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Sourcecode: saoimage version File versions

fitsfile.c

/*** File libwcs/fitsfile.c
 *** November 18, 2003
 *** By Doug Mink, dmink@cfa.harvard.edu
 *** Harvard-Smithsonian Center for Astrophysics
 *** Copyright (C) 1996-2003
 *** Smithsonian Astrophysical Observatory, Cambridge, MA, USA

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
    
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Correspondence concerning WCSTools should be addressed as follows:
           Internet email: dmink@cfa.harvard.edu
           Postal address: Doug Mink
                           Smithsonian Astrophysical Observatory
                           60 Garden St.
                           Cambridge, MA 02138 USA

 * Module:      fitsfile.c (FITS file reading and writing)
 * Purpose:     Read and write FITS image and table files
 * Subroutine:    fitsropen (inpath)
 *          Open a FITS file for reading, returning a FILE pointer
 * Subroutine:    fitsrhead (filename, lhead, nbhead)
 *          Read FITS header and return it
 * Subroutine:    fitsrsect (filename, nbhead, header, fd, x0, y0, nx, ny)
 *          Read section of a FITS image, having already ready the header
 * Subroutine:    fitsrimage (filename, nbhead, header)
 *          Read FITS image, having already ready the header
 * Subroutine:    fitsrfull (filename, nbhead, header)
 *          Read a FITS image of any dimension
 * Subroutine:    fitsrtopen (inpath, nk, kw, nrows, nchar, nbhead)
 *          Open a FITS table file for reading; return header information
 * Subroutine:    fitsrthead (header, nk, kw, nrows, nchar, nbhead)
 *          Extract FITS table information from a FITS header
 * Subroutine:    fitsrtline (fd, nbhead, lbuff, tbuff, irow, nbline, line)
 *          Read next line of FITS table file
 * Subroutine:    ftgetr8 (entry, kw)
 *          Extract column from FITS table line as double
 * Subroutine:    ftgetr4 (entry, kw)
 *          Extract column from FITS table line as float
 * Subroutine:    ftgeti4 (entry, kw)
 *          Extract column from FITS table line as int
 * Subroutine:    ftgeti2 (entry, kw)
 *          Extract column from FITS table line as short
 * Subroutine:    ftgetc (entry, kw, string, maxchar)
 *          Extract column from FITS table line as a character string
 * Subroutine:    fitswimage (filename, header, image)
 *          Write FITS header and image
 * Subroutine:    fitswext (filename, header, image)
 *          Write FITS header and image as extension to existing FITS file
 * Subroutine:    fitswhdu (fd, filename, header, image)
 *          Write FITS header and image as extension to file descriptor
 * Subroutine:    fitscimage (filename, header, filename0)
 *          Write FITS header and copy FITS image
 * Subroutine:    fitswhead (filename, header)
 *          Write FITS header and keep file open for further writing 
 * Subroutine:    isfits (filename)
 *          Return 1 if file is a FITS file, else 0
 */

#include <stdlib.h>
#ifndef VMS
#include <unistd.h>
#endif
#include <stdio.h>
#include <fcntl.h>
#include <sys/file.h>
#include <errno.h>
#include <string.h>
#include "fitsfile.h"

static int verbose=0;         /* if 1 print diagnostics */
static char fitserrmsg[80];

/* FITSRHEAD -- Read a FITS header */

char *
fitsrhead (filename, lhead, nbhead)

char  *filename;  /* Name of FITS image file */
int   *lhead;           /* Allocated length of FITS header in bytes (returned) */
int   *nbhead;    /* Number of bytes before start of data (returned) */
                  /* This includes all skipped image extensions */

{
    int fd;
    char *header; /* FITS image header (filled) */
    int extend;
    int nbytes,naxis, i;
    int ntry,nbr,irec,nrec, nbh, ipos, npos, nbprim, lprim, lext;
    int nax1, nax2, nax3, nax4, nbpix, ibpix, nblock, nbskip;
    char fitsbuf[2884];
    char *headend;      /* Pointer to last line of header */
    char *headnext;     /* Pointer to next line of header to be added */
    int hdu;            /* header/data unit counter */
    int extnum;         /* desired header data number
                     (0=primary -1=first with data -2=use EXTNAME) */
    char extname[32];   /* FITS extension name */
    char extnam[32];    /* Desired FITS extension name */
    char *ext;          /* FITS extension name or number in header, if any */
    char *pheader;      /* Primary header (naxis is 0) */
    char cext;
    char *rbrac;  /* Pointer to right bracket if present in file name */
    char *mwcs;         /* Pointer to WCS name separated by % */
    char *endnext;
    char *pheadend;

    pheader = NULL;
    lprim = 0;
    header = NULL;

    /* Check for FITS WCS specification and ignore for file opening */
    mwcs = strchr (filename, '%');
    if (mwcs != NULL)
      *mwcs = (char) 0;

    /* Check for FITS extension and ignore for file opening */
    rbrac = NULL;
    ext = strchr (filename, ',');
    if (ext == NULL) {
      ext = strchr (filename, '[');
      if (ext != NULL) {
          rbrac = strchr (filename, ']');
          if (rbrac != NULL)
            *rbrac = (char) 0;
          }
      }
    if (ext != NULL) {
      cext = *ext;
      *ext = (char) 0;
      }

    /* Open the image file and read the header */
    if (strncasecmp (filename,"stdin",5)) {
      fd = -1;
      fd = fitsropen (filename);
      }
#ifndef VMS
    else {
      fd = STDIN_FILENO;
      extnum = -1;
      }
#endif

    if (ext != NULL) {
      if (isnum (ext+1))
          extnum = atoi (ext+1);
      else {
          extnum = -2;
          strcpy (extnam, ext+1);
          }
      }
    else
      extnum = -1;

    /* Repair the damage done to the file-name string during parsing */
    if (ext != NULL)
      *ext = cext;
    if (rbrac != NULL)
      *rbrac = ']';
    if (mwcs != NULL)
      *mwcs = '%';

    if (fd < 0) {
      snprintf (fitserrmsg,79, "FITSRHEAD:  cannot read file %s\n", filename);
      return (NULL);
      }

    nbytes = FITSBLOCK;
    *nbhead = 0;
    headend = NULL;
    nbh = FITSBLOCK * 20 + 4;
    header = (char *) calloc ((unsigned int) nbh, 1);
    (void) hlength (header, nbh);
    headnext = header;
    nrec = 1;
    hdu = 0;

    /* Read FITS header from input file one FITS block at a time */
    irec = 0;
    while (irec < 100) {
      nbytes = FITSBLOCK;
      for (ntry = 0; ntry < 10; ntry++) {
          for (i = 0; i < 2884; i++) fitsbuf[i] = 0;
          nbr = read (fd, fitsbuf, nbytes);

