Getting Data From PC at random

I wan to check for incoming data from the PC at certain interval if no data is available move forward to other functions so i wrote a function for getting charater getcharX() for some reason it dose not seem o work. Please Let me know what i'm doing wrong or what
are the alternatives

this is the code i used


j=0;
while(( out[j] = getCharX())!=0xff && j <= 3)
{
j++;
}
if(out[0]=='X')
goto Now;

goto start;

-----------------------------------------------------------


char getCharX()
{
char c;
int i=0;
while(!RI)
{
i++;
if(i==2)
return 0xff;
}
c = SBUF;
RI = 0;
return (c);
}