/*  This file, getcols.c, contains routines that read data elements from   */
/*  a FITS image or table, with a character string datatype.               */

/*  The FITSIO software was written by William Pence at the High Energy    */
/*  Astrophysic Science Archive Research Center (HEASARC) at the NASA      */
/*  Goddard Space Flight Center.                                           */

#include <stdlib.h>
#include <string.h>
/* stddef.h is apparently needed to define size_t */
#include <stddef.h>
#include <ctype.h>
#include "fitsio2.h"
/*--------------------------------------------------------------------------*/
int ffgcvs( fitsfile *fptr,   /* I - FITS file pointer                       */
            int  colnum,      /* I - number of column to read (1 = 1st col)  */
            LONGLONG  firstrow,   /* I - first row to read (1 = 1st row)         */
            LONGLONG  firstelem,  /* I - first vector element to read (1 = 1st)  */
            LONGLONG  nelem,      /* I - number of strings to read               */
            char *nulval,     /* I - string for null pixels                  */
            char **array,     /* O - array of values that are read           */
            int  *anynul,     /* O - set to 1 if any values are null; else 0 */
            int  *status)     /* IO - error status                           */
/*
  Read an array of string values from a column in the current FITS HDU.
  Any undefined pixels will be set equal to the value of 'nulval' unless
  nulval = null in which case no checks for undefined pixels will be made.
*/
{
    char cdummy[2];

    ffgcls(fptr, colnum, firstrow, firstelem, nelem, 1, nulval,
           array, cdummy, anynul, status);
    return(*status);
}
/*--------------------------------------------------------------------------*/
int ffgcfs( fitsfile *fptr,   /* I - FITS file pointer                       */
            int  colnum,      /* I - number of column to read (1 = 1st col) */
            LONGLONG  firstrow,   /* I - first row to read (1 = 1st row)        */
            LONGLONG  firstelem,  /* I - first vector element to read (1 = 1st) */
            LONGLONG  nelem,      /* I - number of strings to read              */
            char **array,     /* O - array of values that are read           */
            char *nularray,   /* O - array of flags = 1 if nultyp = 2        */
            int  *anynul,     /* O - set to 1 if any values are null; else 0 */
            int  *status)     /* IO - error status                           */
/*
  Read an array of string values from a column in the current FITS HDU.
  Nularray will be set = 1 if the corresponding array pixel is undefined, 
  otherwise nularray will = 0.
*/
{
    char dummy[2];

    ffgcls(fptr, colnum, firstrow, firstelem, nelem, 2, dummy,
           array, nularray, anynul, status);
    return(*status);
}
/*--------------------------------------------------------------------------*/
int ffgcls( fitsfile *fptr,   /* I - FITS file pointer                       */
            int  colnum,      /* I - number of column to read (1 = 1st col) */
            LONGLONG  firstrow,   /* I - first row to read (1 = 1st row)        */
            LONGLONG  firstelem,  /* I - first vector element to read (1 = 1st) */
            LONGLONG  nelem,      /* I - number of strings to read              */
            int   nultyp,     /* I - null value handling code:               */
                              /*     1: set undefined pixels = nulval        */
                              /*     2: set nularray=1 for undefined pixels  */
            char  *nulval,    /* I - value for null pixels if nultyp = 1     */
            char **array,     /* O - array of values that are read           */
            char *nularray,   /* O - array of flags = 1 if nultyp = 2        */
            int  *anynul,     /* O - set to 1 if any values are null; else 0 */
            int  *status)     /* IO - error status                           */
/*
  Read an array of string values from a column in the current FITS HDU.
  Returns a formated string value, regardless of the datatype of the column
*/
{
    int tcode, hdutype, tstatus, scaled, intcol, dwidth, nulwidth, ll, dlen;
    long ii, jj;
    tcolumn *colptr;
    char message[FLEN_ERRMSG], *carray, keyname[FLEN_KEYWORD];
    char cform[20], dispfmt[20], tmpstr[400], *flgarray, tmpnull[80];
    unsigned char byteval;
    float *earray;
    double *darray, tscale = 1.0;
    LONGLONG *llarray;

    if (*status > 0 || nelem == 0)  /* inherit input status value if > 0 */
        return(*status);

