text: /**
    ******************************************************************************
    * @file    CortexM/BitBand/main.c 
    * @author  MCD Application Team
    * @version V1.4.0
    * @date    04-August-2014
    * @brief   Main program body
    ******************************************************************************
    * @attention
    *
    * <h2><center>&copy; COPYRIGHT 2013 STMicroelectronics</center></h2>
    *
    * Licensed under MCD-ST Liberty SW License Agreement V2, (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.st.com/software_license_agreement_liberty_v2
    *
    * 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.
    *
    ******************************************************************************
    */
  
  /* Includes ------------------------------------------------------------------*/
  #include "stm32f4xx.h"
  
  /** @addtogroup STM32F4xx_StdPeriph_Examples
    * @{
    */
  
  /** @addtogroup CortexM_BitBand
    * @{
    */ 
  
  /* Private typedef -----------------------------------------------------------*/
  /* Private define ------------------------------------------------------------*/
  /* Private macro -------------------------------------------------------------*/
  #define  Var_ResetBit_BB(VarAddr, BitNumber)    \
            (*(__IO uint32_t *) (SRAM_BB_BASE | ((VarAddr - SRAM_BASE) << 5) | ((BitNumber) << 2)) = 0)
     
  #define Var_SetBit_BB(VarAddr, BitNumber)       \
            (*(__IO uint32_t *) (SRAM_BB_BASE | ((VarAddr - SRAM_BASE) << 5) | ((BitNumber) << 2)) = 1)
  
  #define Var_GetBit_BB(VarAddr, BitNumber)       \
            (*(__IO uint32_t *) (SRAM_BB_BASE | ((VarAddr - SRAM_BASE) << 5) | ((BitNumber) << 2)))
            
  /* Private variables ---------------------------------------------------------*/
  __IO uint32_t Var, VarAddr = 0, VarBitValue = 0;
  
  /* Private function prototypes -----------------------------------------------*/
  /* Private functions ---------------------------------------------------------*/
  
  /**
    * @brief  Main program
    * @param  None
    * @retval None
    */
  int main(void)
  {
    /*!< At this stage the microcontroller clock setting is already configured, 
         this is done through SystemInit() function which is called from startup
         files (startup_stm32f40_41xxx.s/startup_stm32f427_437xx.s/startup_stm32f429_439xx.s)
         before to branch to application main. 
         To reconfigure the default setting of SystemInit() function, refer to
         system_stm32f4xx.c file
       */     
         
    Var = 0x00005AA5;
  
  /* A mapping formula shows how to reference each word in the alias region to a 
     corresponding bit in the bit-band region. The mapping formula is:
     bit_word_addr = bit_band_base + (byte_offset x 32) + (bit_number + 4)
  
  where:
     - bit_word_addr: is the address of the word in the alias memory region that 
                      maps to the targeted bit.
     - bit_band_base is the starting address of the alias region
     - byte_offset is the number of the byte in the bit-band region that contains 
       the targeted bit
     - bit_number is the bit position (0-7) of the targeted bit */
  
  /* Get the variable address --------------------------------------------------*/ 
    VarAddr = (uint32_t)&Var; 
  
  /* Modify variable bit using bit-band access ---------------------------------*/
    /* Modify Var variable bit 0 -----------------------------------------------*/
    Var_ResetBit_BB(VarAddr, 0);  /* Var = 0x00005AA4 */
    Var_SetBit_BB(VarAddr, 0);    /* Var = 0x00005AA5 */
    
    /* Modify Var variable bit 11 ----------------------------------------------*/
    Var_ResetBit_BB(VarAddr, 11);             /* Var = 0x000052A5 */
    /* Get Var variable bit 11 value */
    VarBitValue = Var_GetBit_BB(VarAddr, 11); /* VarBitValue = 0x00000000 */
    
    Var_SetBit_BB(VarAddr, 11);               /* Var = 0x00005AA5 */
    /* Get Var variable bit 11 value */
    VarBitValue = Var_GetBit_BB(VarAddr, 11);    /* VarBitValue = 0x00000001 */
    
    /* Modify Var variable bit 31 ----------------------------------------------*/
    Var_SetBit_BB(VarAddr, 31);               /* Var = 0x80005AA5 */
    /* Get Var variable bit 31 value */
    VarBitValue = Var_GetBit_BB(VarAddr, 31); /* VarBitValue = 0x00000001 */
      
    Var_ResetBit_BB(VarAddr, 31);             /* Var = 0x00005AA5 */
    /* Get Var variable bit 31 value */
    VarBitValue = Var_GetBit_BB(VarAddr, 31); /* VarBitValue = 0x00000000 */
          
    while (1)
    {
    }
  }
  
  #ifdef  USE_FULL_ASSERT
  
  /**
    * @brief  Reports the name of the source file and the source line number
    *         where the assert_param error has occurred.
    * @param  file: pointer to the source file name
    * @param  line: assert_param error line source number
    * @retval None
    */
  void assert_failed(uint8_t* file, uint32_t line)
  { 
    /* User can add his own implementation to report the file name and line number,
       ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  
    /* Infinite loop */
    while (1)
    {
    }
  }
  #endif
  
  /**
    * @}
    */ 
  
  /**
    * @}
    */ 
  
  /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
  