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LibrePilot/flight/Modules/GPS/NMEA.c
peabody124 fc54159369 OP-265 Flight reorganization of UAVObjects and Modules up a directory
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@2415 ebee16cc-31ac-478f-84a7-5cbb03baadba
2011-01-14 01:38:19 +00:00

825 lines
22 KiB
C

#include "openpilot.h"
#include "pios.h"
#include "NMEA.h"
#include "gpsposition.h"
#include "gpstime.h"
#include "gpssatellites.h"
// Debugging
//#define GPSDEBUG
#ifdef GPSDEBUG
#define NMEA_DEBUG_PKT ///< define to enable debug of all NMEA messages
#define NMEA_DEBUG_GGA ///< define to enable debug of GGA messages
#define NMEA_DEBUG_VTG ///< define to enable debug of VTG messages
#define NMEA_DEBUG_RMC ///< define to enable debug of RMC messages
#define NMEA_DEBUG_GSA ///< define to enable debug of GSA messages
#define NMEA_DEBUG_GSV ///< define to enable debug of GSV messages
#define NMEA_DEBUG_ZDA ///< define to enable debug of ZDA messages
#define NMEA_DEBUG_PGTOP ///< define to enable debug of PGTOP messages
#endif
/* Utility functions */
static float NMEA_real_to_float(char *nmea_real);
static bool NMEA_latlon_to_fixed_point(int32_t * latlon, char *nmea_latlon);
/* NMEA sentence parsers */
struct nmea_parser {
const char *prefix;
bool(*handler) (GPSPositionData * GpsData, char *sentence);
};
static bool nmeaProcessGPGGA(GPSPositionData * GpsData, char *sentence);
static bool nmeaProcessGPRMC(GPSPositionData * GpsData, char *sentence);
static bool nmeaProcessGPVTG(GPSPositionData * GpsData, char *sentence);
static bool nmeaProcessGPGSA(GPSPositionData * GpsData, char *sentence);
static bool nmeaProcessGPZDA(GPSPositionData * GpsData, char *sentence);
static bool nmeaProcessGPGSV(GPSPositionData * GpsData, char *sentence);
static bool nmeaProcessPGTOP(GPSPositionData * GpsData, char *sentence);
static struct nmea_parser nmea_parsers[] = {
{
.prefix = "GPGGA",
.handler = nmeaProcessGPGGA,
},
{
.prefix = "GPVTG",
.handler = nmeaProcessGPVTG,
},
{
.prefix = "GPGSA",
.handler = nmeaProcessGPGSA,
},
{
.prefix = "GPRMC",
.handler = nmeaProcessGPRMC,
},
{
.prefix = "GPZDA",
.handler = nmeaProcessGPZDA,
},
{
.prefix = "GPGSV",
.handler = nmeaProcessGPGSV,
},
{
.prefix = "PGTOP",
.handler = nmeaProcessPGTOP,
},
};
static struct nmea_parser *NMEA_find_parser_by_prefix(char *prefix)
{
if (!prefix) {
return (NULL);
}
for (uint8_t i = 0; i < NELEMENTS(nmea_parsers); i++) {
struct nmea_parser *parser = &nmea_parsers[i];
/* Use strcmp to check for exact equality over the entire prefix */
if (!strcmp(prefix, parser->prefix)) {
/* Found an appropriate parser */
return (parser);
}
}
/* No matching parser for this prefix */
return (NULL);
}
/**
* Computes NMEA sentence checksum
* \param[in] Buffer for parsed nmea sentence
* \return false checksum not valid
* \return true checksum valid
*/
bool NMEA_checksum(char *nmea_sentence)
{
uint8_t checksum_computed = 0;
uint8_t checksum_received;
while (*nmea_sentence != '\0' && *nmea_sentence != '*') {
checksum_computed ^= *nmea_sentence;
nmea_sentence++;
}
/* Make sure we're now pointing at the checksum */
if (*nmea_sentence == '\0') {
/* Buffer ran out before we found a checksum marker */
return false;
}
/* Load the checksum from the buffer */
checksum_received = strtol(nmea_sentence + 1, NULL, 16);
//PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART,"$%d=%d\r\n",checksum_received,checksum_computed);
return (checksum_computed == checksum_received);
}
/**