    /* reset position to the correct HDU if necessary */
    if (fptr->HDUposition != (fptr->Fptr)->curhdu)
        ffmahd(fptr, (fptr->HDUposition) + 1, NULL, status);

    /* rescan header if data structure is undefined */
    else if ((fptr->Fptr)->datastart == DATA_UNDEFINED)
        if ( ffrdef(fptr, status) > 0)               
            return(*status);

    if (colnum < 1 || colnum > (fptr->Fptr)->tfield)
    {
        sprintf(message, "Specified column number is out of range: %d",
                colnum);
        ffpmsg(message);
        return(*status = BAD_COL_NUM);
    }

    colptr  = (fptr->Fptr)->tableptr;   /* point to first column */
    colptr += (colnum - 1);     /* offset to correct column structure */
    tcode = abs(colptr->tdatatype);

    if (tcode == TSTRING)
    {
      /* simply call the string column reading routine */
      ffgcls2(fptr, colnum, firstrow, firstelem, nelem, nultyp, nulval,
           array, nularray, anynul, status);
    }
    else if (tcode == TLOGICAL)
    {
      /* allocate memory for the array of logical values */
      carray = (char *) malloc((size_t) nelem);

      /*  call the logical column reading routine */
      ffgcll(fptr, colnum, firstrow, firstelem, nelem, nultyp, *nulval,
           carray, nularray, anynul, status); 

      if (*status <= 0)
      {
         /* convert logical values to "T", "F", or "N" (Null) */
         for (ii = 0; ii < nelem; ii++)
         {
           if (carray[ii] == 1)
              strcpy(array[ii], "T");
           else if (carray[ii] == 0)
              strcpy(array[ii], "F");
           else  /* undefined values = 2 */
              strcpy(array[ii],"N");
         }
      }

      free(carray);  /* free the memory */
    }
    else if (tcode == TCOMPLEX)
    {
      /* allocate memory for the array of double values */
      earray = (float *) calloc((size_t) (nelem * 2), sizeof(float) );
      
      ffgcle(fptr, colnum, firstrow, (firstelem - 1) * 2 + 1, nelem * 2,
        1, 1, FLOATNULLVALUE, earray, nularray, anynul, status);

      if (*status <= 0)
      {

         /* determine the format for the output strings */

         ffgcdw(fptr, colnum, &dwidth, status);
         dwidth = (dwidth - 3) / 2;
 
         /* use the TDISPn keyword if it exists */
         ffkeyn("TDISP", colnum, keyname, status);
         tstatus = 0;
         cform[0] = '\0';

         if (ffgkys(fptr, keyname, dispfmt, NULL, &tstatus) == 0)
         {
             /* convert the Fortran style format to a C style format */
             ffcdsp(dispfmt, cform);
         }

         if (!cform[0])
             strcpy(cform, "%14.6E");

         /* write the formated string for each value:  "(real,imag)" */
         jj = 0;
         for (ii = 0; ii < nelem; ii++)
         {
           strcpy(array[ii], "(");

           /* test for null value */
           if (earray[jj] == FLOATNULLVALUE)
           {
             strcpy(tmpstr, "NULL");
             if (nultyp == 2)
                nularray[ii] = 1;
           }
           else
             sprintf(tmpstr, cform, earray[jj]);

           strncat(array[ii], tmpstr, dwidth);
           strcat(array[ii], ",");
           jj++;

           /* test for null value */
           if (earray[jj] == FLOATNULLVALUE)
           {
             strcpy(tmpstr, "NULL");
             if (nultyp == 2)
                nularray[ii] = 1;
           }
           else
             sprintf(tmpstr, cform, earray[jj]);

           strncat(array[ii], tmpstr, dwidth);
           strcat(array[ii], ")");
           jj++;
         }
      }

      free(earray);  /* free the memory */
    }
    else if (tcode == TDBLCOMPLEX)
    {
      /* allocate memory for the array of double values */
      darray = (double *) calloc((size_t) (nelem * 2), sizeof(double) );
      
      ffgcld(fptr, colnum, firstrow, (firstelem - 1) * 2 + 1, nelem * 2,
        1, 1, DOUBLENULLVALUE, darray, nularray, anynul, status);

      if (*status <= 0)
      {
         /* determine the format for the output strings */

         ffgcdw(fptr, colnum, &dwidth, status);
         dwidth = (dwidth - 3) / 2;

