/* can_select** can4linux -- LINUX CAN device driver source * * This file is subject to the terms and conditions of the GNU General Public * License.  See the file "COPYING" in the main directory of this archive * for more details. * *  * Copyright (c) 2001 port GmbH Halle/Saale * (c) 2001 Heinz-J黵gen Oertel (oe@port.de) *          Claus Schroeter (clausi@chemie.fu-berlin.de) *------------------------------------------------------------------ * $Header: /z2/cvsroot/products/0530/software/can4linux/src/select.c,v 1.2 2007/07/16 07:34:06 oe Exp $ * *-------------------------------------------------------------------------- * * * * */#include "defs.h"__LDDK_SELECT_TYPE can_select( __LDDK_SELECT_PARAM ){unsigned int minor = __LDDK_MINOR;int rx_fifoindex =		((struct _instance_data *)(file->private_data))->rx_index;msg_fifo_t *RxFifo = &Rx_Buf[minor][rx_fifoindex];msg_fifo_t *TxFifo = &Tx_Buf[minor];unsigned int mask = 0;    /* DBGin("can_select"); */	    /* DBGprint(DBG_DATA,("minor = %d", minor)); */#ifdef DEBUG    /* CAN_ShowStat(minor); */#endif    /* DBGprint(DBG_BRANCH,("POLL: fifo empty,poll waiting...\n")); */    /* every event queue that could wake up the process     * and change the status of the poll operation     * can be added to the poll_table structure by     * calling the function poll_wait:       */    /*     _select para, wait queue, _select para */    poll_wait(file, &CanWait[minor][rx_fifoindex], wait);    poll_wait(file, &CanOutWait[minor] , wait);    /* DBGprint(DBG_BRANCH,("POLL: wait returned \n")); */    if( RxFifo->head != RxFifo->tail ) {	/* fifo has some telegrams */	/* Return a bit mask	 * describing operations that could be immediately performed	 * without blocking.	 */	/*	 * POLLIN This bit must be set	 *        if the device can be read without blocking. 	 * POLLRDNORM This bit must be set	 * if "normal'' data is available for reading.	 * A readable device returns (POLLIN | POLLRDNORM)	 *	 *	 *	 */	mask |= POLLIN | POLLRDNORM;	/* readable */    }    if( TxFifo->head == TxFifo->tail ) {	/* fifo is empty */	/* Return a bit mask	 * describing operations that could be immediately performed	 * without blocking.	 */	/*	 * POLLOUT This bit must be set	 *        if the device can be written without blocking. 	 * POLLWRNORM This bit must be set	 */	mask |= POLLOUT | POLLWRNORM;	/* writeable */    }    /* DBGout(); */    return mask;}