This fixes issue 6563:
https://code.google.com/p/dolphin-emu/issues/detail?id=6563
This PR adds a 2nd map to texture cache, which uses the hash as key. Cache entries from this new map are used only if the address matches or if the texture was fully hashed. This restriction avoids false positive cache hits. This results in a possible situation where safe texture cache accuracy could be faster than the fast one.
Small textures means up to 1KB for fast texture cache accuracy, 4KB for medium, and all textures for safe accuracy.
Since this adds a small overhead to all texture cache handling, some regression testing would be nice. Games, which use a lot of textures the same time, should be affected the most.
This drops the "feature" to load level 0 from the custom texture
and all other levels from the native one if the size matches.
But in my opinion, when a custom texture only provide one level,
no more should be used at all.
A number of games make an EFB copy in I4/I8 format, then use it as a
texture in C4/C8 format. Detect when this happens, and decode the copy on
the GPU using the specified palette.
This has a few advantages: it allows using EFB2Tex for a few more games,
it, it preserves the resolution of scaled EFB copies, and it's probably a
bit faster.
D3D only at the moment, but porting to OpenGL should be straightforward..
This is the same trick which is used for Metroid's fonts/texts, but for all textures. If 2 different textures at the same address are loaded during the same frame, create a 2nd entry instead of overwriting the existing one. If the entry was overwritten in this case, there wouldn't be any caching, which results in a big performance drop.
The restriction to textures, which are loaded during the same frame, prevents creating lots of textures when textures are used in the regular way. This restriction is new. Overwriting textures, instead of creating new ones is faster, if the old ones are unlikely to be used again.
Since this would break efb copies, don't do it for efb copies.
Castlevania 3 goes from 80 fps to 115 fps for me.
There might be games that need a higher texture cache accuracy with this, but those games should also see a performance boost from this PR.
Some games, which use paletted textures, which are not efb copies, might be faster now. And also not require a higher texture cache accuracy anymore. (similar sitation as PR https://github.com/dolphin-emu/dolphin/pull/1916)
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