         /* use the TDISPn keyword if it exists */
         ffkeyn("TDISP", colnum, keyname, status);
         tstatus = 0;
         cform[0] = '\0';
 
         if (ffgkys(fptr, keyname, dispfmt, NULL, &tstatus) == 0)
         {
             /* convert the Fortran style format to a C style format */
             ffcdsp(dispfmt, cform);
         }

         if (!cform[0])
            strcpy(cform, "%23.15E");

         /* write the formated string for each value:  "(real,imag)" */
         jj = 0;
         for (ii = 0; ii < nelem; ii++)
         {
           strcpy(array[ii], "(");

           /* test for null value */
           if (darray[jj] == DOUBLENULLVALUE)
           {
             strcpy(tmpstr, "NULL");
             if (nultyp == 2)
                nularray[ii] = 1;
           }
           else
             sprintf(tmpstr, cform, darray[jj]);

           strncat(array[ii], tmpstr, dwidth);
           strcat(array[ii], ",");
           jj++;

           /* test for null value */
           if (darray[jj] == DOUBLENULLVALUE)
           {
             strcpy(tmpstr, "NULL");
             if (nultyp == 2)
                nularray[ii] = 1;
           }
           else
             sprintf(tmpstr, cform, darray[jj]);

           strncat(array[ii], tmpstr, dwidth);
           strcat(array[ii], ")");
           jj++;
         }
      }

      free(darray);  /* free the memory */
    }
    else if (tcode == TLONGLONG)
    {
      /* allocate memory for the array of LONGLONG values */
      llarray = (LONGLONG *) calloc((size_t) nelem, sizeof(LONGLONG) );
      flgarray = (char *) calloc((size_t) nelem, sizeof(char) );
      dwidth = 20;  /* max width of displayed long long integer value */

      if (ffgcfjj(fptr, colnum, firstrow, firstelem, nelem,
            llarray, flgarray, anynul, status) > 0)
      {
         free(flgarray);
         free(llarray);
         return(*status);
      }

      /* write the formated string for each value */
      if (nulval) {
          strcpy(tmpnull, nulval);
          nulwidth = strlen(nulval);
      } else {
          strcpy(tmpnull, " ");
          nulwidth = 1;
      }

      for (ii = 0; ii < nelem; ii++)
      {
           if ( flgarray[ii] )
           {
              *array[ii] = '\0';
              if (dwidth < nulwidth)
                  strncat(array[ii], tmpnull, dwidth);
              else
                  sprintf(array[ii],"%*s",dwidth,tmpnull);
		  
              if (nultyp == 2)
	          nularray[ii] = 1;
           }
           else
           {	   

#if defined(_MSC_VER)
    /* Microsoft Visual C++ 6.0 uses '%I64d' syntax  for 8-byte integers */
        sprintf(tmpstr, "%20I64d", llarray[ii]);
#elif (USE_LL_SUFFIX == 1)
        sprintf(tmpstr, "%20lld", llarray[ii]);
#else
        sprintf(tmpstr, "%20ld", llarray[ii]);
#endif
              *array[ii] = '\0';
              strncat(array[ii], tmpstr, 20);
           }
      }

      free(flgarray);
      free(llarray);  /* free the memory */

    }
    else
    {
      /* allocate memory for the array of double values */
      darray = (double *) calloc((size_t) nelem, sizeof(double) );
      
      /* read all other numeric type columns as doubles */
      if (ffgcld(fptr, colnum, firstrow, firstelem, nelem, 1, nultyp, 
           DOUBLENULLVALUE, darray, nularray, anynul, status) > 0)
      {
         free(darray);
         return(*status);
      }

