コード例 #1
0
ファイル: scalnull.c プロジェクト: portsmouth/cmbview
/*--------------------------------------------------------------------------*/
int ffsnul(fitsfile *fptr,      /* I - FITS file pointer                  */
           int colnum,          /* I - column number to apply nulvalue to */
           char *nulstring,     /* I - null pixel value: value of TNULLn  */
           int *status)         /* IO - error status                      */
/*
  Define the string used to represent undefined pixels in the ASCII TABLE
  column. This routine overrides the null  value given by the TNULLn keyword
  if present.  Note that this routine does not write or modify the TNULLn
  keyword, but instead only modifies the value temporarily in the internal
  buffer. Thus, a subsequent call to the ffrdef routine will reset the null
  value back to the TNULLn keyword value (or not defined if the keyword is not
  present).
*/
{
    tcolumn *colptr;
    int hdutype;

    if (*status > 0)
        return(*status);

    if (ffghdt(fptr, &hdutype, status) > 0)  /* get HDU type */
        return(*status);

    if (hdutype != ASCII_TBL)
        return(*status = NOT_ATABLE);        /* not proper HDU type */
 
    colptr = (fptr->Fptr)->tableptr;   /* set pointer to the first column */
    colptr += (colnum - 1);    /* increment to the correct column */

    colptr->strnull[0] = '\0';
    strncat(colptr->strnull, nulstring, 19);  /* limit string to 19 chars */

    return(*status);
}
コード例 #2
0
ファイル: scalnull.c プロジェクト: portsmouth/cmbview
/*--------------------------------------------------------------------------*/
int fftnul(fitsfile *fptr,      /* I - FITS file pointer                  */
           int colnum,          /* I - column number to apply nulvalue to */
           long nulvalue,       /* I - null pixel value: value of TNULLn  */
           int *status)         /* IO - error status                      */
/*
  Define the value used to represent undefined pixels in the BINTABLE column.
  This only applies to integer datatype columns (TFORM = B, I, or J).
  This routine overrides the null pixel value given by the TNULLn keyword
  if present.  Note that this routine does not write or modify the TNULLn
  keyword, but instead only modifies the value temporarily in the internal
  buffer. Thus, a subsequent call to the ffrdef routine will reset the null
  value back to the TNULLn  keyword value (or not defined if the keyword is not
  present).
*/
{
    tcolumn *colptr;
    int hdutype;

    if (*status > 0)
        return(*status);

    if (ffghdt(fptr, &hdutype, status) > 0)  /* get HDU type */
        return(*status);

    if (hdutype != BINARY_TBL)
        return(*status = NOT_BTABLE);        /* not proper HDU type */
 
    colptr = (fptr->Fptr)->tableptr;   /* set pointer to the first column */
    colptr += (colnum - 1);    /* increment to the correct column */

    colptr->tnull = nulvalue;

    return(*status);
}
コード例 #3
0
ファイル: scalnull.c プロジェクト: portsmouth/cmbview
/*--------------------------------------------------------------------------*/
int ffpscl(fitsfile *fptr,      /* I - FITS file pointer               */
           double scale,        /* I - scaling factor: value of BSCALE */
           double zero,         /* I - zero point: value of bZero      */
           int *status)         /* IO - error status                   */
/*
  Define the linear scaling factor for the primary array or image extension
  pixel values. This routine overrides the scaling values given by the
  BSCALE and bZero keywords if present.  Note that this routine does not
  write or modify the BSCALE and bZero keywords, but instead only modifies
  the values temporarily in the internal buffer.  Thus, a subsequent call to
  the ffrdef routine will reset the scaling back to the BSCALE and bZero
  keyword values (or 1. and 0. respectively if the keywords are not present).
*/
{
    tcolumn *colptr;
    int hdutype;

    if (*status > 0)
        return(*status);

    if (scale == 0)
        return(*status = ZERO_SCALE);  /* zero scale value is illegal */

    if (ffghdt(fptr, &hdutype, status) > 0)  /* get HDU type */
        return(*status);

    if (hdutype != IMAGE_HDU)
        return(*status = NOT_IMAGE);         /* not proper HDU type */

    if (fits_is_compressed_image(fptr, status)) /* compressed images */
    {
        (fptr->Fptr)->cn_bscale = scale;
        (fptr->Fptr)->cn_bZero  = zero;

        return(*status);
    }

    /* set pointer to the first 'column' (contains group parameters if any) */
    colptr = (fptr->Fptr)->tableptr; 

    colptr++;   /* increment to the 2nd 'column' pointer  (the image itself) */

    colptr->tscale = scale;
    colptr->tzero = zero;

    return(*status);
}
コード例 #4
0
ファイル: scalnull.c プロジェクト: portsmouth/cmbview
/*--------------------------------------------------------------------------*/
int ffpnul(fitsfile *fptr,      /* I - FITS file pointer                */
           long nulvalue,       /* I - null pixel value: value of BLANK */
           int *status)         /* IO - error status                    */
/*
  Define the value used to represent undefined pixels in the primary array or
  image extension. This only applies to integer image pixel (i.e. BITPIX > 0).
  This routine overrides the null pixel value given by the BLANK keyword
  if present.  Note that this routine does not write or modify the BLANK
  keyword, but instead only modifies the value temporarily in the internal
  buffer. Thus, a subsequent call to the ffrdef routine will reset the null
  value back to the BLANK  keyword value (or not defined if the keyword is not
  present).
*/
{
    tcolumn *colptr;
    int hdutype;

    if (*status > 0)
        return(*status);

    if (ffghdt(fptr, &hdutype, status) > 0)  /* get HDU type */
        return(*status);

    if (hdutype != IMAGE_HDU)
        return(*status = NOT_IMAGE);         /* not proper HDU type */

    if (fits_is_compressed_image(fptr, status)) /* ignore compressed images */
        return(*status);

    /* set pointer to the first 'column' (contains group parameters if any) */
    colptr = (fptr->Fptr)->tableptr; 

    colptr++;   /* increment to the 2nd 'column' pointer  (the image itself) */

    colptr->tnull = nulvalue;

    return(*status);
}
コード例 #5
0
ファイル: scalnull.c プロジェクト: portsmouth/cmbview
/*--------------------------------------------------------------------------*/
int fftscl(fitsfile *fptr,      /* I - FITS file pointer */
           int colnum,          /* I - column number to apply scaling to */
           double scale,        /* I - scaling factor: value of TSCALn   */
           double zero,         /* I - zero point: value of TZEROn       */
           int *status)         /* IO - error status     */
/*
  Define the linear scaling factor for the TABLE or BINTABLE extension
  column values. This routine overrides the scaling values given by the
  TSCALn and TZEROn keywords if present.  Note that this routine does not
  write or modify the TSCALn and TZEROn keywords, but instead only modifies
  the values temporarily in the internal buffer.  Thus, a subsequent call to
  the ffrdef routine will reset the scaling back to the TSCALn and TZEROn
  keyword values (or 1. and 0. respectively if the keywords are not present).
*/
{
    tcolumn *colptr;
    int hdutype;

    if (*status > 0)
        return(*status);

    if (scale == 0)
        return(*status = ZERO_SCALE);  /* zero scale value is illegal */

    if (ffghdt(fptr, &hdutype, status) > 0)  /* get HDU type */
        return(*status);

    if (hdutype == IMAGE_HDU)
        return(*status = NOT_TABLE);         /* not proper HDU type */

    colptr = (fptr->Fptr)->tableptr;   /* set pointer to the first column */
    colptr += (colnum - 1);     /* increment to the correct column */

    colptr->tscale = scale;
    colptr->tzero = zero;

    return(*status);
}
コード例 #6
0
ファイル: putcol.c プロジェクト: chopley/controlCode
/*--------------------------------------------------------------------------*/
int ffiter(int n_cols,
           iteratorCol *cols,
           long offset,
           long n_per_loop,
           int (*work_fn)(long total_n,
                          long offset,
                          long first_n,
                          long n_values,
                          int n_cols,
                          iteratorCol *cols,
                          void *userPointer),
           void *userPointer,
           int *status)
/*
   The iterator function.  This function will pass the specified
   columns from a FITS table or pixels from a FITS image to the 
   user-supplied function.  Depending on the size of the table
   or image, only a subset of the rows or pixels may be passed to the
   function on each call, in which case the function will be called
   multiple times until all the rows or pixels have been processed.
*/
{
    typedef struct  /* structure to store the column null value */
    {  
        int      nullsize;    /* length of the null value, in bytes */
        union {   /*  default null value for the column */
            char   *stringnull;
            unsigned char   charnull;
            int    intnull;
            short  shortnull;
            long   longnull;
            unsigned int   uintnull;
            unsigned short ushortnull;
            unsigned long  ulongnull;
            float  floatnull;
            double doublenull;
        } null;
    } colNulls;

