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74 lines
2.2 KiB
C
74 lines
2.2 KiB
C
/*
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* SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#pragma once
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#include <time.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef unsigned int sem_t;
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/**
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* This is the maximum value to which any POSIX semaphore can count on ESP chips.
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*/
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#define SEM_VALUE_MAX 0x7FFF
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*
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* Must NOT be called if threads are still blocked on semaphore!
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*/
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int sem_destroy(sem_t *sem);
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*
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* Note that on ESP chips, pshared is ignored. Semaphores can always be shared between FreeRTOS tasks.
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*/
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int sem_init(sem_t *sem, int pshared, unsigned value);
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*
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* Note that, unlike specified in POSIX, this implementation returns -1 and sets errno to
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* EAGAIN if the semaphore can not be unlocked (posted) due to its value being SEM_VALUE_MAX.
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*/
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int sem_post(sem_t *sem);
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*
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* Note the following three deviations/issues originating from the underlying FreeRTOS implementation:
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* * The time value passed by abstime will be rounded up to the next FreeRTOS tick.
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* * The actual timeout will happen after the tick the time was rounded to
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* and before the following tick.
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* * It is possible, though unlikely, that the task is preempted directly after the timeout calculation,
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* delaying timeout of the following blocking operating system call by the duration of the preemption.
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*/
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int sem_timedwait(sem_t *semaphore, const struct timespec *abstime);
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*/
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int sem_trywait(sem_t *sem);
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*/
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int sem_wait(sem_t *sem);
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/**
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* This is a POSIX function, please refer to the POSIX specification for a detailed description.
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*/
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int sem_getvalue(sem_t *sem, int *sval);
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#ifdef __cplusplus
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}
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#endif
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