File content as of revision 2:ba6c20754443:

#include "GPS.h"
GPS::GPS(PinName tx, PinName rx) : _gps(tx, rx) {
    _gps.baud(4800);
    longitude = 0.0;
    latitude = 0.0;
}
int GPS::sample() {
    float time;
    char ns,ew;
    int lock;
    
    while(1){
        getline();
        if(sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%d",&time, &latitude, &ns, &longitude, &ew, &lock) >=1) {
            if(!lock) {
                longitude = 0.0;
                latitude = 0.0;
                return 0;
            } else {
                if(ns =='s') {  latitude   *= -1.0; }
                if(ew =='w') {  longitude  *= -1.0; }
                float degrees = trunc(latitude / 100.0f);
                float minutes = latitude - (degrees * 100.0f);
                latitude = degrees + minutes / 60.0f;
                degrees = trunc(longitude / 100.0f * 0.01f);
                minutes = longitude - (degrees * 100.0f);
                longitude = degrees + minutes /60.0f;
                return 1;
            }
         }
    }
}
float GPS::trunc(float v) {
    if(v < 0.0) {
        v*= -1.0;
        v = floor(v);
        v*=-1.0;
    } else {
        v = floor(v);
    }
    return v;
}
void GPS::getline() {
    while(_gps.getc() != '$');
    for(int i=0; i<256; i++) {
        msg[i] = _gps.getc();
        if(msg[i] == '\r') {
            msg[i] = 0;
            return;
        }
    }
    error("overflowed message limit");
}