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ocornut / imgui

Dear ImGui: Bloat-free Graphical User interface for C++ with minimal dependencies
MIT License
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Use native crc32 on x86 if available. #8169

Open Teselka opened 5 days ago

Teselka commented 5 days ago

This adds support for the native _mm_crc32_u8 on x86 provided by the SSE4.2 instruction set (please note that this one actually is crc32c, which uses a different polynomial that is used internally by the Dear ImGui currently).

Because it's a native instruction, it doesn't require a 1 kb lookup table.

Teselka commented 5 days ago

Oh, i forgot to see if anyone did this before https://github.com/ocornut/imgui/pull/4933

ocornut commented 5 days ago

Hello, thanks for the PR! This looks simpler than #4933.

which uses a different polynomial that is used internally by the Dear ImGui currently).

I would want to tackle this first. What would it take to change the regular C++ implementation to have output matching the use of _mm_crc32_u8() ? (and potentially of wider versions _mm_crc32_u32 if we decide it is worth using them).

Teselka commented 3 days ago

Hello, thanks for the PR! This looks simpler than #4933.

which uses a different polynomial that is used internally by the Dear ImGui currently).

I would want to tackle this first. What would it take to change the regular C++ implementation to have output matching the use of _mm_crc32_u8() ? (and potentially of wider versions _mm_crc32_u32 if we decide it is worth using them).

That would require to change only current crc lookup table

Teselka commented 3 days ago

Changed it, now it produces same results with or without native instruction.