic_fetch_or_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Semi-atomic version of *dest |= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest \| val`
[in]	val	Value to bitwise or into `dest` in-place

Definition at line 1002 of file atomic_utils.h.

◆ semi_atomic_fetch_sub_u16()

static void semi_atomic_fetch_sub_u16	(	uint16_t *	dest,
		uint16_t	subtrahend
	)

inlinestatic

Semi-atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value semi-atomically in-place
[in]	subtrahend	Value to subtract from `dest`

Definition at line 971 of file atomic_utils.h.

◆ semi_atomic_fetch_sub_u32()

static void semi_atomic_fetch_sub_u32	(	uint32_t *	dest,
		uint32_t	subtrahend
	)

inlinestatic

Semi-atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value semi-atomically in-place
[in]	subtrahend	Value to subtract from `dest`

Definition at line 981 of file atomic_utils.h.

◆ semi_atomic_fetch_sub_u64()

static void semi_atomic_fetch_sub_u64	(	uint64_t *	dest,
		uint64_t	subtrahend
	)

inlinestatic

Semi-atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value semi-atomically in-place
[in]	subtrahend	Value to subtract from `dest`

Definition at line 991 of file atomic_utils.h.

◆ semi_atomic_fetch_sub_u8()

static void semi_atomic_fetch_sub_u8	(	uint8_t *	dest,
		uint8_t	subtrahend
	)

inlinestatic

Semi-atomically subtract a value from a given value.

Parameters

[in,out]	dest	Subtract `subtrahend` from this value semi-atomically in-place
[in]	subtrahend	Value to subtract from `dest`

Definition at line 961 of file atomic_utils.h.

◆ semi_atomic_fetch_xor_u16()

static void semi_atomic_fetch_xor_u16	(	uint16_t *	dest,
		uint16_t	val
	)

inlinestatic

Semi-atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

Definition at line 1053 of file atomic_utils.h.

◆ semi_atomic_fetch_xor_u32()

static void semi_atomic_fetch_xor_u32	(	uint32_t *	dest,
		uint32_t	val
	)

inlinestatic

Semi-atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

Definition at line 1063 of file atomic_utils.h.

◆ semi_atomic_fetch_xor_u64()

static void semi_atomic_fetch_xor_u64	(	uint64_t *	dest,
		uint64_t	val
	)

inlinestatic

Semi-atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

Definition at line 1073 of file atomic_utils.h.

◆ semi_atomic_fetch_xor_u8()

static void semi_atomic_fetch_xor_u8	(	uint8_t *	dest,
		uint8_t	val
	)

inlinestatic

Semi-atomic version of *dest ^= val

Parameters

[in,out]	dest	Replace this value with the result of `*dest ^ val`
[in]	val	Value to bitwise xor into `dest` in-place

Definition at line 1043 of file atomic_utils.h.

Detailed Description

Usage

Motivation

Guarantees

Porting to new CPUs

Files

Data Structures

Macros

Atomic Loads

Atomic Stores

Atomic In-Place Addition

Atomic In-Place Subtraction

Atomic In-Place Bitwise OR

Atomic In-Place Bitwise XOR

Atomic In-Place Bitwise AND

Helper Functions to Handle Atomic Bit References

Atomic Bit Setting

Atomic Bit Clearing

Semi-Atomic In-Place Addition

Semi-Atomic In-Place Subtraction

Semi-atomic In-Place Bitwise OR

Semi-Atomic In-Place Bitwise XOR

Semi-Atomic In-Place Bitwise AND

Macro Definition Documentation

◆ ATOMIC_FETCH_OP_IMPL

◆ ATOMIC_LOAD_IMPL

◆ ATOMIC_STORE_IMPL

Function Documentation

◆ atomic_bit_u16()

◆ atomic_bit_u32()

◆ atomic_bit_u64()

◆ atomic_bit_u8()

◆ atomic_clear_bit_u16()

◆ atomic_clear_bit_u32()

◆ atomic_clear_bit_u64()

◆ atomic_clear_bit_u8()

◆ atomic_fetch_add_u16()

◆ atomic_fetch_add_u32()

◆ atomic_fetch_add_u64()

◆ atomic_fetch_add_u8()

◆ atomic_fetch_and_u16()

◆ atomic_fetch_and_u32()

◆ atomic_fetch_and_u64()

◆ atomic_fetch_and_u8()

◆ atomic_fetch_or_u16()

◆ atomic_fetch_or_u32()

◆ atomic_fetch_or_u64()

◆ atomic_fetch_or_u8()

◆ atomic_fetch_sub_u16()

◆ atomic_fetch_sub_u32()

◆ atomic_fetch_sub_u64()

◆ atomic_fetch_sub_u8()

◆ atomic_fetch_xor_u16()

◆ atomic_fetch_xor_u32()

◆ atomic_fetch_xor_u64()

◆ atomic_fetch_xor_u8()

◆ atomic_load_u16()

◆ atomic_load_u32()

◆ atomic_load_u64()

◆ atomic_load_u8()

◆ atomic_set_bit_u16()

◆ atomic_set_bit_u32()

◆ atomic_set_bit_u64()

◆ atomic_set_bit_u8()

◆ atomic_store_u16()

◆ atomic_store_u32()

◆ atomic_store_u64()

◆ atomic_store_u8()

◆ semi_atomic_fetch_add_u16()

◆ semi_atomic_fetch_add_u32()

◆ semi_atomic_fetch_add_u64()

◆ semi_atomic_fetch_add_u8()

◆ semi_atomic_fetch_and_u16()

◆ semi_atomic_fetch_and_u32()

◆ semi_atomic_fetch_and_u64()

◆ semi_atomic_fetch_and_u8()

◆ semi_atomic_fetch_or_u16()

◆ semi_atomic_fetch_or_u32()

◆ semi_atomic_fetch_or_u64()

◆ semi_atomic_fetch_or_u8()