main.c

/* File: Main.c
 * Author: Elliot Robinson
 * Date modified: 3 Sept, 2011
 * Changes:
 *   3 Sept, 2011: Inititial creation
 *   5 Sept, 2011: Adds verifySentence and validateChecksum
 */

#include "stdlib.h"
#include "stdio.h"
#include "string.h"
#include "time.h"

#include "main.h"
#include "parse.h"

/* Author: Elliot Robinson
 * Contains the main event loop for the application
 */

#define MAX_MESSAGE_LENGTH 82 // 80 char max + "\r\n"

int main(int argc, char **argv)
{
    int parseStatus;
    char *inFile = 0, *outFile = 0, *outFile2 = 0;
    parseCommandLine(argc, argv, &inFile, &outFile, &outFile2);

    // Open files
    FILE *fin = fopen(inFile, "r"); // Open input file for reading
    FILE *fout = fopen(outFile, "w"); // Open output file for writing, truncating current file
    FILE *fout2 = fopen(outFile2, "w"); // Open output file for writing, truncating current file

    if ((fout == 0) || (fout2 == 0) || (fin == 0))
    {
	puts("Invalid filename");
	return 1;
    }

    struct NMEAData persistentData = EMPTY_NMEADATA;
    persistentData.date.tm_isdst = -1; // Necessary to keep hour records from being mangled by automatic DST.
    time_t rawtime = time(NULL);
    persistentData.localOffset = gmtime(&rawtime)->tm_hour - localtime(&rawtime)->tm_hour;
    struct NMEAMessage *message = 0;

    char *lineIn = 0; // Will be automatically alloc'ed by getline
    size_t messageLen = 0;

    char *outMessage = malloc(1024); // Way more memory than I'll ever need because I'm too lazy to figure out the maximum length of our output strings. No sizeof because the standard says sizeof(char) always == 1.
    
    // Elliot: strlen() might be of use. ^^^^
    // Doubtful. We'd have to do it in makeNMEADataString and resize the array on the fly. It's easier to just malloc a shit ton of memory.

    // Add a check in here to only output the string when
    // allDataSet == 133 (1+2+4+8+16+32+64)
    // ^^^^^^^^^^ == Math fail. 0xFF is definitely 127.

    // Put header
    fputs("Month, Day, Year, UTC Time (HHMMSS), Epoch Time, TAI Time, Decimal Longitude, Decimal Latitude, DMS Longitude, DMS Latitude, Altitude (m), Satellite 1 PRN, Satellite 1 Elevation, Satellite 1 SNR, Satellite 1 Azimuth, Satellite 2 PRN, Satellite 2 Elevation, Satellite 2 SNR, Satellite 2 Azimuth, Satellite 3 PRN, Satellite 3 Elevation, Satellite 3 SNR, Satellite 3 Azimuth, Satellite 4 PRN, Satellite 4 Elevation, Satellite 4 SNR, Satellite 4 Azimuth, Satellite 5 PRN, Satellite 5 Elevation, Satellite 5 SNR, Satellite 5 Azimuth, Satellite 6 PRN, Satellite 6 Elevation, Satellite 6 SNR, Satellite 6 Azimuth, Satellite 7 PRN, Satellite 7 Elevation, Satellite 7 SNR, Satellite 7 Azimuth, Satellite 8 PRN, Satellite 8 Elevation, Satellite 8 SNR, Satellite 8 Azimuth, Satellite 9 PRN, Satellite 9 Elevation, Satellite 9 SNR, Satellite 9 Azimuth, Satellite 10 PRN, Satellite 10 Elevation, Satellite 10 SNR, Satellite 10 Azimuth, Satellite 11 PRN, Satellite 11 Elevation, Satellite 11 SNR, Satellite 11 Azimuth, Satellite 12 PRN, Satellite 12 Elevation, Satellite 12 SNR, Satellite 12 Azimuth\r\n", fout); 
    fflush(fout);
    
    while (getline(&lineIn, &messageLen, fin) != EOF)
    {
	fputs(lineIn, fout2);
	fflush(fout);

