;#> makeecsvhead.dc2
; Identifier     makeecsvhead
;
; Purpose        Create a real FITS header for data stored in an ECSV
;                IDL structure
;
; Synopsis       status = makeecsvhead( header, data )
;
; Arguments      Name    I/O    Type     Description
;                -----------------------------------------------------
;                header   O     String   header
;                data     I     any      structure/array;
; Returns        Status giving header length or fail code (-1) as
;                integer
;
;#<

  FUNCTION makeecsvhead, head, data=data

;  Headers present in all ecsv files

  get_date, dte
  ecsv_base = $
    ['SIMPLE  =                    T / Standard FITS format',$
           'BITPIX  =                    8 / number of bits per data pixel',$
           'NAXIS   =                    0 / number of data axes',$      
           'EXTEND  =                    T / FITS dataset may contain extension',$
           'ORIGIN  = ''SSC/SIRTF I&T ''   / Data written by MAKEYAAARHEAD',$
           'COMMENT    SIRTF ECSV',$
           'FILENAME= ''        ''           / File name in ISO archive',$
           'DATE    = '''+dte  +'''           / Date of writing: DD/MM/YY',$
           'FILEVERS= ''        ''           / Version ID in ISO archive',$
           'DEC     =              0.00000 / Declination',$
           'TELESCOP= ''OSTL    ''           / Data acquisition telescope',$
           'INSTRUME= ''        ''           / Data acquisition instrument',$
           'OBSERVER= ''        ''           / Observer name/identification',$
           'TMIN1   =              0.00000 / Minimum SCET in file',$
           'TMAX1   =              0.00000 / Maximum SCET in file',$
           'CATEGORY= ''        ''           / Category of data',$
           'DATE-OBS= ''        ''           / Date of data acquisition: DD/MM/YY',$
           'END']

  ecsv_base2=['XTENSION= ''BINTABLE''           / Binary table FITS extension',$
               'BITPIX  =                    8 / 8 BITS character format',$
               'NAXIS   =                    2 / Tables are 2-d character array',$
               'NAXIS1  =                   52 / Characters in a row',$  
               'NAXIS2  =                    0 / Number of rows in a table',$
               'PCOUNT  =                    0 / Parameter count always 0',$
               'GCOUNT  =                    1 / Group count always 1',$
               'TFIELDS =                   14 / No of columns in table',$
               'TFORM1  = ''1E      ''           /',$
               'TTYPE1  = ''SCET    ''           / spacecraft event time',$
               'TUNIT1  = ''        ''           /',$
               'TFORM2  = ''1J      ''           /',$
               'TTYPE2  = ''SECS    ''           / seconds of SCET',$
               'TUNIT2  = ''SEC     ''           /',$
               'TFORM3  = ''1E      ''           /',$
               'TTYPE3  = ''CHAN    ''           / CTD channel',$
               'TUNIT3  = ''        ''           /',$
               'TFORM4  = ''1J      ''           /',$
               'TTYPE4  = ''CHTITLE ''           / channel title',$
               'TUNIT4  = ''        ''           /',$
               'TFORM5  = ''1J      ''           /',$
               'TTYPE5  = ''DNVAL   ''           / channel value in DN',$
               'TUNIT5  = ''        ''           /',$
               'TFORM6  = ''1J      ''           /',$
               'TTYPE6  = ''EUVAL   ''           / channel value in EU',$
               'TFORM7  = ''1J      ''           /',$
               'TTYPE7  = ''SCLK    ''           / spacecraft clock time key',$
               'TFORM8  = ''2B      ''           /',$
               'TTYPE8  = ''CHTYPE  ''           / channel type',$
               'TUNIT8  = ''        ''           /',$
               'TFORM9  = ''1J      ''           / ',$
               'TTYPE9  = ''REDTYPE ''           / red alarm type',$
               'TFORM10 = ''1J      ''           /',$
               'TTYPE10 = ''REDLOW  ''           / red low limit',$
               'TUNIT10 = ''        ''           /',$
               'TFORM11 = ''1J      ''           /',$
               'TTYPE11 = ''REDHIGH ''           / red high limit',$
               'TUNIT11 = ''        ''           /',$
               'TFORM12 = ''1J      ''           /',$
               'TTYPE12 = ''ERT     ''           / earth receive time',$
               'TUNIT12 = ''        ''           /',$
               'END']

; copy base keywords from primary and secondary headers over

  head=''                               ;zero head   


  for i = 0, n_elements(ecsv_base) - 1 do begin
    line = ecsv_base(i) + string(replicate(32b,80))  ; pad with zero's
    head = head + strmid(line,0,80)                  ; truncate to 80 characters
  endfor
  missing = 36 - (strlen(head)/80 mod 36)
  head = head + string(replicate(32b,missing*80))       ; ensure block of 2880
  for i = 0, n_elements(ecsv_base2) - 1 do begin
    line = ecsv_base2(i) + string(replicate(32b,80)) ; pad with zero's
    head = head + strmid(line,0,80)                  ; truncate to 80 characters
  endfor
  missing = 36 - (strlen(head)/80 mod 36)
  head = head + string(replicate(32b,missing*80))       ; ensure block of 2880


  status = strlen( head )

  return, status

END