* Parses a complete NMEA sentence and updates the GPSPosition UAVObject
* \param[in] An NMEA sentence with a valid checksum
* \return true if the sentence was successfully parsed
* \return false if any errors were encountered with the parsing
*/
bool NMEA_update_position(char *nmea_sentence)
{
char *sentence = nmea_sentence;
struct nmea_parser *parser;
char *prefix;
/* Find out what kind of NMEA packet we're dealing with */
prefix = strsep(&sentence, ",");
/* Check if we have a parser for this packet type */
parser = NMEA_find_parser_by_prefix(prefix);
if (!parser) {
/* Valid but unhandled packet type */
return false;
}
/* Found a matching parser for this packet type */
/* Reject empty (but valid) packets without parsing */
if (sentence[0] == ',' && sentence[1] == ',' && sentence[2] == ',') {
/* Nothing to parse, */
return false;
}
/* Parse the sentence and update the GpsData object */
GPSPositionData GpsData;
GPSPositionGet(&GpsData);
if (!parser->handler(&GpsData, sentence)) {
/* Parse failed for valid checksum. Do not update the UAVObject. */
return false;
}
GPSPositionSet(&GpsData);
/* Tell the caller what kind of packet we just parsed */
return true;
}
/**
* Parse an NMEA GPGGA sentence and update the given UAVObject
* \param[in] A pointer to a GPSPosition UAVObject to be updated.
* \param[in] An NMEA sentence with a valid checksum
*/
static bool nmeaProcessGPGGA(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",*";
#ifdef NMEA_DEBUG_GGA
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
// get UTC time [hhmmss.sss]
tokens = strsep(&next, delimiter);
//strcpy(GpsInfo.TimeOfFix,tokens);
// next field: latitude
// get latitude [DDMM.mmmmm]
tokens = strsep(&next, delimiter);
if (!NMEA_latlon_to_fixed_point(&GpsData->Latitude, tokens)) {
return false;
}
// next field: N/S indicator
// correct latitude for N/S
tokens = strsep(&next, delimiter);
if (tokens[0] == 'S')
GpsData->Latitude = -GpsData->Latitude;
// next field: longitude
// get longitude [dddmm.mmmmm]
tokens = strsep(&next, delimiter);
if (!NMEA_latlon_to_fixed_point(&GpsData->Longitude, tokens)) {
return false;
}
// next field: E/W indicator
// correct longitude for E/W
tokens = strsep(&next, delimiter);
if (tokens[0] == 'W')
GpsData->Longitude = -GpsData->Longitude;
// next field: position fix status
// position fix status
// 0 = Invalid, 1 = Valid SPS, 2 = Valid DGPS, 3 = Valid PPS
// check for good position fix
tokens = strsep(&next, delimiter);
//if((tokens[0] != '0') || (tokens[0] != 0))
// GpsData.Updates++;
// next field: satellites used
// get number of satellites used in GPS solution
tokens = strsep(&next, delimiter);
GpsData->Satellites = atoi(tokens);
// next field: HDOP (horizontal dilution of precision)
tokens = strsep(&next, delimiter);
// next field: altitude
// get altitude (in meters mm.m)
tokens = strsep(&next, delimiter);
GpsData->Altitude = NMEA_real_to_float(tokens);
// next field: altitude units, always 'M'
tokens = strsep(&next, delimiter);
// next field: geoid separation
tokens = strsep(&next, delimiter);
GpsData->GeoidSeparation = NMEA_real_to_float(tokens);
// next field: separation units
tokens = strsep(&next, delimiter);
// next field: DGPS age
tokens = strsep(&next, delimiter);
// next field: DGPS station ID
tokens = strsep(&next, delimiter);
// next field: checksum
tokens = strsep(&next, delimiter);
return true;
}
/**
* Parse an NMEA GPRMC sentence and update the given UAVObject
* \param[in] A pointer to a GPSPosition UAVObject to be updated.
