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oziphantom
Registered: Oct 2014
Posts: 488 |
modify Exomiser compressor to black list some memory locations
Does anybody know a way to modify the exomizer compression algorithm to black list FF0X memory locations to never be read from, i.e don't allow them to be used as part of a sequence?
I guess a post process would also work, if there is a simple way to convert use a sequence to literal bytes.. |
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oziphantom
Registered: Oct 2014
Posts: 488 |
ok I see what you are saying, do the forward decompress not the backwards decompress, this then means I only have to do the slow method for 255 bytes tops |
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Krill
Registered: Apr 2002
Posts: 2940 |
No, what i said should apply to either depack direction.
I'm not quite sure which direction would give more optimisation opportunities for the $ff0X range check at the moment, but both would probably have to do with the difference of write pointer vs back-reference read pointer crossing the 64K bank boundary or not.
But if you intend to depack while loading, forward decompression is the way to go. |
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oziphantom
Registered: Oct 2014
Posts: 488 |
wait that won't work, to get PHA one must go backwards.
Since its FF0X going backwards(assuming you start above it, and if you don't just use a version that skips the check altogether) gives you 248 bytes max that won't need the check garanteed.
If you go forward then you only have 248 bytes where one must check for FF0X however you can't use PHA to write.. |
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oziphantom
Registered: Oct 2014
Posts: 488 |
But if you intend to depack while loading, forward decompression is the way to go.
Why is forward better from loading? (apart from it saves you flipping the file ) |
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Krill
Registered: Apr 2002
Posts: 2940 |
Okay, then backward decompression is a given, so any potential performance differences to forward decompression are moot.
Forward decompression is usually suited better for decompression while loading mainly because loading itself is usually performed in the forward direction. You can then decompress in-place* in the same direction. That should work for backward compression as well, given that loading is done in the same direction as well.
* Read buffer (loaded compressed file) is a subset of the write buffer (decompressed file), both end at the same address using forward direction. For Exomizer, there are a few (3-ish) compressed bytes beyond the uncompressed data. |
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oziphantom
Registered: Oct 2014
Posts: 488 |
Its in, and it works :D |
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