; Input the name of a Radarsat image file (.D) from Gatineau.
; Return the number of bytes (pixels) per record of data.
; The .D file has a header of 16252 bytes.
; The number of bytes per record is a 4 digit number at bytes 189-192.
;    (index first bytes as byte 1)
; This number is extracted and returned.
; Then you can figure out the number of data records:
;    ((file size in bytes) - 16252) / (bytes per record)

; Sample usage:
; IDL> f='NSS.R1.CA.D97034.T113006.P46N084.P40N076.A.D'
; IDL> print, gatineau1(f)
;     5752

pro canItOpen

forward_function gatineau1

; Here is the name of a file that can not be opened
f = 'NSS.R1.GT.D00114.T214126.P59N065.P53N055.A.D'

; Number of data records = ((File Size in bytes) - 16252) / (bytes per record)

print, 'File: ', f

c = gatineau1 (f)
print, 'Returned: ', c
end

; ********************************************

function gatineau1, data_file_name
a = bytarr(192)
openr, input, data_file_name, /get_lun
readu, input, a

; print out the 192 bytes just so we can see them
print, 'a: '
print, a
free_lun, input

b = fix(string(a(188:191)))
return, b
end