arch_atomic.h — 原子操作接口头文件

源文件路径: arch/arm/armv7m/include/arch_atomic.h

引用章节: 4.3.6 自旋锁 | 4.8 SMP 多核支持

完整源码

/**
 ***********************************************************************************************************************
 * Copyright (c) 2020, China Mobile Communications Group Co.,Ltd.
 *
 * 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.
 *
 * @file        arch_atomic.h
 *
 * @brief       Header file for atomic interface.
 *
 * @revision
 * Date         Author          Notes
 * 2021-01-08   OneOS Team      First version.
 ***********************************************************************************************************************
 */

#ifndef __ARCH_ATOMIC_H__
#define __ARCH_ATOMIC_H__

#include <os_types.h>

#ifdef __cplusplus
extern "C" {
#endif

struct os_atomic
{
    volatile int32_t counter;
};
typedef struct os_atomic os_atomic_t;

/*
 * Apply to initializtion of variate which is defined by the "os_atomic_t".
 */
#define OS_ATOMIC_INIT(val)                                                                                            \
    {                                                                                                                  \
        (val)                                                                                                          \
    }

#define os_atomic_read(ptr)       ((ptr)->counter)
#define os_atomic_set(ptr, value) (((ptr)->counter) = (value))

extern void os_atomic_add(os_atomic_t *mem, int32_t value);
extern void os_atomic_sub(os_atomic_t *mem, int32_t value);
extern void os_atomic_inc(os_atomic_t *mem);
extern void os_atomic_dec(os_atomic_t *mem);

extern int32_t os_atomic_add_return(os_atomic_t *mem, int32_t value);
extern int32_t os_atomic_sub_return(os_atomic_t *mem, int32_t value);
extern int32_t os_atomic_inc_return(os_atomic_t *mem);
extern int32_t os_atomic_dec_return(os_atomic_t *mem);

extern int32_t os_atomic_xchg(os_atomic_t *mem, int32_t value);
extern os_bool_t  os_atomic_cmpxchg(os_atomic_t *mem, int32_t old, int32_t new);

extern void os_atomic_and(os_atomic_t *mem, int32_t value);
extern void os_atomic_or(os_atomic_t *mem, int32_t value);
extern void os_atomic_nand(os_atomic_t *mem, int32_t value);
extern void os_atomic_xor(os_atomic_t *mem, int32_t value);

extern os_bool_t os_atomic_test_bit(os_atomic_t *mem, int32_t nr);
extern void      os_atomic_set_bit(os_atomic_t *mem, int32_t nr);
extern void      os_atomic_clear_bit(os_atomic_t *mem, int32_t nr);
extern void      os_atomic_change_bit(os_atomic_t *mem, int32_t nr);

#ifdef __cplusplus
}
#endif

#endif /* __ARCH_ATOMIC_H__ */

关键说明

模块	说明
数据结构	os_atomic_t 包含 volatile int32_t counter，使用 volatile 防止编译器优化
初始化	OS_ATOMIC_INIT(val) 宏用于静态初始化，os_atomic_read/set 宏用于读写
算术操作	add/sub/inc/dec 实现原子加减，*_return 版本返回操作后的值
交换操作	os_atomic_xchg 原子交换值，os_atomic_cmpxchg 原子比较并交换（CAS）
位操作	and/or/nand/xor 原子位逻辑操作，test/set/clear/change_bit 原子位操作
实现	ARMv7-M 单核上通过 os_irq_lock/unlock 关中断实现原子性；ARMv7-R/A 多核使用 LDREX/STREX 指令