Show Bid Request
Delphi ZLib decompression
Bid Request Id: 58659
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Posted by: |
timvasquez (3 ratings)
(Software buyer rating 10 )
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Non-action Ratio: |
Above Average - 33.33%
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Buyer Security Verifications: |
Good
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Approved on: |
Apr 20, 2003
11:22:53 AM EDT
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Bidding Closes: |
Apr 23, 2003
11:30:19 PM EDT
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Viewed (by coders): |
130 times
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Deadline: |
4/26/2003 11:59:00 PM
TIME EXPIRED
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Description:
1) Coder will develop a customized Delphi ZLib decompression function
which deflates a compressed data file compressed according to ZLib
1.1.3 specifications (with slight changes; see below).
2) Coder is encouraged to use the Borland ZLib library and its
debugged modification by Davide Moretti (http://www.gzip.org/zlib/).
I may consider use of other off-the-shelf ZLib libraries such as
ZLBArchive if coder feels they are more appropriate.
3) Function must ignore extraneous data that may be present at
the beginning of the file. This entails examining the contents
and discarding them until a ZLib header is found. No extraneous
data will follow the compressed block.
4) The source data may use a $789C sequence to signal a new ZLib
header. Function must account for this (see #6 below).
5) The Function call will be
function DecompressFile(inputfilename, outputfilename : string) : err;
where the above filenames are fully qualified paths and filenames,
and err is a coder-defined error result.
6) An exact C port that accomplishes a nearly-identical decompression
can be found at:
http://weather.unisys.com/noaaport/src/ucnids.c
If you are good at porting C to Delphi, this project may take you
about ten minutes!
7) Test data (comprising binary data) can be found at:
Compressed file: http://weather.cod.edu/digatmos/radar/TLX/TLX.BREF1
Decompressed: http://weather.noaa.gov/pub/SL.us008001/DF.of/DC.radar/DS.p19r0/SI.ktlx
8) Code must compile and execute in Delphi 3 and run under Windows 2000.
If you do not have Delphi 3 I will be willing to work with coder
to report compilation errors, which the coder will need to help
resolve to allow Delphi 3 compatibility.
9) This is only a decompression project. A compression counterpart
will not need to be developed.
Deliverables:
1) Complete source code of all work done. The coder may instead supply the work in the form of a small, simple demo app, complete with source code.
2) Installation instructions for the platform(s) specified in this bid request.
3) Complete ownership and distribution copyrights to all work purchased.
Platform:
Must compile under Delphi 3 (Win 2000)
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OTHER NOTES: Here is some helpful info submitted by a skilled coder who did some preliminary investigative work on this project from the C side of the house. Hope this helps your bid!
"ucnids.c mistakenly claims that it is looking for 789C in the input stream; I fell for this when writing ucrawnids.c, and it is not true.
In reality, it is looking for a zlib control header, which is not necessarily unique over a compressed block. i.e. a perfectly valid zlib header can appear within a compressed block without actually indicating the start of a new block.
I just verified this by trying to count the number of blocks in the file by only looking for zlib control headers. NIDS format.
This is why ucnids.c and ucrawnids.c load TLX.BREF1 into memory either indirectly (by sliding-window buffering) or directly (into a single buffer) to
extract the blocks."
Must be 100% finished and received by buyer on:
Apr 26, 2003 11:59:00 PM EDT
Deadline legal notes: All times are expressed in the time zone of the site EDT (UT - 5). If the buyer omitted a time, then the deadline is 11:59:59 PM EDT on the indicated date.
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Bidding/Comments:
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| Name |
Bid Amount
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Date |
Coder Rating |
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This bid was accepted by the buyer!
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$20 (USD)
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Apr 21, 2003
2:27:17 AM EDT
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10
(Excellent)
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| Hello,
My name is Florin and I just wanted to tell you that I can do this in an hour or so. Please tell me if I should start working on it.
Florin
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