ogsgar2rnx.c

OpenGPSSim是一个gps模拟程序

  default: 
    ptr+=sprintf( ptr, ", page %2d       ", page); 
    break;
  } 

  if ( sf_id == 4)
  {
    switch(page)
    {
    case 0:  
      ptr+=sprintf( ptr, "Dummy sat (no data)\n"); 
      break;
    case 1:  
      ptr+=sprintf( ptr, "Reserved\n"); 
      break;
    case 12: 
      ptr+=sprintf( ptr, "Reserved\n");
      break;
    case 13:

#if 0
      av=extract_bits(57,2);
      switch(av)
      {
      case 0: 
        strcpy( av_message, "Available"); 
        break;
      case 1: 
        strcpy( av_message, "Encrypted"); 
        break;
      case 2: 
        strcpy( av_message, "Not available"); 
        break;
      case 3: 
        strcpy( av_message, "?????"); 
        break;
      } 
      ptr+=sprintf(ptr,"NMCT : %s\n",av_message);
#endif

      ptr+=sprintf( ptr, "NMCT\n");
      break;

    case 14: 
    case 15: 
      ptr+=sprintf( ptr, "Spare\n");
      break;
    case 17: 
      ptr+=sprintf( ptr, "ASCII messages\n");
      break;
    case 18: 
      ptr+=sprintf( ptr, "Iono parameters\n"); break;
    case 19: 
    case 20: 
    case 22: 
    case 23: 
      ptr+=sprintf( ptr, "Reserved\n");
      break;
    case 25: 
      ptr+=sprintf( ptr, "Sat Config\n"); 
      break;
    default:
      if ((sv_id>=25) && (sv_id<=32)) 
        ptr+=sprintf( ptr, "Almanac (sat %d)\n", sv_id);
      else 
        ptr+=sprintf( ptr, "Other function\n");
      break;     
    }
  }
  else
  {
    switch(page)
    {
     case 0:  
       ptr+=sprintf( ptr, "Dummy sat (no data)\n"); 
       break;
     case -1: 
       ptr+=sprintf( ptr, "\n"); 
       break;
     case 25: 
       ptr+=sprintf( ptr, "Sat 1-24 health data\n"); 
       break;
     default: 
       ptr+=sprintf( ptr, "Almanac (sat %d)\n",sv_id);
       break;
    }
  }

  return fail;  
}

static void process_frame( ULONG nfr)
{
  BOOLEAN fail;
  BYTE sf_id;
  char info[256];

  fail = info_frame( nfr, info); 
  if ( fail) 
    printf(" ERROR:"); 
  printf( "%s", info); 
  return;
}


#define MASK_DATA   0x3fffffc0
#define MASK_PARITY 0x0000003f

//
//  calc parity bits
//
static BOOLEAN parity( BYTE *ptr)
{
  BYTE P,T;

//  dest = (BYTE*)&NAV_WORD;
  memcpy( (void*)&NAV_WORD, (void*)ptr, 4);

  if ( P30) 
    NAV_WORD ^= MASK_DATA;  // source bits complement
  
  P = (BYTE)(P29^d1^d2^d3^d5^d6^d10^d11^d12^d13^d14^d17^d18^d20^d23);
  P = (P<<1) + (BYTE)(P30^d2^d3^d4^d6^d7^d11^d12^d13^d14^d15^d18^d19^d21^d24);
  P = (P<<1) + (BYTE)(P29^d1^d3^d4^d5^d7^d8^d12^d13^d14^d15^d16^d19^d20^d22);
  P = (P<<1) + (BYTE)(P30^d2^d4^d5^d6^d8^d9^d13^d14^d15^d16^d17^d20^d21^d23);
  P = (P<<1) + (BYTE)(P30^d1^d3^d5^d6^d7^d9^d10^d14^d15^d16^d17^d18^d21^d22^d24);
  P = (P<<1) + (BYTE)(P29^d3^d5^d6^d8^d9^d10^d11^d13^d15^d19^d22^d23^d24);
   
  T = (BYTE)(NAV_WORD&MASK_PARITY);

  return (P==T);
}                          

int copy_to_navbuf( FILE *fd, int sel_sv, char *buf, 
  long *c50_ptr, int *svprnlist)
{
  int j, k, sfid, nof;
  static BOOLEAN par, all_par = 1;
  static BYTE record[RECLEN], id, len;
  static type_rec0x36 rec;
  static ULONG nsf, word,   // GPS word (0,...,9 !)
               current_frame[32];
  static long last_word = -1;
  static int outputnavbits = 0;  
  int bufpos = 0, loop = 1;
  static int first = 1;

  if ( first)
  {
  
    first = 0;

    if ( !ListOnlyPRN)
    {
      printf( "-------------------------------------------------------------------------\n");
      printf( "     ***** Tracking navigation message from PRN %2d *****\n",sel_sv+1);
      printf( "-------------------------------------------------------------------------\n");
      printf( "Subframe HOW  Words in SF  Parity/Subframe ID/page      Contents\n");
      printf( "-------------------------------------------------------------------------\n");
    }  
 
    for ( k=0; k<32; k++) 
    {
      reset_frame( k); 
      current_frame[k] = 0xffffffff;
    }
  }

  while ( !feof( fd) && loop)
  {

//  read records from data file
    fread( &id, 1, 1, fd); 
    fread( &len, 1, 1, fd); 
    if ( len > RECLEN)
    {
      printf( "inkonsistent data file\n");
      printf( "id = 0x%x, len = %d\n", id, len);
      exit(-1);
    }
    fread( record, 1, len, fd); 
   
    if ( id == 0x36)
    {

      rec = process_0x36( record);  