          /* Short records allowed only if they have the last header line */
          if (nbr < nbytes) {
            headend = ksearch (fitsbuf,"END");
            if (headend == NULL) {
                if (ntry < 9) {
                  if (verbose)
                      fprintf (stderr,"FITSRHEAD: %d / %d bytes read %d\n",
                             nbr,nbytes,ntry);
                  }
                else {
                  snprintf(fitserrmsg,79,"FITSRHEAD: '%d / %d bytes of header read from %s\n"
                        ,nbr,nbytes,filename);
#ifndef VMS
                  if (fd != STDIN_FILENO)
#endif
                      (void)close (fd);
                  free (header);
                  if (pheader != NULL)
                      return (pheader);
                  return (NULL);
                  }
                }
            else
                break;
            }
          else
            break;
          }

      /* Move current FITS record into header string */
      for (i = 0; i < 2880; i++)
          if (fitsbuf[i] < 32) fitsbuf[i] = 32;
      strncpy (headnext, fitsbuf, nbr);
      *nbhead = *nbhead + nbr;
      nrec = nrec + 1;
      *(headnext+nbr) = 0;

      /* Check to see if this is the final record in this header */
      headend = ksearch (fitsbuf,"END");
      if (headend == NULL) {
          if (nrec * FITSBLOCK > nbh) {
            nbh = (nrec + 4) * FITSBLOCK + 4;
            header = (char *) realloc (header,(unsigned int) nbh);
            (void) hlength (header, nbh);
            headnext = header + *nbhead - FITSBLOCK;
            }
          headnext = headnext + FITSBLOCK;
          }

      else {
          naxis = 0;
          hgeti4 (header,"NAXIS",&naxis);

          /* If header has no data, save it for appending to desired header */
          if (naxis < 1) {
            nbprim = nrec * FITSBLOCK;
            headend = ksearch (header,"END");
            endnext = headend;
            lprim = headend + 80 - header;
            pheader = (char *) calloc ((unsigned int) nbprim, 1);
            strncpy (pheader, header, lprim);
            }

          /* If header has no data, start with the next record */
          if (naxis < 1 && extnum == -1) {
            extend = 0;
            hgetl (header,"EXTEND",&extend);
            if (naxis == 0 && extend) {
                headnext = header;
                *headend = ' ';
                headend = NULL;
                /* nrec = 1; */
                hdu = hdu + 1;
                }
            else
                break;
            }

          /* If this is the desired header data unit, keep it */
          else if (ext != NULL) {
            if (extnum > -1 && hdu == extnum)
                break;
            else if (extnum < 0) {
                extname[0] = 0;
                hgets (header, "EXTNAME", 32, extname);
                if (!strcmp (extnam,extname))
                  break;
                }

            /* If this is not desired header data unit, skip over data */
            hdu = hdu + 1;
            nblock = 0;
            if (naxis > 0) {
                ibpix = 0;
                hgeti4 (header,"BITPIX",&ibpix);
                if (ibpix < 0)
                  nbpix = -ibpix / 8;
                else
                  nbpix = ibpix / 8;
                nax1 = 1;
                hgeti4 (header,"NAXIS1",&nax1);
                nax2 = 1;
                if (naxis > 1)
                  hgeti4 (header,"NAXIS2",&nax2);
                nax3 = 1;
                if (naxis > 2)
                  hgeti4 (header,"NAXIS3",&nax3);
                nax4 = 1;
                if (naxis > 3)
                  hgeti4 (header,"NAXIS4",&nax4);
                nbskip = nax1 * nax2 * nax3 * nax4 * nbpix;
                nblock = nbskip / 2880;
                if (nblock*2880 < nbskip)
                  nblock = nblock + 1;
                }
            else
                nblock = 0;
            *nbhead = *nbhead + (nblock * 2880);

            /* Set file pointer to beginning of next header/data unit */
            if (nblock > 0) {
#ifndef VMS
                if (fd != STDIN_FILENO) {
                  ipos = lseek (fd, *nbhead, SEEK_SET);
                  npos = *nbhead;
                  }
                else {
#else
                  {
#endif
                  ipos = 0;
                  for (i = 0; i < nblock; i++) {
                      nbytes = FITSBLOCK;
                      nbr = read (fd, fitsbuf, nbytes);
                      if (nbr < nbytes) {
                        ipos = ipos + nbr;
                        break;
                        }
                      else
                        ipos = ipos + nbytes;
                      }
                  npos = nblock * 2880;
                  }
                if (ipos < npos) {
                  snprintf (fitserrmsg,79,"FITSRHEAD: %d / %d bytes skipped\n",
                         ipos,npos);
                  break;
                  }
                }
            headnext = header;
            headend = NULL;
            nrec = 1;
            }
          else
            break;
          }
      }

#ifndef VMS
    if (fd != STDIN_FILENO)
      (void)close (fd);
#endif

    /* Allocate an extra block for good measure */
    *lhead = (nrec + 1) * FITSBLOCK;
    if (*lhead > nbh) {
      header = (char *) realloc (header,(unsigned int) *lhead);
      (void) hlength (header, *lhead);
      }
    else
      *lhead = nbh;

    if (pheader != NULL && extnum != 0) {
      extname[0] = 0;
      endnext = headend;
      hgets (header, "XTENSION", 32, extname);
      if (!strcmp (extname,"IMAGE")) {
          strncpy (header, "SIMPLE  ", 8);
          hputl (header, "SIMPLE", 1);
          }
      hputs (header,"COMMENT","-------------------------------------------");
      hputs (header,"COMMENT","Information from Primary Header");
      hputs (header,"COMMENT","-------------------------------------------");
      headend = blsearch (header,"END");
      if (headend == NULL)
          headend = ksearch (header, "END");
      lext = headend - header;

      /* Update primary header for inclusion at end of extension header */
      hchange (pheader, "SIMPLE", "ROOTHEAD");
      hchange (pheader, "NEXTEND", "NUMEXT");
      hdel (pheader, "BITPIX");
      hdel (pheader, "NAXIS");
      hdel (pheader, "EXTEND");
      hputl (pheader, "ROOTEND",1);
      pheadend = ksearch (pheader,"END");
      lprim = pheadend + 80 - pheader;
      if (lext + lprim > nbh) {
          nrec = (lext + lprim) / FITSBLOCK;
          if (FITSBLOCK*nrec < lext+lprim)
            nrec = nrec + 1;
          *lhead = (nrec+1) * FITSBLOCK;
          header = (char *) realloc (header,(unsigned int) *lhead);
          (void) hlength (header, *lhead);
          }
      pheader[lprim] = 0;
      strncpy (headend, pheader, lprim);
      free (pheader);
      }

    return (header);
}


/* FITSRSECT -- Read a piece of a FITS image, having already read the header */

char *
fitsrsect (filename, header, nbhead, x0, y0, nx, ny, nlog)

char  *filename;  /* Name of FITS image file */
char  *header;    /* FITS header for image (previously read) */
int   nbhead;           /* Actual length of image header(s) in bytes */
int   x0, y0;           /* FITS image coordinate of first pixel */
int   nx;         /* Number of columns to read (less than NAXIS1) */
int   ny;         /* Number of rows to read (less than NAXIS2) */
int   nlog;       /* Note progress mod this rows */
{
    int fd;       /* File descriptor */
    int nbimage, naxis1, naxis2, bytepix, nbread;
    int bitpix, naxis, nblocks, nbytes, nbr;
    int x1, y1, nbline, impos, nblin, nyleft;
    char *image, *imline, *imlast;
    int ilog = 0;
    int row;

