printf.txt

打印语句源代码参考,在一个源代码中发现的.想研究的人可以参考一下

int printf(const char *format,...)
{
	int i;
	int iCnt = 0;
	int iToSend = 0;
	static char buf[PRINTF_BUFF_SIZE];
	int ret;
      UART_TYPE UartOut;
	UINT8 *pBuff = (UINT8 *)buf;
	UINT8 *pLastBuff = (UINT8 *)buf;
	UINT8 ch = '\r';
	va_list args;
	va_start(args, format);
	ret = vsnprintf(buf,sizeof(buf), format,args);
      switch(OutputUart) 
      {
        case 0:
             return 0;
        case 1:
             UartOut=UART_DEBUG;
             break;
        case 2:
             UartOut=UART_MODEM;
             break;
         default:
            UartOut=UART_DEBUG;
            break;
      }
      
	for (i=0;i<ret;i++) 
	{
		if (pBuff[i] == '\r')
		{
			ret++;
            UART_WriteToHost( UartOut, pLastBuff, iToSend );
            iCnt += iToSend;
			pLastBuff = pBuff+i+1;
			iToSend = 0;
			continue;
		}
		iToSend++;
		if (pBuff[i] == '\n')
		{
//			ret++;
            UART_WriteToHost( UartOut, pLastBuff, iToSend );
            iCnt += iToSend;
            UART_WriteToHost( UartOut, &ch, 1 );
// FIX BY ETAY - also put /r, so increase number of printed
// chars by 1, not by entire line (iToSend) as was before 
            iCnt++;
            //iCnt += iToSend;
			pLastBuff = pBuff+i;
			iToSend = 0;
		}
	}
    UART_WriteToHost( UartOut, pLastBuff, iToSend );
    iCnt += iToSend;
	return iCnt;
}