      /* determine the format for the output strings */

      ffgcdw(fptr, colnum, &dwidth, status);

      /* check if  column is scaled */
      ffkeyn("TSCAL", colnum, keyname, status);
      tstatus = 0;
      scaled = 0;
      if (ffgkyd(fptr, keyname, &tscale, NULL, &tstatus) == 0)
      {
            if (tscale != 1.0)
                scaled = 1;    /* yes, this is a scaled column */
      }

      intcol = 0;
      if (tcode <= TLONG && !scaled)
             intcol = 1;   /* this is an unscaled integer column */

      /* use the TDISPn keyword if it exists */
      ffkeyn("TDISP", colnum, keyname, status);
      tstatus = 0;
      cform[0] = '\0';

      if (ffgkys(fptr, keyname, dispfmt, NULL, &tstatus) == 0)
      {
           /* convert the Fortran style TDISPn to a C style format */
           ffcdsp(dispfmt, cform);
      }

      if (!cform[0])
      {
            /* no TDISPn keyword; use TFORMn instead */

            ffkeyn("TFORM", colnum, keyname, status);
            ffgkys(fptr, keyname, dispfmt, NULL, status);

            if (scaled && tcode <= TSHORT)
            {
                  /* scaled short integer column == float */
                  strcpy(cform, "%#14.6G");
            }
            else if (scaled && tcode == TLONG)
            {
                  /* scaled long integer column == double */
                  strcpy(cform, "%#23.15G");
            }
            else
            {
               ffghdt(fptr, &hdutype, status);
               if (hdutype == ASCII_TBL)
               {
                  /* convert the Fortran style TFORMn to a C style format */
                  ffcdsp(dispfmt, cform);
               }
               else
               {
                 /* this is a binary table, need to convert the format */
                  if (tcode == TBIT) {            /* 'X' */
                     strcpy(cform, "%4d");
                  } else if (tcode == TBYTE) {    /* 'B' */
                     strcpy(cform, "%4d");
                  } else if (tcode == TSHORT) {   /* 'I' */
                     strcpy(cform, "%6d");
                  } else if (tcode == TLONG) {    /* 'J' */
                     strcpy(cform, "%11.0f");
                     intcol = 0;  /* needed to support unsigned int */
                  } else if (tcode == TFLOAT) {   /* 'E' */
                     strcpy(cform, "%#14.6G");
                  } else if (tcode == TDOUBLE) {  /* 'D' */
                     strcpy(cform, "%#23.15G");
                  }
               }
            }
      } 

      if (nulval) {
          strcpy(tmpnull, nulval);
          nulwidth = strlen(nulval);
      } else {
          strcpy(tmpnull, " ");
          nulwidth = 1;
      }

      /* write the formated string for each value */
      for (ii = 0; ii < nelem; ii++)
      {
           if (tcode == TBIT)
           {
               byteval = (char) darray[ii];

               for (ll=0; ll < 8; ll++)
               {
                   if ( ((unsigned char) (byteval << ll)) >> 7 )
                       *(array[ii] + ll) = '1';
                   else
                       *(array[ii] + ll) = '0';
               }
               *(array[ii] + 8) = '\0';
           }
           /* test for null value */
           else if ( (nultyp == 1 && darray[ii] == DOUBLENULLVALUE) ||
                (nultyp == 2 && nularray[ii]) )
           {
              *array[ii] = '\0';
              if (dwidth < nulwidth)
                  strncat(array[ii], tmpnull, dwidth);
              else
                  sprintf(array[ii],"%*s",dwidth,tmpnull);
           }
           else
           {	   
              if (intcol)
                sprintf(tmpstr, cform, (int) darray[ii]);
              else
                sprintf(tmpstr, cform, darray[ii]);

              /* fill field with '*' if number is too wide */
              dlen = strlen(tmpstr);
	      if (dlen > dwidth) {
	         memset(tmpstr, '*', dwidth);
              }

