Add sse2 version of select #1804
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@@ Coverage Diff @@
## master #1804 +/- ##
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- Coverage 87.10% 87.09% -0.01%
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Files 936 936
Lines 47832 47855 +23
Branches 6009 6011 +2
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+ Hits 41662 41681 +19
- Misses 5178 5180 +2
- Partials 992 994 +2
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| Vector128<byte> cb0 = Sse2.SubtractSaturate(c0, b0); | ||
| Vector128<byte> ac = Sse2.Or(ac0, ca0); | ||
| Vector128<byte> bc = Sse2.Or(bc0, cb0); | ||
| Vector128<byte> pa = Sse2.UnpackLow(ac, Zero); // |a - c| |
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While vector creation on pre .net6 is compiled to a really bad sequence of scalar sets, explicit Vector128<T>.Zero compiles to a xor command which would be a little clearer imo. Plus it might be a very tiny bit faster than static variable read.
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FYI: default for the vector creates the same code as Vector128<T>.Zero
(I prefer Vector128.Zero).
| Sse2.Store((ushort*)p, diff); | ||
| } | ||
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| int paMinusPb = output[0] + output[1] + output[2] + output[3]; |
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You can put this into the fixed-block and access it via the pointer to avoid bound checks*.
If output would be too small, then there's a bug somewhere else 😉 (fortunately there's none).
* or reverse the order to read output[3] first, then [2], ... thant there's only one bound-check.
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or reverse the order to read output[3] first, then [2], ... thant there's only one bound-check.
ah yeah, always forget about that trick, thx. Will do with a follow up PR.
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I'll put it (incl. the return) within the fixed block here.
Prerequisites
Description
This adds a SSE2 version of the method Select(), which is used during lossless encoding. Its a bit faster, but its very specific to the image which is encoded, since this only gets used in
Predictor11TODO:
Before:
After with sse2:
