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Revert to slightly tweaked version of "old" safe texture hash. Hopefully fixes issue 636. Does somewhat break pokemon colosseum w/ safe texture hash, but that games works fine with the unsafe texture hash.

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git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@2532 8ced0084-cf51-0410-be5f-012b33b47a6e
This commit is contained in:
hrydgard 2009-03-02 23:01:18 +00:00
parent 18cf664b9d
commit 9ef42aefac
1 changed files with 10 additions and 22 deletions
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32
Source/Core/VideoCommon/Src/TextureDecoder.cpp
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@ -77,29 +77,17 @@ u32 TexDecoder_GetTlutHash(const u8* src, int len)
u32 TexDecoder_GetSafeTextureHash(const u8 *src, int width, int height, int texformat, u32 seed)
{
// Notes (mb2): A relative important mess in data is needed for a good hash. The safest way to satisfy this would be
// to perform the hash on the whole texture. But since it kills perf we use some assuptions for speed:
// -First assumption: texture borders don't carry more different data than the rest of the texture. We skip few
// texels on the edges.
// -Second assumption: consecutives lines may not differ that much. We skip some lines regularly.
// -Third assumption: User info (messy datas), in textures, should be either always centered or at the beginning.
// So we can stop hashing near the center.
// very tweakable (Pokemon Colesseum texts are pretty good test cases, especially short ones)
const int edgeSkip = 3;
const int colSkip = 3;
const int rowSkip = 5;
const int rowEnd = (width - edgeSkip)/4;
const int byteWidth = TexDecoder_GetTextureSizeInBytes(width, 1, texformat);
const int colEnd = height - edgeSkip;
int sz = TexDecoder_GetTextureSizeInBytes(width, height, texformat);
u32 hash = seed ? seed : 0x1337c0de;
for (int y = edgeSkip; y < colEnd; y += colSkip)
{
for (int x = edgeSkip; x < rowEnd; x += rowSkip)
{
hash = _rotl(hash, 17) ^ ((u32 *)src)[x+byteWidth*y];
if (sz < 2048) {
for (int i = 0; i < sz / 4; i += 13) {
hash = _rotl(hash, 19) ^ ((u32 *)src)[i];
}
return hash;
} else {
int step = sz / 23 / 4;
for (int i = 0; i < sz / 4; i += step) {
hash = _rotl(hash, 19) ^ ((u32 *)src)[i];
}
}
return hash;