text: /* ----------------------------------------------------------------------------
   * Copyright (c) Huawei Technologies Co., Ltd. 2013-2019. All rights reserved.
   * Description: Aarch32 Atomic HeadFile
   * 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.
   * --------------------------------------------------------------------------- */
  /* ----------------------------------------------------------------------------
   * Notice of Export Control Law
   * ===============================================
   * Huawei LiteOS may be subject to applicable export control laws and regulations, which might
   * include those applicable to Huawei LiteOS of U.S. and the country in which you are located.
   * Import, export and usage of Huawei LiteOS in any manner by you shall be in compliance with such
   * applicable export control laws and regulations.
   * --------------------------------------------------------------------------- */
  
  /**
   * @defgroup los_atomic Atomic
   * @ingroup kernel
   */
  
  #ifndef __LOS_ATOMIC_H__
  #define __LOS_ATOMIC_H__
  
  #include "los_typedef.h"
  
  #ifdef __cplusplus
  #if __cplusplus
  extern "C" {
  #endif /* __cplusplus */
  #endif /* __cplusplus */
  
  typedef volatile INT32 Atomic;
  typedef volatile INT64 Atomic64;
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic read.
   *
   * @par Description:
   * This API is used to implement the atomic read and return the result value of the read.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * </ul>
   *
   * @param  v         [IN] The reading pointer.
   *
   * @retval #INT32  The result value of the read.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT32 LOS_AtomicRead(const Atomic *v)
  {
      return *(volatile INT32 *)v;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic setting.
   *
   * @par Description:
   * This API is used to implement the atomic setting operation.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * </ul>
   *
   * @param  v         [IN] The variable pointer to be setting.
   * @param  setVal    [IN] The value to be setting.
   *
   * @retval none.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE VOID LOS_AtomicSet(Atomic *v, INT32 setVal)
  {
      *(volatile INT32 *)v = setVal;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic addition.
   *
   * @par Description:
   * This API is used to implement the atomic addition and return the result value of the augend.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>If the addtion result is not in the range of representable values for 32-bit signed integer,
   * an int integer overflow may occur to the return value</li>
   * </ul>
   *
   * @param  v         [IN] The augend pointer.
   * @param  addVal    [IN] The addend.
   *
   * @retval #INT32  The result value of the augend.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicAdd(Atomic *v, INT32 addVal)
  {
      INT32 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrex   %1, [%2]\n"
                               "add   %1, %1, %3\n"
                               "strex   %0, %1, [%2]"
                               : "=&r"(status), "=&r"(val)
                               : "r"(v), "r"(addVal)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic subtraction.
   *
   * @par Description:
   * This API is used to implement the atomic subtraction and return the result value of the minuend.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>If the subtraction result is not in the range of representable values for 32-bit signed integer,
   * an int integer overflow may occur to the return value</li>
   * </ul>
   *
   * @param  v         [IN] The minuend pointer.
   * @param  subVal    [IN] The subtrahend.
   *
   * @retval #INT32  The result value of the minuend.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicSub(Atomic *v, INT32 subVal)
  {
      INT32 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrex   %1, [%2]\n"
                               "sub   %1, %1, %3\n"
                               "strex   %0, %1, [%2]"
                               : "=&r"(status), "=&r"(val)
                               : "r"(v), "r"(subVal)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic addSelf.
   *
   * @par Description:
   * This API is used to implement the atomic addSelf.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT_MAX to avoid integer overflow after adding 1.</li>
   * </ul>
   *
   * @param  v      [IN] The addSelf variable pointer.
   *
   * @retval none.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE VOID LOS_AtomicInc(Atomic *v)
  {
      INT32 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrex   %0, [%3]\n"
                               "add   %0, %0, #1\n"
                               "strex   %1, %0, [%3]"
                               : "=&r"(val), "=&r"(status), "+m"(*v)
                               : "r"(v)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic addSelf.
   *
   * @par Description:
   * This API is used to implement the atomic addSelf and return the result of addSelf.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT_MAX to avoid integer overflow after adding 1.</li>
   * </ul>
   *
   * @param  v      [IN] The addSelf variable pointer.
   *
   * @retval #INT32 The return value of variable addSelf.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicIncRet(Atomic *v)
  {
      INT32 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrex   %0, [%3]\n"
                               "add   %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_atomic
   * @brief Atomic auto-decrement.
   *
   * @par Description:
   * This API is used to implementating the atomic auto-decrement.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT_MIN to avoid overflow after reducing 1.</li>
   * </ul>
   *
   * @param  v      [IN] The auto-decrement variable pointer.
   *
   * @retval none.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE VOID LOS_AtomicDec(Atomic *v)
  {
      INT32 val;
      UINT32 status;
  
