421 lines
10 KiB
C
421 lines
10 KiB
C
/* atomic operations */
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/*
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* Copyright (c) 1997-2015, Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef __ATOMIC_H__
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#define __ATOMIC_H__
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef int atomic_t;
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typedef atomic_t atomic_val_t;
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/**
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* @defgroup atomic_apis Atomic Services APIs
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* @ingroup kernel_apis
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* @{
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*/
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/**
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* @brief Atomic compare-and-set.
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*
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* This routine performs an atomic compare-and-set on @a target. If the current
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* value of @a target equals @a old_value, @a target is set to @a new_value.
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* If the current value of @a target does not equal @a old_value, @a target
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* is left unchanged.
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*
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* @param target Address of atomic variable.
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* @param old_value Original value to compare against.
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* @param new_value New value to store.
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* @return 1 if @a new_value is written, 0 otherwise.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline int atomic_cas(atomic_t *target, atomic_val_t old_value,
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atomic_val_t new_value)
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{
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return __atomic_compare_exchange_n(target, &old_value, new_value,
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0, __ATOMIC_SEQ_CST,
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__ATOMIC_SEQ_CST);
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}
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#else
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extern int atomic_cas(atomic_t *target, atomic_val_t old_value,
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atomic_val_t new_value);
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#endif
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/**
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*
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* @brief Atomic addition.
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*
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* This routine performs an atomic addition on @a target.
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*
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* @param target Address of atomic variable.
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* @param value Value to add.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_add(atomic_t *target, atomic_val_t value)
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{
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return __atomic_fetch_add(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_add(atomic_t *target, atomic_val_t value);
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#endif
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/**
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*
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* @brief Atomic subtraction.
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*
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* This routine performs an atomic subtraction on @a target.
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*
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* @param target Address of atomic variable.
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* @param value Value to subtract.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value)
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{
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return __atomic_fetch_sub(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value);
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#endif
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/**
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*
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* @brief Atomic increment.
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*
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* This routine performs an atomic increment by 1 on @a target.
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_inc(atomic_t *target)
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{
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return atomic_add(target, 1);
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}
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#else
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extern atomic_val_t atomic_inc(atomic_t *target);
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#endif
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/**
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*
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* @brief Atomic decrement.
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*
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* This routine performs an atomic decrement by 1 on @a target.
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_dec(atomic_t *target)
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{
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return atomic_sub(target, 1);
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}
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#else
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extern atomic_val_t atomic_dec(atomic_t *target);
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#endif
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/**
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*
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* @brief Atomic get.
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*
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* This routine performs an atomic read on @a target.
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*
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* @param target Address of atomic variable.
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*
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* @return Value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_get(const atomic_t *target)
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{
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return __atomic_load_n(target, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_get(const atomic_t *target);
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#endif
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/**
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*
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* @brief Atomic get-and-set.
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*
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* This routine atomically sets @a target to @a value and returns
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* the previous value of @a target.
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*
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* @param target Address of atomic variable.
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* @param value Value to write to @a target.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_set(atomic_t *target, atomic_val_t value)
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{
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/* This builtin, as described by Intel, is not a traditional
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* test-and-set operation, but rather an atomic exchange operation. It
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* writes value into *ptr, and returns the previous contents of *ptr.
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*/
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return __atomic_exchange_n(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_set(atomic_t *target, atomic_val_t value);
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#endif
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/**
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*
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* @brief Atomic clear.
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*
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* This routine atomically sets @a target to zero and returns its previous
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* value. (Hence, it is equivalent to atomic_set(target, 0).)
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_clear(atomic_t *target)
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{
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return atomic_set(target, 0);
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}
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#else
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extern atomic_val_t atomic_clear(atomic_t *target);
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#endif
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/**
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*
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* @brief Atomic bitwise inclusive OR.
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*
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* This routine atomically sets @a target to the bitwise inclusive OR of
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* @a target and @a value.
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*
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* @param target Address of atomic variable.
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* @param value Value to OR.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_or(atomic_t *target, atomic_val_t value)
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{
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return __atomic_fetch_or(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_or(atomic_t *target, atomic_val_t value);
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#endif
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/**
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*
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* @brief Atomic bitwise exclusive OR (XOR).
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*
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* This routine atomically sets @a target to the bitwise exclusive OR (XOR) of
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* @a target and @a value.
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*
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* @param target Address of atomic variable.