    void *dataptr, *defaultnull;
    colNulls *col;
    int ii, jj, tstatus;
    int typecode, hdutype, jtype, type, anynul, nfiles, nbytes;
    long totaln, nleft, frow, felement, n_optimum, i_optimum, ntodo;
    long rept, width, tnull;
    double zeros = 0.;
    char message[FLEN_ERRMSG], keyname[FLEN_KEYWORD], nullstr[FLEN_VALUE];
    char **stringptr, *nullptr, *cptr;

    if (*status > 0)
        return(*status);

    if (n_cols  < 0 || n_cols > 999 )
    {
        ffpmsg("Illegal number of columms (ffiter)");
        return(*status = BAD_COL_NUM);  /* negative number of columns */
    }

    col = calloc(n_cols, sizeof(colNulls) ); /* memory for the null values */

    /*------------------------------------------------------------*/
    /* Make sure column numbers and datatypes are in legal range  */
    /* and column numbers and datatypes are legal.                */ 
    /* Also fill in other parameters in the column structure.     */
    /*------------------------------------------------------------*/

    ffghdt(cols[0].fptr, &hdutype, status);  /* type of first HDU */

    for (jj = 0; jj < n_cols; jj++)
    {
        /* check that output datatype code value is legal */
        type = cols[jj].datatype;  
        if (type != 0 &&
            type != TBYTE  && type != TLOGICAL && type != TSTRING &&
            type != TSHORT && type != TINT     && type != TLONG && 
            type != TFLOAT && type != TDOUBLE  && type != TCOMPLEX &&
            type != TULONG && type != TUSHORT  && type != TDBLCOMPLEX)
        {
            sprintf(message,
                   "Illegal datatype for column number %d: %d  (ffiter)",
                    jj + 1, cols[jj].datatype);
            ffpmsg(message);
            return(*status = BAD_DATATYPE);
        }

        /* initialize TLMINn, TLMAXn, column name, and display format */
        cols[jj].tlmin = 0;
        cols[jj].tlmax = 0;
        cols[jj].tunit[0] = '\0';
        cols[jj].tdisp[0] = '\0';

        ffghdt(cols[jj].fptr, &jtype, status);  /* get HDU type */

        if (hdutype == IMAGE_HDU)
        {
            if (jtype != IMAGE_HDU)
            {
                sprintf(message,
                "File %d not positioned to an image extension (ffiter)",
                    jj + 1);
                return(*status = NOT_IMAGE);
            }

            /* images are stored in column 2; ignore the input value */
            cols[jj].colnum = 2;
            strcpy(cols[jj].colname, "IMAGE");  /* dummy name for images */

            tstatus = 0;
            ffgkys(cols[jj].fptr, "BUNIT", cols[jj].tunit, 0, &tstatus);
        }
        else
        {
            if (jtype == IMAGE_HDU)
            {
                sprintf(message,
                "File %d not positioned to a table extension (ffiter)",
                    jj + 1);
                return(*status = NOT_TABLE);
            }

            if (cols[jj].colnum < 1)
            {
                /* find the column number for the named column */
                if (ffgcno(cols[jj].fptr, CASEINSEN, cols[jj].colname,
                           &cols[jj].colnum, status) )
                {
                    sprintf(message,
                      "Column '%s' not found for column number %d  (ffiter)",
                       cols[jj].colname, jj + 1);
                    ffpmsg(message);
                    return(*status);
                }
            }

            if (cols[jj].colnum < 1 || 
                cols[jj].colnum > ((cols[jj].fptr)->Fptr)->tfield)
            {
                sprintf(message,
                  "Column %d has illegal table position number: %d  (ffiter)",
                    jj + 1, cols[jj].colnum);
                ffpmsg(message);
                return(*status = BAD_COL_NUM);
            }