      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));
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic auto-decrement.
   *
   * @par Description:
   * This API is used to implementating the atomic auto-decrement and return the result of auto-decrement.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT_MIN to avoid overflow after reducing 1.</li>
   * </ul>
   *
   * @param  v      [IN] The auto-decrement variable pointer.
   *
   * @retval #INT32  The return value of variable auto-decrement.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicDecRet(Atomic *v)
  {
      INT32 val;
      UINT32 status;
  
      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_atomic
   * @brief Atomic64 read.
   *
   * @par Description:
   * This API is used to implement the atomic64 read and return the result value of the read.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * </ul>
   *
   * @param  v         [IN] The reading pointer.
   *
   * @retval #INT64  The result value of the read.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT64 LOS_Atomic64Read(const Atomic64 *v)
  {
      INT64 val;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%1]"
                               : "=&r"(val)
                               : "r"(v)
                               : "cc");
      } while (0);
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 setting.
   *
   * @par Description:
   * This API is used to implement the atomic64 setting operation.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * </ul>
   *
   * @param  v         [IN] The variable pointer to be setting.
   * @param  setVal    [IN] The value to be setting.
   *
   * @retval none.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE VOID LOS_Atomic64Set(Atomic64 *v, INT64 setVal)
  {
      INT64 tmp;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %1, %H1, [%2]\n"
                               "strexd   %0, %3, %H3, [%2]"
                               : "=&r"(status), "=&r"(tmp)
                               : "r"(v), "r"(setVal)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 addition.
   *
   * @par Description:
   * This API is used to implement the atomic64 addition and return the result value of the augend.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>If the addtion result is not in the range of representable values for 64-bit signed integer,
   * an int integer overflow may occur to the return value</li>
   * </ul>
   *
   * @param  v         [IN] The augend pointer.
   * @param  addVal    [IN] The addend.
   *
   * @retval #INT64  The result value of the augend.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT64 LOS_Atomic64Add(Atomic64 *v, INT64 addVal)
  {
      INT64 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %1, %H1, [%2]\n"
                               "adds   %Q1, %Q1, %Q3\n"
                               "adc   %R1, %R1, %R3\n"
                               "strexd   %0, %1, %H1, [%2]"
                               : "=&r"(status), "=&r"(val)
                               : "r"(v), "r"(addVal)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 subtraction.
   *
   * @par Description:
   * This API is used to implement the atomic64 subtraction and return the result value of the minuend.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>If the subtraction result is not in the range of representable values for 64-bit signed integer,
   * an int integer overflow may occur to the return value</li>
   * </ul>
   *
   * @param  v         [IN] The minuend pointer.
   * @param  subVal    [IN] The subtrahend.
   *
   * @retval #INT64  The result value of the minuend.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT64 LOS_Atomic64Sub(Atomic64 *v, INT64 subVal)
  {
      INT64 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %1, %H1, [%2]\n"
                               "subs   %Q1, %Q1, %Q3\n"
                               "sbc   %R1, %R1, %R3\n"
                               "strexd   %0, %1, %H1, [%2]"
                               : "=&r"(status), "=&r"(val)
                               : "r"(v), "r"(subVal)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 addSelf.
   *
   * @par Description:
   * This API is used to implement the atomic64 addSelf .
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT64_MAX to avoid integer overflow after adding 1.</li>
   * </ul>
   *
   * @param  v      [IN] The addSelf variable pointer.
   *
   * @retval none.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE VOID LOS_Atomic64Inc(Atomic64 *v)
  {
      INT64 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%3]\n"