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* @param value Value to XOR
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value)
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{
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return __atomic_fetch_xor(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value);
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#endif
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/**
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*
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* @brief Atomic bitwise AND.
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*
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* This routine atomically sets @a target to the bitwise AND of @a target
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* and @a value.
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*
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* @param target Address of atomic variable.
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* @param value Value to AND.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_and(atomic_t *target, atomic_val_t value)
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{
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return __atomic_fetch_and(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_and(atomic_t *target, atomic_val_t value);
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#endif
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/**
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*
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* @brief Atomic bitwise NAND.
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*
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* This routine atomically sets @a target to the bitwise NAND of @a target
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* and @a value. (This operation is equivalent to target = ~(target & value).)
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*
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* @param target Address of atomic variable.
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* @param value Value to NAND.
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*
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* @return Previous value of @a target.
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*/
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#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
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static inline atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value)
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{
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return __atomic_fetch_nand(target, value, __ATOMIC_SEQ_CST);
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}
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#else
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extern atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value);
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#endif
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/**
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* @brief Initialize an atomic variable.
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*
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* This macro can be used to initialize an atomic variable. For example,
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* @code atomic_t my_var = ATOMIC_INIT(75); @endcode
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*
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* @param i Value to assign to atomic variable.
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*/
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#define ATOMIC_INIT(i) (i)
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/**
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* @cond INTERNAL_HIDDEN
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*/
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#define ATOMIC_BITS (sizeof(atomic_val_t) * 8)
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#define ATOMIC_MASK(bit) (1 << ((bit) & (ATOMIC_BITS - 1)))
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#define ATOMIC_ELEM(addr, bit) ((addr) + ((bit) / ATOMIC_BITS))
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/**
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* INTERNAL_HIDDEN @endcond
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*/
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/**
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* @brief Define an array of atomic variables.
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*
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* This macro defines an array of atomic variables containing at least
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* @a num_bits bits.
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*
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* @note
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* If used from file scope, the bits of the array are initialized to zero;
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* if used from within a function, the bits are left uninitialized.
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*
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* @param name Name of array of atomic variables.
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* @param num_bits Number of bits needed.
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*/
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#define ATOMIC_DEFINE(name, num_bits) \
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atomic_t name[1 + ((num_bits) - 1) / ATOMIC_BITS]
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/**
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* @brief Atomically test a bit.
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*
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* This routine tests whether bit number @a bit of @a target is set or not.
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* The target may be a single atomic variable or an array of them.
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return 1 if the bit was set, 0 if it wasn't.
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*/
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static inline int atomic_test_bit(const atomic_t *target, int bit)
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{
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atomic_val_t val = atomic_get(ATOMIC_ELEM(target, bit));
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return (1 & (val >> (bit & (ATOMIC_BITS - 1))));
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}
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/**
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* @brief Atomically test and clear a bit.
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*
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* Atomically clear bit number @a bit of @a target and return its old value.
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* The target may be a single atomic variable or an array of them.
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return 1 if the bit was set, 0 if it wasn't.
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*/
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static inline int atomic_test_and_clear_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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atomic_val_t old;
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old = atomic_and(ATOMIC_ELEM(target, bit), ~mask);
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return (old & mask) != 0;
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}
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/**
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* @brief Atomically set a bit.
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*
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* Atomically set bit number @a bit of @a target and return its old value.
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* The target may be a single atomic variable or an array of them.
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return 1 if the bit was set, 0 if it wasn't.
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*/
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static inline int atomic_test_and_set_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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atomic_val_t old;
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old = atomic_or(ATOMIC_ELEM(target, bit), mask);
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return (old & mask) != 0;
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}
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/**
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* @brief Atomically clear a bit.
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*
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* Atomically clear bit number @a bit of @a target.
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* The target may be a single atomic variable or an array of them.
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return N/A
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*/
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static inline void atomic_clear_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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atomic_and(ATOMIC_ELEM(target, bit), ~mask);
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}
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/**
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* @brief Atomically set a bit.
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*
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* Atomically set bit number @a bit of @a target.
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* The target may be a single atomic variable or an array of them.
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return N/A
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*/
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static inline void atomic_set_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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atomic_or(ATOMIC_ELEM(target, bit), mask);
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}
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/**
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* @}
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*/
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#ifdef __cplusplus
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}
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#endif
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#endif /* __ATOMIC_H__ */
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