DiscIO: Store partition key directly in ReuseID #9854
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This is useful for the way Dolphin scrubs Wii discs. The encrypted data is what gets zeroed out, but this zeroed out data then gets decrypted before being stored, and the resulting data does not compress well. However, each block of decrypted scrubbed data is identical given the same encryption key, and there's nothing stopping us from making multiple group entries point to the same offset in the file, so we only have to store one copy of this data per partition. For reference, wit zeroes out the decrypted data, but Dolphin's WIA writer can't do this because it currently doesn't know which parts of the disc are scrubbed. This is also useful for things such as storing Datel discs full of 0x55 blocks (repesenting unreadable blocks) without compression enabled.
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Actually, it seems like this doesn't fix the ICE... |
Same here, was about to comment. Same ICE happens with this code. |
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Well, I'll leave this PR open in case someone thinks this PR is worth merging for its secondary benefit. But hmm, should we add shuffle2's workaround in a separate PR or should we just wait for the next version of MSVC... |
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I personally think it would be worth attempting some kind of fix, so anyone else trying to build for Windows ARM64 doesn't have any unpleasant surprises like I did, until the next version of MSVC (Which I have no idea when that would even be). |
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Submitted as PR #9855. |
This lets us reuse blocks in the case where different partition entries use the same key (which probably isn't very common).
The main reason I'm making this change is to avoid the ICE mentioned in e5b9e1b#r51445090, but there is also the advantage thatthis lets us reuse blocks in the case where different partition entries use the same key (which probably isn't actually all that common).