串口程序求助。

ronan · 发表于 2016-7-4 11:46:10

void USART3_IRQHandler(void)
{
if(USART_GetITStatus(USART3,USART_IT_RXNE) != RESET)
{
  UART3RxCompJudg = VALID_FLAG; UART3RxCompTime = 0;
  Uart3OverTime = 0;
  if( UART3_RxFullFlag == 0)
{
   UART3_RxBuf[UART3_RxEnd++] =  USART_ReceiveData(USART3); /*  保存接收到的数据          */
if(UART3_RxEnd >= UART3_RXBUF_SIZE)
   UART3_RxEnd = 0;
if(UART3_RxEnd == UART3_RxHead)
   UART3_RxFullFlag = 1;
UART3_RxEmptyFlag = 0;
}
}
USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
}

uint16 Uart3ReadBytes(uint8 *pBuf)
{
uint16 nEnd = 0;
uint16 Size = 0;
if(UART3_RxEmptyFlag == 0) //串口0接收数据缓冲区不为空
{
  nEnd = UART3_RxEnd; //中断可能改变此值
  UART3_RxFullFlag = 0;
  if(UART3_RxHead < nEnd) //end > head
{
Size = nEnd - UART3_RxHead;
memcpy(pBuf,(uint8 *)&UART3_RxBuf[0] + UART3_RxHead, Size);
UART3_RxHead = nEnd;
}
  else    //head > end    {
Size = UART3_RXBUF_SIZE + nEnd - UART3_RxHead;
memcpy(pBuf,(uint8 *)&UART3_RxBuf[0] + UART3_RxHead,UART3_RXBUF_SIZE - UART3_RxHead);
if(nEnd > 0)
memcpy(pBuf + UART3_RXBUF_SIZE - UART3_RxHead,(uint8 *)&UART3_RxBuf[0],nEnd);
UART3_RxHead = nEnd;
}
  if(UART3_RxHead == UART3_RxEnd)
UART3_RxEmptyFlag = 1;  //接收数据缓冲区空
}
else
  Size = 0;
memset((uint8*)&UART3_RxBuf[0],0x00,512);
return Size;
}
最近看到这段代码，有点不理解，个人初学，多了UART3_RxEnd，UART3_RxHead几个寄存量以及相互比较关系，想请问是什么设计思路，谢谢。