#if 0
      printf("rec.uk[0] = %x\n", rec.uk[0]);
      printf("rec.uk[1] = %x\n", rec.uk[1]);
      printf("rec.uk[2] = %x\n", rec.uk[2]);
      printf("rec.uk[3] = %x\n", rec.uk[3]);
      printf("rec.sv    = %d\n", rec.sv);
      printf("rec.c50   = %d\n", rec.c50);
      getchar();
#endif

      CurSat = rec.sv;

      if ( svprnlist)
        svprnlist[CurSat+1] += 1;

      if ( CurSat == sel_sv)
      {     

        word = ((rec.c50-30) % 300) / 30;
//  nsf increases by 1 every subframe (10 GPS words)
        nsf  = (rec.c50-30) / 300;  

        if ( current_frame[CurSat] == 0xffffffff) 
        {
          current_frame[CurSat] = nsf;
          printf( " HOW %6d [", 6 * nsf);
//          printf(" c50 %8d [", rec.c50-9*30);
        }

//        printf( "\n");
//        printf( "nsf = %d\n", nsf);
//        printf( "current_frame[CurSat] = %d\n", current_frame[CurSat]);
//        getchar();

        if ( nsf != current_frame[CurSat]) 
        {

//  read first word of next subframe; thus, previous subframe is complete

          printf( "] ");
          if ( all_par) 
            process_frame( nsf); 
          else 
            printf( " BAD PARITY\n");

          reset_frame( CurSat); 
          current_frame[CurSat] = nsf;
          printf( " HOW %6d [", 6 * nsf);

          all_par               = 1;
          last_word             = -1;
        }

//        printf( "\nsfid=%d, word=%d\n", sf_id, word+1);
//        getchar();
        
//        if ( sf_id == 1 && word == 0)
//        {
//          outputnavbits = 1;
//          getchar();
//        }  


        for ( k=1; k < (word-last_word); k++) 
          printf(" ");

        par = parity( rec.uk);

        if ( !par)
        {
          outputnavbits = 0;
          bufpos = 0;
        }

        if ( par) 
          printf("O"); 
        else 
          printf("X");

        all_par &= par;
        last_word = word;

//        printf( "\n");
//        printf( "sfid=%d, word=%d\n", sf_id, word+1);      
//        for ( k=0; k < 30; k++) 
//          printf( " %02x", Frame[CurSat][k]);
//        printf( "\n");

        if ( outputnavbits)
        {         
          for ( k=5; k>=0; k--)
            buf[bufpos++] = ((rec.uk[3] >> k) & 0x1) ? 1 : -1;
          for ( k=7; k>=0; k--)  
            buf[bufpos++] = ((rec.uk[2] >> k) & 0x1) ? 1 : -1;
          for ( k=7; k>=0; k--)  
            buf[bufpos++] = ((rec.uk[1] >> k) & 0x1) ? 1 : -1;
          for ( k=7; k>=0; k--)  
            buf[bufpos++] = ((rec.uk[0] >> k) & 0x1) ? 1 : -1;
           
          if ( bufpos >= 1500)
            loop = 0;
        } // --- if ( outputnavbits) ---

        fflush( stdout);
        strip_parity_and_copy_to_frame( rec.uk, word, CurSat);

//        printf( "sfid=%d, word=%d\n", sf_id, word+1);
//        for ( k=0; k < 30; k++) 
//          printf( " %02x", Frame[CurSat][k]);
//        printf( "\n");
//        getchar();

//  get subframe id from 2nd GPS word
        sfid = (Frame[CurSat][5] >> 2) & 0x7;

//        printf( "\n");
//        printf( "sfid=%d, word=%d\n", sfid, word+1);
//        getchar();

//  next word is GPS word 1 / subframe 1 -> switch on output 
        if ( sfid == 5 && word == 9)
          outputnavbits = 1;

      }  // --- if ( CurSat == sel_sv) ---
    }  // --- if ( id == 0x36)  --- 
  }  // --- while ( !feof(fd)) ---
  
//  printf("\n");
  *c50_ptr = rec.c50;

  return (bufpos);
}

#if 0
//
//
//
int main( int argc, char *argv[])
{
  int k, sel_sv, buflen;
  long c50;
  FILE *fd, *fpout;

  fd = fopen( argv[1], "rb");

  if ( !fd) 
  { 
    printf("error opening file %s.\n", argv[1]); 
    exit(0);
  }

  sel_sv = 10;    // PRN-1 

  char buf[1500];
  char infile[256];

  k = 1;

  do
  {

    buflen = copy_to_navbuf( fd, sel_sv, buf, &c50);

    if ( buflen == 1500)
    {
      sprintf( infile, "nav-%08x.dat", c50);
      fpout = fopen( infile, "wb");
      if ( !fpout)
      {
        printf( "error opening file %s\n", infile);
        exit(-1);
      }          
      fwrite( buf, buflen, 1, fpout);
      fclose( fpout);
    }

  } while( buflen>0);  

  fclose( fd);
  exit( 0);
  return (0);
}
#endif