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/* atomic operations */
/*
* Copyright (c) 1997-2015, Wind River Systems, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __ATOMIC_H__
#define __ATOMIC_H__
#ifdef __cplusplus
extern "C" {
#endif
typedef int atomic_t;
typedef atomic_t atomic_val_t;
/**
* @defgroup atomic_apis Atomic Services APIs
* @ingroup kernel_apis
* @{
*/
/**
* @brief Atomic compare-and-set.
*
* This routine performs an atomic compare-and-set on @a target. If the current
* value of @a target equals @a old_value, @a target is set to @a new_value.
* If the current value of @a target does not equal @a old_value, @a target
* is left unchanged.
*
* @param target Address of atomic variable.
* @param old_value Original value to compare against.
* @param new_value New value to store.
* @return 1 if @a new_value is written, 0 otherwise.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline int atomic_cas(atomic_t *target, atomic_val_t old_value,
atomic_val_t new_value)
{
return __atomic_compare_exchange_n(target, &old_value, new_value,
0, __ATOMIC_SEQ_CST,
__ATOMIC_SEQ_CST);
}
#else
extern int atomic_cas(atomic_t *target, atomic_val_t old_value,
atomic_val_t new_value);
#endif
/**
*
* @brief Atomic addition.
*
* This routine performs an atomic addition on @a target.
*
* @param target Address of atomic variable.
* @param value Value to add.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_add(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_add(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_add(atomic_t *target, atomic_val_t value);
#endif
/**
*
* @brief Atomic subtraction.
*
* This routine performs an atomic subtraction on @a target.
*
* @param target Address of atomic variable.
* @param value Value to subtract.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_sub(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value);
#endif
/**
*
* @brief Atomic increment.
*
* This routine performs an atomic increment by 1 on @a target.
*
* @param target Address of atomic variable.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_inc(atomic_t *target)
{
return atomic_add(target, 1);
}
#else
extern atomic_val_t atomic_inc(atomic_t *target);
#endif
/**
*
* @brief Atomic decrement.
*
* This routine performs an atomic decrement by 1 on @a target.
*
* @param target Address of atomic variable.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_dec(atomic_t *target)
{
return atomic_sub(target, 1);
}
#else
extern atomic_val_t atomic_dec(atomic_t *target);
#endif
/**
*
* @brief Atomic get.
*
* This routine performs an atomic read on @a target.
*
* @param target Address of atomic variable.
*
* @return Value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_get(const atomic_t *target)
{
return __atomic_load_n(target, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_get(const atomic_t *target);
#endif
/**
*
* @brief Atomic get-and-set.
*
* This routine atomically sets @a target to @a value and returns
* the previous value of @a target.
*
* @param target Address of atomic variable.
* @param value Value to write to @a target.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_set(atomic_t *target, atomic_val_t value)
{
/* This builtin, as described by Intel, is not a traditional
* test-and-set operation, but rather an atomic exchange operation. It
* writes value into *ptr, and returns the previous contents of *ptr.
*/
return __atomic_exchange_n(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_set(atomic_t *target, atomic_val_t value);
#endif
/**
*
* @brief Atomic clear.
*
* This routine atomically sets @a target to zero and returns its previous
* value. (Hence, it is equivalent to atomic_set(target, 0).)
*
* @param target Address of atomic variable.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_clear(atomic_t *target)
{
return atomic_set(target, 0);
}
#else
extern atomic_val_t atomic_clear(atomic_t *target);
#endif
/**
*
* @brief Atomic bitwise inclusive OR.
*
* This routine atomically sets @a target to the bitwise inclusive OR of
* @a target and @a value.
*
* @param target Address of atomic variable.
* @param value Value to OR.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_or(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_or(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_or(atomic_t *target, atomic_val_t value);
#endif
/**
*
* @brief Atomic bitwise exclusive OR (XOR).
*
* This routine atomically sets @a target to the bitwise exclusive OR (XOR) of
* @a target and @a value.
*
* @param target Address of atomic variable.
* @param value Value to XOR
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_xor(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value);
#endif
/**
*
* @brief Atomic bitwise AND.