            /* look for column description keywords and update structure */
            tstatus = 0;
            ffkeyn("TLMIN", cols[jj].colnum, keyname, &tstatus);
            ffgkyj(cols[jj].fptr, keyname, &cols[jj].tlmin, 0, &tstatus);

            tstatus = 0;
            ffkeyn("TLMAX", cols[jj].colnum, keyname, &tstatus);
            ffgkyj(cols[jj].fptr, keyname, &cols[jj].tlmax, 0, &tstatus);

            tstatus = 0;
            ffkeyn("TTYPE", cols[jj].colnum, keyname, &tstatus);
            ffgkys(cols[jj].fptr, keyname, cols[jj].colname, 0, &tstatus);
            if (tstatus)
                cols[jj].colname[0] = '\0';

            tstatus = 0;
            ffkeyn("TUNIT", cols[jj].colnum, keyname, &tstatus);
            ffgkys(cols[jj].fptr, keyname, cols[jj].tunit, 0, &tstatus);

            tstatus = 0;
            ffkeyn("TDISP", cols[jj].colnum, keyname, &tstatus);
            ffgkys(cols[jj].fptr, keyname, cols[jj].tdisp, 0, &tstatus);
        }
    }

    /*-----------------------------------------------------------------*/
    /* use the first file to set the total number of values to process */
    /*-----------------------------------------------------------------*/

    offset = maxvalue(offset, 0L);  /* make sure offset is legal */

    if (hdutype == IMAGE_HDU)   /* get total number of pixels in the image */
    {
      ffgtcl(cols[0].fptr, cols[0].colnum, NULL, &totaln, &width, status);
      frow = 1;
      felement = 1 + offset;
    }
    else   /* get total number or rows in the table */
    {
      ffgkyj(cols[0].fptr, "NAXIS2", &totaln, 0, status);
      frow = 1 + offset;
      felement = 1;
    }

    /*  adjust total by the input starting offset value */
    totaln -= offset;
    totaln = maxvalue(totaln, 0L);   /* don't allow negative number */

    /*------------------------------------------------------------------*/
    /* Determine number of values to pass to work function on each loop */
    /*------------------------------------------------------------------*/

    if (n_per_loop == 0)
    {
        /* Determine optimum number of values for each iteration.    */
        /* Look at all the fitsfile pointers to determine the number */
        /* of unique files.                                          */

        nfiles = 1;
        ffgrsz(cols[0].fptr, &n_optimum, status);

        for (jj = 1; jj < n_cols; jj++)
        {
            for (ii = 0; ii < jj; ii++)
            {
                if (cols[ii].fptr == cols[jj].fptr)
                   break;
            }

            if (ii == jj)  /* this is a new file */
            {
                nfiles++;
                ffgrsz(cols[jj].fptr, &i_optimum, status);
                n_optimum = minvalue(n_optimum, i_optimum);
            }
        }

        n_optimum = n_optimum / nfiles;
    }
    else if (n_per_loop < 0)  /* must pass all the values at one time */
    {
        n_optimum = totaln;
    }
    else /* calling routine specified how many values to pass at a time */
    {
        n_optimum = minvalue(n_per_loop, totaln);
    }

    /*--------------------------------------*/
    /* allocate work arrays for each column */
    /* and determine the null pixel value   */
    /*--------------------------------------*/

    for (jj = 0; jj < n_cols; jj++)
    {
        /* get column datatype and vector length */
        if (ffgtcl(cols[jj].fptr, cols[jj].colnum, &typecode, &rept,
                  &width, status) > 0)
            goto cleanup;

        /* special case where sizeof(long) = 8: use TINT instead of TLONG */
        if (typecode == TLONG && sizeof(long) == 8 && sizeof(int) == 4)
            typecode = TINT;

        /* Special case: interprete 'X' column as 'B' */
        if (abs(typecode) == TBIT)
        {
            typecode  = typecode / TBIT * TBYTE;
            rept = (rept + 7) / 8;
        }

        if (cols[jj].datatype == 0)    /* output datatype not specified? */
        {
            /* special case if sizeof(long) = 8: use TINT instead of TLONG */
            if (typecode == TLONG && sizeof(long) == 8 && sizeof(int) == 4)
                cols[jj].datatype = TINT;
            else
                cols[jj].datatype = typecode;
        }

        /* calc total number of elements to do on each iteration */
        if (hdutype == IMAGE_HDU || cols[jj].datatype == TSTRING)
        {
            ntodo = n_optimum; 
            cols[jj].repeat = 1;

            /* get the BLANK keyword value, if it exists */
            if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
            {
                tstatus = 0;
                ffgkyj(cols[jj].fptr, "BLANK", &tnull, 0, &tstatus);
                if (tstatus)
                {
                    tnull = 0L;  /* no null values */
                }
            }
        }
        else
        {
            ntodo = n_optimum * rept;   /* vector columns */
            cols[jj].repeat = rept;

