File content as of revision 118:e831cdb799ab:

#include <stdio.h>
#include "Location.h"
#include "SmartRestConf.h"
#include "logging.h"

// Percentage cut-off for avoiding sending similar sensor readings.
#define THRESHOLD_PERCENT_LOC 0.05
// Timeout for forcing a sending even if readings are similar [seconds].
#define TIME_LIMIT_LOC 900

size_t Location::read(char *buf, size_t maxLen, char *status, size_t num)
{
        static const char *fmt = "108,%ld,%.2f,%.6f,%.6f\r\n109,%ld,%.2f,%.6f,%.6f";
        GPSTracker::Position pos;
        if (!gpsTracker.position(&pos)) {
                return 0;
        }
        float data[3] = { pos.altitude, pos.latitude,
                          pos.longitude };

        if (abs(oldValues[0]-data[0]) <= abs(oldValues[0])*THRESHOLD_PERCENT_LOC &&
            abs(oldValues[1]-data[1]) <= abs(oldValues[1])*THRESHOLD_PERCENT_LOC &&
            abs(oldValues[2]-data[2]) <= abs(oldValues[2])*THRESHOLD_PERCENT_LOC) {
                time_t t_interval = time(NULL) - t_start;
                if (t_interval < TIME_LIMIT_LOC) {
                        return 0;
                }
        }
        size_t l = snprintf(buf, maxLen, fmt, deviceID, data[0], data[1],
                            data[2], deviceID, data[0], data[1], data[2]);
        if (status) {
                snprintf(status, num, "Send GPS %.1f,%.1f,%.1f",
                         data[0], data[1], data[2]);
        }
        oldValues[0] = data[0];
        oldValues[1] = data[1];
        oldValues[2] = data[2];
        t_start = time(NULL);
        return l;
}