ardupilot/libraries/GCS_MAVLink/GCS_MAVLink.cpp

/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/// @file	GCS_MAVLink.cpp

/*
This provides some support code and variables for MAVLink enabled sketches

*/
#include "GCS.h"
#include "GCS_MAVLink.h"

#include <AP_Common/AP_Common.h>
#include <AP_GPS/AP_GPS.h>
#include <AP_HAL/AP_HAL.h>

extern const AP_HAL::HAL& hal;

#ifdef MAVLINK_SEPARATE_HELPERS
// Shut up warnings about missing declarations; TODO: should be fixed on
// mavlink/pymavlink project for when MAVLINK_SEPARATE_HELPERS is defined
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wmissing-declarations"
#include "include/mavlink/v2.0/mavlink_helpers.h"
#pragma GCC diagnostic pop
#endif

AP_HAL::UARTDriver	*mavlink_comm_port[MAVLINK_COMM_NUM_BUFFERS];
bool gcs_alternative_active[MAVLINK_COMM_NUM_BUFFERS];

// per-channel lock
static HAL_Semaphore chan_locks[MAVLINK_COMM_NUM_BUFFERS];

mavlink_system_t mavlink_system = {7,1};

// mask of serial ports disabled to allow for SERIAL_CONTROL
static uint8_t mavlink_locked_mask;

// routing table
MAVLink_routing GCS_MAVLINK::routing;

// static AP_SerialManager pointer
const AP_SerialManager *GCS_MAVLINK::serialmanager_p;

/*
  lock a channel, preventing use by MAVLink
 */
void GCS_MAVLINK::lock_channel(mavlink_channel_t _chan, bool lock)
{
    if (!valid_channel(chan)) {
        return;
    }
    if (lock) {
        mavlink_locked_mask |= (1U<<(unsigned)_chan);
    } else {
        mavlink_locked_mask &= ~(1U<<(unsigned)_chan);
    }
}

// return a MAVLink variable type given a AP_Param type
uint8_t mav_var_type(enum ap_var_type t)
{
    if (t == AP_PARAM_INT8) {
	    return MAVLINK_TYPE_INT8_T;
    }
    if (t == AP_PARAM_INT16) {
	    return MAVLINK_TYPE_INT16_T;
    }
    if (t == AP_PARAM_INT32) {
	    return MAVLINK_TYPE_INT32_T;
    }
    // treat any others as float
    return MAVLINK_TYPE_FLOAT;
}


/// Check for available transmit space on the nominated MAVLink channel
///
/// @param chan		Channel to check
/// @returns		Number of bytes available
uint16_t comm_get_txspace(mavlink_channel_t chan)
{
    if (!valid_channel(chan)) {
        return 0;
    }
    if ((1U<<chan) & mavlink_locked_mask) {
        return 0;
    }
	int16_t ret = mavlink_comm_port[chan]->txspace();
	if (ret < 0) {
		ret = 0;
	}
    return (uint16_t)ret;
}

/// Check for available data on the nominated MAVLink channel
///
/// @param chan		Channel to check
/// @returns		Number of bytes available
uint16_t comm_get_available(mavlink_channel_t chan)
{
    if (!valid_channel(chan)) {
        return 0;
    }
    if ((1U<<chan) & mavlink_locked_mask) {
        return 0;
    }
    int16_t bytes = mavlink_comm_port[chan]->available();
	if (bytes == -1) {
		return 0;
	}
    return (uint16_t)bytes;
}

/*
  send a buffer out a MAVLink channel
 */
void comm_send_buffer(mavlink_channel_t chan, const uint8_t *buf, uint8_t len)
{
    if (!valid_channel(chan)) {
        return;
    }
    if (gcs_alternative_active[chan]) {
        // an alternative protocol is active
        return;
    }
    mavlink_comm_port[chan]->write(buf, len);
}

/*
  lock a channel for send
 */
void comm_send_lock(mavlink_channel_t chan)
{
    chan_locks[(uint8_t)chan].take_blocking();
}

/*
  unlock a channel
 */
void comm_send_unlock(mavlink_channel_t chan)
{
    chan_locks[(uint8_t)chan].give();
}