text: /*!
      \file    main.c
      \brief   backup data register
  
      \version 2014-12-26, V1.0.0, firmware for GD32F10x
      \version 2017-06-20, V2.0.0, firmware for GD32F10x
      \version 2018-07-31, V2.1.0, firmware for GD32F10x
      \version 2020-09-30, V2.2.0, firmware for GD32F10x
  */
  
  /*
      Copyright (c) 2020, GigaDevice Semiconductor Inc.
  
      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.
  */
  
  #include "gd32f10x.h"
  #include "gd32f10x_eval.h"
  
  #define  BKP_DATA_REG_NUM              42
  
  void led_config(void);
  void write_backup_register(uint16_t data);
  uint32_t check_backup_register(uint16_t data);
  
  /*!
      \brief      main function
      \param[in]  none
      \param[out] none
      \retval     none
  */
  int main(void)
  {
      /* led configuration and turn on all led */
      led_config();
      /* PMU lock enable */
      rcu_periph_clock_enable(RCU_PMU);
      /* BKP clock enable */
      rcu_periph_clock_enable(RCU_BKPI);
      /* enable write access to the registers in backup domain */
      pmu_backup_write_enable();
      /* clear the bit flag of tamper event */
      bkp_flag_clear();
      
      /* check if the POR/PDR reset flag is set */
      if(RESET != rcu_flag_get(RCU_FLAG_PORRST)){
          /* clear the RCU all reset flags */
          rcu_all_reset_flag_clear();
          /* turn on LED4 */
          gd_eval_led_on(LED4);
          
          /* check if backup data registers has been written */
          if(0x00 == check_backup_register(0x1226)){
              /* Backup data registers values are correct */
              /* turn on LED2 */
              gd_eval_led_on(LED2);
          }else{
              /* backup data registers values are not correct or they are not written*/
              /* write data to backup data registers */
              write_backup_register(0x1226);
              /* turn on LED3 */
              gd_eval_led_on(LED3);
          }
      }
      /* turn on LED5 */
      gd_eval_led_on(LED5);;
      while(1){
      }
  }
  
  /*!
      \brief      write data to backup DATAx registers
      \param[in]  data: the data to be written to backup data registers
        \arg        0x0000-0xFFFF
      \param[out] none
      \retval     none
  */
  void write_backup_register(uint16_t data)
  {
      uint32_t temp = 0;
      /* write data to backup registers */
      for (temp = 0; temp < BKP_DATA_REG_NUM; temp++){
          if(temp < 10){
              BKP_DATA0_9(temp) = data + (temp * 0x50);
          }else{
              BKP_DATA10_41(temp) = data + (temp * 0x50);
          }
      }
  }
  
  /*!
      \brief      check if the backup DATAx registers values are correct or not
      \param[in]  data: the data to be written to backup data registers
        \arg        0x0000-0xFFFF
      \param[out] none
      \retval     the number of data register
  */
  uint32_t check_backup_register(uint16_t data)
  {
      uint32_t temp = 0;
      /* check the data of backup registers */
      for(temp = 0; temp < BKP_DATA_REG_NUM; temp++){
          if(temp < 10){
              /* get data from data register 0-9 */
              if(data + (temp * 0x50) != BKP_DATA_GET(BKP_DATA0_9(temp))){
                  return temp+1;
              }
          }else{
              /* get data from data register 10-41 */
              if(data + (temp * 0x50) != BKP_DATA_GET(BKP_DATA10_41(temp))){
                  return temp+1;
              }
          }
      }
      return 0;
  }
  
  /*!
      \brief      configure led 
      \param[in]  none
      \param[out] none
      \retval     none
  */
  void led_config(void)
  {
      gd_eval_led_init(LED2);
      gd_eval_led_init(LED3);
      gd_eval_led_init(LED4);
      gd_eval_led_init(LED5);
  }
  