gpslib.cpp

这是一个GPS接收定位的原代码

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <qmessagebox.h>

#include "gpslib.h"

int verbose;	// defining instance

// WHY THE BIZARRE STYLE OF DECLARATIONS IN THIS FILE?
// Because it was originally a DLL for Visual Basic and works.
// Minimum changes only have been made, but changes there are.

// Following functions implement various globals and other things

// When processing a logfile, scale parameters to fit
struct vals{
	double LongMax, LongMin, LatMax, LatMin;
	// No idea what MinTime & MaxTime were ever supposed to do!
	// long MinTime, MaxTime;
	// getline uses these globals
	double lat, longit;
	double utctime;	// This is typically measured to hundredths of a second ...
}rdvals, wvals; // rdvals used when reading, wvals when writing
		// wvals is not currently (may never be) used

FILE *logfp;	// Used when reading

int openlogfile(const char *cp, bool forwriting){
	if(logfp)
		fclose(logfp);
	logfp = fopen(cp, forwriting ? "ab" : "rb");
	return logfp != 0;
	printf("Logfile opened for reading\n");
}

// write a newline-terminatd string to the logfile if open
void putlogfpstring(const char *cp){
	if(logfp)fprintf(logfp, "%s\n", cp);
}

int closelogfile(){
	if(logfp){
		fclose(logfp);
		logfp = 0;
		return 1;
	}
	return 0;
}

int getline();

int getscale(double *minlat, double *maxlat, double *minlong, double *maxlong){
	if(logfp == 0)
		return 0;
	int first = 1;
	while(getline()){
		if(first){
			rdvals.LatMax = rdvals.LatMin = rdvals.lat;
			rdvals.LongMax = rdvals.LongMin = rdvals.longit;
			// rdvals.MinTime = rdvals.MaxTime = rdvals.ms;
			first = 0;
		}else{
			// if(rdvals.ms < rdvals.MinTime) rdvals.MinTime = rdvals.ms;
			// if(rdvals.ms > rdvals.MaxTime) rdvals.MaxTime = rdvals.ms;
			if(rdvals.lat < rdvals.LatMin) rdvals.LatMin = rdvals.lat;
			if(rdvals.lat > rdvals.LatMax) rdvals.LatMax = rdvals.lat;
			if(rdvals.longit < rdvals.LongMin) rdvals.LongMin = rdvals.longit;
			if(rdvals.longit > rdvals.LongMax) rdvals.LongMax = rdvals.longit;
		}
      //printf ("Lat (deg) = %f, Long (deg) = %f\n", lat, longit);
		// getchar();
	}
	*minlat = rdvals.LatMin;
	*maxlat = rdvals.LatMax;
	*minlong = rdvals.LongMin;
	*maxlong = rdvals.LongMax;
	rewind(logfp);
	return 1;
}

int convert(const char *, vals *);

int getline(){
	char rbuff[512];
	long count=0;
	int rval;
loop:
	if ((rval = (fgets(rbuff, sizeof(rbuff), logfp) != 0)) != 0){
		count++;
		if(!isdigit(rbuff[0]))
			goto loop;
		convert(rbuff, &rdvals);
	}
	return rval;
}

// convert n chars to int
int rdint(const char *&cpr, int ndigs){
	int result = 0;
	while(ndigs-- && *cpr){
		result = result*10 + *cpr++-'0';
	}
	return result;
}

// convert xx[x]nn.nnn to fractional degrees
double getlatlong(const char *&cpr, int ndigs){
	int ipart = rdint(cpr, ndigs);
	double fracdegs = strtod((char *)cpr, (char **)&cpr);
	fracdegs = fracdegs/60+ipart;
	// Strtod absorbs a trailing 'E' (sigh)
	char c = cpr[-1];
	if(c && tolower(c) == 'e')
   	cpr--;
	return fracdegs;
}

double getlatitude(const char *&cpr){
	double res = getlatlong(cpr, 2);
	switch(tolower(*cpr++)){
		case 'n': break;
		case 's': res = -res; break;
		default: return 1000;
	}
	return res;
}

double getlongitude(const char *&cpr){
	double res = getlatlong(cpr, 3);
	switch(tolower(*cpr++)){
		case 'e': break;
		case 'w': res = -res; break;
		default: return 1000;
	}
	return res;
}

