getchar.c

altera串口源代码程序

/*---------------------------------------------------------*
       _getchar() - Read char from Input Stream (Receive
                   Buffer).

       This is a blocking routine so it will wait forever
	Until a char comes in
*----------------------------------------------------------*/

#include "buffer.h"

//Global variables
extern unsigned char RxBuf[RXBUFSIZE];	// the receiver buffer.
extern int RxHead;			// the circular buffer index
extern int RxTail;

unsigned char _getchar() 
{
	unsigned char temp;

	while (RxTail == RxHead)
	{
		nr_delay(1);
	}
	temp = RxBuf[RxTail];

	if (++RxTail > (RXBUFSIZE -1))
      	{
           	RxTail = 0;
     	}
     	return(temp);
}