Merge branch 'branchless-tweaks'

2026-08-30 02:08:24 +03:00
parent 1386caba9f 7e82f3d01a
commit b769e55753
3 changed files with 15 additions and 4 deletions
@@ -52,8 +52,8 @@ public:
        uint8_t padSizeIncrement = 1;
        uint8_t padSize = 0;

-        uint8_t encountered0x80 = 0x00;
-        uint8_t onlyZerosPast0x80 = 0xFF;
+        uint8_t encountered0x80 = Branchless::FalseMask;
+        uint8_t onlyZerosPast0x80 = Branchless::TrueMask;

        InputIt it = end;
        while (it != begin && padSize < std::numeric_limits<uint8_t>::max())
@@ -73,7 +73,7 @@ public:

        return
        {
-            .IsOkay_ = static_cast<bool>(isOkay),
+            .IsOkay_ = Branchless::ToBool(isOkay),
            .PadSize_ = Branchless::Sel<uint8_t>(isOkay, padSize, 0)
        };
    }
@@ -66,7 +66,7 @@ public:

        return
        {
-            .IsOkay_ = static_cast<bool>(isOkay),
+            .IsOkay_ = Branchless::ToBool(isOkay),
            .PadSize_ = Branchless::Sel<uint8_t>(isOkay, padSize, 0)
        };
    }
@@ -10,6 +10,9 @@ namespace Chaos::Service

 struct Branchless
 {
+    static constexpr uint8_t FalseMask = 0x00;
+    static constexpr uint8_t TrueMask = 0xFF;
+
    template<typename OutUInt, typename InUInt>
    static constexpr OutUInt MsbMask(InUInt in) noexcept
    {
@@ -79,6 +82,14 @@ struct Branchless

        return (mask & onTrue) | (~mask & onFalse);
    }
+
+    template<typename UInt>
+    static constexpr bool ToBool(UInt mask) noexcept
+    {
+        static_assert(std::is_unsigned_v<UInt>);
+
+        return Sel<UInt>(mask, 1, 0);
+    }
 };

 } // namespace Chaos::Service