            /* get the TNULL keyword value, if it exists */
            if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
            {
                tstatus = 0;
                if (hdutype == ASCII_TBL) /* TNULLn value is a string */
                {
                    ffkeyn("TNULL", cols[jj].colnum, keyname, &tstatus);
                    ffgkys(cols[jj].fptr, keyname, nullstr, 0, &tstatus);
                    if (tstatus)
                    {
                        tnull = 0L; /* keyword doesn't exist; no null values */
                    }
                    else
                    {
                        cptr = nullstr;
                        while (*cptr == ' ')  /* skip over leading blanks */
                           cptr++;

                        if (*cptr == '\0')  /* TNULLn is all blanks? */
                            tnull = LONG_MIN;
                        else
                        {                                                
                            /* attempt to read TNULLn string as an integer */
                            ffc2ii(nullstr, &tnull, &tstatus);

                            if (tstatus)
                                tnull = LONG_MIN;  /* choose smallest value */
                        }                          /* to represent nulls */
                    }
                }
                else  /* Binary table; TNULLn value is an integer */
                {
                    ffkeyn("TNULL", cols[jj].colnum, keyname, &tstatus);
                    ffgkyj(cols[jj].fptr, keyname, &tnull, 0, &tstatus);
                    if (tstatus)
                    {
                        tnull = 0L; /* keyword doesn't exist; no null values */
                    }
                    else if (tnull == 0)
                    {
                        /* worst possible case: a value of 0 is used to   */
                        /* represent nulls in the FITS file.  We have to  */
                        /* use a non-zero null value here (zero is used to */
                        /* mean there are no null values in the array) so we */
                        /* will use the smallest possible integer instead. */

                        tnull = LONG_MIN;  /* choose smallest possible value */
                    }
                }
            }
        }

        /* Note that the data array starts with 2nd element;  */
        /* 1st element of the array gives the null data value */

        switch (cols[jj].datatype)
        {
         case TBYTE:
          cols[jj].array = calloc(ntodo + 1, sizeof(char));
          col[jj].nullsize  = sizeof(char);  /* number of bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              tnull = minvalue(tnull, 255);
              tnull = maxvalue(tnull, 0);
              col[jj].null.charnull = (unsigned char) tnull;
          }
          else
          {
              col[jj].null.charnull = (unsigned char) 255; /* use 255 as null */
          }
          break;

         case TSHORT:
          cols[jj].array = calloc(ntodo + 1, sizeof(short));
          col[jj].nullsize  = sizeof(short);  /* number of bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              tnull = minvalue(tnull, SHRT_MAX);
              tnull = maxvalue(tnull, SHRT_MIN);
              col[jj].null.shortnull = (short) tnull;
          }
          else
          {
              col[jj].null.shortnull = SHRT_MIN;  /* use minimum as null */
          }
          break;

         case TUSHORT:
          cols[jj].array = calloc(ntodo + 1, sizeof(unsigned short));
          col[jj].nullsize  = sizeof(unsigned short);  /* bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              tnull = minvalue(tnull, USHRT_MAX);
              tnull = maxvalue(tnull, 0);  /* don't allow negative value */
              col[jj].null.ushortnull = (unsigned short) tnull;
          }
          else
          {
              col[jj].null.ushortnull = USHRT_MAX;   /* use maximum null */
          }
          break;

         case TINT:
          cols[jj].array = calloc(ntodo + 1, sizeof(int));
          col[jj].nullsize  = sizeof(int);  /* number of bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              tnull = minvalue(tnull, INT_MAX);
              tnull = maxvalue(tnull, INT_MIN);
              col[jj].null.intnull = (int) tnull;
          }
          else
          {
              col[jj].null.intnull = INT_MIN;  /* use minimum as null */
          }
          break;

         case TUINT:
          cols[jj].array = calloc(ntodo + 1, sizeof(unsigned int));
          col[jj].nullsize  = sizeof(unsigned int);  /* bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              tnull = minvalue(tnull, INT32_MAX);
              tnull = maxvalue(tnull, 0);
              col[jj].null.uintnull = (unsigned int) tnull;
          }
          else
          {
              col[jj].null.intnull = UINT_MAX;  /* use maximum as null */
          }
          break;