    /* Open the image file and read the header */
    if (strncasecmp (filename,"stdin", 5)) {
      fd = -1;

      fd = fitsropen (filename);
      if (fd < 0) {
          snprintf (fitserrmsg,79, "FITSRSECT:  cannot read file %s\n", filename);
          return (NULL);
          }

      /* Skip over FITS header and whatever else needs to be skipped */
      if (lseek (fd, nbhead, SEEK_SET) < 0) {
          (void)close (fd);
          snprintf (fitserrmsg,79, "FITSRSECT:  cannot skip header of file %s\n",
                 filename);
          return (NULL);
          }
      }
#ifndef VMS
    else
      fd = STDIN_FILENO;
#endif

    /* Compute size of image in bytes using relevant header parameters */
    naxis = 1;
    hgeti4 (header,"NAXIS",&naxis);
    naxis1 = 1;
    hgeti4 (header,"NAXIS1",&naxis1);
    naxis2 = 1;
    hgeti4 (header,"NAXIS2",&naxis2);
    bitpix = 0;
    hgeti4 (header,"BITPIX",&bitpix);
    if (bitpix == 0) {
      /* snprintf (fitserrmsg,79, "FITSRSECT:  BITPIX is 0; image not read\n"); */
      (void)close (fd);
      return (NULL);
      }
    bytepix = bitpix / 8;
    if (bytepix < 0) bytepix = -bytepix;

    /* Keep X coordinates within image limits */
    if (x0 < 1)
      x0 = 1;
    else if (x0 > naxis1)
      x0 = naxis1;
    x1 = x0 + nx - 1;
    if (x1 < 1)
      x1 = 1;
    else if (x1 > naxis1)
      x1 = naxis1;
    nx = x1 - x0 + 1;

    /* Keep Y coordinates within image limits */
    if (y0 < 1)
      y0 = 1;
    else if (y0 > naxis2)
      y0 = naxis2;
    y1 = y0 + ny - 1;
    if (y1 < 1)
      y1 = 1;
    else if (y1 > naxis2)
      y1 = naxis2;
    ny = y1 - y0 + 1;

    /* Number of bytes in output image */
    nbline = nx * bytepix;
    nbimage = nbline * ny;

    /* Set number of bytes to integral number of 2880-byte blocks */
    nblocks = nbimage / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbimage)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;

    /* Allocate image section to be read */
    image = (char *) malloc (nbytes);
    nyleft = ny;
    imline = image;
    nbr = 0;

    /* Computer pointer to first byte of input image to read */
    nblin = naxis1 * bytepix;
    impos = nbhead + ((y0 - 1) * nblin) + ((x0 - 1) * bytepix);
    row = y0 - 1;

    /* Read image section one line at a time */
    while (nyleft-- > 0) {
      if (lseek (fd, impos, SEEK_SET) >= 0) {
          nbread = read (fd, imline, nbline);
          nbr = nbr + nbread;
          impos = impos + nblin;
          imline = imline + nbline;
          row++;
          if (++ilog == nlog) {
            ilog = 0;
            fprintf (stderr, "Row %5d extracted   ", row);
                (void) putc (13,stderr);
            }
          }
      }
    if (nlog)
      fprintf (stderr, "\n");

    /* Fill rest of image with zeroes */
    imline = image + nbimage;
    imlast = image + nbytes;
    while (imline++ < imlast)
      *imline = (char) 0;

    /* Byte-reverse image, if necessary */
    if (imswapped ())
      imswap (bitpix, image, nbytes);

    return (image);
}


/* FITSRIMAGE -- Read a FITS image */

char *
fitsrimage (filename, nbhead, header)

char  *filename;  /* Name of FITS image file */
int   nbhead;           /* Actual length of image header(s) in bytes */
char  *header;    /* FITS header for image (previously read) */
{
    int fd;
    int nbimage, naxis1, naxis2, bytepix, nbread;
    int bitpix, naxis, nblocks, nbytes, nbleft, nbr;
    char *image, *imleft;

    /* Open the image file and read the header */
    if (strncasecmp (filename,"stdin", 5)) {
      fd = -1;

      fd = fitsropen (filename);
      if (fd < 0) {
          snprintf (fitserrmsg,79, "FITSRIMAGE:  cannot read file %s\n", filename);
          return (NULL);
          }

      /* Skip over FITS header and whatever else needs to be skipped */
      if (lseek (fd, nbhead, SEEK_SET) < 0) {
          (void)close (fd);
          snprintf (fitserrmsg,79, "FITSRIMAGE:  cannot skip header of file %s\n",
                 filename);
          return (NULL);
          }
      }
#ifndef VMS
    else
      fd = STDIN_FILENO;
#endif

    /* Compute size of image in bytes using relevant header parameters */
    naxis = 1;
    hgeti4 (header,"NAXIS",&naxis);
    naxis1 = 1;
    hgeti4 (header,"NAXIS1",&naxis1);
    naxis2 = 1;
    hgeti4 (header,"NAXIS2",&naxis2);
    bitpix = 0;
    hgeti4 (header,"BITPIX",&bitpix);
    if (bitpix == 0) {
      /* snprintf (fitserrmsg,79, "FITSRIMAGE:  BITPIX is 0; image not read\n"); */
      (void)close (fd);
      return (NULL);
      }
    bytepix = bitpix / 8;
    if (bytepix < 0) bytepix = -bytepix;

    /* If either dimension is one and image is 3-D, read all three dimensions */
    if (naxis == 3 && (naxis1 ==1 || naxis2 == 1)) {
      int naxis3;
      hgeti4 (header,"NAXIS3",&naxis3);
      nbimage = naxis1 * naxis2 * naxis3 * bytepix;
      }
    else
      nbimage = naxis1 * naxis2 * bytepix;

    /* Set number of bytes to integral number of 2880-byte blocks */
    nblocks = nbimage / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbimage)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;

    /* Allocate and read image */
    image = (char *) malloc (nbytes);
    nbleft = nbytes;
    imleft = image;
    nbr = 0;
    while (nbleft > 0) {
      nbread = read (fd, imleft, nbleft);
      nbr = nbr + nbread;
#ifndef VMS
      if (fd == STDIN_FILENO && nbread < nbleft && nbread > 0) {
          nbleft = nbleft - nbread;
          imleft = imleft + nbread;
          }
      else
#endif
          nbleft = 0;
      }
#ifndef VMS
    if (fd != STDIN_FILENO)
      (void)close (fd);
#endif
    if (nbr < nbimage) {
      snprintf (fitserrmsg,79, "FITSRIMAGE:  %d of %d bytes read from file %s\n",
             nbr, nbimage, filename);
      return (NULL);
      }

