pro sxhwrite,name,h
;+
; NAME:
;	SXHWRITE
; PURPOSE:
;	Procedure to write an STSDAS or FITS header to disk as a *.hhh file.
;
; CALLING SEQUENCE:
;	sxhwrite,name,h
;
; INPUTS:
;	name - file name. If an extension is supplied it must be 3 characters
;		ending in "h".
;	h - FITS header, string array
;
; SIDE EFFECTS:
;	File with specified name is written.  If qualifier not specified
;	then .hhh is used
;   
;	SXHWRITE will modify the header in the following ways, if necessary
;	(1)  If not already present, an END statement is added as the 
;		last line.   Lines after an existing END statment are
;		deleted.
;	(2)  Spaces are appended to force each line to be 80 characters.
;	(3)  On Unix machines, a carriage return is appended at the end
;		of each line.   This is consistent with STSDAS and allows
;		the file to be directly displayed on a stream device
;
; PROCEDURES USED:
;	zparcheck, fdecomp
; HISTORY:
;	version 1  D. Lindler  June 1987
;	conversion cleaned up.  M. Greason, June 1990
;	Add carriage return at the end of Unix files   W. Landsman Oct 1991
;	Use SYSTIME() instead of !STIME for V5.0 compatibility Aug 1997
;	Converted to IDL V5.0   W. Landsman   September 1997
;-
;----------------------------------------------------------------
 On_error,2

; Create output file name

 zparcheck, 'SXHWRITE', name, 1, 7, 0, 'Disk file name'  ;Check for valid param
 fdecomp,name, disk, dir, file, qual
 if ( qual EQ '' ) then qual = 'hhh'			;default qualifier

; Check for valid qualifier

 if ( strlen(qual) NE 3 ) or ( strupcase(strmid(qual,2,1)) NE 'H' ) then $
	message,'Qualifier on file name must be 3 characters, ending in H'

 hname = disk + dir + file + '.' + qual		  ;header file name

; Check that valid FITS header was supplied

 zparcheck, 'SXHWRITE', h, 2, 7, 1, 'FITS header'   

 sxaddpar, h, 'SIMPLE', 'F', ' Written by IDL:  ' + systime()

; Determine if an END line occurs, and add one if necessary

 endline = where( strtrim( strmid(h,0,8), 2) EQ 'END', Nend)
 if Nend EQ 0 then begin

    message, /INF, $
        'WARNING - An END statement has been appended to the FITS header'
    h = [ h, 'END' + string( replicate(32b,77) ) ]
    endline = N_elements(h) - 1 

 endif
 nmax = endline[0] + 1

; Convert to byte and force into 80 character lines

 temp = replicate( 32b, 80, nmax)
 for n = 0, endline[0] do temp[0,n] = byte( h[n] )

; Under Unix append a carriage return ( = string(10b) )

 if !VERSION.OS NE "vms" then $
     temp = [ temp, rotate( replicate(10b,nmax), 1 ) ]

; Open the output file and write as byte array.

 openw, unit, hname, 80, /GET_LUN
 a = assoc( unit, temp )
 a[0] = temp

 free_lun,unit
 return
 end