         case TLONG:
          cols[jj].array = calloc(ntodo + 1, sizeof(long));
          col[jj].nullsize  = sizeof(long);  /* number of bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              col[jj].null.longnull = tnull;
          }
          else
          {
              col[jj].null.longnull = LONG_MIN;   /* use minimum as null */
          }
          break;

         case TULONG:
          cols[jj].array = calloc(ntodo + 1, sizeof(unsigned long));
          col[jj].nullsize  = sizeof(unsigned long);  /* bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              if (tnull < 0)  /* can't use a negative null value */
                  col[jj].null.ulongnull = LONG_MAX;
              else
                  col[jj].null.ulongnull = (unsigned long) tnull;
          }
          else
          {
              col[jj].null.ulongnull = LONG_MAX;   /* use maximum as null */
          }
          break;

         case TFLOAT:
          cols[jj].array = calloc(ntodo + 1, sizeof(float));
          col[jj].nullsize  = sizeof(float);  /* number of bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              col[jj].null.floatnull = (float) tnull;
          }
          else
          {
              col[jj].null.floatnull = FLOATNULLVALUE;  /* special value */
          }
          break;

         case TCOMPLEX:
          cols[jj].array = calloc((ntodo * 2) + 1, sizeof(float));
          col[jj].nullsize  = sizeof(float);  /* number of bytes per value */
          col[jj].null.floatnull = FLOATNULLVALUE;  /* special value */
          break;

         case TDOUBLE:
          cols[jj].array = calloc(ntodo + 1, sizeof(double));
          col[jj].nullsize  = sizeof(double);  /* number of bytes per value */

          if (typecode == TBYTE || typecode == TSHORT || typecode == TLONG)
          {
              col[jj].null.doublenull = (double) tnull;
          }
          else
          {
              col[jj].null.doublenull = DOUBLENULLVALUE;  /* special value */
          }
          break;

         case TDBLCOMPLEX:
          cols[jj].array = calloc((ntodo * 2) + 1, sizeof(double));
          col[jj].nullsize  = sizeof(double);  /* number of bytes per value */
          col[jj].null.doublenull = DOUBLENULLVALUE;  /* special value */
          break;

         case TSTRING:
          /* allocate array of pointers to all the strings  */
	  if( hdutype==ASCII_TBL ) rept = width;
          stringptr = calloc((ntodo + 1) , sizeof(stringptr));
          cols[jj].array = stringptr;
          col[jj].nullsize  = rept + 1;  /* number of bytes per value */

          if (stringptr)
          {
            /* allocate string to store the null string value */
            col[jj].null.stringnull = calloc(rept + 1, sizeof(char) );
            col[jj].null.stringnull[1] = 1; /* to make sure string != 0 */

            /* allocate big block for the array of table column strings */
            stringptr[0] = calloc((ntodo + 1) * (rept + 1), sizeof(char) );

            if (stringptr[0])
            {
              for (ii = 1; ii <= ntodo; ii++)
              {   /* pointer to each string */
                stringptr[ii] = stringptr[ii - 1] + (rept + 1);
              }

              /* get the TNULL keyword value, if it exists */
              tstatus = 0;
              ffkeyn("TNULL", cols[jj].colnum, keyname, &tstatus);
              ffgkys(cols[jj].fptr, keyname, nullstr, 0, &tstatus);
              if (!tstatus)
                  strncat(col[jj].null.stringnull, nullstr, rept);
            }
            else
            {
              ffpmsg("ffiter failed to allocate memory arrays");
              *status = MEMORY_ALLOCATION;  /* memory allocation failed */
              goto cleanup;
            }
          }
          break;

         case TLOGICAL:

          cols[jj].array = calloc(ntodo + 1, sizeof(char));
          col[jj].nullsize  = sizeof(char);  /* number of bytes per value */

          /* use value = 2 to flag null values in logical columns */
          col[jj].null.charnull = 2;
          break;

         default:
          sprintf(message,
                  "Column %d datatype currently not supported: %d:  (ffiter)",
                   jj + 1, cols[jj].datatype);
          ffpmsg(message);
          *status = BAD_DATATYPE;
          goto cleanup;

        }   /* end of switch block */

        /* check that all the arrays were allocated successfully */
        if (!cols[jj].array)
        {
            ffpmsg("ffiter failed to allocate memory arrays");
            *status = MEMORY_ALLOCATION;  /* memory allocation failed */
            goto cleanup;
        }
    }
 
