/* @(#)fitsthd.c	17.1.1.1 (ES0-DMD) 01/25/02 17:39:10 */
/*===========================================================================
  Copyright (C) 1995 European Southern Observatory (ESO)
 
  This program is free software; you can redistribute it and/or 
  modify it under the terms of the GNU General Public License as 
  published by the Free Software Foundation; either version 2 of 
  the License, or (at your option) any later version.
 
  This program 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 General Public License for more details.
 
  You should have received a copy of the GNU General Public 
  License along with this program; if not, write to the Free 
  Software Foundation, Inc., 675 Massachusetss Ave, Cambridge, 
  MA 02139, USA.
 
  Corresponding concerning ESO-MIDAS should be addressed as follows:
	Internet e-mail: midas@eso.org
	Postal address: European Southern Observatory
			Data Management Division 
			Karl-Schwarzschild-Strasse 2
			D 85748 Garching bei Muenchen 
			GERMANY
===========================================================================*/

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.COPYRIGHT  (c)  1993   European Southern Observatory
.IDENT      fitsthd.c
.LAUGUAGE   C
.AUTHOR     P.Grosbol   ESO/IPG
.KEYWORDS   FITS, header type
.COMMENT    determine the type of a FITS header
.VERSION    1.0  1988-Nov-18 : Creation,   PJG 
.VERSION    1.1  1990-Jan-02 : Update to new keyword structure, PJG 
.VERSION    1.2  1991-Mar-16 : Change include file, add BINTABLE, PJG 
.VERSION    1.3  1992-Feb-20 : Include IMAGE extension, PJG 
.VERSION    1.4  1992-Aug-13 : Correct definition of IMAGE extension, PJG 
.VERSION    1.5  1993-Apr-16 : Skip tailing spaces in string comp,, PJG 
---------------------------------------------------------------------*/
#include   <fitsfmt.h>
#include   <fitsdef.h>

static int                 htype;  /* present header type            */
static int                 exthd;  /* flag for extension header      */
static int                   nax;  /* no. of axes in data matrix     */

typedef struct {                   /* names and type for extensions  */
                 char      *name;  /* name of extension              */
                 int        type;  /* extension type no.             */
               } XTYPE;

static  XTYPE  xtype[] = { {"TABLE   ",ATABLE},   /* ASCII table     */
                           {"BINTABLE",BTABLE},   /* Binary table    */
                           {"A3DTABLE",BTABLE},   /* Binary table    */
                           {"IMAGE   ",IMAGE},    /* Image ext.      */
                           {(char *) 0, 0},
                         };

int fitsthd(lno,kw)
/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.PURPOSE       Check format and type of FITS header
.RETURN        type of FITS header (see fitsdef.h), -2: error
---------------------------------------------------------------------*/
int           lno;                 /* line no. of keyword in header  */
KWORD         *kw;                 /* pointer to keyword structure   */
{
  int            ok,n;

  switch (lno) {                /* check position dependent keywords */
       case  1 :                             /* first header line    */
                 htype = EOFITS;
                 if (kwcomp(kw->kw,"SIMPLE  ")) {    /* main header  */
                    exthd = 0; htype = FBFITS;
                    if (kw->fmt=='L' && kw->val.i) htype = BFITS;
                 }
                 else {
                    if (kwcomp(kw->kw,"XTENSION"))   /* extension    */
                       if (kw->fmt=='S') {
                          exthd = 1; htype = UKNOWN;
                          for (n=0; xtype[n].name; n++)
                              if (kwcomp(kw->val.pc,xtype[n].name)) {
                                 htype = xtype[n].type; break;
                              }
                       }
                 }
                 break;
       case  2 :                             /* second header line   */
                 ok = 0;
                 if (kwcomp(kw->kw,"BITPIX  "))
                    if (kw->fmt=='I')
                       switch (htype) {
			  case IMAGE  :
                          case BFITS  : if ((n=kw->val.i)==32 ||
                                             n==16 || n==-32 ||
                                             n==8 || n==-64) ok = 1;
                                        break;
                          case UKNOWN : ok = 1;
                                        break;
                          case ATABLE :
                          case BTABLE : if (kw->val.i == 8) ok = 1;
                                        break;
                       }
                 if (!ok) htype = FBFITS;
                 break;
       case  3 :                             /* third header line    */
                 if (!kwcomp(kw->kw,"NAXIS   ") ||
                     kw->fmt!='I' || kw->val.i<0) htype = NOFITS;
                 nax = kw->val.i;
                 break;
       case  4 :                             /* fourth header line   */
                 if (0<nax)
                    if (kwcomp(kw->kw,"NAXIS1  ") && kw->fmt=='I') {
                       if (!(kw->val.i || exthd)) htype = RGROUP;
                    }
                    else htype = FBFITS;
                 break;
  }
  return htype;
}

int kwcomp(pk,ps)
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.PURPOSE      compare two strings
.RETURN       0: not equal, 1: equal
---------------------------------------------------------------------*/
char          *pk;               /* keyword string                   */
char          *ps;               /* string to compare keyword with   */
{
  while (*ps && (*pk == *ps)) pk++, ps++;
  while (*pk == ' ') pk++;
  return !(*ps || *pk);
}