function READPDS, filename, label, NOSCALE = noscale, SILENT = silent
;+
; NAME:
;	READPDS
; PURPOSE:
;	Read a PDS file into IDL data and label variables.
;
; CALLING SEQUENCE:
;	Result=READPDS (Filename,[ Label,/NOSCALE,/SILENT] )
;
; INPUTS:
;	FILENAME = Scalar string containing the name of the PDS file  
;		to be read.
;
; OUTPUTS:
;	Result = PDS data array constructed from designated record.
;
; OPTIONAL OUTPUT:
;	Label = String array containing the "header" from the PDS file.
;
; OPTIONAL INPUT KEYWORDS:
;	NOSCALE - If present and non-zero, then the ouput data will not be
;		scaled using the optional SCALING_FACTOR and OFFSETkeywords 
;		in the PDS header.   Default is to scale.
;
;	SILENT - Normally, READPDS will display the size of the array at 
;		the terminal.  The SILENT keyword will suppress this
;
; EXAMPLE:
;	Read a PDS file TEST.PDS into an IDL image array, IM and PDS 
;	header array, lbl. Do not scale the data with BSCALE and BZERO.
;
;		IDL> im = READPDS( 'TEST.PDS', lbl, /NOSCALE)
; WARNINGS:
; 	This version of READPDS only returns IMAGE data files, TABLES,
;	SERIES, PALETTE, and SPECTRUM; other file types have yet to
;	be dealt with. READPDS will eventually work on all forms of
;	PDS data files, as it is modified to be more 'universal'.
;
;	It is also intended to be used only on MSB architectures ('big-
;	endian')if the file being read was written on an MSB architecture; 
;	it has no conversion from MSB to other architectures, yet.
;
; PROCEDURES USED:
;	Functions:  HEADPDS, PDSPAR, IMAGEPDS, TASCPDS
;
; MODIFICATION HISTORY:
;	Adapted by John D. Koch from READFITS by Wayne Landsman,August,1994
;-

  On_error,2                    ;Return to user            
							
; Check for filename input

 if N_params() LT 1 then begin		
    print,'Syntax - result = READPDS( filename,[ label, /NOSCALE, /SILENT])'
    return, -1
 endif

 silent = keyword_set( SILENT )
 fname = filename     
;	Use HEADPDS to extract the PDS label

 label = headpds(filename)

;	Read object to determine type of data in file

 object = pdspar(label,'OBJECT',COUNT=objects,INDEX=obindex)
 if !ERR EQ -1 then message, $
        'ERROR - '+filename+' missing required OBJECT keyword'

;	Set a test varible to determine format of following function calls

 st = 0
 if keyword_set(NOSCALE) then st = st + 1
 if keyword_set(SILENT) then st = st + 2
 i = fix(0)
 while i LT objects(0) do begin  	
   if strpos(object(i),'IMAGE') GT -1 then begin
      CASE st(0) of
	   0: data = imagepds(fname,label)		 	;neither option
	   1: data = imagepds(fname,label,/NOSCALE)  		;/NOSCALE only
	   2: data = imagepds(fname,label,/SILENT)   		;/SILENT only
	   3: data = imagepds(fname,label,/NOSCALE,/SILENT)	;both options
	else: message, 'ERROR - too many inputs in call to IMAGEPDS'
      ENDCASE
      i = objects(0)+10	; if viable object found, increment i to escape loop
   endif else if strpos(object(i),'TABLE') GT -1 then begin
      inform = pdspar( label, 'INTERCHANGE_FORMAT',INDEX = index )     
      if !ERR EQ -1 then message, $
        'ERROR - '+fname+' missing required INTERCHANGE_FORMAT keyword'
      w = where(index GT obindex(i))
      if strpos(inform(w(0)),'ASCII') GT -1 then begin
	 if st(0) GT 1 then data = tascpds(fname,label,/SILENT) else $
	 data = tascpds(fname,label)
      endif else if strpos(inform(w(0)),'BINARY') GT -1 then begin
         if st(0) GT 1 then data = tbinpds(fname,label,/SILENT) else $
	 data = tbinpds(fname,label)
      endif else message,$
	'ERROR - Invalid PDS table interchange format '+inform(0)
      i = objects(0)+10	; if viable object found, increment i to escape loop
   endif else if strpos(object(i),'SERIES') GT -1 then begin
      inform = pdspar( label, 'INTERCHANGE_FORMAT',INDEX = index )     
      if !ERR EQ -1 then message, $
        'ERROR - '+fname+' missing required INTERCHANGE_FORMAT keyword'
      w = where(index GT obindex(i))
      if strpos(inform(w(0)),'ASCII') GT -1 then begin
	 if st(0) GT 1 then data = tascpds(fname,label,/SILENT) else $
	 data = tascpds(fname,label)
      endif else if strpos(inform(w(0)),'BINARY') GT -1 then begin
         if st(0) GT 1 then data = tbinpds(fname,label,/SILENT) else $
	 data = tbinpds(fname,label)
      endif else message,$
	'ERROR - Invalid PDS table interchange format '+inform(0)
      i = objects(0)+10	; if viable object found, increment i to escape loop
   endif else if strpos(object(i),'PALETTE') GT -1 then begin
      inform = pdspar( label, 'INTERCHANGE_FORMAT',INDEX = index )     
      if !ERR EQ -1 then message, $
        'ERROR - '+fname+' missing required INTERCHANGE_FORMAT keyword'
      w = where(index GT obindex(i))
      if strpos(inform(w(0)),'ASCII') GT -1 then begin
	 if st(0) GT 1 then data = tascpds(fname,label,/SILENT) else $
	 data = tascpds(fname,label)
      endif else if strpos(inform(w(0)),'BINARY') GT -1 then begin
         if st(0) GT 1 then data = tbinpds(fname,label,/SILENT) else $
	 data = tbinpds(fname,label)
      endif else message,$
	'ERROR - Invalid PDS table interchange format '+inform(0)
      i = objects(0)+10	; if viable object found, increment i to escape loop
   endif else if strpos(object(i),'SPECTRUM') GT -1 then begin
      inform = pdspar( label, 'INTERCHANGE_FORMAT',INDEX = index )     
      if !ERR EQ -1 then message, $
        'ERROR - '+fname+' missing required INTERCHANGE_FORMAT keyword'
      w = where(index GT obindex(i))
      if strpos(inform(w(0)),'ASCII') GT -1 then begin
	 if st(0) GT 1 then data = tascpds(fname,label,/SILENT) else $
	 data = tascpds(fname,label)
      endif else if strpos(inform(w(0)),'BINARY') GT -1 then begin
         if st(0) GT 1 then data = tbinpds(fname,label,/SILENT) else $
	 data = tbinpds(fname,label)
      endif else message,$
	'ERROR - Invalid PDS table interchange format '+inform(0)
      i = objects(0)+10	; if viable object found, increment i to escape loop
   endif 
   i = i + 1
 endwhile
 if i LT objects(0)+10 then message,$
   'No valid data type (image,table,series,palette,spectrum) found in '+fname 

; 	Return file data and exit program

 return, data  

 end