              *array[ii] = '\0';
              strncat(array[ii], tmpstr, dwidth);
           }
      }

      free(darray);  /* free the memory */
    }
    return(*status);
}
/*--------------------------------------------------------------------------*/
int ffgcdw( fitsfile *fptr,   /* I - FITS file pointer                       */
            int  colnum,      /* I - number of column (1 = 1st col)      */
            int  *width,      /* O - display width                       */
            int  *status)     /* IO - error status                           */
/*
  Get Column Display Width.
*/
{
    tcolumn *colptr;
    char *cptr;
    char message[FLEN_ERRMSG], keyname[FLEN_KEYWORD], dispfmt[20];
    int tcode, hdutype, tstatus, scaled;
    double tscale;

    if (*status > 0)  /* inherit input status value if > 0 */
        return(*status);

    if (fptr->HDUposition != (fptr->Fptr)->curhdu)
        ffmahd(fptr, (fptr->HDUposition) + 1, NULL, status);

    if (colnum < 1 || colnum > (fptr->Fptr)->tfield)
    {
        sprintf(message, "Specified column number is out of range: %d",
                colnum);
        ffpmsg(message);
        return(*status = BAD_COL_NUM);
    }

    colptr  = (fptr->Fptr)->tableptr;   /* point to first column */
    colptr += (colnum - 1);     /* offset to correct column structure */
    tcode = abs(colptr->tdatatype);

    /* use the TDISPn keyword if it exists */
    ffkeyn("TDISP", colnum, keyname, status);

    *width = 0;
    tstatus = 0;
    if (ffgkys(fptr, keyname, dispfmt, NULL, &tstatus) == 0)
    {
          /* parse TDISPn get the display width */
          cptr = dispfmt;
          while(*cptr == ' ') /* skip leading blanks */
              cptr++;

          if (*cptr == 'A' || *cptr == 'a' ||
              *cptr == 'I' || *cptr == 'i' ||
              *cptr == 'O' || *cptr == 'o' ||
              *cptr == 'Z' || *cptr == 'z' ||
              *cptr == 'F' || *cptr == 'f' ||
              *cptr == 'E' || *cptr == 'e' ||
              *cptr == 'D' || *cptr == 'd' ||
              *cptr == 'G' || *cptr == 'g')
          {

            while(!isdigit((int) *cptr) && *cptr != '\0') /* find 1st digit */
              cptr++;

            *width = atoi(cptr);
            if (tcode >= TCOMPLEX)
              *width = (2 * (*width)) + 3;
          }
    }

    if (*width == 0)
    {
        /* no valid TDISPn keyword; use TFORMn instead */

        ffkeyn("TFORM", colnum, keyname, status);
        ffgkys(fptr, keyname, dispfmt, NULL, status);

        /* check if  column is scaled */
        ffkeyn("TSCAL", colnum, keyname, status);
        tstatus = 0;
        scaled = 0;

        if (ffgkyd(fptr, keyname, &tscale, NULL, &tstatus) == 0)
        {
            if (tscale != 1.0)
                scaled = 1;    /* yes, this is a scaled column */
        }

        if (scaled && tcode <= TSHORT)
        {
            /* scaled short integer col == float; default format is 14.6G */
            *width = 14;
        }
        else if (scaled && tcode == TLONG)
        {
            /* scaled long integer col == double; default format is 23.15G */
            *width = 23;
        }
        else
        {
           ffghdt(fptr, &hdutype, status);  /* get type of table */
           if (hdutype == ASCII_TBL)
           {
              /* parse TFORMn get the display width */
              cptr = dispfmt;
              while(!isdigit((int) *cptr) && *cptr != '\0') /* find 1st digit */
                 cptr++;