    /* Byte-reverse image, if necessary */
    if (imswapped ())
      imswap (bitpix, image, nbytes);

    return (image);
}


/* FITSRFULL -- Read a FITS image of any dimension */

char *
fitsrfull (filename, nbhead, header)

char  *filename;  /* Name of FITS image file */
int   nbhead;           /* Actual length of image header(s) in bytes */
char  *header;    /* FITS header for image (previously read) */
{
    int fd;
    int nbimage, naxisi, iaxis, bytepix, nbread;
    int bitpix, naxis, nblocks, nbytes, nbleft, nbr;
    char keyword[16];
    char *image, *imleft;

    /* Open the image file and read the header */
    if (strncasecmp (filename,"stdin", 5)) {
      fd = -1;

      fd = fitsropen (filename);
      if (fd < 0) {
          snprintf (fitserrmsg,79, "FITSRIMAGE:  cannot read file %s\n", filename);
          return (NULL);
          }

      /* Skip over FITS header and whatever else needs to be skipped */
      if (lseek (fd, nbhead, SEEK_SET) < 0) {
          (void)close (fd);
          snprintf (fitserrmsg,79, "FITSRIMAGE:  cannot skip header of file %s\n",
                 filename);
          return (NULL);
          }
      }
#ifndef VMS
    else
      fd = STDIN_FILENO;
#endif

    /* Find number of bytes per pixel */
    bitpix = 0;
    hgeti4 (header,"BITPIX",&bitpix);
    if (bitpix == 0) {
      /* snprintf (fitserrmsg,79, "FITSRIMAGE:  BITPIX is 0; image not read\n"); */
      (void)close (fd);
      return (NULL);
      }
    bytepix = bitpix / 8;
    if (bytepix < 0) bytepix = -bytepix;
    nbimage = bytepix;

    /* Compute size of image in bytes using relevant header parameters */
    naxis = 1;
    hgeti4 (header,"NAXIS",&naxis);
    for (iaxis = 1; iaxis <= naxis; iaxis++) {
      sprintf (keyword, "NAXIS%d", iaxis);
      naxisi = 1;
      hgeti4 (header,keyword,&naxisi);
      nbimage = nbimage * naxisi;
      }

    /* Set number of bytes to integral number of 2880-byte blocks */
    nblocks = nbimage / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbimage)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;

    /* Allocate and read image */
    image = (char *) malloc (nbytes);
    nbleft = nbytes;
    imleft = image;
    nbr = 0;
    while (nbleft > 0) {
      nbread = read (fd, imleft, nbleft);
      nbr = nbr + nbread;
#ifndef VMS
      if (fd == STDIN_FILENO && nbread < nbleft && nbread > 0) {
          nbleft = nbleft - nbread;
          imleft = imleft + nbread;
          }
      else
#endif
          nbleft = 0;
      }
#ifndef VMS
    if (fd != STDIN_FILENO)
      (void)close (fd);
#endif
    if (nbr < nbimage) {
      snprintf (fitserrmsg,79, "FITSRIMAGE:  %d of %d bytes read from file %s\n",
             nbr, nbimage, filename);
      return (NULL);
      }

    /* Byte-reverse image, if necessary */
    if (imswapped ())
      imswap (bitpix, image, nbytes);

    return (image);
}


/* FITSROPEN -- Open a FITS file, returning the file descriptor */

int
fitsropen (inpath)

char  *inpath;    /* Pathname for FITS tables file to read */

{
    int ntry;
    int fd;       /* file descriptor for FITS tables file (returned) */
    char *ext;          /* extension name or number */
    char cext;
    char *rbrac;
    char *mwcs;         /* Pointer to WCS name separated by % */

/* Check for FITS WCS specification and ignore for file opening */
    mwcs = strchr (inpath, '%');

/* Check for FITS extension and ignore for file opening */
    ext = strchr (inpath, ',');
    rbrac = NULL;
    if (ext == NULL) {
      ext = strchr (inpath, '[');
      if (ext != NULL) {
          rbrac = strchr (inpath, ']');
          }
      }

/* Open input file */
    for (ntry = 0; ntry < 3; ntry++) {
      if (ext != NULL) {
          cext = *ext;
          *ext = 0;
          }
      if (rbrac != NULL)
          *rbrac = (char) 0;
      if (mwcs != NULL)
          *mwcs = (char) 0;
      fd = open (inpath, O_RDONLY);
      if (ext != NULL)
          *ext = cext;
      if (rbrac != NULL)
          *rbrac = ']';
      if (mwcs != NULL)
          *mwcs = '%';
      if (fd >= 0)
          break;
      else if (ntry == 2) {
          snprintf (fitserrmsg,79, "FITSROPEN:  cannot read file %s\n", inpath);
          return (-1);
          }
      }

    if (verbose)
      fprintf (stderr,"FITSROPEN:  input file %s opened\n",inpath);

    return (fd);
}


static int offset1=0;
static int offset2=0;

/* FITSRTOPEN -- Open FITS table file and fill structure with
 *           pointers to selected keywords
 *           Return file descriptor (-1 if unsuccessful)
 */

int
fitsrtopen (inpath, nk, kw, nrows, nchar, nbhead)

char  *inpath;    /* Pathname for FITS tables file to read */
int   *nk;        /* Number of keywords to use */
struct Keyword    **kw; /* Structure for desired entries */
int   *nrows;           /* Number of rows in table (returned) */
int   *nchar;           /* Number of characters in one table row (returned) */
int   *nbhead;    /* Number of characters before table starts */

{
    char temp[16];
    int fd;
    int     lhead;            /* Maximum length in bytes of FITS header */
    char *header; /* Header for FITS tables file to read */

/* Read FITS header from input file */
    header = fitsrhead (inpath, &lhead, nbhead);
    if (!header) {
      snprintf (fitserrmsg,79,"FITSRTOPEN:  %s is not a FITS file\n",inpath);
      return (0);
      }

/* Make sure this file is really a FITS table file */
    temp[0] = 0;
    (void) hgets (header,"XTENSION",16,temp);
    if (strncmp (temp, "TABLE", 5)) {
      snprintf (fitserrmsg,79, "FITSRTOPEN:  %s is not a FITS table file\n",inpath);
      free ((void *) header);
      return (0);
      }

/* If it is a FITS file, get table information from the header */
    else {
      if (fitsrthead (header, nk, kw, nrows, nchar)) {
          snprintf (fitserrmsg,79, "FITSRTOPEN: Cannot read FITS table from %s\n",inpath);
          free ((void *) header);
          return (-1);
          }
      else {
          fd = fitsropen (inpath);
          offset1 = 0;
          offset2 = 0;
          free ((void *) header);
          return (fd);
          }
      }
}

static struct Keyword *pw;    /* Structure for all entries */
static int *lpnam;            /* length of name for each field */
static int bfields = 0;

/* FITSRTHEAD -- From FITS table header, read pointers to selected keywords */

int
fitsrthead (header, nk, kw, nrows, nchar)

char  *header;    /* Header for FITS tables file to read */
int   *nk;        /* Number of keywords to use */
struct Keyword    **kw; /* Structure for desired entries */
int   *nrows;           /* Number of rows in table (returned) */
int   *nchar;           /* Number of characters in one table row (returned) */

{
    struct Keyword *rw; /* Structure for desired entries */
    int nfields;
    int ifield,ik,ln, i;
    char *h0, *h1, *tf1, *tf2;
    char tname[12];
    char temp[16];
    char tform[16];
    int tverb;

    h0 = header;

