~(tmp << ((GPIO_Remap >> 0x15)*0x10))这个语句的作用是什么？

nichao0

void GPIO_PinRemapConfig(uint32_t GPIO_Remap, FunctionalState NewState)
{
  uint32_t tmp = 0x00, tmp1 = 0x00, tmpreg = 0x00, tmpmask = 0x00;

  /* Check the parameters */
  assert_param(IS_GPIO_REMAP(GPIO_Remap));
  assert_param(IS_FUNCTIONAL_STATE(NewState));  

  if((GPIO_Remap & 0x80000000) == 0x80000000)
  {
    tmpreg = AFIO->MAPR2;
  }
  else
  {
    tmpreg = AFIO->MAPR;
  }

  tmpmask = (GPIO_Remap & DBGAFR_POSITION_MASK) >> 0x10;
  tmp = GPIO_Remap & LSB_MASK;

  if ((GPIO_Remap & (DBGAFR_LOCATION_MASK | DBGAFR_NUMBITS_MASK)) == (DBGAFR_LOCATION_MASK | DBGAFR_NUMBITS_MASK))
  {
    tmpreg &= DBGAFR_SWJCFG_MASK;
    AFIO->MAPR &= DBGAFR_SWJCFG_MASK;
  }
  else if ((GPIO_Remap & DBGAFR_NUMBITS_MASK) == DBGAFR_NUMBITS_MASK)
  {
    tmp1 = ((uint32_t)0x03) << tmpmask;
    tmpreg &= ~tmp1;
    tmpreg |= ~DBGAFR_SWJCFG_MASK;
  }
  else
  {
    tmpreg &= ~(tmp << ((GPIO_Remap >> 0x15)*0x10));
    tmpreg |= ~DBGAFR_SWJCFG_MASK;
  }

  if (NewState != DISABLE)
  {
    tmpreg |= (tmp << ((GPIO_Remap >> 0x15)*0x10));
  }

  if((GPIO_Remap & 0x80000000) == 0x80000000)
  {
    AFIO->MAPR2 = tmpreg;
  }
  else
  {
    AFIO->MAPR = tmpreg;
  }  
}

Tlava

将要配置的内容赋值给变量tmpreg