              *width = atoi(cptr);
           }
           else
           {
                 /* this is a binary table */
                  if (tcode == TBIT)           /* 'X' */
                     *width = 8;
                  else if (tcode == TBYTE)     /* 'B' */
                     *width = 4;
                  else if (tcode == TSHORT)    /* 'I' */
                     *width = 6;
                  else if (tcode == TLONG)     /* 'J' */
                     *width = 11;
                  else if (tcode == TLONGLONG) /* 'K' */
                     *width = 20;
                  else if (tcode == TFLOAT)    /* 'E' */
                     *width = 14;
                  else if (tcode == TDOUBLE)   /* 'D' */
                     *width = 23;
                  else if (tcode == TCOMPLEX)  /* 'C' */
                     *width = 31;
                  else if (tcode == TDBLCOMPLEX)  /* 'M' */
                     *width = 49;
                  else if (tcode == TLOGICAL)  /* 'L' */
                     *width = 1;
                  else if (tcode == TSTRING)   /* 'A' */
                  {
                     cptr = dispfmt;
                     while(!isdigit((int) *cptr) && *cptr != '\0') 
                         cptr++;

                     *width = atoi(cptr);

                     if (*width < 1)
                         *width = 1;  /* default is at least 1 column */
                  }
            }
        }
    } 
    return(*status);
}
/*--------------------------------------------------------------------------*/
int ffgcls2 ( fitsfile *fptr,   /* I - FITS file pointer                       */
            int  colnum,      /* I - number of column to read (1 = 1st col) */
            LONGLONG  firstrow,   /* I - first row to read (1 = 1st row)        */
            LONGLONG  firstelem,  /* I - first vector element to read (1 = 1st) */
            LONGLONG  nelem,      /* I - number of strings to read              */
            int   nultyp,     /* I - null value handling code:               */
                              /*     1: set undefined pixels = nulval        */
                              /*     2: set nularray=1 for undefined pixels  */
            char  *nulval,    /* I - value for null pixels if nultyp = 1     */
            char **array,     /* O - array of values that are read           */
            char *nularray,   /* O - array of flags = 1 if nultyp = 2        */
            int  *anynul,     /* O - set to 1 if any values are null; else 0 */
            int  *status)     /* IO - error status                           */
/*
  Read an array of string values from a column in the current FITS HDU.
*/
{
    double dtemp;
    long nullen; 
    int tcode, maxelem, hdutype, nulcheck;
    long twidth, incre;
    long ii, jj, ntodo;
    LONGLONG repeat, startpos, elemnum, readptr, tnull, rowlen, rownum, remain, next;
    double scale, zero;
    char tform[20];
    char message[FLEN_ERRMSG];
    char snull[20];   /*  the FITS null value  */
    tcolumn *colptr;

    double cbuff[DBUFFSIZE / sizeof(double)]; /* align cbuff on word boundary */
    char *buffer, *arrayptr;

    if (*status > 0 || nelem == 0)  /* inherit input status value if > 0 */
        return(*status);

    if (fptr->HDUposition != (fptr->Fptr)->curhdu)
        ffmahd(fptr, (fptr->HDUposition) + 1, NULL, status);

    if (anynul)
        *anynul = 0;

    if (nultyp == 2)
        memset(nularray, 0, (size_t) nelem);   /* initialize nullarray */

    /*---------------------------------------------------*/
    /*  Check input and get parameters about the column: */
    /*---------------------------------------------------*/
    if (colnum < 1 || colnum > (fptr->Fptr)->tfield)
    {
        sprintf(message, "Specified column number is out of range: %d",
                colnum);
        ffpmsg(message);
        return(*status = BAD_COL_NUM);
    }

    colptr  = (fptr->Fptr)->tableptr;   /* point to first column */
    colptr += (colnum - 1);     /* offset to correct column structure */
    tcode = colptr->tdatatype;

    if (tcode == -TSTRING) /* variable length column in a binary table? */
    {
      /* only read a single string; ignore value of firstelem */

      if (ffgcprll( fptr, colnum, firstrow, 1, 1, 0, &scale, &zero,
        tform, &twidth, &tcode, &maxelem, &startpos,  &elemnum, &incre,
        &repeat, &rowlen, &hdutype, &tnull, snull, status) > 0)
        return(*status);

      remain = 1;
      twidth = (long) repeat;  
    }
    else if (tcode == TSTRING)
    {
      if (ffgcprll( fptr, colnum, firstrow, firstelem, nelem, 0, &scale, &zero,
        tform, &twidth, &tcode, &maxelem, &startpos,  &elemnum, &incre,
        &repeat, &rowlen, &hdutype, &tnull, snull, status) > 0)
        return(*status);

      remain = nelem;
    }
    else
        return(*status = NOT_ASCII_COL);

    nullen = strlen(snull);   /* length of the undefined pixel string */
    if (nullen == 0)
        nullen = 1;
 
