一个printf的实现源代码

				#include 
				#include "printf.h"  
				#include "commctrl.h"
				
				extern XJ_HANDLE hDebugPort;
				
				extern void    COMM_WriteBuff( int iPotr, unsigned char * ucData, int ulen );
				void printf ( const char * fmt, ... )
				{
				    va_list args;
				    int n;
				    char printbuffer[256];
				    va_start ( args, fmt );
				    n = vsprintf ( printbuffer, fmt, args );
				    va_end ( args );             
				    xjcomm_write( hDebugPort,( unsigned char *)printbuffer, strlen( printbuffer ));
				}