	if((verifySentence(lineIn) == 0) && (validateChecksum(lineIn) == 0))
	{
	    // If we're in here, the lines were good
	    message = messagify(lineIn);
	    parseStatus = parse(&persistentData, message);
	    if ((parseStatus == 0) && (persistentData.isDelta == 1) && (persistentData.allDataSet == 0x7F))
	    {
		makeNMEADataString(outMessage, &persistentData);
		fputs(outMessage, fout);
		fflush(fout);
		persistentData.isDelta = 0;

		printf("Time (UTC): %02u:%02u.%02u\nCurrent Satellites: %u\nCurrent Lat: %f\nCurrentLon: %f\nCurrentAltitude (m): %f\n\n", persistentData.date.tm_hour + persistentData.localOffset, persistentData.date.tm_min, persistentData.date.tm_sec, persistentData.numSatellites, persistentData.lat/100, persistentData.lon/100, persistentData.altitude);
	    }
	    else
	    {
//		printf("Validated sentence not parsed: %s", lineIn);
//		printf("%u - %u - %x\n", parseStatus, persistentData.isDelta, persistentData.allDataSet);
		persistentData.isDelta = 0;
	    }
	}
	else
	{
//	    printf("Invalid sentence: %s", lineIn);
	}

	free(message); // Have to free this, since it gets malloc'ed in a function
	message = 0; // Avoiding re-free errors is a Good Thing™
    }

    free(outMessage); // Yep, more freeing.
    outMessage = 0; // Now I'm just being pedantic.

    puts("");

    return 0;
}

/* Author: Elliot Robinson
 * Parses command line into char arrays inFile and outFile. Prints usage message and exits if argc != 3
 */
    void parseCommandLine(int argc, char **argv, char **inFile, char **outFile, char **outFile2)
{
    if (argc == 4)
    {
	*inFile = argv[1];
        *outFile = argv[2];
	*outFile2 = argv[3];
	return;
    }
    else
    {
	printf("Usage: %s infile parsed_outfile raw_outfile\n", argv[0]);
	exit(1);
    }
}

/* Author: Elliot Robinson
 * Parses a raw string into a NMEAMessage struct
 */
struct NMEAMessage * messagify(char *message)
{
    struct NMEAMessage *str = malloc(sizeof(struct NMEAMessage));

    char *intMsg = message + 1; // Skip the initial '$'

    int n = 0;
    while(message[n] != ',')
	++n;

    strncpy(str->type, intMsg, n-1); // Everything up to but not including the comma is the type

    intMsg += n; // Move the pointer up to ignore the header

    n = 0; // Reset n;
    while(intMsg[n] != '*')
	++n;

    strncpy(str->data, intMsg, n); // Everything up to but not including the * is the data

    if (str->data[n-1] == ',')
    {
	str->data[n] = ',';
	++n;
    }

    str->data[n] = '\0';

    return str;
}

/* Author: Elliot Robinson
 * Takes a NMEAData struct and turns it into an output string for file storage.
 */
int makeNMEADataString(char *toFill, struct NMEAData *data)
{
    char t[1024];
    int offset = 0;

    offset += sprintf(t, "%u,%u,%u,%02u%02u%02u,%u,%u,%.4f,%.4f,%s,%s,%.4f,%u", data->date.tm_mon + 1, data->date.tm_mday, data->date.tm_year + 1900, data->date.tm_hour + data->localOffset, data->date.tm_min, data->date.tm_sec, (unsigned int)data->epochTime, (unsigned int)data->taiTime, data->lat, data->lon, data->dmsLat, data->dmsLon, data->altitude, data->numSatellites);