    /*------------------------------------------------------------------*/
    /*  Decide whether to check for null values in the input FITS file: */
    /*------------------------------------------------------------------*/
    nulcheck = nultyp; /* by default check for null values in the FITS file */

    if (nultyp == 1 && nulval == 0)
       nulcheck = 0;    /* calling routine does not want to check for nulls */

    else if (nultyp == 1 && nulval && nulval[0] == 0)
       nulcheck = 0;    /* calling routine does not want to check for nulls */

    else if (snull[0] == ASCII_NULL_UNDEFINED)
       nulcheck = 0;   /* null value string in ASCII table not defined */

    else if (nullen > twidth)
       nulcheck = 0;   /* null value string is longer than width of column  */
                       /* thus impossible for any column elements to = null */

    /*---------------------------------------------------------------------*/
    /*  Now read the strings one at a time from the FITS column.           */
    /*---------------------------------------------------------------------*/
    next = 0;                 /* next element in array to be read  */
    rownum = 0;               /* row number, relative to firstrow     */

    while (remain)
    {
      /* limit the number of pixels to process a one time to the number that
         will fit in the buffer space or to the number of pixels that remain
         in the current vector, which ever is smaller.
      */
      ntodo = (long) minvalue(remain, maxelem);      
      ntodo = (long) minvalue(ntodo, (repeat - elemnum));

      readptr = startpos + ((LONGLONG)rownum * rowlen) + (elemnum * incre);
      ffmbyt(fptr, readptr, REPORT_EOF, status);  /* move to read position */

      /* read the array of strings from the FITS file into the buffer */

      if (incre == twidth)
         ffgbyt(fptr, ntodo * twidth, cbuff, status);
      else
         ffgbytoff(fptr, twidth, ntodo, incre - twidth, cbuff, status);

      /* copy from the buffer into the user's array of strings */
      /* work backwards from last char of last string to 1st char of 1st */

      buffer = ((char *) cbuff) + (ntodo * twidth) - 1;

      for (ii = (long) (next + ntodo - 1); ii >= next; ii--)
      {
         arrayptr = array[ii] + twidth - 1;

         for (jj = twidth - 1; jj > 0; jj--)  /* ignore trailing blanks */
         {
            if (*buffer == ' ')
            {
              buffer--;
              arrayptr--;
            }
            else
              break;
         }
         *(arrayptr + 1) = 0;  /* write the string terminator */
         
         for (; jj >= 0; jj--)    /* copy the string itself */
         {
           *arrayptr = *buffer;
           buffer--;
           arrayptr--;
         }

         /* check if null value is defined, and if the   */
         /* column string is identical to the null string */
         if (nulcheck && !strncmp(snull, array[ii], nullen) )
         {
           *anynul = 1;   /* this is a null value */
           if (nultyp == 1) {
	   
	     if (nulval)
                strcpy(array[ii], nulval);
	     else
	        strcpy(array[ii], " ");
	     
           } else
             nularray[ii] = 1;
         }
      }
    
      if (*status > 0)  /* test for error during previous read operation */
      {
         dtemp = (double) next;
         sprintf(message,
          "Error reading elements %.0f thru %.0f of data array (ffpcls).",
             dtemp+1., dtemp+ntodo);

         ffpmsg(message);
         return(*status);
      }

      /*--------------------------------------------*/
      /*  increment the counters for the next loop  */
      /*--------------------------------------------*/
      next += ntodo;
      remain -= ntodo;
      if (remain)
      {
          elemnum += ntodo;
          if (elemnum == repeat)  /* completed a row; start on next row */
          {
              elemnum = 0;
              rownum++;
          }
      }
    }  /*  End of main while Loop  */

    return(*status);
}