nmea_test.c

the example file that can decode the NMEA protocol

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "NMEA_Lib.h"
#include "NMEA_Test.h"



static enum NMEAType NMEAFindNMEAType(CHAR * sentence)
{
    INT16 typeIndex;

    for(typeIndex=0; typeIndex<(INT16)NMEATypeMax; typeIndex++)
    {
        if(0==strncmp(sentence+2, NMEAObject[typeIndex].TypeStr, 3))
        {
            break;
        }
    }
    return (enum NMEAType)typeIndex;
} /* NMEAFindNMEAType */

static enum NMEAType NMEAFindProprietaryType(CHAR * sentence)
{
    INT16 typeIndex;

    for(typeIndex=0; typeIndex<(INT16)NMEATypeMax; typeIndex++)
    {
        if(0==strncmp(sentence+1, NMEAObject[typeIndex].TypeStr, 4))
        {
            break;
        }
    }
    return (enum NMEAType)typeIndex;
} /* NMEAFindProprietaryType() */

static void NMEAParseSentence(CHAR * sentence)
{
    enum NMEAType typeIndex;
    struct NMEAObject_t LocalNMEAObject;
    CHAR Talker[2];
    INT16 i;

    if('P' == sentence[0])
    {
        typeIndex = NMEAFindProprietaryType(sentence);
    }
    else
    {
        Talker[0] = sentence[0];
        Talker[1] = sentence[1];
        for(i=0; i<(INT16)NMEATalkerMax; i++)
        {
            if(Talker[0] == NMEATalkerStr[i][0] 
               && Talker[1] == NMEATalkerStr[i][1] )
            {
                printf("Talker is %s (%d)\n", NMEATalkerStr[i], i);
            }
        }
        typeIndex = NMEAFindNMEAType(sentence);
    }
    printf("typeIndex=%d (%s)\n\n", typeIndex, (typeIndex<NMEATypeMax)?NMEAObject[typeIndex].TypeStr:"INVALID TYPE");

    memcpy(sentence, sentence+2, strlen(sentence));
    
    if(NMEATypeMax > typeIndex)
    {
        if(NULL != NMEAObject[typeIndex].parseFunc)
        {
            UINT32 flags = 0;
            (NMEAObject[typeIndex].parseFunc)(sentence, &LocalNMEAObject, &flags);
        }
    }


} /* end of NMEAParseSentence() */


static void NMEAExtractSubSentence(CHAR * sentence)
{
   int sentence_index = 1;
   while('*' != sentence[sentence_index])
   {
      sentence[sentence_index-1] = sentence[sentence_index];
      sentence_index++;
   }
   sentence[sentence_index-1] = '\0';
   return;
}

/*
char test_data[100][100] =
{
    "$PGRMM,WGS 84*06",
    "$PGRME,,M,,M,,M*00",
    "$GPBOD,,T,,M,,*47",
    "$GPRMC,204149,V,,,,,,,,170698,,*3A",
    "$GPGSA,A,3,19,28,14,18,27,22,31,39,,,,,1.7,1.0,1.3*35",
	"$GPRMC,154232,A,2758.612,N,08210.515,W,085.4,084.4,230394,003.1,W*43",
    "$GPGSV,4,1,13,02,02,213,,03,-3,000,,11,00,121,,14,13,172,05*67",
    "$GPRTE,1,1,c,0*07",
    "$GPJMC,1,1,c,0*00",
};
*/


int main(int argc, char *argv[]) /*lint !e715 argc & argv not referenced*/
{
    char calced_checksum[3];
	char read_checksum[3];
    char * sentence;
	char buff[256];
    FILE * fp;
    
	fp = fopen("test_sentences.txt", "r");
    if(NULL != fp)
    {
        while(fgets(buff, 255, fp) != NULL)
        {
            sentence = buff;
            printf("%s", sentence);
            NMEACalcChecksum(sentence, calced_checksum);
            strncpy(read_checksum,sentence+(strlen(sentence)-3),2);
            read_checksum[2] = '\0';
            printf("checksum %s %s %s ", read_checksum, calced_checksum, (0==strcmp(read_checksum,calced_checksum)?"PASSED":"FAILED"));
            NMEAExtractSubSentence(sentence);
            NMEAParseSentence(sentence);
        }
        fclose(fp);
    }

    return 0;
}