text: /*
   * 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 __ASM_H
  #define __ASM_H
  
  #ifdef __cplusplus
  #if __cplusplus
  extern "C" {
  #endif /* __cplusplus */
  #endif /* __cplusplus */
  
  #define FUNCTION(x) .global x; .text; .code 32; x:
  #define MPIDR_CPUID_MASK 0xFFU
  
  /*
   *           ------------------------------------------
   * stackTop |   cpu n   |  ... |   cpu 1   |   cpu 0   | stackBottom
   *           ------------------------------------------
   *          | stackSize |  ... | stackSize | stackSize |
   */
  .macro EXC_SP_SET stackBottom, stackSize, reg0, reg1
      mrc    p15, 0, \reg0, c0, c0, 5        @获取CPU信息
      and    \reg0, \reg0, #MPIDR_CPUID_MASK /* get cpu id */ @获取当前运行CPUID
      mov    \reg1, #\stackSize			   @reg1 记录 栈大小
      mul    \reg1, \reg1, \reg0             /* calculate current cpu stack offset */ @计算当前CPU栈的偏移位置
      ldr    \reg0, =\stackBottom			   @reg0 记录栈底
      sub    \reg0, \reg0, \reg1             /* calculate current cpu stack bottom */ @相减得到栈顶
      mov    sp, \reg0                       /* set  sp */ @设置SP,将SP移到栈顶
  .endm
  
  #ifdef __cplusplus
  #if __cplusplus
  }
  #endif /* __cplusplus */
  #endif /* __cplusplus */
  
  #endif /* __ASM_H */
  