* \param[in] An NMEA sentence with a valid checksum
*/
static bool nmeaProcessGPRMC(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",*";
GPSTimeData gpst;
GPSTimeGet(&gpst);
#ifdef NMEA_DEBUG_RMC
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
// get UTC time [hhmmss.sss]
tokens = strsep(&next, delimiter);
float hms = NMEA_real_to_float(tokens);
gpst.Second = (int)hms % 100;
gpst.Minute = (((int)hms - gpst.Second) / 100) % 100;
gpst.Hour = (int)hms / 10000;
// next field: Navigation receiver warning A = OK, V = warning
tokens = strsep(&next, delimiter);
// next field: latitude
// get latitude [ddmm.mmmmm]
tokens = strsep(&next, delimiter);
if (!NMEA_latlon_to_fixed_point(&GpsData->Latitude, tokens)) {
return false;
}
// next field: N/S indicator
// correct latitude for N/S
tokens = strsep(&next, delimiter);
if (tokens[0] == 'S')
GpsData->Latitude = -GpsData->Latitude;
// next field: longitude
// get longitude [dddmm.mmmmm]
tokens = strsep(&next, delimiter);
if (!NMEA_latlon_to_fixed_point(&GpsData->Longitude, tokens)) {
return false;
}
// next field: E/W indicator
// correct longitude for E/W
tokens = strsep(&next, delimiter);
if (tokens[0] == 'W')
GpsData->Longitude = -GpsData->Longitude;
// next field: speed (knots)
// get speed in knots
tokens = strsep(&next, delimiter);
GpsData->Groundspeed = NMEA_real_to_float(tokens);
// to m/s
GpsData->Groundspeed *= 0.51444;
// next field: True course
// get True course
tokens = strsep(&next, delimiter);
GpsData->Heading = NMEA_real_to_float(tokens);
// next field: Date of fix
// get Date of fix
tokens = strsep(&next, delimiter);
// TODO: Should really not use a float here to be safe
float date = NMEA_real_to_float(tokens);
gpst.Year = (int)date % 100;
gpst.Month = (((int)date - gpst.Year) / 100) % 100;
gpst.Day = (int)(date / 10000);
gpst.Year += 2000;
// next field: Magnetic variation
tokens = strsep(&next, delimiter);
// next field: E or W
tokens = strsep(&next, delimiter);
// next field: Mode: A=autonomous, D=differential, E=Estimated, N=not valid, S=Simulator
tokens = strsep(&next, delimiter);
// next field: checksum
tokens = strsep(&next, delimiter);
GPSTimeSet(&gpst);
return true;
}
/**
* Parse an NMEA GPVTG sentence and update the given UAVObject
* \param[in] A pointer to a GPSPosition UAVObject to be updated.
* \param[in] An NMEA sentence with a valid checksum
*/
static bool nmeaProcessGPVTG(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",*";
#ifdef NMEA_DEBUG_VTG
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
// get course (true north ref) in degrees [ddd.dd]
tokens = strsep(&next, delimiter);
GpsData->Heading = NMEA_real_to_float(tokens);
// next field: 'T'
tokens = strsep(&next, delimiter);
// next field: course (magnetic north)
// get course (magnetic north ref) in degrees [ddd.dd]
tokens = strsep(&next, delimiter);
// next field: 'M'
tokens = strsep(&next, delimiter);
// next field: speed (knots)
// get speed in knots
tokens = strsep(&next, delimiter);
GpsData->Groundspeed = NMEA_real_to_float(tokens);
// to m/s
GpsData->Groundspeed *= 0.51444;
// next field: 'N'
tokens = strsep(&next, delimiter);
// next field: speed (km/h)
// get speed in km/h
tokens = strsep(&next, delimiter);
// next field: 'K'
tokens = strsep(&next, delimiter);
// next field: checksum
tokens = strsep(&next, delimiter);
return true;
}
/**
* Parse an NMEA GPZDA sentence and update the @ref GPSTime object
* \param[in] A pointer to a GPSPosition UAVObject to be updated (unused).
