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Re: archived data [message #54334 is a reply to message #54333]

Tue, 05 June 2007 10:12

Vince Hradil
Messages: 574
Registered: December 1999

Senior Member

On Jun 3, 10:54 am, Wox <nom...@hotmail.com> wrote:
> Hi All,
>
> I face the following situation: I'd like to do some online data
> processing (i.e. during measurements) using IDL. However the data is
> directly zipped by the acquisition system. Is it possible to read and
> search (like file_search) in a zip archive without spawning unzip and
> extract everything? Windows explorer does it, so it must be
> possible...
>
> I remember a similar question beeing posted here, but I couldn't find
> it.
>
> Thanks

I just threw this together. Your milage may vary:

function byte_to_hex, bytes

nbytes = n_elements(bytes)

hstr = string(bytes, format="(z2.2)")

vform = '(' + strtrim(nbytes,2) + 'A)'
hval = string( reverse(hstr),format=vform )
val = 0l
reads, hval, val, format="(z)"

return, val
end

function zipcontents, fname

endsig = '504b0506'

finfo = file_info(fname)
fsize = finfo.size
fdata = bytarr(fsize)

openr, lun, fname, /get_lun
readu, lun, fdata
free_lun, lun

fcode = '(' + strtrim(fsize,2) + 'z2.2)'

sdata = string(fdata, format=fcode)

fptr = strpos(sdata, endsig) / 2

fptr += 8
numentries = byte_to_hex( fdata[fptr:fptr+1] )
fptr += 8

cd_offset = byte_to_hex( fdata[fptr:fptr+3] )
fptr = cd_offset

contents = strarr(numentries)

for i=0l, numentries-1 do begin
fptr += 28

fnamelen = byte_to_hex( fdata[fptr:fptr+1] )
fptr += 2

extrafieldlen = byte_to_hex( fdata[fptr:fptr+1] )
fptr += 2

fcommentlen = byte_to_hex( fdata[fptr:fptr+1] )
fptr += 14

contents[i] = string(fdata[fptr:fptr+fnamelen-1])

fptr = fptr + fnamelen + extrafieldlen + fcommentlen

endfor

return, contents
end

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[Message index]

		Re: archived data By: Wox on Wed, 06 June 2007 00:42
		Re: archived data By: Vince Hradil on Tue, 05 June 2007 10:15
		Re: archived data By: Vince Hradil on Tue, 05 June 2007 10:12
		Re: archived data By: jkj on Tue, 05 June 2007 08:15
		Re: archived data By: Wox on Tue, 05 June 2007 07:13
		Re: archived data By: Brian Larsen on Tue, 05 June 2007 06:15
		Re: archived data By: cmancone on Tue, 05 June 2007 05:26

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