sattools/src/satutl.c

/* > satutl.c
 *
 */


#include "sgdp4h.h"

#include <ctype.h>

static char *st_start (char *buf);
static long i_read (char *str, int start, int stop);
static double d_read (char *str, int start, int stop);

 /* ====================================================================
    Read a string from key board, remove CR/LF etc.
    ==================================================================== */

void
read_kb (char *buf)
{
  int ii;

  fgets (buf, ST_SIZE - 1, stdin);

  /* Remove the CR/LF etc. */
  for (ii = 0; ii < ST_SIZE; ii++)
    {
      if (buf[ii] == '\r' || buf[ii] == '\n')
	{
	  buf[ii] = '\0';
	  break;
	}
    }
}

/* ====================================================================
   Read orbit parameters for "satno" in file "filename", return -1 if
   failed to find the corresponding data. Call with satno = 0 to get the
   next elements of whatever sort.
   ==================================================================== */

int
read_twoline (FILE * fp, long search_satno, orbit_t * orb)
{
  static char search[ST_SIZE];
  static char line1[ST_SIZE];
  static char line2[ST_SIZE];
  char *st1, *st2;
  int found;
  double bm, bx;

  // Set defaults
  strcpy (orb->desig, "");

  st1 = line1;
  st2 = line2;

  do
    {
      if (fgets (line1, ST_SIZE - 1, fp) == NULL)
	return -1;
      st1 = st_start (line1);
    }
  while (st1[0] != '1');

  if (search_satno > 0)
    {
      found = 0;
    }
  else
    {
      found = 1;
      search_satno = atol (st1 + 2);
    }
  sprintf (search, "1 %05ld", search_satno);

  do
    {
      st1 = st_start (line1);
      if (strncmp (st1, search, 7) == 0)
	{
	  found = 1;
	  break;
	}
    }
  while (fgets (line1, ST_SIZE - 1, fp) != NULL);

  sprintf (search, "2 %05ld", search_satno);

  if (found)
    {
      fgets (line2, ST_SIZE - 1, fp);
      st2 = st_start (line2);
    }

  if (!found || strncmp (st2, search, 7) != 0)
    {
      return -1;
    }
  orb->ep_year = (int) i_read (st1, 19, 20);

  if (orb->ep_year < 57)
    orb->ep_year += 2000;
  else
    orb->ep_year += 1900;

  orb->ep_day = d_read (st1, 21, 32);

  orb->ndot2 = d_read (st1, 34, 43);
  bm = d_read (st1, 45, 50) * 1.0e-5;
  bx = d_read (st1, 51, 52);
  orb->nddot6 = bm * pow (10.0, bx);
  bm = d_read (st1, 54, 59) * 1.0e-5;
  bx = d_read (st1, 60, 61);
  orb->bstar = bm * pow (10.0, bx);

  orb->eqinc = RAD (d_read (st2, 9, 16));
  orb->ascn = RAD (d_read (st2, 18, 25));
  orb->ecc = d_read (st2, 27, 33) * 1.0e-7;
  orb->argp = RAD (d_read (st2, 35, 42));
  orb->mnan = RAD (d_read (st2, 44, 51));
  orb->rev = d_read (st2, 53, 63);
  orb->norb = i_read (st2, 64, 68);

  orb->satno = search_satno;

  //  sscanf(st1+9,"%s",orb->desig);
  strncpy (orb->desig, st1 + 9, 8);
  orb->desig[8] = '\0';

  return 0;
}

/* ==================================================================
   Locate the first non-white space character, return location.
   ================================================================== */

static char *
st_start (char *buf)
{
  if (buf == NULL)
    return buf;

  while (*buf != '\0' && isspace (*buf))
    buf++;

  return buf;
}

/* ==================================================================
   Mimick the FORTRAN formatted read (assumes array starts at 1), copy
   characters to buffer then convert.
   ================================================================== */

static long
i_read (char *str, int start, int stop)
{
  long itmp = 0;
  char *buf, *tmp;
  int ii;

  start--;			/* 'C' arrays start at 0 */
  stop--;

  tmp = buf = (char *) vector (stop - start + 2, sizeof (char));

  for (ii = start; ii <= stop; ii++)
    {
      *tmp++ = str[ii];		/* Copy the characters. */
    }
  *tmp = '\0';			/* NUL terminate */

  itmp = atol (buf);		/* Convert to long integer. */
  free (buf);

  return itmp;
}

/* ==================================================================
   Mimick the FORTRAN formatted read (assumes array starts at 1), copy
   characters to buffer then convert.
   ================================================================== */

static double
d_read (char *str, int start, int stop)
{
  double dtmp = 0;
  char *buf, *tmp;
  int ii;

  start--;
  stop--;

  tmp = buf = (char *) vector (stop - start + 2, sizeof (char));

  for (ii = start; ii <= stop; ii++)
    {
      *tmp++ = str[ii];		/* Copy the characters. */
    }
  *tmp = '\0';			/* NUL terminate */

  dtmp = atof (buf);		/* Convert to long integer. */
  free (buf);

  return dtmp;
}

/* ==================================================================
   Allocate and check an all-zero array of memory (storage vector).
   ================================================================== */

void *
vector (size_t num, size_t size)
{
  void *ptr;

  ptr = calloc (num, size);
  if (ptr == NULL)
    {
      fatal_error ("vector: Allocation failed %u * %u", num, size);
    }

  return ptr;
}

/* ==================================================================
   Print out orbital parameters.
   ================================================================== */

void
print_orb (orbit_t * orb)
{
  printf ("# Satellite ID = %ld\n", (long) orb->satno);
  printf ("# Satellite designation = %s\n", orb->desig);
  printf ("# Epoch year = %d day = %.8f\n", orb->ep_year, orb->ep_day);
  printf ("# Eccentricity = %.7f\n", orb->ecc);
  printf ("# Equatorial inclination = %.4f deg\n", DEG (orb->eqinc));
  printf ("# Argument of perigee = %.4f deg\n", DEG (orb->argp));
  printf ("# Mean anomaly = %.4f deg\n", DEG (orb->mnan));
  printf ("# Right Ascension of Ascending Node = %.4f deg\n",
	  DEG (orb->ascn));
  printf ("# Mean Motion (number of rev/day) = %.8f\n", orb->rev);
  printf ("# First derivative of mean motion = %e\n", orb->ndot2);
  printf ("# Second derivative of mean motion = %e\n", orb->nddot6);
  printf ("# BSTAR drag = %.4e\n", orb->bstar);
  printf ("# Orbit number = %ld\n", orb->norb);
}

/* ====================================================================== */