* \param[in] An NMEA sentence with a valid checksum
*/
static bool nmeaProcessGPZDA(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",*";
#ifdef NMEA_DEBUG_ZDA
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
GPSTimeData gpst;
GPSTimeGet(&gpst);
tokens = strsep(&next, delimiter);
float hms = NMEA_real_to_float(tokens);
gpst.Second = (int)hms % 100;
gpst.Minute = (((int)hms - gpst.Second) / 100) % 100;
gpst.Hour = (int)hms / 10000;
tokens = strsep(&next, delimiter);
gpst.Day = atoi(tokens);
tokens = strsep(&next, delimiter);
gpst.Month = atoi(tokens);
tokens = strsep(&next, delimiter);
gpst.Year = atoi(tokens);
GPSTimeSet(&gpst);
return true;
}
static GPSSatellitesData gsv_partial;
/* Bitmaps of which sentences we're looking for to allow us to handle out-of-order GSVs */
static uint8_t gsv_expected_mask;
static uint8_t gsv_processed_mask;
/* Error counters */
static uint16_t gsv_incomplete_error;
static uint16_t gsv_duplicate_error;
static bool nmeaProcessGPGSV(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",";
#ifdef NMEA_DEBUG_GSV
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
/* Drop the checksum */
char *tmp = sentence;
char *tmp_delim = "*";
next = strsep(&tmp, tmp_delim);
/* # of sentences in full GSV data set */
tokens = strsep(&next, delimiter);
uint8_t total_sentences = atoi(tokens);
if ((total_sentences < 1) || (total_sentences > 8)) {
return false;
}
/* Sentence number within the current GSV data set */
tokens = strsep(&next, delimiter);
uint8_t current_sentence = atoi(tokens);
if (current_sentence < 1) {
return false;
}
/* # of satellites currently in view */
tokens = strsep(&next, delimiter);
gsv_partial.SatsInView = atoi(tokens);
/* Find out if this is the first sentence in the GSV set */
if (current_sentence == 1) {
if (gsv_expected_mask != gsv_processed_mask) {
/* We are starting over when we haven't yet finished our previous GSV group */
gsv_incomplete_error++;
}
/* First GSV sentence in the sequence, reset our expected_mask */
gsv_expected_mask = (1 << total_sentences) - 1;
}
uint8_t current_sentence_id = (1 << (current_sentence - 1));
if (gsv_processed_mask & current_sentence_id) {
/* Duplicate sentence in this GSV set */
gsv_duplicate_error++;
} else {
/* Note that we've seen this sentence */
gsv_processed_mask |= current_sentence_id;
}
/* Make sure this sentence can fit in our GPSSatellites object */
if ((current_sentence * 4) <= NELEMENTS(gsv_partial.PRN)) {
/* Process 4 blocks of satellite info */
for (uint8_t i = 0; next && i < 4; i++) {
uint8_t sat_index = ((current_sentence - 1) * 4) + i;
/* PRN number */
tokens = strsep(&next, delimiter);
gsv_partial.PRN[sat_index] = atoi(tokens);
/* Elevation */
tokens = strsep(&next, delimiter);
gsv_partial.Elevation[sat_index] = NMEA_real_to_float(tokens);
/* Azimuth */
tokens = strsep(&next, delimiter);
gsv_partial.Azimuth[sat_index] = NMEA_real_to_float(tokens);
/* SNR */
tokens = strsep(&next, delimiter);
gsv_partial.SNR[sat_index] = atoi(tokens);
}
}
/* Find out if we're finished processing all GSV sentences in the set */
if ((gsv_expected_mask != 0) && (gsv_processed_mask == gsv_expected_mask)) {
/* GSV set has been fully processed. Update the GPSSatellites object. */
GPSSatellitesSet(&gsv_partial);
memset((void *)&gsv_partial, 0, sizeof(gsv_partial));
gsv_expected_mask = 0;
gsv_processed_mask = 0;
}
return true;
}
/**
* Parse an NMEA GPGSA sentence and update the given UAVObject
* \param[in] A pointer to a GPSPosition UAVObject to be updated.
