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Re: big file navigation [message #36777 is a reply to message #36776]

Tue, 28 October 2003 13:33

btt
Messages: 345
Registered: December 2000

Senior Member

R.G. Stockwell wrote:
> "Ben Tupper" <btupper@bigelow.org> wrote in message
> news:bnm487$1317fk$1@ID-189398.news.uni-berlin.de...
> ...
>
>> IDL> for i = 0L, 55855-1 do readU, U,d
>>
>>
>> Problem solved! I can break the file into smaller 'chunks' of 4GB by
>
> reading in
>
>> images and writing them to a new file. OK!
>>
>> But here's what I wish I understood (and could exploit!) Somewhere the
>
> system is
>
>> keeping track of the file location so that READU knows where to read. So,
>
> deep
>
>> down in its guts, IDL is navigating its way through with 64-bit file
>
> offsets.
>
>> Ain't it? Is there anything here I could get my hooks into so I don't
>
> have to
>
>> break the original file into smaller ones?
>>
>> Cheers,
>> Ben
>
>
> The point_lun seems to use a 64 bit offset
>
> from the help:
>
> If Unit is negative, Position must be a named variable into which the
> current file position will be stored. The returned type will be a longword
> signed integer if the position is small enough to fit, and an unsigned
> 64-bit integer otherwise.
>
>
> Cheers,
> bob
>
>
Hi Bob,

I saw that and thought it was quite interesting. So, I can find out where I am
within a file - but I can't go anywhere within it.

Ben

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[Message index]

		Re: big file navigation By: R.G. Stockwell on Tue, 28 October 2003 13:42
		Re: big file navigation By: btt on Tue, 28 October 2003 13:33
		Re: big file navigation By: R.G. Stockwell on Tue, 28 October 2003 11:53
		Re: big file navigation By: btt on Fri, 31 October 2003 06:00

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