net_gui.hxx

// net_gui.hxx -- defines a simple subset I/O interface to the flight
//                     dynamics model variables
//
// Written by Curtis Olson - curt@flightgear.com, started January 2002.
//
// This file is in the Public Domain, and comes with no warranty.
//
// $Id$


#ifndef _NET_GUI_HXX
#define _NET_GUI_HXX

#include <simgear/misc/stdint.hxx>

// NOTE: this file defines an external interface structure.  Due to
// variability between platforms and architectures, we only used fixed
// length types here.  Specifically, integer types can vary in length.
// I am not aware of any platforms that don't use 4 bytes for float
// and 8 bytes for double.


const uint32_t FG_NET_GUI_VERSION = 8;


// Define a structure containing the top level flight dynamics model
// parameters

class FGNetGUI {

public:

    enum {
        FG_MAX_ENGINES = 4,
        FG_MAX_WHEELS = 3,
        FG_MAX_TANKS = 4
    };

// Note: align fields properly and manually to avoid incompatibilities
// between 32bit and 64bit CPUs. Make sure that each field is already
// placed on an offset which is a multiple of the size of its data
// type, i.e. uint32/float need to have on offset of 4, doubles need
// an offset of 8. This guarantees that compilers will _not_ add
// CPU-specific padding bytes. Whenever in doubt about padding rules,
// check "data structure alignment" in Wikipedia/Google :).

    uint32_t version;           // increment when data values change
    uint32_t padding1;          // 4 padding bytes, so the next (64bit) var is aligned to 8

    // Positions (note: offset for these doubles is already aligned to 8 - to avoid architecture specific alignments)
    double longitude;           // geodetic (radians)
    double latitude;            // geodetic (radians)

    float altitude;             // above sea level (meters)
    float agl;                  // above ground level (meters)
    float phi;                  // roll (radians)
    float theta;                // pitch (radians)
    float psi;                  // yaw or true heading (radians)

    // Velocities
    float vcas;
    float climb_rate;           // feet per second

    // Consumables
    uint32_t num_tanks;         // Max number of fuel tanks
    float fuel_quantity[FG_MAX_TANKS];

    // Environment
    uint32_t cur_time;          // current unix time
                                // FIXME: make this uint64_t before 2038
    uint32_t warp;              // offset in seconds to unix time
    float ground_elev;          // ground elev (meters)

    // Approach
    float tuned_freq;           // currently tuned frequency
    float nav_radial;           // target nav radial
    uint32_t in_range;           // tuned navaid is in range?
    float dist_nm;              // distance to tuned navaid in nautical miles
    float course_deviation_deg; // degrees off target course
    float gs_deviation_deg;     // degrees off target glide slope
};


#endif // _NET_GUI_HXX