/* Make sure this is really a FITS table file header */
    temp[0] = 0;
    hgets (header,"XTENSION",16,temp);
    if (strncmp (temp, "TABLE", 5) != 0) {
      snprintf (fitserrmsg,79, "FITSRTHEAD:  Not a FITS table file\n");
      free (temp);
      return (-1);
      }

/* Get table size from FITS header */
    *nchar = 0;
    hgeti4 (header,"NAXIS1",nchar);
    *nrows = 0;
    hgeti4 (header,"NAXIS2", nrows);
    if (*nrows <= 0 || *nchar <= 0) {
      snprintf (fitserrmsg,79, "FITSRTHEAD: cannot read %d x %d table\n",
             *nrows,*nchar);
      return (-1);
      }

/* Set up table for access to individual fields */
    nfields = 0;
    hgeti4 (header,"TFIELDS",&nfields);
    if (verbose)
      fprintf (stderr, "FITSRTHEAD: %d fields per table entry\n", nfields);
    if (nfields > bfields) {
      if (bfields > 0)
          free ((void *)pw);
      pw = (struct Keyword *) calloc (nfields, sizeof(struct Keyword));
      if (pw == NULL) {
          snprintf (fitserrmsg,79,"FITSRTHEAD: cannot allocate table structure\n");
          return (-1);
          }
      if (bfields > 0)
          free ((void *)lpnam);
      lpnam = (int *) calloc (nfields, sizeof(int));
      if (lpnam == NULL) {
          snprintf (fitserrmsg,79,"FITSRTHEAD: cannot allocate length structure\n");
          return (-1);
          }
      bfields = nfields;
      }

    tverb = verbose;
    verbose = 0;

    for (ifield = 0; ifield < nfields; ifield++) {

    /* First column of field */
      for (i = 0; i < 12; i++) tname[i] = 0;
      sprintf (tname, "TBCOL%d", ifield+1);
      h1 = ksearch (h0,tname);
      pw[ifield].kf = 0;
      hgeti4 (h0,tname, &pw[ifield].kf);

    /* Length of field */
      for (i = 0; i < 12; i++) tname[i] = 0;
      sprintf (tname, "TFORM%d", ifield+1);;
      tform[0] = 0;
      hgets (h0,tname,16,tform);
      tf1 = tform + 1;
      tf2 = strchr (tform,'.');
      if (tf2 != NULL)
          *tf2 = ' ';
      pw[ifield].kl = atoi (tf1);

    /* Name of field */
      for (i = 0; i < 12; i++) tname[i] = 0;
      sprintf (tname, "TTYPE%d", ifield+1);;
      temp[0] = 0;
      hgets (h0,tname,16,temp);
      strcpy (pw[ifield].kname,temp);
      lpnam[ifield] = strlen (pw[ifield].kname);
      h0 = h1;
      }

/* Set up table for access to desired fields */
    verbose = tverb;
    if (verbose)
      fprintf (stderr, "FITSRTHEAD: %d keywords read\n", *nk);

/* If nk = 0, allocate and return structures for all table fields */
    if (*nk <= 0) {
      *kw = pw;
      *nk = nfields;
      return (0);
      }
    else
      rw = *kw;

/* Find each desired keyword in the header */
    for (ik = 0; ik < *nk; ik++) {
      if (rw[ik].kn <= 0) {
          for (ifield = 0; ifield < nfields; ifield++) {
            ln = lpnam[ifield];
            if (rw[ik].lname > ln)
                ln = rw[ik].lname;
            if (strncmp (pw[ifield].kname, rw[ik].kname, ln) == 0) {
                break;
                }
            }
          }
      else
          ifield = rw[ik].kn - 1;

/* Set pointer, lentth, and name in returned array of structures */
      rw[ik].kn = ifield + 1;
      rw[ik].kf = pw[ifield].kf - 1;
      rw[ik].kl = pw[ifield].kl;
      strcpy (rw[ik].kname, pw[ifield].kname);
      }

    return (0);
}


int
fitsrtline (fd, nbhead, lbuff, tbuff, irow, nbline, line)

int   fd;         /* File descriptor for FITS file */
int   nbhead;           /* Number of bytes in FITS header */
int   lbuff;            /* Number of bytes in table buffer */
char  *tbuff;           /* FITS table buffer */
int   irow;       /* Number of table row to read */
int   nbline;           /* Number of bytes to read for this line */
char  *line;            /* One line of FITS table (returned) */

{
    int nbuff,nlbuff,nbr;
    int offset, offend, ntry, ioff;
    char *tbuff1;

    offset = nbhead + (nbline * irow);
    offend = offset + nbline - 1;

/* Read a new buffer of the FITS table into memory if needed */
    if (offset < offset1 || offend > offset2) {
      nlbuff = lbuff / nbline;
      nbuff = nlbuff * nbline;
      for (ntry = 0; ntry < 3; ntry++) {
          ioff = lseek (fd, offset, SEEK_SET);
          if (ioff < offset) {
            if (ntry == 2)
                return (0);
            else
                continue;
            }
          nbr = read (fd, tbuff, nbuff);
          if (nbr < nbline) {
            if (verbose)
                fprintf (stderr, "FITSRTLINE: %d / %d bytes read %d\n",
                        nbr,nbuff,ntry);
            if (ntry == 2)
                return (nbr);
            }
          else
            break;
          }
      offset1 = offset;
      offset2 = offset + nbr - 1;
      strncpy (line, tbuff, nbline);
      return (nbline);
      }
    else {
      tbuff1 = tbuff + (offset - offset1);
      strncpy (line, tbuff1, nbline);
      return (nbline);
      }
}


void
fitsrtlset ()
{
    offset1 = 0;
    offset2 = 0;
    return;
}


/* FTGETI2 -- Extract n'th column from FITS table line as short */

short
ftgeti2 (entry, kw)

char  *entry;           /* Row or entry from table */
struct Keyword *kw;     /* Table column information from FITS header */
{
    char temp[30];

    if (ftgetc (entry, kw, temp, 30))
      return ( (short) atof (temp) );
    else
      return ((short) 0);
}


/* FTGETI4 -- Extract n'th column from FITS table line as int */

int
ftgeti4 (entry, kw)

char  *entry;           /* Row or entry from table */
struct Keyword *kw;     /* Table column information from FITS header */
{
    char temp[30];

    if (ftgetc (entry, kw, temp, 30))
      return ( (int) atof (temp) );
    else
      return (0);
}


/* FTGETR4 -- Extract n'th column from FITS table line as float */

float
ftgetr4 (entry, kw)

char  *entry;           /* Row or entry from table */
struct Keyword *kw;     /* Table column information from FITS header */
{
    char temp[30];

    if (ftgetc (entry, kw, temp, 30))
      return ( (float) atof (temp) );
    else
      return ((float) 0.0);
}