* \param[in] An NMEA sentence with a valid checksum
*/
static bool nmeaProcessGPGSA(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",*";
#ifdef NMEA_DEBUG_GSA
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
// next field: Mode
// Mode: M=Manual, forced to operate in 2D or 3D, A=Automatic, 3D/2D
tokens = strsep(&next, delimiter);
// next field: Mode
// Mode: 1=Fix not available, 2=2D, 3=3D
tokens = strsep(&next, delimiter);
switch (atoi(tokens)) {
case 1:
GpsData->Status = GPSPOSITION_STATUS_NOFIX;
break;
case 2:
GpsData->Status = GPSPOSITION_STATUS_FIX2D;
break;
case 3:
GpsData->Status = GPSPOSITION_STATUS_FIX3D;
break;
default:
/* Unhandled */
return false;
break;
}
// next field: 3-14 IDs of SVs used in position fix (null for unused fields)
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
tokens = strsep(&next, delimiter);
// next field: PDOP
tokens = strsep(&next, delimiter);
GpsData->PDOP = NMEA_real_to_float(tokens);
// next field: HDOP
tokens = strsep(&next, delimiter);
GpsData->HDOP = NMEA_real_to_float(tokens);
// next field: VDOP
tokens = strsep(&next, delimiter);
GpsData->VDOP = NMEA_real_to_float(tokens);
// next field: checksum
tokens = strsep(&next, delimiter);
return true;
}
/**
* Parse an NMEA PGTOP sentence and update the given UAVObject
* \param[in] A pointer to a GPSPosition UAVObject to be updated.
* \param[in] An NMEA sentence with a valid checksum
*/
static bool nmeaProcessPGTOP(GPSPositionData * GpsData, char *sentence)
{
char *next = sentence;
char *tokens;
char *delimiter = ",*";
#ifdef NMEA_DEBUG_PGTOP
PIOS_COM_SendFormattedStringNonBlocking(COM_DEBUG_USART, "$%s\r\n", sentence);
#endif
GPSTimeData gpst;
GPSTimeGet(&gpst);
// get UTC time [hhmmss.sss]
tokens = strsep(&next, delimiter);
float hms = NMEA_real_to_float(tokens);
gpst.Second = (int)hms % 100;
gpst.Minute = (((int)hms - gpst.Second) / 100) % 100;
gpst.Hour = (int)hms / 10000;
// next field: latitude
// get latitude decimal degrees
tokens = strsep(&next, delimiter);
GpsData->Latitude = NMEA_real_to_float(tokens)*1e7;
// next field: N/S indicator
// correct latitude for N/S
tokens = strsep(&next, delimiter);
if (tokens[0] == 'S')
GpsData->Latitude = -GpsData->Latitude;
// next field: longitude
// get longitude decimal degrees
tokens = strsep(&next, delimiter);
GpsData->Longitude = NMEA_real_to_float(tokens)*1e7;
// next field: E/W indicator
// correct longitude for E/W
tokens = strsep(&next, delimiter);
if (tokens[0] == 'W')
GpsData->Longitude = -GpsData->Longitude;
// next field: Fix Quality
// Mode: 0=Fix not available, 1=GPS fix, 2=DGPS fix
tokens = strsep(&next, delimiter);
// next field: satellites used
// get number of satellites used in GPS solution
tokens = strsep(&next, delimiter);
GpsData->Satellites = atoi(tokens);
// next field: HDOP
tokens = strsep(&next, delimiter);
GpsData->HDOP = NMEA_real_to_float(tokens);
// next field: altitude
// get altitude (in meters mm.m)
tokens = strsep(&next, delimiter);
GpsData->Altitude = NMEA_real_to_float(tokens);
// next field: geoid separation
tokens = strsep(&next, delimiter);
GpsData->GeoidSeparation = NMEA_real_to_float(tokens);
// next field: Fix Type
// Mode: 1=Fix not available, 2=2D, 3=3D
tokens = strsep(&next, delimiter);
switch (atoi(tokens)) {
case 1:
GpsData->Status = GPSPOSITION_STATUS_NOFIX;
break;
case 2:
GpsData->Status = GPSPOSITION_STATUS_FIX2D;
break;
case 3:
GpsData->Status = GPSPOSITION_STATUS_FIX3D;
break;
default:
/* Unhandled */
return false;
break;
}
// get course over ground in degrees [ddd.dd]
tokens = strsep(&next, delimiter);
GpsData->Heading = NMEA_real_to_float(tokens);
// next field: speed (km/h)
// get speed in km/h
tokens = strsep(&next, delimiter);
GpsData->Groundspeed = NMEA_real_to_float(tokens);
// to m/s
GpsData->Groundspeed /= 3.6;
tokens = strsep(&next, delimiter);
gpst.Day = atoi(tokens);
tokens = strsep(&next, delimiter);
gpst.Month = atoi(tokens);
tokens = strsep(&next, delimiter);
gpst.Year = atoi(tokens);
GPSTimeSet(&gpst);
// next field: checksum
tokens = strsep(&next, delimiter);
return true;
}
/* Parse a number encoded in a string of the format:
* [-]NN.nnnnn
* into a signed whole part and an unsigned fractional part.
