38 lines
2.0 KiB
Plaintext
38 lines
2.0 KiB
Plaintext
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The Arkive format
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Disclaimer: The description below is a mere extrapolation from the files I
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have encountered. It does not take Arkive archives containing relative files
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into account since I have never seen one.
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The archive format of the program Arkive has a structure that is similar to
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the Lynx format. The archives start with a byte showing the number of files in
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in the archive, then comes the directory of the files in the archive (unlike
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in Lynx, no BASIC program is prepended to the archive) which is followed by
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the files themselves, all aligned to sector boundary. Arkive archives are in
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no way compressed, the files are simply linked after each other in it. Another
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difference between Arkive and Lynx archives is that Arkive puts trailing
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garbage even after the last file, creating an archive with the size of a
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multiple of 254.
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A directory entry has the following structure:
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POSITION DESCRIPTION
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$00 File attribute (file type, "closed" and "write-protected"
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flag)
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$01 Number of used bytes plus 1 in the last sector (the same value
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as the second byte of the last sector of the original file)
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$02-$11 Original name of the file, with trailing Shift-spaces
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$12-$1A Extended info (of relative files and GEOS files) found in the
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directory entry of the original file
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$1B-$1C Original length of the file in blocks
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The first file starts at the beginning of the block that follows the last
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block of the directory. All files are similarly aligned so that they start at
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the beginning of a block. This method has the advantage that the extractor
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program running on a real Commodore machine doesn't have to move data, only
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cut the archive into the original files. Block alignment means that in DOS
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files the particular data starts at an offset of a multiple of 254: when it is
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copied onto a disk or into a disk image, such an offset will be at the start
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of a block.
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