/* FTGETR8 -- Extract n'th column from FITS table line as double */

double
ftgetr8 (entry, kw)

char  *entry;           /* Row or entry from table */
struct Keyword *kw;     /* Table column information from FITS header */
{
    char temp[30];

    if (ftgetc (entry, kw, temp, 30))
      return ( atof (temp) );
    else
      return ((double) 0.0);
}


/* FTGETC -- Extract n'th column from FITS table line as character string */

int
ftgetc (entry, kw, string, maxchar)

char  *entry;           /* Row or entry from table */
struct Keyword *kw;     /* Table column information from FITS header */
char  *string;    /* Returned string */
int   maxchar;    /* Maximum number of characters in returned string */
{
    int length = maxchar;

    if (kw->kl < length)
      length = kw->kl;
    if (length > 0) {
      strncpy (string, entry+kw->kf, length);
      string[length] = 0;
      return ( 1 );
      }
    else
      return ( 0 );
}

extern int errno;


/*FITSWIMAGE -- Write FITS header and image */

int
fitswimage (filename, header, image)

char  *filename;  /* Name of FITS image file */
char  *header;    /* FITS image header */
char  *image;           /* FITS image pixels */

{
    int fd;

    /* Open the output file */
    if (strcasecmp (filename,"stdout") ) {

      if (!access (filename, 0)) {
          fd = open (filename, O_WRONLY);
          if (fd < 3) {
            snprintf (fitserrmsg,79, "FITSWIMAGE:  file %s not writeable\n", filename);
            return (0);
            }
          }
      else {
          fd = open (filename, O_RDWR+O_CREAT, 0666);
          if (fd < 3) {
            snprintf (fitserrmsg,79, "FITSWIMAGE:  cannot create file %s\n", filename);
            return (0);
            }
          }
      }
#ifndef VMS
    else
      fd = STDOUT_FILENO;
#endif

    return (fitswhdu (fd, filename, header, image));
}


/*FITSWEXT -- Write FITS header and image as extension to a file */

int
fitswext (filename, header, image)

char  *filename;  /* Name of IFTS image file */
char  *header;    /* FITS image header */
char  *image;           /* FITS image pixels */

{
    int fd;

    /* Open the output file */
    if (strcasecmp (filename,"stdout") ) {

      if (!access (filename, 0)) {
          fd = open (filename, O_WRONLY);
          if (fd < 3) {
            snprintf (fitserrmsg,79, "FITSWEXT:  file %s not writeable\n",
                   filename);
            return (0);
            }
          }
      else {
          fd = open (filename, O_APPEND, 0666);
          if (fd < 3) {
            snprintf (fitserrmsg,79, "FITSWEXT:  cannot append to file %s\n",
                   filename);
            return (0);
            }
          }
      }
#ifndef VMS
    else
      fd = STDOUT_FILENO;
#endif

    return (fitswhdu (fd, filename, header, image));
}


int
fitswhdu (fd, filename, header, image)

int   fd;         /* File descriptor */
char  *filename;  /* Name of IFTS image file */
char  *header;    /* FITS image header */
char  *image;           /* FITS image pixels */
{
    int nbhead, nbimage, nblocks, bytepix, i, nbhw;
    int bitpix, naxis, iaxis, naxisi, nbytes, nbw, nbpad, nbwp;
    char *endhead, *lasthead, *padding;
    double bzero, bscale;
    char keyword[32];

    /* Change BITPIX=-16 files to BITPIX=16 with BZERO and BSCALE */
    bitpix = 0;
    hgeti4 (header,"BITPIX",&bitpix);
    if (bitpix == -16) {
      if (!hgetr8 (header, "BZERO", &bzero) &&
          !hgetr8 (header, "BSCALE", &bscale)) {
          bitpix = 16;
          hputi4 (header, "BITPIX", bitpix);
          hputr8 (header, "BZERO", 32768.0);
          hputr8 (header, "BSCALE", 1.0);
          }
      }

    /* Write header to file */
    endhead = ksearch (header,"END") + 80;
    nbhead = endhead - header;
    nbhw = write (fd, header, nbhead);
    if (nbhw < nbhead) {
      snprintf (fitserrmsg,79, "FITSWHDU:  wrote %d / %d bytes of header to file %s\n",
             nbhw, nbhead, filename);
      (void)close (fd);
      return (0);
      }

    /* Write extra spaces to make an integral number of 2880-byte blocks */
    nblocks = nbhead / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbhead)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;
    nbpad = nbytes - nbhead;
    padding = (char *)calloc (1, nbpad);
    for (i = 0; i < nbpad; i++)
      padding[i] = ' ';
    nbwp = write (fd, padding, nbpad);
    if (nbwp < nbpad) {
      snprintf (fitserrmsg,79, "FITSWHDU:  wrote %d / %d bytes of header padding to file %s\n",
             nbwp, nbpad, filename);
      (void)close (fd);
      return (0);
      }
    nbhw = nbhw + nbwp;
    free (padding);

    /* Return if file has no data */
    if (bitpix == 0) {
      /* snprintf (fitserrmsg,79, "FITSWHDU:  BITPIX is 0; image not written\n"); */
      (void)close (fd);
      return (0);
      }

    /* Compute size of pixel in bytes */
    bytepix = bitpix / 8;
    if (bytepix < 0) bytepix = -bytepix;
    nbimage = bytepix;

    /* Compute size of image in bytes using relevant header parameters */
    naxis = 1;
    hgeti4 (header,"NAXIS",&naxis);
    for (iaxis = 1; iaxis <= naxis; iaxis++) {
      sprintf (keyword, "NAXIS%d", iaxis);
      naxisi = 1;
      hgeti4 (header,keyword,&naxisi);
      nbimage = nbimage * naxisi;
      }

    /* Number of bytes to write is an integral number of FITS blocks */
    nblocks = nbimage / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbimage)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;

    /* Byte-reverse image before writing, if necessary */
    if (imswapped ())
      imswap (bitpix, image, nbimage);

    /* Write image to file */
    nbw = write (fd, image, nbimage);
    if (nbw < nbimage) {
      snprintf (fitserrmsg,79, "FITSWHDU:  wrote %d / %d bytes of image to file %s\n",
             nbw, nbimage, filename);
      return (0);
      }

    /* Write extra zeroes to make an integral number of 2880-byte blocks */
    nbpad = nbytes - nbimage;
    padding = (char *)calloc (1, nbpad);
    nbwp = write (fd, padding, nbpad);
    if (nbwp < nbpad) {
      snprintf (fitserrmsg,79, "FITSWHDU:  wrote %d / %d bytes of image padding to file %s\n",
             nbwp, nbpad, filename);
      (void)close (fd);
      return (0);
      }
    free (padding);

    (void)close (fd);

    /* Byte-reverse image after writing, if necessary */
    if (imswapped ())
      imswap (bitpix, image, nbimage);

    nbw = nbw + nbwp + nbhw;
    return (nbw);
}


/*FITSCIMAGE -- Write FITS header and copy FITS image
            Return number of bytes in output image, 0 if failure */

int
fitscimage (filename, header, filename0)

char  *filename;  /* Name of output FITS image file */
char  *header;    /* FITS image header */
char  *filename0; /* Name of input FITS image file */

