readmessage.c
Author: cmaier@cmassoc.net

    /*====================================================================*
     *
     *   Copyright (c) 2013 Qualcomm Atheros, Inc.
     *
     *   All rights reserved.
     *
     *   Redistribution and use in source and binary forms, with or
     *   without modification, are permitted (subject to the limitations
     *   in the disclaimer below) provided that the following conditions
     *   are met:
     *
     *   * Redistributions of source code must retain the above copyright
     *     notice, this list of conditions and the following disclaimer.
     *
     *   * Redistributions in binary form must reproduce the above
     *     copyright notice, this list of conditions and the following
     *     disclaimer in the documentation and/or other materials
     *     provided with the distribution.
     *
     *   * Neither the name of Qualcomm Atheros nor the names of
     *     its contributors may be used to endorse or promote products
     *     derived from this software without specific prior written
     *     permission.
     *
     *   NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE
     *   GRANTED BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE
     *   COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
     *   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     *   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     *   PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
     *   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     *   NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     *   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     *   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     *   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
     *   OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     *   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     *--------------------------------------------------------------------*/

    /*====================================================================*
     *
     *   ssize_t readmessage (struct channel const * channel, struct message * message, uint8_t MMV, uint16_t MMTYPE);
     *
     *   plc.h
     *
     *   wait for a QCA vendor specific message of given MMV and MMTYPE;
     *   discard unwanted messages until the desired message arrives or
     *   the channel timeout expires; return packet length on success,
     *   0 on timeout or -1 on error;
     *
     *   see sendmessage for the send counterpart to this function;
     *
     *   a well designed UnwantedMessage function is critical here;
     *
     *   Contributor(s):
     *      Charles Maier <cmaier@qca.qualcomm.com>
     *      Nathaniel Houghton <nhoughto@qca.qualcomm.com>
     *
     *--------------------------------------------------------------------*/

    #ifndef READMESSAGE_SOURCE
    #define READMESSAGE_SOURCE

    #include <sys/time.h>
    #include <memory.h>
    #include <errno.h>

    #include "../tools/error.h"
    #include "../tools/timer.h"
    #include "../plc/plc.h"

    ssize_t readmessage (struct channel const * channel, struct message * message, uint8_t MMV, uint16_t MMTYPE)

    {
    	struct timeval ts;
    	struct timeval tc;
    	ssize_t length;
    	if (gettimeofday (& ts, NULL) == - 1)
    	{
    		error (1, errno, CANT_START_TIMER);
    	}
    	while ((length = readpacket (channel, message, sizeof (* message))) >= 0)
    	{
    		if (! UnwantedMessage (message, length, MMV, MMTYPE))
    		{
    			return (length);
    		}
    		if (gettimeofday (& tc, NULL) == - 1)
    		{
    			error (1, errno, CANT_RESET_TIMER);
    		}
    		if (channel->timeout < 0)
    		{
    			continue;
    		}
    		if (channel->timeout > MILLISECONDS (ts, tc))
    		{
    			continue;
    		}
    		return (0);
    	}
    	return (- 1);
    }

    #endif

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