* The fract_units field indicates the units of the fractional part as
* 1 whole = 10^fract_units fract
*/
static bool NMEA_parse_real(int32_t * whole, uint32_t * fract, uint8_t * fract_units, char *field)
{
char *s = field;
char *field_w;
char *field_f;
PIOS_DEBUG_Assert(whole);
PIOS_DEBUG_Assert(fract);
PIOS_DEBUG_Assert(fract_units);
field_w = strsep(&s, ".");
field_f = s;
*whole = strtol(field_w, NULL, 10);
if (field_w) {
/* decimal was found so we may have a fractional part */
*fract = strtoul(field_f, NULL, 10);
*fract_units = strlen(field_f);
} else {
/* no decimal was found, fractional part is zero */
*fract = 0;
*fract_units = 0;
}
return true;
}
/*
* This function only exists to deal with a linking
* failure in the stdlib function strtof(). This
* implementation does not rely on the _sbrk() syscall
* like strtof() does.
*/
static float NMEA_real_to_float(char *nmea_real)
{
int32_t whole;
uint32_t fract;
uint8_t fract_units;
/* Sanity checks */
PIOS_DEBUG_Assert(nmea_real);
if (!NMEA_parse_real(&whole, &fract, &fract_units, nmea_real)) {
return false;
}
/* Convert to float */
return (((float)whole) + fract * pow(10, -fract_units));
}
/*
* Parse a field in the format:
* DD[D]MM.mmmm[mm]
* into a fixed-point representation in units of (degrees * 1e-7)
*/
static bool NMEA_latlon_to_fixed_point(int32_t * latlon, char *nmea_latlon)
{
int32_t num_DDDMM;
uint32_t num_m;
uint8_t units;
/* Sanity checks */
PIOS_DEBUG_Assert(nmea_latlon);
PIOS_DEBUG_Assert(latlon);
if (!NMEA_parse_real(&num_DDDMM, &num_m, &units, nmea_latlon)) {
return false;
}
/* scale up the mmmm[mm] field apropriately depending on # of digits */
switch (units) {
case 0:
/* no digits, value is zero so no scaling */
break;
case 1: /* m */
num_m *= 1e6; /* m000000 */
break;
case 2: /* mm */
num_m *= 1e5; /* mm00000 */
break;
case 3: /* mmm */
num_m *= 1e4; /* mmm0000 */
break;
case 4: /* mmmm */
num_m *= 1e3; /* mmmm000 */
break;
case 5: /* mmmmm */
num_m *= 1e2; /* mmmmm00 */
break;
case 6: /* mmmmmm */
num_m *= 1e1; /* mmmmmm0 */
break;
default:
/* unhandled format */
num_m = 0;
break;
}
*latlon = (num_DDDMM / 100) * 1e7; /* scale the whole degrees */
*latlon += (num_DDDMM % 100) * 1e7 / 60; /* add in the scaled decimal whole minutes */
*latlon += num_m / 60; /* add in the scaled decimal fractional minutes */
return true;
}