{
    int fdout, fdin;
    int nbhead, nbimage, nblocks, bytepix;
    int bitpix, naxis, naxis1, naxis2, nbytes, nbw, nbpad, nbwp;
    char *endhead, *lasthead, *padding;
    char *image;  /* FITS image pixels */
    char *oldhead;      /* Input file image header */
    int nbhead0;  /* Length of input file image header */
    int lhead0;
    int nbbuff, nbuff, ibuff, nbr, nbdata;
    int fitsheadsize();

    /* Compute size of image in bytes using relevant header parameters */
    naxis = 1;
    hgeti4 (header, "NAXIS", &naxis);
    naxis1 = 1;
    hgeti4 (header, "NAXIS1", &naxis1);
    naxis2 = 1;
    hgeti4 (header, "NAXIS2", &naxis2);
    hgeti4 (header, "BITPIX", &bitpix);
    bytepix = bitpix / 8;
    if (bytepix < 0) bytepix = -bytepix;

    /* If either dimension is one and image is 3-D, read all three dimensions */
    if (naxis == 3 && (naxis1 ==1 || naxis2 == 1)) {
      int naxis3;
      hgeti4 (header,"NAXIS3",&naxis3);
      nbimage = naxis1 * naxis2 * naxis3 * bytepix;
      }
    else
      nbimage = naxis1 * naxis2 * bytepix;

    nblocks = nbimage / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbimage)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;

    /* Allocate image buffer */
    nbbuff = FITSBLOCK * 100;
    if (nbytes < nbbuff)
      nbbuff = nbytes;
    image = (char *) calloc (1, nbbuff);
    nbuff = nbytes / nbbuff;
    if (nbytes > nbuff * nbbuff)
      nbuff = nbuff + 1;

    /* Read input file header */
    if ((oldhead = fitsrhead (filename0, &lhead0, &nbhead0)) == NULL) {
      snprintf (fitserrmsg, 79,"FITSCIMAGE: header of input file %s cannot be read\n",
             filename0);
      return (0);
      }

    /* Find size of output header */
    nbhead = fitsheadsize (header);

    /* If overwriting, be more careful if new header is longer than old */
    if (!strcmp (filename, filename0) && nbhead > nbhead0) {
      if ((image = fitsrimage (filename0, nbhead0, oldhead)) == NULL) {
          snprintf (fitserrmsg,79, "FITSCIMAGE:  cannot read image from file %s\n",
                 filename0);
          free (oldhead);
          return (0);
          }
      return (fitswimage (filename, header, image));
      }
    free (oldhead);

    /* Open the input file and skip over the header */
    if (strcasecmp (filename0,"stdin")) {
      fdin = -1;
      fdin = fitsropen (filename0);
      if (fdin < 0) {
          snprintf (fitserrmsg, 79,"FITSCIMAGE:  cannot read file %s\n", filename0);
          return (0);
          }

      /* Skip over FITS header */
      if (lseek (fdin, nbhead0, SEEK_SET) < 0) {
          (void)close (fdin);
          snprintf (fitserrmsg,79, "FITSCIMAGE:  cannot skip header of file %s\n",
                 filename0);
          return (0);
          }
      }
#ifndef VMS
    else
      fdin = STDIN_FILENO;
#endif

    /* Open the output file */
    if (!access (filename, 0)) {
      fdout = open (filename, O_WRONLY);
      if (fdout < 3) {
          snprintf (fitserrmsg,79, "FITSCIMAGE:  file %s not writeable\n", filename);
          return (0);
          }
      }
    else {
      fdout = open (filename, O_RDWR+O_CREAT, 0666);
      if (fdout < 3) {
          snprintf (fitserrmsg,79, "FITSCHEAD:  cannot create file %s\n", filename);
          return (0);
          }
      }

    /* Pad header with spaces */
    endhead = ksearch (header,"END") + 80;
    lasthead = header + nbhead;
    while (endhead < lasthead)
      *(endhead++) = ' ';

    /* Write header to file */
    nbw = write (fdout, header, nbhead);
    if (nbw < nbhead) {
      snprintf (fitserrmsg, 79,"FITSCIMAGE:  wrote %d / %d bytes of header to file %s\n",
             nbw, nbytes, filename);
      (void)close (fdout);
      (void)close (fdin);
      return (0);
      }

    /* Return if no data */
    if (bitpix == 0) {
      (void)close (fdout);
      (void)close (fdin);
      return (nbhead);
      }

    nbdata = 0;
    for (ibuff = 0; ibuff < nbuff; ibuff++) {
      nbr = read (fdin, image, nbbuff);
      if (nbr > 0) {
          nbw = write (fdout, image, nbr);
          nbdata = nbdata + nbw;
          }
      }

    /* Write extra to make integral number of 2880-byte blocks */
    nblocks = nbdata / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbdata)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;
    nbpad = nbytes - nbdata;
    padding = (char *)calloc (1,nbpad);
    nbwp = write (fdout, padding, nbpad);
    nbw = nbdata + nbwp;
    free (padding);

    (void)close (fdout);
    (void)close (fdin);

    if (nbw < nbimage) {
      snprintf (fitserrmsg, 79, "FITSWIMAGE:  wrote %d / %d bytes of image to file %s\n",
             nbw, nbimage, filename);
      return (0);
      }
    else
      return (nbw);
}


/* FITSWHEAD -- Write FITS header and keep file open for further writing */

int
fitswhead (filename, header)

char  *filename;  /* Name of IFTS image file */
char  *header;    /* FITS image header */

{
    int fd;
    int nbhead, nblocks;
    int nbytes, nbw;
    char *endhead, *lasthead;

    /* Open the output file */
    if (!access (filename, 0)) {
      fd = open (filename, O_WRONLY);
      if (fd < 3) {
          snprintf (fitserrmsg, 79, "FITSWHEAD:  file %s not writeable\n", filename);
          return (0);
          }
      }
    else {
      fd = open (filename, O_RDWR+O_CREAT, 0666);
      if (fd < 3) {
          snprintf (fitserrmsg, 79, "FITSWHEAD:  cannot create file %s\n", filename);
          return (0);
          }
      }

    /* Write header to file */
    endhead = ksearch (header,"END") + 80;
    nbhead = endhead - header;
    nblocks = nbhead / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbhead)
      nblocks = nblocks + 1;
    nbytes = nblocks * FITSBLOCK;

    /* Pad header with spaces */
    lasthead = header + nbytes;
    while (endhead < lasthead)
      *(endhead++) = ' ';
    
    nbw = write (fd, header, nbytes);
    if (nbw < nbhead) {
      fprintf (stderr, "FITSWHEAD:  wrote %d / %d bytes of header to file %s\n",
             nbw, nbytes, filename);
      (void)close (fd);
      return (0);
      }
    return (fd);
}


/* ISFITS -- Return 1 if FITS file, else 0 */
int
isfits (filename)

char    *filename;      /* Name of file for which to find size */
{
    FILE *diskfile;
    char keyword[16];
    int nbr;

    /* First check to see if this is an assignment */
    if (strchr (filename, '='))
      return (0);