*
* This routine atomically sets @a target to the bitwise AND of @a target
* and @a value.
*
* @param target Address of atomic variable.
* @param value Value to AND.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_and(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_and(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_and(atomic_t *target, atomic_val_t value);
#endif
/**
*
* @brief Atomic bitwise NAND.
*
* This routine atomically sets @a target to the bitwise NAND of @a target
* and @a value. (This operation is equivalent to target = ~(target & value).)
*
* @param target Address of atomic variable.
* @param value Value to NAND.
*
* @return Previous value of @a target.
*/
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_nand(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value);
#endif
/**
* @brief Initialize an atomic variable.
*
* This macro can be used to initialize an atomic variable. For example,
* @code atomic_t my_var = ATOMIC_INIT(75); @endcode
*
* @param i Value to assign to atomic variable.
*/
#define ATOMIC_INIT(i) (i)
/**
* @cond INTERNAL_HIDDEN
*/
#define ATOMIC_BITS (sizeof(atomic_val_t) * 8)
#define ATOMIC_MASK(bit) (1 << ((bit) & (ATOMIC_BITS - 1)))
#define ATOMIC_ELEM(addr, bit) ((addr) + ((bit) / ATOMIC_BITS))
/**
* INTERNAL_HIDDEN @endcond
*/
/**
* @brief Define an array of atomic variables.
*
* This macro defines an array of atomic variables containing at least
* @a 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.
*
* @param name Name of array of atomic variables.
* @param num_bits Number of bits needed.
*/
#define ATOMIC_DEFINE(name, num_bits) \
atomic_t name[1 + ((num_bits) - 1) / ATOMIC_BITS]
/**
* @brief Atomically test a bit.
*
* This routine tests whether bit number @a bit of @a target is set or not.
* The target may be a single atomic variable or an array of them.
*
* @param target Address of atomic variable or array.
* @param bit Bit number (starting from 0).
*
* @return 1 if the bit was set, 0 if it wasn't.
*/
static inline int atomic_test_bit(const atomic_t *target, int bit)
{
atomic_val_t val = atomic_get(ATOMIC_ELEM(target, bit));
return (1 & (val >> (bit & (ATOMIC_BITS - 1))));
}
/**
* @brief Atomically test and clear a bit.
*
* Atomically clear bit number @a bit of @a target and return its old value.
* The target may be a single atomic variable or an array of them.
*
* @param target Address of atomic variable or array.
* @param bit Bit number (starting from 0).
*
* @return 1 if the bit was set, 0 if it wasn't.
*/
static inline int atomic_test_and_clear_bit(atomic_t *target, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_val_t old;
old = atomic_and(ATOMIC_ELEM(target, bit), ~mask);
return (old & mask) != 0;
}
/**
* @brief Atomically set a bit.
*
* Atomically set bit number @a bit of @a target and return its old value.
* The target may be a single atomic variable or an array of them.
*
* @param target Address of atomic variable or array.
* @param bit Bit number (starting from 0).
*
* @return 1 if the bit was set, 0 if it wasn't.
*/
static inline int atomic_test_and_set_bit(atomic_t *target, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_val_t old;
old = atomic_or(ATOMIC_ELEM(target, bit), mask);
return (old & mask) != 0;
}
/**
* @brief Atomically clear a bit.
*
* Atomically clear bit number @a bit of @a target.
* The target may be a single atomic variable or an array of them.
*
* @param target Address of atomic variable or array.
* @param bit Bit number (starting from 0).
*
* @return N/A
*/
static inline void atomic_clear_bit(atomic_t *target, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_and(ATOMIC_ELEM(target, bit), ~mask);
}
/**
* @brief Atomically set a bit.
*
* Atomically set bit number @a bit of @a target.
* The target may be a single atomic variable or an array of them.
*
* @param target Address of atomic variable or array.
* @param bit Bit number (starting from 0).
*
* @return N/A
*/
static inline void atomic_set_bit(atomic_t *target, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_or(ATOMIC_ELEM(target, bit), mask);
}
/**
* @}
*/
#ifdef __cplusplus
}
#endif
#endif /* __ATOMIC_H__ */