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118 lines
3.7 KiB
C++
118 lines
3.7 KiB
C++
/****************************************************************************
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*
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* Copyright (c) 2014 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file mavlink_stream.cpp
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* Mavlink messages stream implementation.
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*
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* @author Anton Babushkin <anton.babushkin@me.com>
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*/
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#include <stdlib.h>
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#include "mavlink_stream.h"
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#include "mavlink_main.h"
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MavlinkStream::MavlinkStream(Mavlink *mavlink) :
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next(nullptr),
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_mavlink(mavlink),
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_interval(1000000),
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_last_sent(0 /* 0 means unlimited - updates on every iteration */)
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{
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}
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MavlinkStream::~MavlinkStream()
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{
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}
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/**
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* Set messages interval in ms
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*/
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void
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MavlinkStream::set_interval(const unsigned int interval)
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{
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_interval = interval;
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}
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/**
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* Update subscriptions and send message if necessary
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*/
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int
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MavlinkStream::update(const hrt_abstime t)
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{
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// If the message has never been sent before we want
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// to send it immediately and can return right away
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if (_last_sent == 0) {
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// this will give different messages on the same run a different
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// initial timestamp which will help spacing them out
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// on the link scheduling
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_last_sent = hrt_absolute_time();
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#ifndef __PX4_QURT
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send(t);
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#endif
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return 0;
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}
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int64_t dt = t - _last_sent;
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int interval = _interval;
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if (!const_rate()) {
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interval /= _mavlink->get_rate_mult();
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}
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// send the message if it is due or
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// if it will overrun the next scheduled send interval
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// by 40% of the interval time. This helps to avoid
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// sending a scheduled message on average slower than
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// scheduled. Doing this at 50% would risk sending
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// the message too often as the loop runtime of the app
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// needs to be accounted for as well.
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// This method is not theoretically optimal but a suitable
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// stopgap as it hits its deadlines well (0.5 Hz, 50 Hz and 250 Hz)
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if (dt > (interval - (_mavlink->get_main_loop_delay() / 10) * 4)) {
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// interval expired, send message
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#ifndef __PX4_QURT
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send(t);
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#endif
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// if the interval is non-zero do not use the actual time but
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// increment at a fixed rate, so that processing delays do not
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// distort the average rate
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_last_sent = (interval > 0) ? _last_sent + interval : t;
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return 0;
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}
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return -1;
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}
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