                               "adds   %Q0, %Q0, #1\n"
                               "adc   %R0, %R0, #0\n"
                               "strexd   %1, %0, %H0, [%3]"
                               : "=&r"(val), "=&r"(status), "+m"(*v)
                               : "r"(v)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 addSelf.
   *
   * @par Description:
   * This API is used to implement the atomic64 addSelf and return the result of addSelf.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT64_MAX to avoid integer overflow after adding 1.</li>
   * </ul>
   *
   * @param  v      [IN] The addSelf variable pointer.
   *
   * @retval #INT64 The return value of variable addSelf.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT64 LOS_Atomic64IncRet(Atomic64 *v)
  {
      INT64 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%3]\n"
                               "adds   %Q0, %Q0, #1\n"
                               "adc   %R0, %R0, #0\n"
                               "strexd   %1, %0, %H0, [%3]"
                               : "=&r"(val), "=&r"(status), "+m"(*v)
                               : "r"(v)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 auto-decrement.
   *
   * @par Description:
   * This API is used to implementating the atomic64 auto-decrement.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT64_MIN to avoid overflow after reducing 1.</li>
   * </ul>
   *
   * @param  v      [IN] The auto-decrement variable pointer.
   *
   * @retval none.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE VOID LOS_Atomic64Dec(Atomic64 *v)
  {
      INT64 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%3]\n"
                               "subs   %Q0, %Q0, #1\n"
                               "sbc   %R0, %R0, #0\n"
                               "strexd   %1, %0, %H0, [%3]"
                               : "=&r"(val), "=&r"(status), "+m"(*v)
                               : "r"(v)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic64 auto-decrement.
   *
   * @par Description:
   * This API is used to implementating the atomic64 auto-decrement and return the result of auto-decrement.
   * @attention
   * <ul>
   * <li>The pointer v must not be NULL.</li>
   * <li>The value which v point to must not be INT64_MIN to avoid overflow after reducing 1.</li>
   * </ul>
   *
   * @param  v      [IN] The auto-decrement variable pointer.
   *
   * @retval #INT64  The return value of variable auto-decrement.
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT64 LOS_Atomic64DecRet(Atomic64 *v)
  {
      INT64 val;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%3]\n"
                               "subs   %Q0, %Q0, #1\n"
                               "sbc   %R0, %R0, #0\n"
                               "strexd   %1, %0, %H0, [%3]"
                               : "=&r"(val), "=&r"(status), "+m"(*v)
                               : "r"(v)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return val;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic exchange for 8-bit variable.
   *
   * @par Description:
   * This API is used to implement the atomic exchange for 8-bit variable and
   * return the previous value of the atomic variable.
   * @attention
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @param  v         [IN] The variable pointer.
   * @param  val       [IN] The exchange value.
   *
   * @retval #INT32       The previous value of the atomic variable
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicXchgByte(volatile INT8 *v, INT32 val)
  {
      INT32 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexb   %0, [%3]\n"
                               "strexb   %1, %4, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(v), "r"(val)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return prevVal;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic exchange for 16-bit variable.
   *
   * @par Description:
   * This API is used to implement the atomic exchange for 16-bit variable and
   * return the previous value of the atomic variable.
   * @attention
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @param  v         [IN] The variable pointer.
   * @param  val       [IN] The exchange value.
   *
   * @retval #INT32       The previous value of the atomic variable
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicXchg16bits(volatile INT16 *v, INT32 val)
  {
      INT32 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexh   %0, [%3]\n"
                               "strexh   %1, %4, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(v), "r"(val)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return prevVal;
  }
  