    /*--------------------------------------------------*/
    /* main loop while there are values left to process */
    /*--------------------------------------------------*/

    nleft = totaln;

    while (nleft)
    {
      ntodo = minvalue(nleft, n_optimum); /* no. of values for this loop */

      /*  read input columns from FITS file(s)  */
      for (jj = 0; jj < n_cols; jj++)
      {
        if (cols[jj].iotype != OutputCol)
        {
          if (cols[jj].datatype == TSTRING)
          {
            stringptr = cols[jj].array;
            dataptr = stringptr + 1;
            defaultnull = col[jj].null.stringnull; /* ptr to the null value */
          }
          else
          {
            dataptr = (char *) cols[jj].array + col[jj].nullsize;
            defaultnull = &col[jj].null.charnull; /* ptr to the null value */
          }
          if (ffgcv(cols[jj].fptr, cols[jj].datatype, cols[jj].colnum,
                    frow, felement, cols[jj].repeat * ntodo, defaultnull,
                    dataptr,  &anynul, status) > 0)
          {
            break;
          }

          /* copy the appropriate null value into first array element */

          if (anynul)   /* are there any nulls in the data? */
          {   
            if (cols[jj].datatype == TSTRING)
            {
              stringptr = cols[jj].array;
              memcpy(*stringptr, col[jj].null.stringnull, col[jj].nullsize);
            }
            else
            {
              memcpy(cols[jj].array, defaultnull, col[jj].nullsize);
            }
          }
          else /* no null values so copy zero into first element */
          {
            if (cols[jj].datatype == TSTRING)
            {
              stringptr = cols[jj].array;
              memset(*stringptr, 0, col[jj].nullsize);  
            }
            else
            {
              memset(cols[jj].array, 0, col[jj].nullsize);  
            }
          }
        }
      }

      if (*status > 0) 
         break;   /* looks like an error occurred; quit immediately */

      /* call work function */

      if (hdutype == IMAGE_HDU) 
          *status = work_fn(totaln, offset, felement, ntodo, n_cols, cols,
                    userPointer);
      else
          *status = work_fn(totaln, offset, frow, ntodo, n_cols, cols,
                    userPointer);

      if (*status > 0 || *status < -1 ) 
         break;   /* looks like an error occurred; quit immediately */

      /*  write output columns  before quiting if status = -1 */
      tstatus = 0;
      for (jj = 0; jj < n_cols; jj++)
      {
        if (cols[jj].iotype != InputCol)
        {
          if (cols[jj].datatype == TSTRING)
          {
            stringptr = cols[jj].array;
            dataptr = stringptr + 1;
            nullptr = *stringptr;
            nbytes = 2;
          }
          else
          {
            dataptr = (char *) cols[jj].array + col[jj].nullsize;
            nullptr = (char *) cols[jj].array;
            nbytes = col[jj].nullsize;
          }

          if (memcmp(nullptr, &zeros, nbytes) ) 
          {
            /* null value flag not zero; must check for and write nulls */
            if (ffpcn(cols[jj].fptr, cols[jj].datatype, cols[jj].colnum, frow,
                      felement, cols[jj].repeat * ntodo, dataptr,
                      nullptr, &tstatus) > 0)
              break;
          }
          else
          { 
            /* no null values; just write the array */
            if (ffpcl(cols[jj].fptr, cols[jj].datatype, cols[jj].colnum, frow,
                      felement, cols[jj].repeat * ntodo, dataptr,
                      &tstatus) > 0)
              break;
          }
        }
      }

      if (*status == 0)
         *status = tstatus;   /* propagate any error status from the writes */

      if (*status) 
         break;   /* exit on any error */

      nleft -= ntodo;

      if (hdutype == IMAGE_HDU)
          felement += ntodo;
      else
          frow  += ntodo;
    }

cleanup:

    /*----------------------------------*/
    /* free work arrays for the columns */
    /*----------------------------------*/

    for (jj = 0; jj < n_cols; jj++)
    {
        if (cols[jj].datatype == TSTRING)
        {
            if (cols[jj].array)
            {
                stringptr = cols[jj].array;
                free(*stringptr);     /* free the block of strings */
                free(col[jj].null.stringnull); /* free the null string */
            }
        }
        free(cols[jj].array); /* memory for the array of values from the col */
    }
    free(col);   /* the structure containing the null values */
    return(*status);
}