mirror of
https://github.com/RIOT-OS/RIOT.git
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99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
/*
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* Copyright (C) 2014 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup pthread
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* @{
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* @file
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* @brief Spin locks.
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* @note Do not include this header file directly, but pthread.h.
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* @warning Spinlocks should be avoided.
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* They will burn away the battery needlessly, and may not work because RIOT is tickless.
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* Use irq_disable() and irq_restore() for shortterm locks instead.
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*/
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#ifndef PTHREAD_SPIN_H
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#define PTHREAD_SPIN_H
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#include <stdatomic.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief A spinlock.
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* @warning Spinlocks should be avoided.
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* They will burn away the battery needlessly, and may not work because RIOT is tickless.
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* Use irq_disable() and irq_restore() for shortterm locks instead.
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*/
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typedef struct {
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atomic_flag flag; /**< Current lock state */
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} pthread_spinlock_t;
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/**
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* @brief Intializes a spinlock.
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* @warning See the warning in pthread_spinlock_t.
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* @details A zeroed out datum is initialized.
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* @param[in,out] lock Datum to initialize.
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* @param[in] pshared Unused.
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* @returns `0` on success.
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* `EINVAL` if `lock == NULL`.
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*/
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int pthread_spin_init(pthread_spinlock_t *lock, int pshared);
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/**
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* @brief Destroys a spinlock.
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* @warning See the warning in pthread_spinlock_t.
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* @details Destroying a spinlock while a thread is waiting for it causes undefined behavior.
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* This is a no-op.
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* @param[in,out] lock Datum to destroy.
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* @returns `0` on success.
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* `EINVAL` if `lock == NULL`.
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*/
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int pthread_spin_destroy(pthread_spinlock_t *lock);
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/**
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* @brief Lock a spinlock.
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* @warning See the warning in pthread_spinlock_t.
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* @param[in,out] lock Lock to acquire.
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* @return `0` on success.
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* `EINVAL` if `lock == NULL`.
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*/
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int pthread_spin_lock(pthread_spinlock_t *lock);
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/**
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* @brief Tries to lock a spinlock, returns immediately if already locked.
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* @warning See the warning in pthread_spinlock_t.
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* @param[in,out] lock Lock to acquire.
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* @return `0` on success.
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* `EBUSY` if the lock was already locked.
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* `EINVAL` if `lock == NULL`.
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*/
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int pthread_spin_trylock(pthread_spinlock_t *lock);
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/**
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* @brief Releases a spinlock.
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* @warning See the warning in pthread_spinlock_t.
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* @param[in,out] lock Lock to release
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* @return `0` on success.
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* `EPERM` if the lock was not locked.
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* `EINVAL` if `lock == NULL`.
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*/
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int pthread_spin_unlock(pthread_spinlock_t *lock);
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#ifdef __cplusplus
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}
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#endif
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#endif /* PTHREAD_SPIN_H */
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/**
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* @}
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*/
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