Merge pull request #30 from wx257osn2/remove-ub

wx257osn2 · web-flow · commit b6ab86322022 · 2026-04-20T00:42:10.000+09:00
Remove UB
diff --git a/include/qoixx.hpp b/include/qoixx.hpp
@@ -758,7 +758,7 @@ class qoi{
     0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8, 31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
   };
   static constexpr unsigned lsb32(std::uint32_t x)noexcept{
-    return de_bruijn_bit_position_sequence[(static_cast<std::uint32_t>(x&-static_cast<std::int32_t>(x))*0x077cb531u) >> 27];
+    return de_bruijn_bit_position_sequence[(static_cast<std::uint32_t>(x&(~x+1u))*0x077cb531u) >> 27u];
   }
   template<std::uint8_t M>
   static inline __m256i slli_epi8(__m256i v)noexcept{

Original file line number	Diff line number	Diff line change
`@@ -758,7 +758,7 @@ class qoi{`
`758`	`758`	`0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8, 31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9`
`759`	`759`	`};`
`760`	`760`	`static constexpr unsigned lsb32(std::uint32_t x)noexcept{`
`761`		`- return de_bruijn_bit_position_sequence[(static_cast<std::uint32_t>(x&-static_cast<std::int32_t>(x))*0x077cb531u) >> 27];`
	`761`	`+ return de_bruijn_bit_position_sequence[(static_cast<std::uint32_t>(x&(~x+1u))*0x077cb531u) >> 27u];`
`762`	`762`	`}`
`763`	`763`	`template<std::uint8_t M>`
`764`	`764`	`static inline __m256i slli_epi8(__m256i v)noexcept{`