// convert
int convert(const char *rbuff, vals *vp){
		const ncommas = 13;
		const char *fields[ncommas];
		fields[0] = rbuff;
		for(int i = 1; i < ncommas; i++){
			const char *cp = strchr(fields[i-1], ',');
			if(cp == 0){
				fprintf(stderr, "Convert: too few commas in %s", rbuff);
				return 0;
			}
			fields[i] = cp+1;
			// *cp = 0;
			// printf("Field %d = %s\n", i, fields[i-1]);
		}
		// Now validate that it's all sensible characters
		for(const char *cp = rbuff; *cp; cp++){
			if(iscntrl(*cp) && *cp != '\r' && *cp != '\n'){
				printf("convert: bad character 0x%x(%c) in %s\n", *cp, *cp, rbuff);
				return 0;
			}
		}
		// printf("read log line %s\n", rbuff);
/*
		const char *thisf = fields[0]+8;
		// collect hundredths of seconds
		vp->ms = *thisf-- -'0';
		vp->ms += (*thisf-- -'0')*     10;
		thisf--;
		vp->ms += (*thisf-- -'0')*    100;
		vp->ms += (*thisf-- -'0')*   1000;
		vp->ms += (*thisf-- -'0')*   6000l;
		vp->ms += (*thisf-- -'0')*  60000l;
		vp->ms += (*thisf-- -'0')* 360000l;
		vp->ms += (*thisf-- -'0')*3600000l;
		// long secs = vp->ms/100;
		// printf("Seconds = %ld (%.2ld:%.2ld:%.2ld) ", ms, secs / 3600, secs % 3600 / 60, secs %60);
*/
		const char *thisf = fields[0];
		vp->utctime = rdint(thisf, 2)*60l*60l;
		vp->utctime += rdint(thisf, 2)*60;
		vp->utctime += strtod(thisf, 0);

		thisf = fields[1];
		vp->lat = getlatlong(thisf, 2);
		if(*(fields[2]) == 'S'){
			vp->lat = -vp->lat;
		}
		thisf = fields[3];
		vp->longit = getlatlong(thisf, 3);
		if(*(fields[4]) == 'W'){
			vp->longit = -vp->longit;
		}
		return 1;
}
int getlogstr(char *latp){
	char rbuff[512];
loop:
	if (fgets(rbuff, sizeof(rbuff), logfp)){
		if(!isdigit(rbuff[0]))
			goto loop;
		strcpy(latp, rbuff);
		return strlen(rbuff);
	}
	return 0;
}

int rcvplotstr(const String &plotstr, double &latit, double &longit, double &utctime){
	if(verbose)printf("Read GPS input %s\n", plotstr.cstring());
	if(plotstr.left(7) != "$GPGGA,"){
		return 0;
	}
	const char *cp = plotstr.cstring()+7;
	if(verbose) printf("Received valid GPGGA string: %s\n", cp);
	putlogfpstring(cp);
	if(!convert(cp, &rdvals)){
		printf("Couldn't convert GPGGA string: %s\n", cp);
		return 0;
	}
	latit = rdvals.lat;
	longit = rdvals.longit;
	utctime = rdvals.utctime;
	return 1;

}

int getlogll(double &latit, double &longit, double &utctime){
	int rval = getline();
	if(rval){
		latit = rdvals.lat;
		longit = rdvals.longit;
		utctime = rdvals.utctime;
	}else{
		rewind(logfp);
	}
	return rval;
}

char ngrletters[] = "ABCDEFGHJKLMNOPQRSTUVWXYZ";
int glet2int(char c){
	char *lp = strchr(ngrletters, toupper(c));
	if(lp == 0)
		return -1;
		return int(lp-ngrletters);
}

FILE *lmfp;
int openlandmarkfile(const char *cp){
	if(lmfp) fclose(lmfp);
	lmfp = fopen(cp, "r");
	return lmfp != 0;
}
int closelandmarkfile(){
	if(!lmfp) return 0;
	fclose(lmfp);
	return 1;
}

int cvtngrstr(const char *ngrstr, long *eastres, long *northres, double *latres, double *longres){
	const char *cp = ngrstr;
	return _cvtngrstr(cp, eastres, northres, latres, longres);
}

int _cvtngrstr(const char * &cp, long *eastres, long *northres, double *latres, double *longres){
// Stuff that VB should have
	// presume ngr
	long north, east;

	int lval = glet2int(*cp++);
	if(lval < 0) return 0;
	// flip to give useful base
	lval = 21-lval;
	if(lval < 0) return 0;
	east = (4-lval%5)*500000l;
	north = lval/5*500000l;
	// printf("East %ld, north %ld\n", east, north);
	if((lval = glet2int(*cp++)) < 0) return 0;
	east += (lval%5)*100000l;
	north += (4-lval/5)*100000l;
	// printf("East %ld, north %ld\n", east, north);
	if(*cp == ' ')cp++;
	// allowable format is now nnn nnn, nnnn nnnn, nnnnnn, nnnnnnnn
	// not strictly checked though