#ifndef _NET_GUI_HXX
#define _NET_GUI_HXX
+#include <simgear/misc/stdint.hxx>
-#ifndef __cplusplus
-# error This library requires C++
-#endif
+// 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 int FG_NET_GUI_VERSION = 4;
+const uint32_t FG_NET_GUI_VERSION = 8;
// Define a structure containing the top level flight dynamics model
FG_MAX_TANKS = 4
};
- int version; // increment when data values change
- int pad; // keep doubles 64-bit aligned for some
- // hardware platforms, such as the Sun
- // SPARC, which don't like misaligned
- // data
-
- // Positions
- 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)
+// 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
+ float climb_rate; // feet per second
// Consumables
- int num_tanks; // Max number of fuel tanks
+ uint32_t num_tanks; // Max number of fuel tanks
float fuel_quantity[FG_MAX_TANKS];
// Environment
- time_t cur_time; // current unix time
- long int warp; // offset in seconds to unix time
+ 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
- bool in_range; // tuned navaid is in range?
+ 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