how to receive data from uart using this program

i am editing the program some one already made.i want help to receive the data from uart using the program.here is the interrupt program they have used.

 void serial_interrupt() interrupt 4 using 1
{
        if(RI)
                {
                RI=0;
                com_tmr_rx=5;
                com_r_busy=1;
                //datas[0]=SBUF;
                //datas[com_r_index++]=SBUF;
                if(com_r_index>=34)
                        com_r_index=0;

                }

        if(TI)
                {
                TI=0;
                TX_RX=0;
                if(com_t_index<com_t_length)
                        {
                        TX_RX=1;
                        SBUF=datas[com_t_index++];
                        }
                else
                        {
                        com_t_index=com_t_length=0;
                        TX_RX=0;
                        }

                }

}

.