Vdc decompress reimagined

hydrophilic
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Vdc decompress reimagined Feb 27, 2015 8:08:15 GMT

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Post by hydrophilic on Feb 27, 2015 8:08:15 GMT

I haven't had the time to try compiling your code, but if I understand correctly, the "far copy" uses (HHH)(NNN)10 LLLLLLLL... so "far copy" has a "length" of 3 bits (length of 8 or 8+1 = 9 bytes) ? And your "far copy" has a "range" of 3+8 = 11 bits... I assume this is an unsigned "negative" offset upto -2048 ? Otherwise it seems (correct me if I am wrong) it might be a signed range of -1024 to +1023 ?

I assume purely negative offset (11 bit), because any positive offset (10bit+sign) would only be useful if "old RAM" was to be re-used (like in a video).

Err... I have a day off from work, so maybe I'll have the time to try this and report back!

Last Edit: Feb 27, 2015 8:09:57 GMT by hydrophilic: Typos!

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VDC 8x2
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VDC 8x2

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Vdc decompress reimagined Feb 27, 2015 9:47:35 GMT

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Post by VDC 8x2 on Feb 27, 2015 9:47:35 GMT

The copy is always from behind the current point. You can't copy what has not been sent to the vdc yet. so its like this:
(sliding window)(future window). The data stream is fed into future window one byte at a time. Then as it is processed it goes into the sliding window then out of scope.

so, a negative number is never needed.

If the copy is 2 to 8 bytes (encoded as 1-7) If the copy is 64 bytes, its (encoded as 0)

Edit: you don't have to compile. The files have been attached to that post. one d64 and one zip

Last Edit: Feb 27, 2015 21:08:54 GMT by VDC 8x2

hydrophilic Global Moderator Posts: 794	Vdc decompress reimagined Mar 2, 2015 7:42:40 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by hydrophilic on Mar 2, 2015 7:42:40 GMT Yeah, I thought your code was purely negative because you don't use video... Sadly I haven't received any time off to actually test your code... (and of course I would love to finish my code... sigh)
	I'm kupo for Kupo Nuts! ∇ • hydrophilic ≠ 0

Commodore 128

Vdc decompress reimagined

Post by hydrophilic on Feb 27, 2015 8:08:15 GMT

Post by VDC 8x2 on Feb 27, 2015 9:47:35 GMT

Post by hydrophilic on Mar 2, 2015 7:42:40 GMT

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