    /* Then check file extension */
    else if (strsrch (filename, ".fit") ||
      strsrch (filename, ".fits") ||
      strsrch (filename, ".fts"))
      return (1);

    /* Check for stdin (input from pipe) */
    else if (!strcasecmp (filename,"stdin"))
      return (1);

    /* If no FITS file extension, try opening the file */
    else {
      if ((diskfile = fopen (filename, "rb")) == NULL)
          return (0);
      else {
          nbr = fread (keyword, 1, 8, diskfile);
          fclose (diskfile);
          if (nbr < 8)
            return (0);
          else if (!strncmp (keyword, "SIMPLE", 6))
            return (1);
          else
            return (0);
          }
      }
}

/* FITSHEADSIZE -- Find size of FITS header */

int
fitsheadsize (header)

char  *header;    /* FITS header */
{
    char *endhead;
    int nbhead, nblocks;

    endhead = ksearch (header,"END") + 80;
    nbhead = endhead - header;
    nblocks = nbhead / FITSBLOCK;
    if (nblocks * FITSBLOCK < nbhead)
        nblocks = nblocks + 1;
    return (nblocks * FITSBLOCK);
}

/* Print error message */
void
fitserr ()
{   fprintf (stderr, "%s\n",fitserrmsg);
    return; }

/*
 * Feb  8 1996    New subroutines
 * Apr 10 1996    Add subroutine list at start of file
 * Apr 17 1996    Print error message to stderr
 * May  2 1996    Write using stream IO
 * May 14 1996    If FITSRTOPEN NK is zero, return all keywords in header
 * May 17 1996    Make header internal to FITSRTOPEN
 * Jun  3 1996    Use stream I/O for input as well as output
 * Jun 10 1996    Remove unused variables after running lint
 * Jun 12 1996    Deal with byte-swapped images
 * Jul 11 1996    Rewrite code to separate header and data reading
 * Aug  6 1996  Fixed small defects after lint
 * Aug  6 1996  Drop unused NBHEAD argument from FITSRTHEAD
 * Aug 13 1996    If filename is stdin, read from standard input instead of file
 * Aug 30 1996    Use write for output, not fwrite
 * Sep  4 1996    Fix mode when file is created
 * Oct 15 1996    Drop column argument from FGET* subroutines
 * Oct 15 1996    Drop unused variable 
 * Dec 17 1996    Add option to skip bytes in file before reading the header
 * Dec 27 1996    Turn nonprinting header characters into spaces
 *
 * Oct  9 1997    Add FITS extension support as filename,extension
 * Dec 15 1997    Fix minor bugs after lint
 *
 * Feb 23 1998    Do not append primary header if getting header for ext. 0
 * Feb 23 1998    Accept either bracketed or comma extension
 * Feb 24 1998    Add SIMPLE keyword to start of extracted extension
 * Apr 30 1998    Fix error return if not table file after Allan Brighton
 * May  4 1998    Fix error in argument sequence in HGETS call
 * May 27 1998    Include fitsio.h and imio.h
 * Jun  1 1998    Add VMS fixes from Harry Payne at STScI
 * Jun  3 1998    Fix bug reading EXTNAME
 * Jun 11 1998    Initialize all header parameters before reading them
 * Jul 13 1998    Clarify argument definitions
 * Aug  6 1998    Rename fitsio.c to fitsfile.c to avoid conflict with CFITSIO
 * Aug 13 1998    Add FITSWHEAD to write only header
 * Sep 25 1998    Allow STDIN or stdin for standard input reading
 * Oct  5 1998    Add isfits() to decide whether a file is FITS
 * Oct  9 1998    Assume stdin and STDIN to be FITS files in isfits()
 * Nov 30 1998    Fix bug found by Andreas Wicenec when reading large headers
 * Dec  8 1998    Fix bug introduced by previous bug fix
 *
 * Jan  4 1999    Do not print error message if BITPIX is 0
 * Jan 27 1999    Read and write all of 3D images if one dimension is 1
 * Jan 27 1999    Pad out data to integral number of 2880-byte blocks
 * Apr 29 1999    Write BITPIX=-16 files as BITPIX=16 with BSCALE and BZERO
 * Apr 30 1999    Add % as alternative to , to denote sub-images
 * May 25 1999    Set buffer offsets to 0 when FITS table file is opened
 * Jul 14 1999    Do not try to write image data if BITPIX is 0
 * Sep 27 1999    Add STDOUT as output filename option in fitswimage()
 * Oct  6 1999    Set header length global variable hget.lhead0 in fitsrhead()
 * Oct 14 1999    Update header length as it is changed in fitsrhead()
 * Oct 20 1999    Change | in if statements to ||
 * Oct 25 1999    Change most malloc() calls to calloc()
 * Nov 24 1999    Add fitscimage()
 *
 * Feb 23 2000    Fix problem with some error returns in fitscimage()
 * Mar 17 2000    Drop unused variables after lint
 * Jul 20 2000    Drop BITPIX and NAXIS from primary header if extension printerd
 * Jul 20 2000    Start primary part of header with ROOTHEAD keyword
 * Jul 28 2000    Add loop to deal with buffered stdin
 *
 * Jan 11 2001    Print all messages to stderr
 * Jan 12 2001    Add extension back onto filename after fitsropen() (Guy Rixon)
 * Jan 18 2001    Drop EXTEND keyword when extracting an extension
 * Jan 18 2001    Add fitswext() to append HDU and fitswhdu() to do actual writing
 * Jan 22 2001    Ignore WCS name or letter following a : in file name in fitsrhead()
 * Jan 30 2001    Fix FITSCIMAGE so it doesn't overwrite data when overwriting a file
 * Feb 20 2001    Ignore WCS name or letter following a : in file name in fitsropen()
 * Feb 23 2001    Initialize rbrac in fitsropen()
 * Mar  8 2001    Use % instead of : for WCS specification in file name
 * Mar  9 2001    Fix bug so primary header is always appended to secondary header
 * Mar  9 2001    Change NEXTEND to NUMEXT in appended primary header
 * Mar 20 2001    Declare fitsheadsize() in fitschead()
 * Apr 24 2001    When matching column names, use longest length
 * Jun 27 2001    In fitsrthead(), allocate pw and lpnam only if more space needed
 * Aug 24 2001    In isfits(), return 0 if argument contains an equal sign
 *
 * Jan 28 2002    In fitsrhead(), allow stdin to include extension and/or WCS selection
 * Jun 18 2002    Save error messages as fitserrmsg and use fitserr() to print them
 * Oct 21 2002    Add fitsrsect() to read a section of an image
 *
 * Feb  4 2003    Open catalog file rb instead of r (Martin Ploner, Bern)
 * Apr  2 2003    Drop unused variable in fitsrsect()
 * Jul 11 2003    Use strcasecmp() to check for stdout and stdin
 * Aug  1 2003    If no other header, return root header from fitsrhead()
 * Aug 20 2003    Add fitsrfull() to read n-dimensional FITS images
 * Aug 21 2003    Modify fitswimage() to always write n-dimensional FITS images
 * Nov 18 2003    Fix minor bug in fitswhdu()
 */

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