| Re: point_lun question [message #17582] |
Tue, 02 November 1999 00:00  |
Pavel Romashkin
Messages: 166
Registered: April 1999
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Senior Member |
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Frank,
I have not found POINT_LUN in the code you sent and therefore see no
problem with it. I wrote several file reading procedures for very
convoluted file formats and had to liberally use cursor positioning
information. I never did it the way you are doing it and don't know why is
FSTAT field not working for you. I also missed the point of attempting to
store positions in the code you sent, to start with. I guess you have a
reason for that, which is not clear to me from the code clip. I also
anticipate that the code you sent is undue slow due to re-creation of
arrays and reading variables throug a string.
I know that using POINT_LUN worked perfectly fine for me for both setting
and retrieving cursor position. I checked the code on Macintosh, Windows
and UNIX and never had failures. You may want to try this approach if you
really want to get positions, although I see you make no use of them in the
code.
I tried to see what is your code doing here:
function rd_data_header
current_line=""
count=0
filen=pickfile()
openr,unit,filen,/get_lun
while not (EOF(unit)) do begin
; Read one line from the file
readf,unit,current_line
; If it is a comment line, remember the position at its end.
if (strpos(current_line,'#S ') eq 0) then begin
current_pos=fstat(unit) ; Try replacing with point_lun, -unit, current_pos
; For the very first time, do the following:
if (count=0) then begin
result_header=current_line ; This is a string!
result_pos=current_pos.cur_ptr
count=1
endif
; All other times, do this:
if (count=1) then begin
; Produce array of size +1
tmp=strarr(size(result_header,/n_elements)+1)
; Produce array of size +1
tmp_pos=lon64arr(size(result_pos,/n_elements)+1)
; Place result_header in up to -1 elements of tmp.
tmp[0:size(result_header,/n_elements)-1]=result_header
; Place the position in up to -1 elements of tmp_pos
tmp_pos[0:size(result_pos,/n_elements)-1]=result_pos
; record the same line in [1] position of tmp
tmp[size(result_header,/n_elements)]=current_line
; Do the same with position
tmp_pos[size(result_pos,/n_elements)]=current_pos.cur_ptr
result_header=tmp
result_pos=tmp_pos ; set tmp vars to current result
; Positions are stored and never used.
; Data not placed anywhere for future use. The result contains byte
;locations in file.
endif
endif
endwhile
free_lun,unit
result={header:result_header, position:result_pos}
return,result
end
************
It looks to me that the code needs to be heavily optimized.
Good luck,
Pavel
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