  /**
   * @ingroup  los_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
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @param  v         [IN] The variable pointer.
   * @param  val       [IN] The exchange value.
   *
   * @retval #INT32       The previous value of the atomic variable
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE INT32 LOS_AtomicXchg32bits(Atomic *v, INT32 val)
  {
      INT32 prevVal;
      UINT32 status;
  
      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_atomic
   * @brief Atomic exchange for 64-bit variable.
   *
   * @par Description:
   * This API is used to implement the atomic exchange for 64-bit variable
   * and return the previous value of the atomic variable.
   * @attention
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @param  v         [IN] The variable pointer.
   * @param  val       [IN] The exchange value.
   *
   * @retval #INT64       The previous value of the atomic variable
   * @par Dependency:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE INT64 LOS_AtomicXchg64bits(Atomic64 *v, INT64 val)
  {
      INT64 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%3]\n"
                               "strexd   %1, %4, %H4, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(v), "r"(val)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return prevVal;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic exchange for 8-bit variable with compare.
   *
   * @par Description:
   * This API is used to implement the atomic exchange for 8-bit variable, if the value of variable is equal to oldVal.
   * @attention
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @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:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE BOOL LOS_AtomicCmpXchgByte(volatile INT8 *v, INT32 val, INT32 oldVal)
  {
      INT32 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexb %0, [%3]\n"
                               "mov %1, #0\n"
                               "teq %0, %4\n"
                               "strexbeq %1, %5, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(v), "r"(oldVal), "r"(val)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return prevVal != oldVal;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic exchange for 16-bit variable with compare.
   *
   * @par Description:
   * This API is used to implement the atomic exchange for 16-bit variable, if the value of variable is equal to oldVal.
   * @attention
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @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:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE BOOL LOS_AtomicCmpXchg16bits(volatile INT16 *v, INT32 val, INT32 oldVal)
  {
      INT32 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexh %0, [%3]\n"
                               "mov %1, #0\n"
                               "teq %0, %4\n"
                               "strexheq %1, %5, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(v), "r"(oldVal), "r"(val)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return prevVal != oldVal;
  }
  
  /**
   * @ingroup  los_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
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @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:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V100R001C00
   */
  STATIC INLINE BOOL LOS_AtomicCmpXchg32bits(Atomic *v, INT32 val, INT32 oldVal)
  {
      INT32 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrex %0, [%3]\n"
                               "mov %1, #0\n"
                               "teq %0, %4\n"
                               "strexeq %1, %5, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(v), "r"(oldVal), "r"(val)
                               : "cc");
      } while (__builtin_expect(status != 0, 0));
  
      return prevVal != oldVal;
  }
  
  /**
   * @ingroup  los_atomic
   * @brief Atomic exchange for 64-bit variable with compare.
   *
   * @par Description:
   * This API is used to implement the atomic exchange for 64-bit variable, if the value of variable is equal to oldVal.
   * @attention
   * <ul>The pointer v must not be NULL.</ul>
   *
   * @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:
   * <ul><li>los_atomic.h: the header file that contains the API declaration.</li></ul>
   * @see
   * @since Huawei LiteOS V200R003C00
   */
  STATIC INLINE BOOL LOS_AtomicCmpXchg64bits(Atomic64 *v, INT64 val, INT64 oldVal)
  {
      INT64 prevVal;
      UINT32 status;
  
      do {
          __asm__ __volatile__("ldrexd   %0, %H0, [%3]\n"
                               "mov   %1, #0\n"
                               "teq   %0, %4\n"
                               "teqeq   %H0, %H4\n"
                               "strexdeq   %1, %5, %H5, [%3]"
                               : "=&r"(prevVal), "=&r"(status), "+m"(*v)
                               : "r"(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_ATOMIC_H__ */
  