sem.h

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/*
 * Copyright (c) 2019 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef ZEPHYR_INCLUDE_SYS_SEM_H_
#define ZEPHYR_INCLUDE_SYS_SEM_H_
 
/*
 * sys_sem exists in user memory working as counter semaphore for
 * user mode thread when user mode enabled. When user mode isn't
 * enabled, sys_sem behaves like k_sem.
 */
 
#include <zephyr/kernel.h>
#include <zephyr/sys/atomic.h>
#include <zephyr/types.h>
#include <zephyr/sys/iterable_sections.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
struct sys_sem {
#ifdef CONFIG_USERSPACE
        struct k_futex futex;
        int limit;
#else
        struct k_sem kernel_sem;
#endif
};
 
#ifdef CONFIG_USERSPACE
#define SYS_SEM_DEFINE(_name, _initial_count, _count_limit) \
        struct sys_sem _name = { \
                .futex = { _initial_count }, \
                .limit = _count_limit \
        }; \
        BUILD_ASSERT(((_count_limit) != 0) && \
                     ((_initial_count) <= (_count_limit)))
#else
/* Stuff this in the section with the rest of the k_sem objects, since they
 * are identical and can be treated as a k_sem in the boot initialization code
 */
#define SYS_SEM_DEFINE(_name, _initial_count, _count_limit) \
        STRUCT_SECTION_ITERABLE_ALTERNATE(k_sem, sys_sem, _name) = { \
                .kernel_sem = Z_SEM_INITIALIZER(_name.kernel_sem, \
                                                _initial_count, _count_limit) \
        }; \
        BUILD_ASSERT(((_count_limit) != 0) && \
                     ((_initial_count) <= (_count_limit)))
#endif
 
int sys_sem_init(struct sys_sem *sem, unsigned int initial_count,
                unsigned int limit);
 
int sys_sem_give(struct sys_sem *sem);
 
int sys_sem_take(struct sys_sem *sem, k_timeout_t timeout);
 
unsigned int sys_sem_count_get(struct sys_sem *sem);
 
#ifdef __cplusplus
}
#endif
 
#endif