    // We can pull off this next part because the satellites all have PRNs between 01 and 32
    if (data->satellites[0].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[0].prn, data->satellites[0].elevation, data->satellites[0].snr, data->satellites[0].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[1].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[1].prn, data->satellites[1].elevation, data->satellites[1].snr, data->satellites[1].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[2].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[2].prn, data->satellites[2].elevation, data->satellites[2].snr, data->satellites[2].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[3].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[3].prn, data->satellites[3].elevation, data->satellites[3].snr, data->satellites[3].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[4].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[4].prn, data->satellites[4].elevation, data->satellites[4].snr, data->satellites[4].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[5].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[5].prn, data->satellites[5].elevation, data->satellites[5].snr, data->satellites[5].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[6].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[6].prn, data->satellites[6].elevation, data->satellites[6].snr, data->satellites[6].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[7].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[7].prn, data->satellites[7].elevation, data->satellites[7].snr, data->satellites[7].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[8].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[8].prn, data->satellites[8].elevation, data->satellites[8].snr, data->satellites[8].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[9].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[9].prn, data->satellites[9].elevation, data->satellites[9].snr, data->satellites[9].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[10].prn != 0)
    {
	offset += sprintf(t + offset, ",%u,%u,%u,%u", data->satellites[10].prn, data->satellites[10].elevation, data->satellites[10].snr, data->satellites[10].azimuth);
    }
    else
    {
	offset += sprintf(t + offset, ",,,,");
    }

    if (data->satellites[11].prn != 0)
    {
	sprintf(t + offset, ",%u,%u,%u,%u\r\n", data->satellites[11].prn, data->satellites[11].elevation, data->satellites[11].snr, data->satellites[11].azimuth);
    }
    else
    {
        sprintf(t + offset, "\r\n");
    }

    strcpy(toFill, t);
    return 0;
}

/* Author: Bryce Dodds
 * Checks to see if the NMEA string provided is a valid NMEA string. If string the string is valid return 0 and 2 on on invalid string
 * 9//2011
 */
int validateChecksum(char *sentence)
{
    int i=0; 
    int sum=0, sump=0;   
    int a = strlen(sentence) - 4;
    char sumProvided[3];
    strncpy(sumProvided, sentence + a, 2);

    sump = strtol(sumProvided, NULL, 16);

    for(i=1; i<(a - 1); i++)
    {
	sum=sum ^ sentence[i];
    } //calculate the checksum

    if(sump != sum) //check if the checksum is the same with the prodived one. 
    {
	return 1;
    }
    else
    {
	return 0;  
    }
}  

/* Author: Bryce Dodds
 *  Checks to see if the NMEA string provided is a valid NMEA string.  If string the string is valid return 0 and 1 on invalid string
 *  9/4/2011
 */
int verifySentence(char *sentence)
{
    //check to see if string is longer than 82 characters
    if(strlen(sentence) > MAX_MESSAGE_LENGTH)
	return 1;

    //check to see if the length is less than 12
    if(strlen(sentence) < 12)
	return 1;

    //check to see if there is a dollar sign at the beginning of the string 
    if(sentence[0] != '$')
	return 1;

    //check to see if there is a G
    if(sentence[1] != 'G')
	return 1;

    //check to see if there is a P
    if(sentence[2] != 'P')
	return 1;

    //check to see if the checksum is a valid checksum
    if(sentence[strlen(sentence) - 5] != '*')
	return 1;

    //checks the frist number in the checksum is correct 
    if(! (((sentence[strlen(sentence) - 4] <= 57) && (sentence[strlen(sentence) - 4] >= 48)) || ((sentence[strlen(sentence) - 4] <= 70) && (sentence[strlen(sentence) - 4] >= 65))))
	return 1;

    if(! (((sentence[strlen(sentence) - 3] <= 57) && (sentence[strlen(sentence) - 3] >= 48)) || ((sentence[strlen(sentence) - 3] <= 70) && (sentence[strlen(sentence) - 3] >= 65))))
	return 1;

    //checks to see if formate at the end of the NMEA sequence is correct
    if(sentence[strlen(sentence) - 2] != '\r')
	return 1;

    if(sentence[strlen(sentence) - 1] != '\n')
	return 1;

    //checks to see if the NMEA strings are between the proper ASCII values 
    int dotCount = 0;
    int comCount = 0;
    int i;
    for( i = 1; i < strlen(sentence) - 5; i++)
    {
	char w = sentence[i];
	if (!(((w <= 57) && (w >= 48)) || ((w <= 90) && (w >= 65)) || (w == '.') || (w == ',') || (w == '-')))  
            return 1;            
         

	//if a dot is found increment the dotcounter 
	if(w == '.')
	    dotCount++;

	//if a , is found reset the dotcount
	if(w == ',') {
	    dotCount = 0;
	    comCount++;       
	}
         
    }

    if(comCount == 0)
	return 1;
    
    return 0;
}