ardupilot/libraries/AP_GPS/GPS.h

151 lines
3.8 KiB
C++

// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
/// @file GPS.h
/// @brief Interface definition for the various GPS drivers.
#ifndef GPS_h
#define GPS_h
#include <inttypes.h>
#include <Stream.h>
/// @class GPS
/// @brief Abstract base class for GPS receiver drivers.
class GPS
{
public:
/// Constructor
///
/// @note The stream is expected to be set up and configured for the
/// correct bitrate before ::init is called.
///
/// @param s Stream connected to the GPS module. If NULL, assumed
/// to be set up at ::init time. Support for setting
/// the port in the ctor for backwards compatibility.
///
GPS(Stream *s = NULL) : _port(s) {};
/// Startup initialisation.
///
/// This routine performs any one-off initialisation required to set the
/// GPS up for use.
///
/// Must be implemented by the GPS driver.
///
/// @param s Stream connected to the GPS module. If NULL, assumed to
/// have been set up at constructor time.
///
virtual void init(void) = 0;
/// Update GPS state based on possible bytes received from the module.
///
/// This routine must be called periodically to process incoming data.
///
/// Must be implemented by the GPS driver.
///
virtual void update(void) = 0;
/// Query GPS status
///
/// The 'valid message' status indicates that a recognised message was
/// received from the GPS within the last 500ms.
///
/// @todo should probably return an enumeration here.
///
/// @return 0 No GPS connected/detected
/// @return 1 Receiving valid GPS messages but no lock
/// @return 2 Receiving valid messages and locked
///
int status(void);
// Properties
long time; ///< GPS time in milliseconds from the start of the week
long latitude; ///< latitude in degrees * 10,000,000
long longitude; ///< longitude in degrees * 10,000,000
long altitude; ///< altitude in cm
long ground_speed; ///< ground speed in cm/sec
long ground_course; ///< ground course in 100ths of a degree
long speed_3d; ///< 3D speed in cm/sec (not always available)
uint8_t num_sats; ///< Number of visible satelites
/// Set to true when new data arrives. A client may set this
/// to false in order to avoid processing data they have
/// already seen.
bool new_data;
// Deprecated properties
bool fix; ///< true if we have a position fix (use ::status instead)
bool valid_read; ///< true if we have seen data from the GPS (use ::status instead)
// Debug support
bool print_errors; ///< if true, errors will be printed to stderr
protected:
Stream *_port; ///< stream port the GPS is attached to
unsigned long _lastTime; ///< Timer for lost connection
/// reset the last-message-received timer used by ::status
///
void _setTime(void);
/// perform an endian swap on a long
///
/// @param bytes pointer to a buffer containing bytes representing a
/// long in the wrong byte order
/// @returns endian-swapped value
///
long _swapl(const void *bytes);
/// perform an endian swap on an int
///
/// @param bytes pointer to a buffer containing bytes representing an
/// int in the wrong byte order
/// @returns endian-swapped value
int _swapi(const void *bytes);
/// emit an error message
///
/// based on the value of print_errors, emits the printf-formatted message
/// in msg,... to stderr
///
/// @param fmt printf-like format string
///
void _error(const char *msg, ...);
};
inline long
GPS::_swapl(const void *bytes)
{
const uint8_t *b = (const uint8_t *)bytes;
union {
long v;
uint8_t b[4];
} u;
u.b[0] = b[3];
u.b[1] = b[2];
u.b[2] = b[1];
u.b[3] = b[0];
return(u.v);
}
inline int16_t
GPS::_swapi(const void *bytes)
{
const uint8_t *b = (const uint8_t *)bytes;
union {
int16_t v;
uint8_t b[2];
} u;
u.b[0] = b[1];
u.b[1] = b[0];
return(u.v);
}
#endif