extern "C" __declspec(dllexport) int GccReadGps(short &hour, short &min, short &sec, short &msec, // from GPRMC
double &latitude, double &longitude, // from GPRMC
int &num_sat, double &hdop, double &altitude, // from GPGGA
double &geoid_sep, int &max_snr, // from GPGSV
double &speed, double &heading, // from GPRMC
short &day, short &month, short &year) // from GPRMC
{
if(__read_lock) { return 0; }
const int BUF_SIZE = 4096;
DWORD dwBytesRead;
char buf[BUF_SIZE+1];
int return_status = 0;
FILE *file = NULL;
if (logRawNmea)
{
file = fopen("\\tmp.txt", "a");
fprintf(file, "File handle status: %d\n", (__hGpsPort != INVALID_HANDLE_VALUE ? 1 : 0));
}
// reset output vars
hour = -1; min = -1; sec = -1;
latitude = -32768.0; longitude = -32768.0;
num_sat = -1; hdop = -32768.0; altitude = -32768.0;
geoid_sep = -32768.0; max_snr = -1;
speed = -1.0; heading = -1.0;
day = -1; month = -1; year = -1;
if(__hGpsPort == INVALID_HANDLE_VALUE)
{
if (logRawNmea)
fclose(file);
return return_status;
}
// read file
__read_lock = true;
BOOL status = ReadFile(__hGpsPort, // handle of file to read
buf, // address of buffer that receives data
filemode ? 600 : BUF_SIZE, // number of bytes to read
&dwBytesRead, // address of number of bytes read
NULL // address of structure for data
);
__read_lock = false;
if (logRawNmea)
fprintf(file, "GPS status: %d, read status: %d, bytes read: %d \n", GccGpsStatus(), (status ? 1 : 0), dwBytesRead);
// clear errors if any
if(status == false)
{
DWORD dwErrors;
COMSTAT ComStat;
ClearCommError(__hGpsPort,&dwErrors,&ComStat);
if (logRawNmea)
fclose(file);
return return_status;
}
// terminate string
buf[dwBytesRead] = '\0';
// nothing read - return
if(dwBytesRead == 0)
{
return_status |= READ_NO_ERRORS;
if (logRawNmea)
fclose(file);
return return_status;
}
// has some data
return_status |= READ_NO_ERRORS;
return_status |= READ_HAS_DATA;
if(filemode)
{
char* ptr = strstr(buf+1, "$GPGGA");
if(ptr != NULL)
{
SetFilePointer(__hGpsPort, (ptr - buf) - dwBytesRead, NULL, FILE_CURRENT);
dwBytesRead = ptr - buf;
*ptr = '\0';
}
}
// too much bytes indicate lack of computing power
if(dwBytesRead > 600)
{
//MessageBeep(0); //test
if (logRawNmea)
fprintf(file, "Warning: Too much Bytes read: %d\n", dwBytesRead);
if(dwBytesRead == BUF_SIZE)
{
PurgeComm(__hGpsPort, PURGE_RXCLEAR);
MessageBeep(1); //test
}
__save_str = std::string(buf);
__save_str = __save_str.erase(0, dwBytesRead - 600); //remove old data (would be overwritten anyway)
}
else
{
// append to string stored from the last read
__save_str += std::string(buf);
}
// chop into lines
std::vector<std::string> lines;
std::vector<std::string> words;
ChopIntoLines(__save_str, lines);
// check what to do with the last segment. If it is not complete - store.
if(lines.size() && !filemode) //in filemode would store "----- received 7 lines ----" without CRLF!
{
std::string &last_line = lines[lines.size()-1];
if(last_line.size() > 3)
{
if(last_line[last_line.size()-3] != '*')
{
__save_str = last_line;
lines.pop_back();
}
}
else
{
__save_str = last_line;
lines.pop_back();
}
}
if (logRawNmea)
fprintf(file, "------------ received %d lines ------------ \n", lines.size() );
// parse lines
for(unsigned int i = 0; i < lines.size(); i++)
{
if (logRawNmea)
fprintf(file, "%s\n", lines[i].c_str());
// process valid lines only, i.e. the one with correct checksum
if(IsLineValid(lines[i]))
{
ChopIntoCommaSepWords(lines[i], words);
if(words.size() == 0) { continue; }
if(words[0] == "$GPGSV")
{
ParseGPGSV(words);
gpgsv_trust_count = 10;
}
else if(words[0] == "$GPGGA")
{
ParseGPGGA(words);
return_status |= READ_HAS_GPGGA;
//hour = ___hour; min = ___min; sec = ___sec;
//latitude = ___latitude; longitude = ___longitude;
hdop = ___hdop; altitude = ___altitude; geoid_sep = ___geoid_sep;
}
else if(words[0] == "$GPRMC")
{
ParseGPRMC(words);
return_status |= READ_HAS_GPRMC;
hour = ___hour; min = ___min; sec = ___sec; msec = ___msec;
latitude = ___latitude; longitude = ___longitude;
speed = ___speed; heading = ___heading;
day = ___day; month = ___month; year = ___year;
}
}
else if (logRawNmea)
{ fprintf(file, "^invalid line\n"); }
}
if(gpgsv_trust_count > 0)
{
max_snr = ___max_snr; num_sat = ___num_sat; //use last values of SNR and NUM to avoid blinking (for 10s)
return_status |= READ_HAS_GPGSV; //(some receivers deliver $GPGSV only every 2s or 5s)
gpgsv_trust_count--;
}
if (logRawNmea)
fclose(file);
/* debug write (if want to dump the read buffer, if line chopping did not work)
if(dwBytesRead)
{
FILE *file = fopen("\\tmp.txt", "a");
fwrite(buf, sizeof(char), dwBytesRead, file);
fclose(file);
}
*/
return return_status;
}
bool NMEA::Parse(char read)
{
switch(read)
{
case '$':
//Null the pointers
ChecksumIn = false;
Checksum = 0;
StrChecksum = 0;
c = 0;
break;
default:
sentence[c++] = read;
if(ChecksumIn)
{
if(!StrChecksum)
StrChecksum = 16 * ((read >= '0' && read <= '9') ?
( read - 48 ) : ( read - 65 + 10 ));
else
StrChecksum += ((read >= '0' && read <= '9') ?
( read - 48 ) : ( read - 65 + 10 ));
}
else if(read != ',')
Checksum ^= read;
break;
case '*':
sentence[c++] = read;
ChecksumIn = true;
break;
case '\r':
sentence[c++] = '\0';
break;
case '\n':
if(Checksum == StrChecksum)
{
//Switch on hash value of NMEA sentance name EX GPGGA = 287(P+G+G+A)
switch( sentence[1] + sentence[2] + sentence[3] + sentence[4] )
{
//TODO: Switch over to ENUMS in future to avoid magic numbers
case 287:
ParseGPGGA(sentence);
break;
case 299:
ParseGPGSA(sentence);
break;
case 320:
ParseGPGSV(sentence);
break;
case 306:
ParseGPRMC(sentence);
break;
case 296:
//GPRMB Not Implemented;
break;
default:
/*Serial.print("Parse Failed: ");
Serial.print(sentence[0]);
Serial.print(sentence[1]);
Serial.print(sentence[2]);
Serial.print(sentence[3]);
Serial.print(sentence[4]);
Serial.print(sentence[5]);
Serial.println( sentence[2] + sentence[3] + sentence[4] + sentence[5] , DEC );*/
break;
}
}
else
{
//TODO: Report bad checksum here
}
break;
}
//VS2008 code - Have to return something in VS2008
return false;
}
