/*
* Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
* Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _LOS_ARCH_ATOMIC_H
#define _LOS_ARCH_ATOMIC_H
#include "los_compiler.h"
#ifdef __cplusplus
#if __cplusplus
extern "C" {
#endif /* __cplusplus */
#endif /* __cplusplus */
/**
* @ingroup los_arch_atomic
* @brief Atomic exchange for 32-bit variable.
*
* @par Description:
* This API is used to implement the atomic exchange for 32-bit variable and return the previous value of the atomic variable.
* @attention
*
The pointer v must not be NULL.
*
* @param v [IN] The variable pointer.
* @param val [IN] The exchange value.
*
* @retval #INT32 The previous value of the atomic variable
* @par Dependency:
* - los_arch_atomic.h: the header file that contains the API declaration.
* @see
*/
STATIC INLINE INT32 ArchAtomicXchg32bits(volatile INT32 *v, INT32 val)
{
INT32 prevVal = 0;
UINT32 status = 0;
do {
__asm__ __volatile__("ldrex %0, [%3]\n"
"strex %1, %4, [%3]"
: "=&r"(prevVal), "=&r"(status), "+m"(*v)
: "r"(v), "r"(val)
: "cc");
} while (__builtin_expect(status != 0, 0));
return prevVal;
}
/**
* @ingroup los_arch_atomic
* @brief Atomic auto-decrement.
*
* @par Description:
* This API is used to implement the atomic auto-decrement and return the result of auto-decrement.
* @attention
*
* - The pointer v must not be NULL.
* - The value which v point to must not be INT_MIN to avoid overflow after reducing 1.
*
*
* @param v [IN] The addSelf variable pointer.
*
* @retval #INT32 The return value of variable auto-decrement.
* @par Dependency:
* - los_arch_atomic.h: the header file that contains the API declaration.
* @see
*/
STATIC INLINE INT32 ArchAtomicDecRet(volatile INT32 *v)
{
INT32 val = 0;
UINT32 status = 0;
do {
__asm__ __volatile__("ldrex %0, [%3]\n"
"sub %0, %0, #1\n"
"strex %1, %0, [%3]"
: "=&r"(val), "=&r"(status), "+m"(*v)
: "r"(v)
: "cc");
} while (__builtin_expect(status != 0, 0));
return val;
}
/**
* @ingroup los_arch_atomic
* @brief Atomic exchange for 32-bit variable with compare.
*
* @par Description:
* This API is used to implement the atomic exchange for 32-bit variable, if the value of variable is equal to oldVal.
* @attention
* The pointer v must not be NULL.
*
* @param v [IN] The variable pointer.
* @param val [IN] The new value.
* @param oldVal [IN] The old value.
*
* @retval TRUE The previous value of the atomic variable is not equal to oldVal.
* @retval FALSE The previous value of the atomic variable is equal to oldVal.
* @par Dependency:
* - los_arch_atomic.h: the header file that contains the API declaration.
* @see
*/
STATIC INLINE BOOL ArchAtomicCmpXchg32bits(volatile INT32 *v, INT32 val, INT32 oldVal)
{
INT32 prevVal = 0;
UINT32 status = 0;
do {
__asm__ __volatile__("1: ldrex %0, %2\n"
" mov %1, #0\n"
" cmp %0, %3\n"
" bne 2f\n"
" strex %1, %4, %2\n"
"2:"
: "=&r"(prevVal), "=&r"(status), "+Q"(*v)
: "r"(oldVal), "r"(val)
: "cc");
} while (__builtin_expect(status != 0, 0));
return prevVal != oldVal;
}
#ifdef __cplusplus
#if __cplusplus
}
#endif /* __cplusplus */
#endif /* __cplusplus */
#endif /* _LOS_ARCH_ATOMIC_H */