串口接收数据不完整,该如何解决

/*********************************************    UART1初始化程序*********************************************/STATUS UART1P_Init(void){    sfd = open("/tyCo/1",O_RDWR,0);            if(sfd!=ERROR)    {                 ioctl(sfd, FIOSETOPTIONS, OPT_RAW);            /*RAW模式*/        ioctl(sfd, FIOBAUDRATE, 9600);                /*9600 bps*/           ioctl(sfd, SIO_HW_OPTS_SET, CS8|PARENB);                return OK;    };        return ERROR;        }//主要接收代码            while(1)            {                stat = *((unsigned int *)(USTAT1));                if((stat&UART1_TC)==UART1_TC) break;            };                           *((unsigned int *)(UCON1)) |= 0x20;                     for(i=0,sum=0;i<100;i++)            {                ioctl(sfd,FIONREAD,(int)&len);                            if(len>0)                {                                                    len = read(sfd,rbuf+sum,1023-sum);                       sum += len;                };                    taskDelay(10);                        };